Start here: choose the system before you choose the setting
A portable vertical is not just the stainless whip you can see. It is the radiator, loading or tuning device, return-current path, mount, feed line, nearby ground, and operating band working together. Change one of those pieces and you have changed the antenna system—even when the parts still look familiar.
This handbook is built for two kinds of readers. If you are choosing equipment, start with the quick routes below. If you already own a system, open the exact product chapter and follow its current Chameleon User Guide for assembly. The handbook explains why the system behaves as it does, how to make a repeatable field decision, and what an SWR reading or NEC pattern can and cannot prove.
What do you need to do?
Choose the question closest to the job in front of you. Each route opens one stable section of this same handbook, so CKB search and the Chameleon Help Desk can take an operator directly to the relevant answer.
What a portable vertical antenna system actually includes
A vertical radiator carries current in a predominantly vertical direction. That simple description does not tell you how the current returns, how long the radiator is electrically, where loading is placed, what impedance appears at the feed point, or whether the feed line has become part of the antenna. Those details determine how the installed system tunes and radiates.
A practical Chameleon field vertical normally includes six jobs:
- Radiation: a telescopic whip or other conductor carries RF current.
- Electrical length: the physical radiator and any loading component establish current distribution and the resonant region.
- Return current: radials, counterpoise wires, or another documented structure complete the RF circuit.
- Matching: resonant adjustment or a tuner presents an acceptable load at a defined reference plane.
- Mechanical support: the mount keeps geometry stable without turning a connector or coil into a structural handle.
- Feed and control: coax carries RF; in a CHA URT1 installation, one coax segment also carries DC and control.
That complete-system view prevents the most common field mistake: adjusting the visible whip while ignoring a loose radial plug, a different mount height, wet soil, a vehicle beside the antenna, or a feed line routed along the radiator. The antenna did not mysteriously change. The installation changed.
Resonant adjustment and remote tuning solve different problems
A resonant portable vertical is adjusted so the complete radiator and return system presents a useful impedance near the operating frequency. With CHA BV, the selected radiator length and guide-defined loading-coil path establish the band. With CHA PRV 2.0, the MCC 2.0 and radiator arrangement provide the field adjustment. These systems reward repeatable geometry.
The CHA URT1 takes a different approach. Its Tuner Unit is placed at or near the antenna feed point and transforms the impedance presented by the installed antenna. This can make one radiator useful over a much wider set of frequencies and can reduce loss that would otherwise occur when a highly mismatched feed line runs all the way back to a tuner in the shack.
Neither approach is automatically superior. Resonant operation avoids depending on a powered matching network and gives the operator a physically understandable band setting. Remote tuning provides frequency agility and can keep the high-SWR portion of the system short. The right choice depends on how often you change bands, whether you can adjust the antenna, what power and duty cycle you use, and how much equipment you want to carry.
A tuner does not create a return-current path, repair a poor connector, remove loading-coil loss, guarantee a desired radiation pattern, or make an unsafe installation acceptable. A resonant reading does not prove that all accepted power is radiated.
Physical height and electrical length are not the same thing
A full-size quarter-wave vertical is physically long on the lower HF bands. Portable antennas use shorter radiators because they must fit in a vehicle, pack, yard, campsite, or temporary operating area. Loading adds inductive reactance so a shorter conductor can be brought to resonance, but it does not turn that conductor into a lossless full-size radiator.
As a vertical becomes electrically shorter, its radiation resistance generally decreases and the importance of conductor, connection, coil, and ground losses increases. The system can still be highly useful—especially when portability is part of the mission—but a low SWR does not prove that the short antenna performs like a full-size one.
Electrical height is best understood as a fraction of wavelength. A 17 ft whip is close to a quarter wavelength around 20 meters, but it is a much smaller fraction on 40 or 80 meters. That is why the same radiator may operate directly on a higher band, require loading on a lower band, or depend on a wide-range tuner in a multiband installation.
A metal roof, fence, vehicle body, wet tree, mast, railing, or bundled feed line can change electrical length through coupling. When the environment changes, the old mechanical setting is a starting point—not a promise.
What the operator notices first
On a lower band, a short loaded vertical will usually have a sharper tuning point than the same radiator on a higher band. A small change in whip length or coil setting can therefore move the useful part of the response farther than expected. This is normal behavior for an electrically short, loaded system; it is not a reason to chase the adjustment with several simultaneous changes.
The useful field response is to slow down. Sweep a range wide enough to find the actual minimum, move only the guide-defined adjustment, and sweep again. If the response is unusually broad and flat, inspect for loss or a poor connection before celebrating the bandwidth.
Loading is a trade, not free electrical length
A loading coil cancels part of the short radiator's capacitive reactance at the operating frequency. It does not replace the missing current-carrying conductor. Coil resistance, connection resistance, and return-path loss consume a larger share of the available power as radiation resistance falls. That is why clean joints, a deliberate counterpoise, and the correct coil matter most on the bands where the antenna is shortest in wavelengths.
The radiator is only half of the current path
RF current must return to the source. In a monopole-style vertical, the visible whip is one side of the system and the radial or counterpoise arrangement provides the other. If the intended path is inadequate, current will search for another route through coax shield, control wiring, a tripod, a vehicle, or nearby conductors.
This is why moving the coax can change SWR, why touching a connector may change the reading, and why RF can appear in audio or computer equipment. Those symptoms do not automatically prove a defective tuner. They often indicate that the installed current path is different from the intended one.
For CHA BV and CHA PRV 2.0, begin with the exact guide-specified counterpoise system. For a single-wire CHA URT1 antenna, connect the guide-defined counterpoise or ground arrangement to the Tuner Unit ground terminal. For a coax-fed balanced antenna, the return system is part of that antenna architecture and the URT1 connection is made through the coaxial ANTENNA port.
Three different jobs are often called “ground”
Electrical safety grounding, lightning protection and bonding, and the antenna's RF return path are related parts of a station, but they are not interchangeable. A ground rod installed for safety or lightning control does not automatically provide a low-loss RF return path for a short portable vertical. Conversely, four portable counterpoise wires are not a lightning-protection system.
When a customer says “the antenna is grounded,” the useful next question is: grounded for which job? The answer determines whether to inspect the electrical service bond, the lightning path, or the radial and counterpoise arrangement.
How the coax gets recruited
If the intended return path is weak or asymmetric, the outside of the coax shield can carry common-mode current. That can alter the apparent tuning, distort the installed pattern, couple RF into station wiring, and make the result sensitive to where the cable lies. A choke can help control an unwanted path, but it should not be used to hide a missing or poorly connected guide-defined counterpoise.
Counterpoise and radial layout: make the invisible half repeatable
The current CHA BV and CHA PRV 2.0 field configurations use four 12.5 ft counterpoise wires in their principal vertical paths. Spread them around the base as evenly as the site safely allows, keep connections clean and secure, and prevent people or vehicles from crossing them. If the footprint forces a different layout, record it and expect the resonant point to move.
