Archive for August, 2010

Tough Electrical Issues on Radios

Well, I’m back to an almost completed airplane after building a new radio harness for the bird.  Rather than try to keep “fixing” things, I decided to pull out the intercom/radio harness that is within the cockpit and replace it completely–new cannon plugs, wire, etc. 

The problems were numerous and confusing:  scratchy noise, feedbacks, blank-outs, intermittent coms, etc.  Seemed to come out of nowhere.  Anyway, with the complete new harness soldered in, we fired her up. Damn thing still acted goofy.  Through trial and error, we found that if we removed the “required” inline converter (military to civilian) for the mics, 90% of problems disappeared. 

Anyway, both sides work now, except copilot cannot transmit on VHF coms. He can hear everything, speak over intercome, etc, but just can’t talk with the ground. Looks like the internal RF filter and mic amplfier in the box is bad and must be repaired or replaced.  Looking for replacments now. 

Whatta mess!

Whatta mess!

So if ANYONE out there knows where I can come up with a couple of spare T37-A37 boxes, let me know. By the way, these things are actually on a LOT of Air Force birds, including C130s. Unit is C-2106A/AIC-18 (Andrea A81-13-1). 

Will add photo of intercom later.

Intercom boxes--need Replacements

The silk screening on the faceplate is irrelevant. It’s the box button positions that count here.