Well, for a few weeks now I’ve been (metaphorically) tearing my hair out, trying to figure out why I had such bad antenna problems on VHF. HF, I still have work to do as right now, the RF just induces currents where it pleases, including in my microphone cabling, but that’s a different matter. VHF until recently had been rock solid.
I tried replacing coax, re-terminating leads, checking solder joints, replacing antennas. Yesterday, I re-wired the entire antenna system, doing away with the BNC connectors in the top box and hard-wiring the antenna mounts to the coax inside. Rode up to Ashgrove today thinking I had fixed the problem.
Each bump in the road, I watched the S-meter graph move from S9 to S4 and back again.
What could it be? Why is it that it only occurs when I’m mobile, and not stationary? There’s a bad link somewhere, but where? No amount of jiggling cables was locating the problem. Finally today, I decided to take a peek inside the FT-857D.
I looked closely at the point where the N connector solders to the PCB. I noticed a small line around the wire where it met the solder blob. So I picked at it with pliers, and pulled it away from the blob: it was a dry joint!
Tomorrow, I shall know if this was the final problem. At least I don’t run full power on FM, my license only affords me 30W continuous, so the only time I do 50W is when I’m doing SSB at which point it’s only on voice peaks.
Update: It’s been a few days, the difference is like the difference between chalk and cheese. Prior to the fix my set was deaf as a post, and it’s not hard to see why!