Ground-laid wires interact with soil. Moisture, conductivity, surface material, and the amount of wire near the feed point affect loss and input impedance. A desert site, damp park, concrete patio, and metal-roof installation are not electrically interchangeable. That is why a portable setting can be repeatable without being universal.
Elevated radials are a different design choice. Their lengths, height, symmetry, and isolation matter, and they should not be substituted for a ground-laid portable configuration without a deliberate design and safety plan. Likewise, a permanent broadcast-style field is not the same object as the compact four-wire field system in a product guide.
More radial wire can reduce loss in some installations, but “more” is not a tuning instruction. Start with the controlled configuration. If you test a change, keep the radiator, loading, feed line, measurement point, and site constant.
Portable counterpoise versus permanent radial field
A field system is designed around speed, packability, public safety, and repeatable setup. A permanent ground-mounted vertical can justify more wire, careful burial or surface placement, weather-resistant connections, and a measured site study. The goals are different, so the same recommendation should not be copied between them.
ARRL vertical-antenna guidance shows that the useful radial system depends on antenna electrical length, soil, radial number, radial length, and whether the wires are elevated or ground-laid. Short loaded verticals are especially sensitive to loss around the base. That principle explains why the return system deserves attention; it does not override Chameleon's product-specific setup.
For a portable operator, the best first improvement is often consistency: the same number of wires, similar spacing, fully seated connectors, and a known feed-line route. For a fixed station, improvements should be evaluated with lightning protection, bonding, drainage, corrosion control, and local structural requirements.
Base loading versus center loading
A loading coil carries the current available where it is placed. Moving it upward changes how much radiator current flows below the coil and changes current distribution over the entire conductor. As a general engineering principle, placing necessary loading above the base can improve radiation efficiency, but it also creates a taller assembly and different mechanical stresses.
That tradeoff is visible in the CHA PRV 2.0 family. The primary SS58 configuration places the MCC 2.0 between lower and upper radiator sections. The guide also documents base-loaded and optional MPAS Ready arrangements. Each has its own component order, total height, adjustment range, and use. Do not copy a coil position or tuning mark from one geometry to another.
Base loading can be easier to reach and produce a shorter installation. Center loading can put more active conductor below the coil. The right answer is the configuration that fits the site and is supported by the current guide—not a universal slogan about coil position.
Mount, height, and surroundings are electrical variables
A ground spike, tripod, vehicle mount, balcony clamp, and roof installation place the antenna in different electrical environments. Even when radiator dimensions do not change, coupling to ground and nearby metal changes. A mount is therefore both a mechanical choice and part of the installed RF context.
Use a mount that safely carries the system's weight and wind load. Tighten threaded antenna parts hand-snug unless the guide calls for a tool. Do not drive a ground spike by striking an assembled loading coil or using the radiator as a handle. Keep coax strain off tuner and antenna connectors.
Retune or recheck resonance after changing height, mount type, radial layout, or surroundings. Controlled NEC mount-height studies explain pattern changes for exact modeled cases; they do not approve an arbitrary balcony, vehicle, rooftop, or mast installation.
Know where the measurement is made
An analyzer at the antenna feed point sees the impedance there. An analyzer at the station end of a coax line sees that impedance after the line has transformed it and after line loss has reduced the apparent mismatch. Those readings can both be real while being different.
For resonant field adjustment, keep the analyzer location and test cable consistent. If you compare settings with different cable lengths or with one measurement at the feed point and another in the shack, you have changed the reference plane.
With the CHA URT1, the high-mismatch path is normally on the antenna side of the outdoor Tuner Unit. Once the tuner matches that load, the long coax back to the Coupler and radio is on the matched side. This is the central practical reason for feed-point tuning.
Why a station-end tuner cannot repair the line ahead of it
A tuner at the radio transforms the impedance presented to the transmitter. It does not change the standing-wave ratio already present on the feed line between that tuner and the antenna. If that line is long, small, or lossy, a severe mismatch can turn useful RF into heat before it reaches the radiator. The transmitter may see an excellent match while the antenna system remains inefficient.
A remote tuner changes where the boundary falls. With a short antenna-side connection and the Tuner Unit at the feed point, most of the long coax operates close to its intended impedance after a successful match. This does not make the tuner lossless or the radiator efficient; it removes one avoidable high-SWR coax run from the problem.
A fair A/B comparison
To compare two settings, use the same analyzer, calibration, cable, reference plane, radial layout, and surroundings. Record frequency as well as SWR. Moving the analyzer from the feed point to the radio end is not merely moving the instrument—it changes what network is included in the measurement.
A repeatable resonant-vertical tuning workflow
- Confirm identity. Use the exact product, radiator, loading component, band, and current guide.
- Build the complete geometry. Install the documented mount, component order, whip length, and radial system.
- Inspect before power. Check threaded joints, banana plugs, coax connectors, insulation, coil condition, and stability.
- Choose one reference plane. Use the same test cable or station-end arrangement for every comparison.
- Sweep broadly. Find the response below, through, and above the intended band.
- Change one control. Adjust whip length, the guide-defined tuning tube, or the allowed radial length—not several things.
- Read the direction. If resonance is too low, the system is electrically too long; if too high, it is electrically too short.
- Verify the operating segment. A minimum at one point does not guarantee acceptable SWR across a wide band.
- Begin transmitting at low power. Stop for unstable readings, arcing, heating, or RF feedback.
- Record the final setting. Save band, component order, dimensions, radial layout, site, and reference plane.
When the next site behaves differently, restore the recorded baseline before improvising. Most field troubleshooting becomes faster when you distinguish a product problem from a changed installation.
A low SWR is useful. It is not a performance certificate.
SWR describes the relationship between forward and reflected waves at the measurement plane. It helps protect equipment and confirms that a matching objective has been reached. It does not tell you how much power became radiation, how much was lost in soil or a loading coil, what the elevation pattern looks like, or whether common-mode current is flowing on the feed line.
A lossy system can look broad and easy to match because loss absorbs energy. A narrow, low-loss resonant system may require more precise adjustment. Neither bandwidth alone nor the lowest displayed SWR identifies the better antenna.
Use SWR as one instrument reading. Combine it with a known configuration, stable connections, temperature checks, pattern evidence, controlled receive comparisons, and on-air observations. One distant contact proves a path existed at that moment; it does not measure efficiency or guarantee future range.
Two antennas can show the same SWR and behave very differently
One may be a low-loss resonant radiator with a deliberate return system. The other may reach the same number through a tuner while losing power in a coil, transformer, feed line, wet connector, or soil. The meter at the radio cannot separate those losses. It reports the impedance condition at its own reference plane.
The practical question is not “How close can I get to 1:1?” It is “Is the complete system correctly assembled, within its limits, stable under power, and suitable for this path?” A clean 1.4:1 in a controlled configuration may be a better operating result than a suspiciously broad 1.0:1 obtained by adding loss.
