Cha Blank
"One of those essential pieces of kit that should be in everyone's Antenna EDC. . . . 101 uses and a must for anyone with vertical whips. ."
BLANK ADAPTER · Accessories & Components
A replacement, service, interface, or modular accessory for a documented product or system.
Why operators make room for it
Make the connector in your hand fit the antenna system you want to build
A portable antenna plan can stop over one small mismatch: the radiator, cable, or mount is ready, but the interfaces do not meet. The right adapter keeps the operator from rebuilding an otherwise useful MPAS READY setup.
CHA BLANK ADAPTER solves a deceptively important field problem: joining a selected RF connector to the proven 3/8-24 MPAS READY mounting ecosystem. Choose the BNC-to-3/8-24, SO-239-to-3/8-24, or SO-239-to-SO-239 format to create the exact interface your documented antenna build requires without replacing the mount already in the kit.
For the operator, that means a cleaner path from known equipment to a documented deployment—while preserving the electrical and mechanical limits of the completed antenna system.
Quick product reference
Key Specifications
- Product type
- MPAS READY RF feedpoint and mounting adapter family
- Available formats
- BNC
- SO-239
- SQUARE (SO-239 to SO-239)
- BNC format
- BNC to 3/8-24 — BNC RF interface to 3/8-24 radiator / mounting interface
- SO-239 format
- SO-239 to 3/8-24 — SO-239 RF interface to 3/8-24 radiator / mounting interface
- SQUARE format
- SO-239 to SO-239 interface path
- MPAS READY role
- Creates a documented RF and mechanical interface for compatible 3/8-24 modular radiators, mounts, and accessories
- Radial expansion
- Can be combined with a compatible CHA PUCK HUB when the documented unbalanced vertical requires radials
- Supported Chameleon radiators
- Product record identifies CHA SS58, CHA SS17, and CHA SS25 use paths; completed configuration governs bands and loading
- Third-party SQUARE use
- For antennas with a verified Type-M / M-P / PL-259 / UHF-male base that require an SO-239-female mating interface
- Electrical boundary
- An adapter does not set frequency coverage, power, tuning, or counterpoise requirements; the completed antenna system does
- Mechanical boundary
- Verify thread engagement, antenna leverage, mount strength, grounding, weather exposure, and guying before deployment
- Primary role
- A replacement, service, interface, or modular accessory for a documented product or system.
- Selection rule
- Confirm product family, revision, interface, size, and quantity
- Compatibility
- Verify electrical, power, and structural requirements where applicable
Operator decision support
Plan the complete setup
See what this product is best suited for, what the documented setup needs, and the boundaries to confirm before deployment.
- Best for
A portable antenna plan can stop over one small mismatch: the radiator, cable, or mount is ready, but the interfaces do not meet. The right adapter keeps the operator from rebuilding an otherwise useful MPAS READY setup.
- What else you need
Confirm product family, revision, interface, size, and quantity
- Compatible with
- Creates a documented RF and mechanical interface for compatible 3/8-24 modular radiators, mounts, and accessories
- Product record identifies CHA SS58, CHA SS17, and CHA SS25 use paths
- completed configuration governs bands and loading
- Verify electrical, power, and structural requirements where applicable
- Limitations
- An adapter does not set frequency coverage, power, tuning, or counterpoise requirements
- the completed antenna system does
- Verify thread engagement, antenna leverage, mount strength, grounding, weather exposure, and guying before deployment
What an operator can do
- Confirm the exact product, revision, interface, size, quantity, and position the component is intended to serve.
- Install it according to the completed product or system guide.
- Treat physical fit as only one part of compatibility; verify electrical, power, and structural requirements where applicable.
Compatibility: Physical fit does not by itself establish RF, power, environmental, or structural approval. Follow a documented completed-system configuration.
CHA BLANK SQUARE third-party interface reference
The SQUARE format provides an SO-239-female mating path for specifically verified antennas with a compatible UHF-male / Type-M / M-P / PL-259 base. This table confirms the interface path; it does not replace the antenna manufacturer's electrical, control, mounting, grounding, tuning, or safety instructions.
