BIRD TECHNOLOGIES 28-52-02A Vari Notch Duplexer 215-220MHZ 217.1250-219.1250

( Brand: Bird Technologies ), ( Manufacturer Part Number: 28-52-02A ), ( Compatible Brand: Universal ), ( Type: Pass Reject Duplexer ), ( Band: Uhf ), ( Country Of Origin: United States )

Review BIRD TECHNOLOGIES Vari notch Duplexer 215-220mhz

The **Bird 28-52-02A Vari-Notch Duplexer** is a high-performance, precision-engineered RF component designed specifically for the 215 220 MHz frequency range, making it an ideal solution for modern two-way radio systems, military communications, and specialized public safety applications. This duplexer operates within the narrow but critical band of 217.1250 219.1250 MHz, ensuring seamless separation between transmit and receive signals while maintaining exceptional isolation and minimal insertion loss. Built with Bird Electronics reputation for reliability and engineering excellence, the 28-52-02A employs a robust vari-notch filter architecture, allowing for dynamic adjustment of the notch frequency to accommodate different channel requirements without compromising signal integrity. Its compact yet durable construction ensures compatibility with a wide range of antenna systems, making it a versatile choice for both fixed and mobile installations. The duplexer s high isolation performance typically exceeding 60 dB prevents interference between transmit and receive paths, while its low insertion loss (typically under 0.5 dB) maximizes signal strength and range. Additionally, the unit is designed to withstand harsh environmental conditions, featuring rugged metal housing and protective shielding to guard against electromagnetic interference (EMI) and radio frequency interference (RFI). Whether deployed in military command centers, emergency response networks, or high-density public safety operations, the Bird 28-52-02A delivers unparalleled clarity and efficiency, ensuring crystal-clear communications in even the most demanding applications.

### **Pros and Cons of buying a Bird 28-52-02A Vari-Notch Duplexer (215-220 MHz, 217.1250-219.1250 MHz)**

1. **Frequency Coverage and Flexibility**

The duplexer is designed for the 215 220 MHz band, which is commonly used in amateur radio (e.g., 220 MHz FM repeater operations). The specific notch range (217.1250 219.1250 MHz) allows it to filter out interference or unwanted signals in that segment, making it useful for repeaters or dedicated simplex operations.

2. **Vari-Notch Design**

- Isolating a single repeater input/output pair.

- Preventing interference from other signals in the band.

- Customizing the duplexer for different repeater configurations.

3. **Durability and Build Quality**

Bird Electronics is known for producing high-quality RF components. The 28-52-02A is built to handle the power levels typical in amateur radio (e.g., 100W ), making it reliable for long-term use.

4. **Compatibility with Common Equipment**

The duplexer is designed to work with standard coaxial cables (e.g., RG-213, LMR-400) and can be integrated into existing repeater or mobile setups with minimal modifications.

5. **Cost-Effective for Specific Applications**

For users who need a dedicated duplexer for a narrow frequency range (e.g., a single repeater), this unit may be more affordable than a full-band duplexer while providing the necessary isolation.

6. **Easy Installation and Adjustment**

The vari-notch feature can be tuned on-site, allowing operators to fine-tune the notch frequency without needing to replace the entire unit.

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1. **Limited Frequency Range**

The duplexer only covers 215 220 MHz, which restricts its use to this specific band. If you need coverage for other bands (e.g., 144 MHz, 432 MHz, or VHF/UHF), you would require additional duplexers or filters.

2. **Notch Adjustment Complexity**

While the vari-notch feature is useful, tuning it correctly requires some experience with RF measurements (e.g., using a spectrum analyzer or SWR meter). Misalignment could lead to poor performance or interference.

3. **Potential for Signal Loss**

Duplexers inherently introduce some insertion loss (typically 0.5 1.5 dB per port). While this is usually negligible for most amateur radio applications, it may be a consideration for high-power or long-distance links.

4. **Physical Size and Space Requirements**

The duplexer is a standalone unit that may require additional mounting space in a repeater shack or mobile installation. Its size could be a constraint in compact setups.

5. **Dependence on Proper Installation**

Poor installation (e.g., incorrect cable lengths, improper grounding, or mismatched impedances) can degrade performance. This requires careful attention to detail during setup.

6. **Limited Availability of Replacement Parts**

As with many specialized RF components, finding replacement parts or support for older Bird units may become difficult over time, especially if the unit fails.

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### **Conclusion**

The **Bird 28-52-02A Vari-Notch Duplexer** is a well-suited choice for amateur radio operators who specifically need a duplexer for the 215 220 MHz band, particularly for repeater or simplex operations within the 217.1250 219.1250 MHz range. Its vari-notch capability provides flexibility for customizing signal isolation, and its build quality ensures reliability for high-power applications.

However, its **narrow frequency range** and the **requirement for careful tuning and installation** may limit its appeal to users with broader frequency needs or those without experience in RF adjustments. If your primary use case aligns with the duplexer s specifications and you are comfortable with its setup, it is a solid investment. For those needing multi-band coverage or simpler, plug-and-play solutions, alternative duplexers or filter combinations might be more appropriate.

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### **Recommendation**

- You operate a 220 MHz repeater or need a duplexer for this specific band.

- You are comfortable tuning the vari-notch feature and have access to basic RF measurement tools.

- You prioritize durability and performance for high-power applications.

- You need coverage for other bands (e.g., 144 MHz, 432 MHz) and would benefit from a multi-band duplexer.

- You prefer a simpler, fixed-notch duplexer without the need for manual tuning.

- Your budget allows for a more integrated solution (e.g., a pre-tuned duplexer module from a manufacturer like MFJ or Hy-Gain).

For most **220 MHz repeater operators**, the Bird 28-52-02A is a practical and effective choice. Pair it with proper installation guidelines and testing to ensure optimal performance.

Details:

This includes items purchased in error. We normally ship to the 48 continental USA. Please review the detailed specifications below. All key functions have been tested to be in working order.

Vari-Notch Duplexer. R2v3 Grading: C4 - F3. PL-230/29357.

Bird Technologies.

part #: 285202a price

• $789.95

specifications hamamateuradio:

• brand: Bird Technologies
• mpn: 28-52-02a
• compatible brand: Universal
• type: Pass Reject Duplexer
• band: Uhf
• country of origin: United States

offer hamamateuradio:

• best offers: True
• availability: In Stock
• quantity: 1
• started: April 10, 2026
• sold: 0
• options: Ship-to-home

seller hamamateuradio:

• # reviews: 5791
• city: Oklahoma City, Oklahoma
• rating: 99.9%

general hamamateuradio:

• condition: Used
• Radio Communication > Ham, Amateur Radio > Other Ham Radio Equipment

payments hamamateuradio:

• wallet: Google-pay
• other
• credit card: Diners-club

shipping hamamateuradio:

• service: USPS Ground Advantage
• cost: $32.40
• transit: 3-6 Days
• type: Fixed
• class: Standard
• carrier: USPS

returns hamamateuradio:

• time: 30 Days
• policy: Returns Accepted
• paid by: Seller
• method: Money back

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