How to read Chameleon's 2D and 3D NEC patterns
Each published pattern belongs to one exact modeled configuration: radiator geometry, loading position, band, height, ground assumptions, and model revision. Select the model that matches the system you are actually studying. A curve from a neighboring product is not a substitute.
Elevation view
The elevation plot is a vertical slice. Energy near the horizon is associated with lower-angle paths; energy at higher angles can support shorter ionospheric paths when propagation allows. A modeled lobe angle is not a mileage promise because ionospheric conditions, terrain, clutter, polarization, and losses are outside the normalized shape.
Azimuth view
The azimuth plot is a horizontal slice at the stated elevation angle. A symmetrical vertical over symmetrical surroundings is often broadly omnidirectional, but loading, asymmetric radials, feed-line current, and nearby objects can distort the real installation.
Three-dimensional view
The 3D model exposes lobes and nulls that are difficult to understand from one slice. Rotate it to understand shape, not to search for an absolute “strongest color.” Confirm normalization and coordinate labels before comparing models.
What the library does not prove
The normalized library does not by itself establish installed SWR, impedance, efficiency, realized gain, tuner loss, loading-coil heating, common-mode current, reliable range, or field correlation. Rejected or guide-contradicting cases are withheld rather than relabeled as another product.
MPAS Ready: a modular system with controlled electrical paths
MPAS Ready is Chameleon's name for the modular, building-block compatibility shared by many radiators, loading components, mounts, transformers, and accessories. The benefit is practical: an operator can reuse proven parts, replace a field component, or build a different documented antenna without starting over with unrelated hardware.
The important word is documented. A 3/8-24 connection can confirm that two pieces screw together, but it cannot establish current distribution, feed-point impedance, power handling, wind load, matching range, or a safe mechanical stack. The MPAS Ready Product Guide is the map of available components and known system relationships. The exact User Guide for the chosen antenna remains the assembly and operating authority.
Use the system in this order
- Name the complete configuration. “CHA MPAS 2.0 Portable Vertical” is useful; “a whip and a coil” is not specific enough.
- Open its current guide. Confirm the radiator, transformer or tuner, return path, mount, band, and component order.
- Confirm the limiting part. Power, duty cycle, connector, feed line, tuner, transformer, and mechanical limits all remain in force.
- Open the matching NEC case. Use the model only when its geometry and evidence state match the installed system.
This discipline preserves the real advantage of modularity. You can change missions quickly without turning the parts bin into an uncontrolled experiment.
CHA MPAS 2.0 or CHA MPAS Lite?
Choose CHA MPAS 2.0 when breadth is the priority. Its current manual documents six configurations: Manpack Vertical, Portable Vertical, Horizontal NVIS, Sloping Wire, End-Fed Inverted-L, and End-Fed Inverted-V. That makes it the more complete field toolbox for an operator who expects the site, support, propagation objective, or available footprint to change.
Choose CHA MPAS Lite when carried weight and setup simplicity have higher priority. Its current guide documents four paths: Telescoping Vertical, End-Fed Inverted-V, Sloping Wire, and Horizontal NVIS. It keeps genuine configuration choice while removing part of the larger kit's inventory.
Do not decide from the product name alone. Decide whether you need a fast self-supported vertical, a low or high wire path, a broadside NVIS arrangement, or several of them from one bag. Then compare the exact included parts, support requirements, return-path footprint, and adjustment workflow.
CHA MPAS 2.0: one field kit, six documented antenna choices
The strength of CHA MPAS 2.0 is not that one antenna shape does everything. It is that one controlled component set can be reorganized into several genuinely different antennas. The operator chooses the configuration that fits the path, site, available support, and setup time instead of forcing a vertical into every job.
Manpack Vertical
This is the compact vertical path for restricted space and rapid movement. The manual controls the exact Hybrid, radiator, mount, and counterpoise arrangement. Its smaller physical size is useful, but lower-band operation asks more of loading, matching, and the return system. Keep the coax route and counterpoise repeatable before judging the result.
Portable Vertical
The taller vertical path uses the guide-defined telescopic and extension components to place more conductor in the current path. It remains a monopole system: the visible radiator and the documented counterpoise are both part of the antenna. A successful tuner match does not make the counterpoise optional.
Horizontal NVIS
The low horizontal wire arrangement is the deliberate choice when the operating objective favors stronger high-angle radiation for shorter regional ionospheric paths. Height, wire shape, soil, and frequency determine the result. “NVIS” describes the intended deployment and propagation use; it does not guarantee that the ionosphere will support a path at that moment.
Sloping Wire
A sloper is often easier to erect from one support and can move the feed point to an accessible location. Its pattern is not equivalent to the symmetrical horizontal arrangement: slope direction, feed-point height, wire end height, and surroundings create asymmetry. Preserve the exact diagram when using a corresponding NEC pattern.
End-Fed Inverted-L and Inverted-V
These wire paths use vertical and horizontal conductor sections differently. The inverted-L is useful when one support permits a vertical rise and a horizontal run. The inverted-V uses a high center region with both legs descending. Neither should be described merely as “the long wire”; each has its own geometry, support demands, coupling, and pattern.
The current MPAS 2.0 manual is the final authority for parts, knots, connections, safety, and configuration drawings. This chapter explains the decisions behind those drawings and keeps the CKB from collapsing six antennas into one generic product answer.
CHA MPAS Lite: deliberate versatility with a smaller field load
CHA MPAS Lite is for the operator who still wants a real choice of antenna forms but does not need the full MPAS 2.0 inventory. The system's value is strongest when the operating plan is made before arrival: choose the vertical for minimum support dependence, or choose one of the wire paths when height, space, and propagation objective justify it.
Telescoping Vertical
The issued guide treats the vertical as a complete system, including the SS17 radiator, matching component, mount, and a 25–35 ft counterpoise. On the higher bands, the guide's whip-length table provides starting points. Those numbers are not universal calibration marks; confirm them after changing soil, radial placement, mount, or nearby conductors.
End-Fed Inverted-V, Sloping Wire, and Horizontal NVIS
These three wire arrangements solve different site problems. The inverted-V can use one principal support; the sloper trades symmetry for an accessible one-support layout; the horizontal NVIS path emphasizes a broadside, high-angle arrangement at the guide-defined height. Keep the transformer, wire length, feed point, support height, and routing together as one configuration.
MPAS Lite should not be sold as a smaller MPAS 2.0 with every larger-system option implied. It is its own documented kit. That distinction makes both systems easier to understand and prevents unsupported component substitutions.
Radiators, loading coils, and extensions: identify the job of each part
CHA SS17, CHA SS25, and CHA SS58 are telescopic radiators of different lengths and construction. A longer physical radiator can place more conductor in the active current path, but length alone does not approve a band or component stack. Use the radiator named in the exact guide.
