Fido Filter



Fido Filter Product Page

My range with the filter/mag-mount is better than any I have seen.
Corey T.
Coyote Hunter, Mabel, MN

Now a solution to using portable radios with GPS dog tracking receivers


Many of our customers are hunters, and have called us with a common problem: when using portable VHF or UHF radios alongside Garmin dog tracking receivers, the portable radios overwhelm the weak signal from the dog collars at the input of the Garmin receiver, causing it to lose sync with the dogs' collar transmitters.

The Garmin dog collar transmitter utilizes the unlicensed MURS frequencies in the 151.82 to 154.60 range.  Many hunters opt to use off-the-shelf marine band radios operating in the 156 MHz range.  The very close proximity of the marine radios result in the Garmin receiver being overwhelmed by power VHF energy

Some hunters use UHF radios, such as those operating in the GMRS frequency band (462-467 MHz range); but even at UHF frequencies, the high power output of a nearby portable radio can overwhelm the sensitive Garmin receiver which is designed to receive a very weak signal from miles away.

Garmin'support website states:

Alpha 100, Astro 320 and Astro 220 utilize a radio frequency that is in close proximity to other communication devices utilized by hunters. Occasionally these devices are Very High Frequency (VHF) or Ultra High Frequency (UHF). These communication devices often times utilize high-powered frequencies that can cause interference or permanent damage to the device.

  • Garmin does not recommend using your device within 10 feet of VHF or UHF radio(s) emitting more than 5 watts
  • Magnetic Mount Antenna and/or Portable Long-Range Antenna can increase the chance of damage when within the above range

Utilizing communication devices within expected ranges will prevent device damage and decrease the chance of interference

Source: Can I use my dog tracking and/or training devices within close proximity to VHF or Marine band radios?

We Listened, and Created a Solution

Realizing that portable and mobile radios can overload the inputs to the sensitive Garmin receivers, we designed a filter solution to specifically eliminate out the interfering signal at the Garmin receiver input.

Our filter is inserted between the antenna and the Garmin receiver. We offer two filter choices, one for hunters who prefer to use VHF radios, and one for UHF radios.

The VHF filter has deep, selective notches at two locations: the 156.5 MHz portion of the Marine band (Channels 68, 69, 70, 71, 72) and also at the 158.400 MHz “itinerant” frequency allocation. This means you can operate your VHF radios either in the Marine band, or, on a licensed VHF frequency. We have field-tested our VHF filter and found that it permits operation in the vicinity of 5 watt portable AND 50 watt mobile radios.

We supply a special “quick-release” type portable whip antenna which attaches to the top of the filter, and a very low-loss length of coax to directly attach to the Garmin. Double-sided Velcro tape attaches the filter to the back of the Garmin unit. We also offer a magnet mount high gain antenna option with a “quick-release” connector that attaches via a 17’ length of coax to the filter for roof top mounting. This antenna dramatically increases the effective range of the Garmin receiver.

The UHF filter has a broad, deep notch that covers the entire UHF band (450-470 MHz). This means you can use the Garmin receiver with UHF portable and mobile radios operating in the GMRS or licensed portions of the UHF band. The same magnet mount antenna kit with the “quick-release” connector is available for the UHF filter as well.

Marine Channels vs Licensed Frequencies

You are ultimately responsible for proper and legal use of your VHF radio. Many states do not permit hunters to use Marine band radios for inland communications. The FCC does not permit the use of portable marine radios on land FCC Marine Radio Rules, so, you may want to consider getting a Part 90 Land Mobile license for one of the “itinerant” VHF channels above 158 MHz. Our filter accommodates two of these channels, one at 158.4000 and another at 158.4075 MHz. Red Dog Radios can assist with the licensing process for a VHF itinerant license.

GMRS Channels & Licensed UHF Frequencies

It’s easy to apply for a GMRS license for the UHF band, you can do this online and receive your license in a matter of days GMRS FCC Information. First you must apply for an FCC Registration Number (FRN); once the FRN is assigned you can immediately apply for your GMRS license. GMRS offers an economical alternative to the cost of obtaining a Part 90 Land Mobile license.


The Fido Filter


The Fido Filter Kit consists of a filter, antenna and cable.  The cable attaches to the filter, which removes the interfering radio signals from the input to the Garmin receiver.


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