ARC (Cessna) 41260-0000 power filter

[Larry Korona]

I'm currently in the process of doing a major avionics wiring overhaul and upgrading with GI 275's replacing the vacuum system.

I'm looking to get a better understanding on the role that the ARC (Cessna) 41260-0000 power filter plays and what are the best practices to connect the radio's power input wire to the planes power.

I'm guessing that these filters provide the best possible power to each radio, and while we now have modern electronics in our planes, we still need these devices? I have a Garmin 430W and KX-155 for the radios. I've asked my mechanic, he felt that I don't need these filters anymore but he wasn't 100 percent certain.

The filter input is connected to the circuit breaker (buss power) and the output is connected to the radio power input. I assume that this is the correct wiring for both radios?

 

[40YearDream]

I think it's not so much a question of newer electronics, but rather, how noisy is the power coming in (from a generator or alternator, or possibly ignition noise riding along the power leads). Does the newer electronics have better internal filtering? Maybe, maybe not.
You could do a test (assuming the old radios are still operable) - bypass the filter temporarily, and see how noisy the radios are - with the squelch opened up.

 

[AV8R_87]

we still need these devices?

They probay have an inductor and a couple capacitors to smooth out power and prevent noisy radio and intercom audio. Maybe a transient voltage suppressor, but I'm not sure, never taken one apart.

Point is, most modern radios can take a lot, so you're not likely to damage them, even if the power has spikes and noise. But some of that generator/alternator noise could get in the radio and make things sound bad.

Easy way to check, disconnect the input and output from the filter and tie them together. Do a ground run and maybe a flight, listen to some weak radio signals and have someone listen to your transmissions. If your avionics shop has a com/nav ramp tester, you an use that to generate a weak signal on the ground.

If it all sounds good, go ahead and remove them.

 

[NordicDave]

Most of these filters were required for ancient avionics and especially for ADF's. Remember listening to AM radios in a car with all the crackling and noise caused by the ignitions system or traveling under power lines back in the day? Pretty standard procedure to remove these devices on panel upgrades.

One suggestion... Just disconnect and jumper around them and see if the radios get noisy. Bet you find no noticeable difference.

 

[Larry Korona]

Thanks for all the responses and suggestions. I'm going to remove these filters. I'm surprised that with all the upgrades that I've gotten done over the years that no one ever removed them.

 

[Papa Pilot]

If they are working, doesn't hurt to leave them in. I'd clean those lead, though.