CHA MIL WHIP 2.0 is a sectional whip built for fast field deployment and compact transport. Its mechanical format changes how it is carried and assembled; its electrical behavior still depends on installed length, loading or matching device, return path, and surroundings.
CHA M-COIL and CHA M25-COIL are fixed loading components for specific documented radiator-and-band configurations. They are not universal lower-band adapters. The M-COIL inventory includes approved 30 m and 40 m modeled families; M25-COIL coverage belongs to its SS25/40 m configurations. The current product guide controls actual assembly and power.
CHA MCC 2.0 is continuously adjustable within its documented configurations. Its tuning tube changes effective inductance, but the setting has meaning only with the named radiator below and above it, the same return system, band, and installation.
CHA MIL EXT 2.0 and CHA CAP HAT alter the radiator geometry. An extension changes conductor length and loading position; a capacity hat changes end capacitance and current distribution. Both can materially move resonance and change the modeled pattern. Their presence in the MPAS Ready ecosystem does not authorize an arbitrary combination.
When troubleshooting, name every part in order from mount to tip. “MPAS vertical” is too vague to select a tuning value or NEC curve. “Puck Hub, MCC 2.0, lower SS58, upper SS58, four 12.5 ft counterpoise wires, 20 m” is a configuration that can be checked.
HYBRIDs, counterpoises, and mounts do different jobs
CHA HYBRID family components provide guide-defined feed and impedance-transition functions in particular wire and vertical systems. They do not automatically make the connected wire resonant, replace a tuner in every installation, or prove that two mechanically connected parts form an approved antenna. HYBRID, HYBRID-MINI, and HYBRID-MICRO are not interchangeable names; follow the exact guide.
The counterpoise or radial system provides an intended RF return path for an unbalanced vertical. The mount supports geometry. A ground spike can supply mechanical support and environmental coupling, but it is not a substitute for every guide-defined counterpoise. A tripod can stabilize the antenna without becoming an engineered radial field.
That separation is useful in the field. If the antenna moves in the wind, inspect the mount. If tuning changes when the coax is moved, inspect the return path and common-mode current. If several bands fall outside a tuner's range, confirm the radiator, transformer or tuner architecture, and wire length. One symptom should not cause random changes to all three jobs.
Vertical-family NEC coverage: choose evidence, not just a picture
The Steven Krumm guide-asset package contains paired 2D and static 3D exports for a broad set of MPAS 2.0, MPAS Lite, BV, PRV 2.0, URT1, V-DIPOLE, radiator, loading, and CAP HAT models. The package is a distribution index—not automatic proof that every row is customer-ready. The storefront registry's evidence state, current product guide, and exact model identity still control publication.
For example, MPAS 2.0 and MPAS Lite have extensive multi-configuration, multiband assets. CHA URT1 has a modeled HOA vertical family, but the tuner network is excluded from the normalized far-field model. URT1 MB has no independent pattern because it is a bracket. V-DIPOLE has specific 30 m and 40 m models; that does not authorize copying those curves to its higher-band physical configurations.
Before comparing plots, confirm five fields: product, complete configuration label, band, modeled height or environment, and evidence state. If any one differs from the installed antenna, treat the plot as background education rather than product-specific evidence.
CHA URT1: move the matching point to the antenna
The CHA URT1 is a wide-range automatic tuner built as two units. The indoor Coupler Unit sits near the radio and gives the operator power, tuning control, and status indications. The weather-resistant Tuner Unit contains the matching network and is normally installed outdoors at or near the antenna feed point. Coax between them carries RF as well as DC and control through the Coupler's bias-T system.
This architecture solves a real feed-line problem. When a non-resonant antenna is connected to a tuner in the shack, the coax between tuner and antenna may operate at high SWR. The tuner can make the radio happy, but it cannot recover energy already dissipated in that mismatched line. Placing the matching network at the antenna end means the long coax run is on the matched side.
The URT1 does not require a radio-brand-specific control cable. It covers 1.8–54 MHz, stores up to 16,000 tuning solutions, and is intended to work with a wide range of single-wire and coax-fed antennas when the complete installation falls within its matching and operating limits.
That flexibility is not permission to connect everything at once. The single-wire Beehive terminal and coaxial ANTENNA connector are alternative outputs. The powered Coupler-to-Tuner coax must remain uninterrupted. The radiator, return path, feed arrangement, power level, and duty cycle still control whether an installation is sensible.
Who benefits most from this architecture?
The strongest use case is an operator who changes bands or frequencies often and can place the Tuner Unit at the antenna. An HOA operator can leave a discreet radiator in place instead of mechanically retuning it for every band. A field or emergency station can standardize one antenna-side geometry, store proven solutions, and move frequencies without walking back to the radiator after every change.
A resonant antenna remains the simpler answer when one band, low complexity, and operation without tuner power matter more than agility. The URT1 earns its place when feed-point matching solves an actual operating problem—not merely because a tuner can produce a low number on the display.
The URT1 signal path, in plain language
Follow the system from the radio outward:
- The transceiver connects by a short 50-ohm coax jumper to the Coupler Unit's TRANSMITTER connector.
- The Coupler Unit's TUNER connector connects by coax to the outdoor Tuner Unit's COUPLER connector.
- The Tuner Unit connects to the antenna through either the top Beehive terminal for a single-wire path or the bottom ANTENNA connector for a coax-fed path.
- The required counterpoise, balanced transition, or antenna-side return system completes the chosen configuration.
- A 12–14 V DC supply powers the Coupler; confirm the current requirement in the newest guide and product listing.
The middle coax segment is special. It is not simply an RF patch cable. The Coupler injects DC and control onto it. Any device inserted there can block the control path, short the supply, or encounter a condition for which it was not designed.
Meters, amplifiers, filters, switches, diplexers, and station-side protective devices belong between the transceiver and Coupler only when their own instructions and the complete station design permit them. Do not place them between Coupler and Tuner.
Think of the Coupler-to-Tuner cable as a controlled bus
Although it looks like ordinary coax, this segment is carrying more than RF. Treat both connectors and the cable as part of the URT1 control system. An accessory that is transparent to RF may still interrupt DC, introduce a short, or expose internal circuitry to control voltage. “It passes RF” is therefore not a sufficient compatibility test.
Before troubleshooting the antenna, trace this path physically from one labeled connector to the other. Remove every unapproved intermediate device, inspect both ends, and confirm the power supply. That simple walk-down catches many installation faults faster than changing radiator length.
Choose one URT1 antenna output
Use the Beehive terminal for a single-wire path
The insulated Beehive terminal on top of the Tuner Unit is for a single conductor such as a guide-defined end-fed random wire or direct-fed vertical. The ground terminal receives the required counterpoise or ground connection. Leave the coaxial ANTENNA connector unused.
