FT-100D mobile install issues!

[W8OSP]

OK, My brain is frazzled on this one! Yaesu FT-100D Mobile install with separation kit running a little tarheel 2. Power wire is running straight from battery to radio with roughly 12-14ft of 10ga.
When the vehicle is running the audio is fine on all bands. With the vehicle off the audio is all garbled and I can see my signal fluttering and hear it in my ext speaker. This is only of HF and with the vehicle turned off! Once I start the vehicle it is fine. Now just for a few seconds once I turn the vehicle off the audio is fine then it starts doing the weird stuff again after a few moments!

I have torroids in the power cord next to the radio, one in the mic cable next to radio and one in the coax feed line next to radio! I have ground wire on the - side of the power lead at the battery and one close to the radio. I am clueless! Standing wave is 1.5 or less!

 

[Keith_W7KEW]

You are most likely getting interference from some device in the radio's audio amp or even speaker. As long as the radio works fine outside of the vehicle you need to find the EMI/RFI. You could have the radio on and start pulling fuses to see if you can find the source of the problem. I had a similar problem with my FT-897 and a wifi router that was nearby.

 

[wyomingmedic]

Voltage drop to the radio. I have an FT-100D in my truck and I have had the same problem for years.

The FT-100 is EXTREMELY sensitive to voltage drop. That is why it is ok when the vehicle is running. The alternator gives it 13.5ish volts. But when you turn it off, the battery alone has to run the radio. For a few seconds, it is ok as the battery voltage is high. But as the voltage drops, the radio goes nuts.

The only thing you can try is to shorten the power wires to the battery to prevent as much drop. Or you can buy one of the MFJ booster things that boost 12 volts to 13.5. Or you can leave your vehicle running.

But I am 99% sure that is your problem.

WM

 

[wv8mat]

Did you figure anything out yet, I herd you on the radio this morning talking to KA8AQR

 

[W8OSP]

Yeah got it worked out! I re worked all the connections from radio to battery and cleaned the battery post! Seemed to have done the trick!