| Third-party antenna | Published base interface | CHA BLANK path | Operating boundary |
|---|---|---|---|
| Yaesu ATAS-120A | Type-M male base | SO-239-female SQUARE mating path | Motorized tuning and control require an ATAS-capable Yaesu radio; use a strong grounded mount and counterpoise. |
| Diamond SD330 | M-P / PL-259 male base | SO-239-female SQUARE mating path | Requires its 12 V control system and a mechanically adequate support; confirm the exact SD330 revision. |
| Comet HFJ-350M | SO-239 mating adapter documented by Comet | SO-239-to-SO-239 SQUARE path | Band setup, radial / ground arrangement, and tuning remain antenna-specific. |
| Chelegance M-104 | UHF-J connector in manufacturer manual | SQUARE path after exact connector revision is confirmed | 50 W PEP published; correct band coil, radial / ground arrangement, and SWR verification remain required. |
| Moonraker MD-3500 | PL-259 male mount | SO-239-female SQUARE mating path | Manufacturer documentation requires an antenna tuner and restricts the antenna to portable operation. |
| JS / Harvest HD-330 family | Manufacturer lists Connector M; revision must be confirmed | SQUARE path only after exact connector and model verification | Motorized models require their 12 V control system; use the rating and instructions for the exact supplied revision. |
Primary verification sources: Yaesu ATAS-120A instructions; Diamond SD330 manufacturer specifications; Comet HFJ-350M / HFJ Tripod documentation; Chelegance M-104 manual; Moonraker MD-3500 instructions; and the JS Wireless HD-330 family product record. Confirm the exact antenna model and revision before ordering or deployment.
Complete product details
The CHA BLANK is a foundational and highly adaptable component within Chameleon Antenna's portable antenna systems, providing versatility by supporting the CHA SS58, CHA SS17, and CHA SS25 whips. These options enable users to choose the best configuration for their needs, from compact setups to extended-range solutions.
Compatible Whips and Their Advantages
CHA SS58:
- Size: 58 inches (approximately 4.8 feet), collapsible stainless steel whip.
- Usage: Ideal for operators needing a shorter, lightweight antenna option. Its size makes it suitable for more compact setups where portability and quick deployment are critical, while still providing effective HF operation.
- Frequency Range: Supports multiple bands within the HF range, and works well with the CHA M-COIL for extending frequency coverage. This whip is especially beneficial in environments where a full-sized whip may be challenging to use, like dense vegetation or urban areas with space limitations.
CHA SS17:
- Size: 17 feet, telescopic stainless steel whip.
- Usage: Suitable for field operations where a longer whip can enhance communication range and overall efficiency. The SS17’s length allows it to resonate efficiently from approximately 13.8 MHz to 117 MHz, covering popular amateur radio bands from 20-6 meters when fully extended.
- Frequency Range: The SS17 works effectively on the 20-10 meter bands without additional loading coils, and it can be adjusted with a Medium Loading Coil to support 30 and 40 meters, giving it added flexibility for single-band operation.
CHA SS25:
- Size: 25 feet, telescopic stainless steel whip.
- Usage: The SS25 is ideal for operators seeking an extended reach, as its length provides a stronger signal and broader operational range. This whip is particularly beneficial for applications requiring improved propagation, such as emergency communications or operating in rural or isolated areas where maximizing range is essential.
- Frequency Range: Designed for enhanced multi-band performance and offers an efficient radiation pattern across HF frequencies. When paired with the CHA BLANK and other compatible MPAS components, the SS25 whip can be adjusted to cover various bands with minimal tuning, which is advantageous for users who need broad band coverage.
CHA BLANK Features and Integration
- 3/8" x 24 Threaded Connection: The CHA BLANK’s threaded connection enables secure attachment of compatible whips like the SS58, SS17, and SS25, ensuring a stable and reliable setup in any configuration.
- Coaxial Adapter Options: Converts to either an SO-239 or BNC connection, allowing easy integration with different types of coaxial cables and RF equipment.
- Base and Radial Support: When combined with the CHA PUCK HUB, the CHA BLANK supports up to six radials using Banana Jacks. Radials enhance the antenna’s efficiency by completing the ground circuit for unbalanced antenna designs like vertical whips, improving SWR and overall performance.
Benefits of Using the CHA BLANK with Each Whip
- Versatile Configuration Options: Depending on the whip used, the CHA BLANK allows operators to tailor their setup for various band conditions and operating environments. For instance, using the CHA SS17 and CHA M-COIL, operators can cover the 30 and 40 meter bands, ideal for longer-distance HF communication. The shorter SS58 provides a more compact option while still performing well on upper HF bands.
- Enhanced Portability: The CHA BLANK and compatible whips offer quick setup and breakdown, making them suitable for operators who frequently move locations or need a lightweight, transportable solution.
- Optimal SWR Tuning: The CHA BLANK enables precise tuning through whip adjustments and radial length modifications, ensuring a low SWR across the chosen operating band. This is particularly useful for portable operations where site conditions, nearby objects, and ground conductivity might affect resonance.
Example Setups with the CHA BLANK
Compact Setup with CHA SS58:
- Ideal for short-range HF communication on higher bands like 20, 15, and 10 meters.
- The SS58 is compact and easy to deploy, making it suitable for fast setups in environments where space is limited.