Use the ANTENNA connector for a coax-fed path
The SO-239 ANTENNA connector on the bottom is for an antenna system already presented through coax, such as a dipole with its proper feed-point BALUN, a loop path, or another guide-defined coax-fed system. Leave the Beehive terminal unused.
Never use both outputs together
The two connectors are not a combiner, diversity system, or two-antenna switch. Connecting both changes the load and creates uncontrolled current paths. Choose the one connection shown for the application.
Weather and strain
Seal outdoor coax connections with a proper weatherproofing system, create drip loops where appropriate, and provide strain relief. The connector should carry electrical current, not the pull of the antenna or feed line.
What can the CHA URT1 tune?
The URT1 User Guide and Applications Guide document several installation families. They are not identical, but they share one principle: put the Tuner Unit close to the load it must match and preserve the correct return-current and feed arrangement.
Single-wire and end-fed random-wire systems
Connect the radiator to the Beehive terminal and the required counterpoise or ground arrangement to the ground terminal. “Random” does not mean “any convenient length.” A length near a half wavelength on an intended band can present an extremely high impedance. Begin with the current guide's length guidance and expect site geometry to affect the load.
Ground-mounted verticals
A whip or other direct-fed vertical can use the Beehive path when installed as a documented single-wire radiator with a deliberate return system. The URT1 HOA Special and MPAS Ready examples use this architecture. The tuner supplies matching; the counterpoise or radial system supplies the other side of the RF circuit.
Coax-fed dipoles and inverted-V antennas
Connect the antenna coax to the bottom ANTENNA port and leave the Beehive unused. Keep the Tuner Unit near the antenna feed point or feed-point BALUN when practical. The dipole geometry and feed-point device still determine balance, loss, and pattern.
Balanced-feedline antennas
Ladder line and a center-fed balanced antenna require a suitable current BALUN between the URT1's unbalanced ANTENNA output and the balanced line. Connect a short coax jumper from ANTENNA to the BALUN. Do not connect ladder line between the Beehive and ground terminals, and never put the BALUN in the powered Coupler-to-Tuner coax.
CHA TDL, CHA SKYLOOP, MPAS, and EMCOMM paths
The applications guide shows the URT1 replacing the normal matching device in specific Chameleon systems. That substitution must follow the illustrated architecture; it is not a claim that every MPAS Ready mechanical combination is electrically approved.
Mobile installations
A short mobile whip can be tuned over a useful range when the Tuner Unit is close to the mount and the vehicle provides the intended return structure. Mobile installations demand careful bonding, weather protection, cable routing, and RF-exposure evaluation. A successful match does not prove low loss on the lower bands.
URT1 with ladder line: BALUN first, ratio second
The URT1 ANTENNA output is unbalanced. A center-fed doublet, dipole, or balanced loop fed with two-conductor line is intended to be balanced. A current BALUN provides the transition. This is a current-balance job first; the printed impedance on the line does not tell you the correct transformer ratio by itself.
“450-ohm line” describes the line's characteristic impedance under a particular termination. The load seen at the tuner changes with antenna length, operating frequency, balanced-line length, height, geometry, and surroundings. On different bands, the same line can transform the antenna impedance to a low, moderate, very high, or strongly reactive value.
A 1:1 current BALUN provides the transition without an intentional ratio change. A 4:1 current BALUN may be useful when the complete antenna and line present a suitably high impedance. Choose from the measured or modeled complete system—not by dividing the line label by 50.
Route balanced line away from metal and ground, preserve conductor spacing, avoid tight coils of unused line, cross unavoidable metal near a right angle, and provide strain relief. Stop for arcing, hot terminals, transformer heating, damaged insulation, or unstable supports.
Why line length can decide whether one band is friendly
Balanced line transforms impedance as a function of electrical length. A line length that presents a comfortable load on one band can present a very low, very high, or strongly reactive load on another. The tuner sees the transformed impedance at the end of the line—not the antenna's feed-point impedance and not simply the line's printed characteristic impedance.
If one intended band will not tune while others do, first restore the guide-defined arrangement and inspect the BALUN and line routing. When the application guide permits a line-length adjustment, change it deliberately by several feet and retest every required band. A change that helps one frequency can make another worse.
URT1 counterpoise and return-path decisions
A single-wire installation needs a deliberate return path at the Tuner Unit. The July 29, 2026 guide provides minimum counterpoise starting lengths by lowest operating band: 52 ft for 160 m, 27 ft for 80 m, 18 ft for 60 m, 13 ft for 40 m, 9 ft for 30 m, 7 ft for 20 m, 5 ft for 17 m, 4 ft for 15 or 12 m, 3 ft for 10 m, and 2 ft for 6 m.
These are product-guide starting points, not proof that one wire produces an ideal ground system at every site. A single 27 ft counterpoise is described as satisfactory for most 80 m installations, but soil, routing, coupling, and radiator geometry still influence the result.
If tuning changes when coax moves, do not immediately add random wire. Restore the documented connection, inspect the ground terminal, separate coax from the radiator, and check whether the intended counterpoise is carrying return current.
Choosing the starting length
Use the lowest band you genuinely intend to operate, not the lowest band printed on the radio. A longer counterpoise can occupy more space, cross public paths, and couple to nearby objects. A shorter one may make the lowest intended band harder to match or encourage more current onto the coax. The guide's table is a starting point for that trade, followed by a real-site check.
When several wires are easier than one
Multiple wires can sometimes fit a site more safely than one long conductor and can make the return path less dependent on a single direction. That is a separate installed geometry, however. Do not call it equivalent to the documented single-wire example without measurement. Keep every conductor clear of people and vehicles, and never connect or reposition it while transmitting.
How to tune the CHA URT1 without guessing
- Confirm the complete antenna, return path, Coupler, Tuner, and coax connections.
- Turn the Coupler on and confirm the green TUNER indicator.
- Set the radio to the exact operating frequency.
- Bypass the radio's internal tuner.
- Select a mode that produces a steady carrier, following the transceiver instructions.
- Set transmit power between 0.5 and 15 W. Ten watts is the normal field starting point.
- Key the transmitter and briefly press the TUNING button.
- Unkey when the cycle completes. A one-second green COMPLETE indication means success; a quick green flash means failure.
- Verify SWR before increasing power and remain within the complete system's lowest rating.
A normal new cycle can take about five seconds. When the frequency matches a stored solution, recall can be much faster. Tuning requires both RF and the button action; pressing the button without transmitting, or transmitting without initiating the cycle, is not the complete procedure.
Retune after power-up and whenever a frequency change produces unacceptable SWR. A saved memory belongs to the load that existed when it was created. If wire route, counterpoise, weather, or surroundings change, verify the result.
If the tune fails, do not repeat it at higher power
A failed search means the Tuner Unit did not find an acceptable combination for the load it saw. More power does not extend the matching range and can increase stress. Confirm the selected output, return path, radiator length, frequency, and unobstructed powered coax segment. Then make one antenna-side change and retry at low power.
Build memories from a known installation
For a planned deployment, tune the actual antenna geometry at the intended site or in a representative setup, then record the frequency and physical arrangement. Memories make a stable system faster. They cannot make a changing or poorly defined load repeatable.
CHA URT1 power and duty-cycle limits
6 m SSB/CW: 100 W maximum.
Digital/high duty: 30 W maximum.
The lowest applicable rating of the tuner, BALUN, feedline, connectors, and completed system controls.
These are ceilings, not targets. Match at 0.5–15 W before raising power. A reactive load can create high voltage or current inside the tuner, along balanced line, at a connector, or in a BALUN even when output is below the headline limit. Long transmissions and digital modes create more average heating than intermittent voice peaks.
Stop if the Tuner Unit, transformer, connector, or feed line becomes unexpectedly warm; if SWR changes during a transmission; or if arcing, odor, smoke, or unstable behavior appears. Let the system cool and correct the load or operating cycle before transmitting again.
Why mode matters
A voice signal reaches peaks but spends much of its time below peak power. A digital carrier or other high-duty signal can hold substantial power continuously. Components that remain cool during brief SSB peaks can heat during a long digital transmission at a much lower indicated peak. The 30 W digital/high-duty ceiling exists for that different thermal job.
The system limit is a chain
The URT1 rating does not raise the rating of a BALUN, jumper, feed line, connector, radiator, or loading component. Nor does a high-rated radiator protect a tuner from a difficult reactive load. Identify the lowest applicable limit before transmitting and reduce power further when the match is unstable, the load is near an operating boundary, ventilation is poor, or ambient temperature is high.
What the URT1's 16,000 memories do for an operator
The URT1 stores tuning solutions so returning to a previously used frequency can be faster than a full search. In a rehearsed field installation, band changes feel less like rebuilding the antenna and more like selecting a channel.
Memory recall is not a substitute for verification. The stored relay state assumes the antenna-side load is sufficiently similar. If whip length, wire route, counterpoise, BALUN, balanced-line length, weather, or surroundings changed, the old solution may no longer be best.
For an emergency or expedition kit, rehearse the installation and save known working frequencies using the geometry you intend to deploy. Label radiator and counterpoise, standardize the cable path, and keep a short setup note with the equipment.
A practical frequency plan
Store the frequencies the station is actually expected to use: primary voice channels, digital channels, nets, and alternates. Verify each at the intended power class and duty cycle. A memory bank filled with random test frequencies is less useful than a small, rehearsed communications plan.
When the station changes location, treat the first recall on each band as a check rather than an assumption. If the indicated match has shifted, run a fresh low-power tune and update the operating note.
Remote versus local URT1 installation
The preferred role is remote: place the Tuner Unit outside near the feed point, keep the Coupler indoors, and let the coax between them carry matched RF plus control power. This reduces the length of line exposed to high SWR.
The guide also permits a local-tuner arrangement when replacing an existing station tuner or using installed coax. The Tuner Unit is then near the Coupler indoors and only coax-fed antennas are used. Feed line beyond the tuner can still operate at high SWR, so line type and length matter more.
Choose the local arrangement because the installation requires it—not because it is electrically identical to remote tuning. Preserve the no-device Coupler-to-Tuner rule in either arrangement.
Installation details that prevent field failures
Mount the outdoor Tuner Unit so water drains away, connectors remain accessible, and antenna tension is carried by a proper support. Use the included mounting hardware or the guide-defined CHA URT1 MB path. The Coupler Unit is not weatherproof and belongs indoors or in a protected enclosure.
Use a known-good 50-ohm coax line between Coupler and Tuner. Confirm both ends go to the correct labeled connectors before applying power. Route cable away from sharp edges, hot surfaces, foot traffic, and points where a vehicle door or tripod leg can crush it.
Plan lightning protection and bonding for the actual installation. Because the Coupler-to-Tuner segment carries DC and control, do not insert an arbitrary arrestor there. Disconnect and ground the antenna system safely when not in use and whenever lightning is possible.
Troubleshooting the CHA URT1
The TUNER indicator does not light
Turn off power. Verify the DC source, polarity, connector, cable condition, switch position, and current capacity against the current guide. Confirm the Coupler-to-Tuner coax is connected to the correct ports and is not open or shorted. Do not repeatedly power a system that shows the red ERROR indication.
The tuner reports a failed match
Confirm a steady carrier within the 0.5–15 W tuning range and bypass the radio's internal tuner. Verify the intended antenna output is used, the other is empty, and the return path is connected. If the load is outside range, change the antenna or feed arrangement—not the power.
The match changes when the coax moves
Inspect connectors and cable first. Then evaluate common-mode current and return path. Restore separation between radiator and coax, confirm the counterpoise, and keep the cable route consistent.
One balanced-line band will not tune
Confirm a current BALUN is at the antenna side of the Tuner Unit, not in the powered control segment. Restore symmetrical routing and keep line away from metal and ground. If permitted, change balanced-line length by several feet and retest every intended band.
RF appears in audio, controls, or computers
Reduce power. Inspect antenna balance or return path, cable routing, bonding, and current BALUN where applicable. Confirm station accessories are on the radio side of the Coupler. A ground rod alone does not automatically cure common-mode current.
A connector, BALUN, or tuner heats
Stop transmitting and remove power. Heating can indicate loss, excessive current, excessive voltage, poor contact, a difficult reactive load, or too much average power. Do not continue merely because the SWR display is low.
CHA BV: a modular resonant vertical
CHA BV is for an operator who wants a field-adjusted, band-specific vertical using familiar MPAS Ready components. The April 23, 2025 User Guide controls component order, radiator settings, loading-coil selection, tuning, power, and safety.
The standard SS17 path uses the CHA M-COIL on 40 and 30 meters and direct radiator settings on higher documented bands. The optional SS25 path has different settings and uses the CHA M25-COIL for its guide-defined 40 m path. Do not transfer settings or curves between SS17 and SS25 systems.
The standard return system uses four 12.5 ft B-RADIAL wires through the Puck Hub. The guide includes an optional wire arrangement using a 60 ft CHA LZ SLOPER for selected lower bands, one band at a time. That wire configuration is not the same antenna as the vertical, and a two-M-COIL 60 m vertical is not an authorized substitute.
Choose BV when you value modularity, field serviceability, and a clear resonant setup. Expect to select the band mechanically and verify it at the site.
CHA BV pattern and configuration evidence
The governed NEC inventory separates SS17 and SS25 radiators, direct-fed bands, fixed-coil bands, wire configurations, and controlled mount-height studies. Every selector label preserves the exact radiator, band, loading position, and modeled height.
Use a BV pattern to understand normalized shape for that case. Do not infer a different product's impedance or performance. If a model is rejected, non-convergent, or inconsistent with the current guide, it is withheld rather than replaced.