Extended Coverage with CHA SS17 and Loading Coil:
- This setup supports a broader frequency range, enabling operation on 30 and 40 meters by adding the Medium Loading Coil.
- The SS17’s length helps achieve stronger signal strength, making it suitable for moderate-range HF contacts.
Maximized Range with CHA SS25:
- The 25-foot SS25 whip provides the highest efficiency and longest-range capabilities for the CHA BV configuration.
- This setup is recommended for users who need reliable, long-distance communication or for emergency response scenarios where maximizing signal strength is crucial.
Technical Specifications for CHA BLANK Configurations
- Power Rating: Supports up to 500W SSB and 300W CW and digital modes, ensuring flexibility across various transmission modes.
- Frequency Range: From 6.9 to 30 MHz for the CHA BV setup, with potential extended range to 80 meters when used with the Inverted Lazy “L” configuration.
- Setup Time: Typically under 10 minutes with practice, making it suitable for quick deployment needs.
- Water Resistance: Built to withstand various weather conditions, allowing outdoor operation in diverse climates.
CHA BLANK SO-239 SQUARE
The CHA BLANK SO-239 SQUARE is a compact, heavy-duty inline adapter featuring dual SO-239 (UHF female) connectors — one on the input side and one on the output side — and a 3/8”-24 threaded bottom male stud. This configuration allows the adapter to connect directly to any antenna or accessory equipped with a SO-239 (UHF male) jack while also threading into any standard antenna mount with a 3/8”-24 female thread.
This unique design provides maximum versatility across a wide range of antennas, mounts, and configurations — ideal for portable, mobile, and base station setups. Precision-machined from high-grade materials, the CHA BLANK SO-239 SQUARE ensures excellent RF conductivity, rugged mechanical strength, and long-term reliability across HF, VHF, and UHF frequencies.
FEATURES
- Dual SO-239 (UHF Female) Connectors: Allows seamless in-line connection between any two SO-239 (UHF male) components such as antennas, matching units, or couplers.
- 3/8”-24 Threaded Base: The bottom male stud fits any mount with a 3/8”-24 female thread, enabling direct installation on tripods, masts, magnetic mounts, or vehicle brackets.
- Universal Compatibility: Works with antennas and accessories using SO-239 (UHF Male) connectors across HF, VHF, and UHF bands.
- Rugged Construction: Machined aluminum square body provides superior strength, corrosion resistance, and stable RF performance.
- Modular Integration: Ideal for portable, mobile, or test configurations requiring fast equipment changes without adapters or couplers.
COMPATIBLE ANTENNAS
Yaesu ATAS-120A – Motorized, automatic-tuning HF/VHF/UHF mobile antenna featuring a SO-239 (UHF male) connector. The CHA BLANK SO-239 SQUARE ensures a strong and efficient RF interface for mobile or portable use.
Diamond SD330 – Professional HF screwdriver antenna with a SO-239 (UHF male) connector. The CHA BLANK SO-239 SQUARE provides solid, low-loss RF continuity and mechanical stability.
Comet HFJ-350 Series – Compact, portable HF antennas covering 3.5–30 MHz, all equipped with SO-239 (UHF male) connectors. Perfect for rapid field deployment using the CHA BLANK SO-239 SQUARE.
Chelegance M-104 HF – High-efficiency HF mobile antenna for 40 m to 10 m operation with a SO-239 (UHF male) base connector. Fully compatible with the CHA BLANK SO-239 SQUARE for mobile and tactical operations.
Moonraker MD-3500 – Motorized HF screwdriver antenna (3.5–30 MHz) with a SO-239 (UHF male) connector. Directly compatible with the CHA BLANK SO-239 SQUARE for high-performance RF transfer.
HD-330 (3.5–50 MHz) – Professional HF screwdriver antenna equipped with a SO-239 (UHF male) base connector. The CHA BLANK SO-239 SQUARE provides a stable and efficient connection for mobile or fixed operations.
SUMMARY
The CHA BLANK SO-239 SQUARE is a precision-engineered, multi-purpose adapter designed for operators who need maximum connection flexibility. Its dual SO-239 (UHF female) design provides a robust RF interface between SO-239-equipped antennas and accessories, while the 3/8”-24 threaded base allows direct mounting onto standard antenna supports.
Connector Configuration: Dual SO-239 (UHF male) + 3/8”-24 threaded bottom male stud
Compatible With: Yaesu ATAS-120A, Diamond SD330, Comet HFJ-350 Series, Chelegance M-104 HF, Moonraker MD-3500, HD-330 (3.5–50 MHz), and any antenna using a SO-239 (UHF male) connector.
Mount Compatibility: Any 3/8”-24 female threaded mount or support.
Applications: Base stations, mobile installations, tactical setups, field deployments, and test environments.
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