CHA PRV 2.0: an adjustable resonant field system
CHA PRV 2.0 combines the MCC 2.0 adjustable loading coil, two SS58 radiator sections, a Puck Hub, four 12.5 ft counterpoise wires, an RF choke, mounting choices, and band-setting aids in a complete portable system. Its May 4, 2026 User Guide controls the build.
The principal center-loaded SS58 vertical covers the guide-defined 40–10 m paths. A guide-defined off-center-fed arrangement provides the 6 m configuration. Optional MPAS Ready arrangements use different radiators and component positions. Treat them as separate systems, not spare-parts improvisations.
The MCC tuning tube changes the coil's effective inductance. Move it in small steps, lock it after adjustment, and verify with an analyzer. Band keys are repeatable starting aids, not universal calibration standards.
Choose PRV 2.0 when you want one packaged resonant system with several guide-defined configurations and you are willing to adjust it at the site.
PRV 2.0 optional configurations: read the whole diagram
The guide documents a continuum from compact base-loaded arrangements to taller center-loaded systems using optional MPAS Ready components. Component order, total height, counterpoise, and band determine the configuration.
Do not select an arrangement from its silhouette alone. Confirm the exact radiator model, extension, insulator, mount, and radial system. A threaded connection establishes mechanical fit; it does not prove the electrical configuration.
The current guide contains known wording and package-list ambiguities awaiting a Krumm correction. Those documents remain online. Until the revision arrives, the illustrated build and current Shopify package record control; the CKB must not turn a conflicting sentence into a universal setting.
CHA MCC 2.0: the adjustable loading component
The MCC 2.0 is not a complete antenna. It is the adjustable inductive element used in guide-defined vertical configurations. Its role depends on the radiator below it, radiator above it, band, counterpoise, mount, and tuning-tube position.
Because it does not operate independently, there is no meaningful standalone MCC 2.0 radiation pattern. The CKB routes an operator to the full configuration in which it was modeled. A component can be central to an antenna without owning the antenna's pattern.
Protect the coil mechanically. Do not use it to drive a spike, lift an assembled antenna, or absorb cable strain. Keep the winding and moving tube clean and inspect for damage before transmitting.
CHA V-DIPOLE: an add-on path built from the CHA TDL system
The CHA V-DIPOLE package is an add-on, not a complete standalone antenna. Its guide uses compatible components from an owned CHA TDL system, including two SS17 telescopic whips, hub, support arrangement, and feed line. The kit adds the hardware required to form the V configuration.
On 40 and 30 meters, the documented build uses two M-COILs and the supplied hairpin match. On 20 through 6 meters, it uses neither the loading coils nor the hairpin. Those are different electrical configurations, so copy the complete band diagram.
The published 40 and 30 m NEC patterns model radiating geometry while excluding the physical hairpin network from the solver. They explain normalized shape; they do not establish installed match or network loss.
Choose this path when an existing CHA TDL owner wants a compact dipole-style option from the compatible system. Confirm the current guide and owned parts before ordering.
CHA URT1 MB: the mechanical bridge into MPAS Ready
The CHA URT1 MB mounts the URT1 Tuner Unit into a compatible 3/8-24 MPAS Ready mechanical path and provides the short antenna-side connection described in its Quick Start. It is a mounting and feed-point accessory—not an antenna, tuner, transformer, or pattern-producing product by itself.
Use hardware in the documented order, support the Tuner Unit, keep the jumper short, and prevent antenna load from twisting the enclosure. URT1 MB has no independent NEC pattern. Open the exact radiator and return-path configuration connected to it.
CHA BV or CHA PRV 2.0?
Choose CHA BV when modular radiator and fixed-coil choices fit your operating style. It suits an operator who wants a mechanically straightforward resonant vertical and values reuse of familiar MPAS Ready parts.
Choose CHA PRV 2.0 when you want the MCC 2.0's continuous field adjustment and the system's broader set of packaged configurations. It provides a deliberate path from compact base loading to taller center-loaded arrangements.
Choose neither solely because of maximum power or minimum SWR. Compare bands, frequency-change speed, footprint, height, setup time, carried weight, and adjustment method.
If rapid frequency changes without mechanical retuning are the priority, compare either radiator architecture with a guide-defined CHA URT1 path. That becomes a remotely tuned system and must follow URT1 connection and power rules.
POTA and field deployment: repeatability wins
A good portable vertical is the one you can erect safely, tune quickly, and reproduce before operating time disappears. Pack the system as one kit: radiator, loading or tuner component, mount, counterpoise, coax, analyzer, weather seals, stakes, and current guide.
Choose the band plan before leaving. A BV or PRV operator should know component order and starting setting. A URT1 operator should rehearse antenna-side geometry, power, and tuning, then verify saved memories at the new site.
Keep radials visible and controlled in public areas. Do not trade stability for a few extra feet of height when wind, soil, or traffic makes the taller setup unsafe.
A ten-minute pre-transmit routine
Walk the full system before keying: support, radiator joints, loading or tuner component, radial plugs, coax connectors, cable route, and public clearance. Sweep the intended segment or complete a low-power URT1 tune. Then listen before transmitting and begin at the minimum power needed for the contact.
When a field setting works, capture only the facts needed to reproduce it: product and radiator, band or frequency, coil or tuner state, counterpoise layout, mount, and site condition. This is an operator note, not a laboratory worksheet.
HOA and restricted-property use: concealment changes the installation
A patio, flower pot, fence line, balcony, or temporary yard location can make a vertical practical where a permanent tower is not. It can also place the radiator near walls, gutters, wiring, vehicles, and people. Every concealment decision is therefore an RF and safety decision.
The URT1 HOA Special is useful because the whip can remain mechanically unchanged while the tuner changes bands. The return path still matters, and a counterpoise routed differently each day can change the load. Record the arrangement that works and verify it after moving furniture, vehicles, or landscaping.
Temporary does not remove local rules, lease terms, RF-exposure responsibilities, or lightning risk.
Design for the daily setup, not the perfect setup
A system that performs well only when a counterpoise crosses a doorway or the whip is within reach of a power line is not a usable HOA solution. Choose a repeatable route that can be deployed and removed without improvising around people, pets, vehicles, sprinklers, or shared space.
Photograph the safe geometry for your own reference, mark the permitted wire route, and recheck tuning when seasonal moisture, metal furniture, parked vehicles, or landscaping changes. Concealment is useful only when it remains electrically stable and physically responsible.
Emergency communications: build a rehearsed system
Frequency agility is valuable only when the station can reproduce it under pressure. For a resonant system, label band settings and pack every coil, key, radial, and adapter. For a URT1 system, standardize radiator and counterpoise, protect the powered coax path, and confirm the DC source.
Rehearse failures: a damaged radial, wet connector, lost adapter, no tuner power, or one frequency that will not match. Decide the safe fallback before deployment. A second simple resonant antenna may be a better backup than more complexity in the primary path.
Document station power limits, duty cycle, and modes. Digital traffic creates more average heating than voice. The lowest-rated component controls.
Standardize what another operator must be able to reproduce
Label the radio-side and tuner-side coax, the intended antenna output, each radiator, and the return conductor. Keep the current guides with the kit. An operator taking over in the dark should not need to infer which connector carries control power or which coil setting belongs to another radiator.
Exercise the fallback as seriously as the primary system. If URT1 power is unavailable, know which resonant configuration can be erected with the remaining parts. If a radial is damaged, know the safe replacement. A documented fallback reduces pressure to operate a hot, unstable, or partially assembled system.
Troubleshooting CHA BV and CHA PRV 2.0
Resonance is below the band
The system is electrically too long. Confirm the correct coil and component order, then shorten only the guide-defined adjustable element in small steps.
Resonance is above the band
The system is electrically too short. Lengthen the allowed radiator adjustment or move the MCC tuning tube in the guide-defined direction.
The SWR minimum is shallow
Inspect return path, connectors, loading component, and measurement setup. Loss can flatten a response. A shallow minimum is not automatically fixed by chasing a perfect number.
The setting changed at a new site
Compare soil, moisture, radial placement, mount, height, nearby metal, and coax route. Restore the original geometry before changing the radiator.
The reading jumps when touched
Stop transmitting. Check threaded joints, banana plugs, coax connectors, damaged cable, and unstable connections. Human touch also adds capacitance; make adjustments with the operator clear.
Safety and stop-work conditions
Never install an antenna, wire, mast, or support where it could contact a power line. Assume every overhead conductor is energized. Keep enough distance that a falling whip, mast, wire, or tool cannot reach it.
Control access to radiator, counterpoise, balanced line, and feed-point hardware. RF voltage and current can cause burns. Evaluate RF exposure for actual frequency, power, mode, duty cycle, geometry, pattern, and public-access conditions.
Stop for lightning, rising wind, unstable supports, arcing, smoke, damaged insulation, unexpected heating, water intrusion, a red URT1 ERROR indication, or unexplained SWR movement.
Carbon-fiber supports can conduct electricity. Metal tripods, vehicles, railings, and mounting hardware can carry RF or fault current. Electrical bonding, lightning protection, RF return current, and common-mode suppression are related but separate jobs.
Glossary
- BALUN
- A device used in a balanced-to-unbalanced transition. A current BALUN also helps control unwanted common-mode current.
- Bias-T
- A circuit that combines DC or control with RF on one coaxial path and separates them at the other end.
- Common-mode current
- Current on conductors that does not form the intended equal-and-opposite transmission-line pair, often including the outside of a coax shield.
- Counterpoise
- A conductor or conductor system that provides an RF return path for an unbalanced antenna.
- Electrical length
- Conductor length expressed relative to wavelength and modified by loading, conductor dimensions, insulation, and surroundings.
- Feed point
- The location where RF power is delivered to the antenna system.
- Loading coil
- An inductor used to change electrical length and bring a physically short radiator toward resonance.
- MPAS Ready
- Chameleon's modular mechanical and documented compatibility concept. Mechanical fit alone never establishes an electrical configuration.
- NEC
- Numerical Electromagnetics Code, used to model current and radiation for defined wire-antenna geometries and environments.
- Reference plane
- The exact location in a system at which impedance, SWR, or another electrical quantity is defined or measured.
- Resonance
- A condition at a chosen reference plane where net reactance is near zero. It does not automatically mean 50 ohms or high efficiency.
- SWR
- Standing-wave ratio, a measure of mismatch on a transmission line at the measurement plane.
- UNUN
- A transformer or transition between two unbalanced systems.
Useful equations and bounded examples
Free-space wavelength
Wavelength in metres ≈ 300 ÷ frequency in MHz. At 7.1 MHz, one wavelength is approximately 42.3 m and one quarter wavelength is approximately 10.6 m. A much shorter whip therefore needs loading or a different matching strategy on 40 m.
Approximate quarter-wave starting length
Length in feet ≈ 234 ÷ frequency in MHz. This is only a starting estimate. Conductor diameter, loading, ground, mounting, and surroundings change the installed result.
Reflection coefficient from SWR
|Γ| = (SWR − 1) ÷ (SWR + 1). At 2:1 SWR, the magnitude is about 0.333. This describes mismatch at the reference plane; it is not the fraction of transmitter power the complete station permanently loses.
Electrical height
Height in wavelengths = physical height ÷ wavelength. Comparing in wavelengths is more useful than comparing raw feet across different bands.
Sources, authority, and revision control
Product-specific content was reconciled against the CHA MPAS 2.0 Manual; CHA MPAS Lite User Guide dated July 21, 2024; MPAS Ready Product Guide dated July 25, 2025; CHA BV User Guide dated April 23, 2025; CHA PRV 2.0 User Guide dated May 4, 2026; CHA V-DIPOLE User Guide dated April 30, 2026; CHA URT1 User Guide dated July 29, 2026; URT1 Applications Guide dated June 12, 2026; CHA URT1 Ladder-Line Field Guide dated July 30, 2026; and CHA URT1 MB Quick Start dated May 24, 2026.
The controlling CHA URT1 product-owner policy is: HF SSB/CW 125 W maximum; 6 m SSB/CW 100 W maximum; digital/high duty 30 W maximum. The lowest applicable rating of the tuner, BALUN, feedline, connectors, and completed system controls. This supersedes older 120 W wording until Krumm issues corrected revisions.
General RF principles were checked first against The ARRL Antenna Book for Radio Communications, 24th edition—especially vertical-antenna, ground-system, loading, feed-line, matching, and measurement material—the ARRL Handbook for Radio Communications, Thomas A. Milligan's Modern Antenna Design, and Jerry Sevick's Transmission Line Transformers: Theory and Practice, 5th edition for BALUN, UNUN, balance, and transformer principles. Those references explain engineering; they do not authorize a Chameleon product combination.
The public gap audit also checked ARRL's current Verticals, Grounding, Transmission Lines, and More About Antenna Tuners resources, plus the FCC's RF-exposure rules and guidance. These links provide accessible background; the controlled Chameleon guides remain authoritative for Chameleon hardware.
Each governed product record preserves aliases, current and superseded documents, source checksums, CKB destinations, NEC evidence boundaries, lifecycle status, and human approvals. The newest approved Chameleon product guide controls assembly and safety. This handbook supplies explanation and navigation; it does not replace the guide.
Revision: 1.3.0 candidate · 2026-09-09. Adds first-class MPAS Ready, CHA MPAS 2.0, CHA MPAS Lite, component-role, and governed NEC coverage while preserving the approved EFHW pilot pattern: one substantial source-governed guide, stable section IDs, focused deep links, customer-first explanations, and explicit evidence boundaries. Human desktop and mobile approval is required before this revision can replace the published handbook.
