[amsat-bb] Re: weird 847 behavior

Nate Duehr nate at natetech.com
Wed Oct 11 13:34:10 PDT 2006

Jeff Griffin wrote:

>   So it appears the fix was a loose semi-grounded board, most notably the
> AF-CNTL unit board. Thanks to everyone that emailed me privately with
> their suggestions....

I'd be interested in what you heard about various ideas.  I have an 
FT-847 that any time a mic that draws power for features (i.e. DTMF mic) 
is used, a noticeable but light hum is introduced in the transmitted audio.

Yaesu took a look at it and replaced a cap in the power supply section, 
but it didn't fix the problem.  (And cost $90... what a waste sending 
things to Yaesu is these days... apparently they don't look at anything 
on a service monitor before sending it back.)

One of the "common" failures in the FT-847 appears to be bad grounds 
from loose boards inside.  I may have to open mine up and check that 
out, if I can ever make the time to do it.   Maybe it'll end up on my 
checklist for radio maintenance annually -- just open the thing up and 
tighten everything.  Maybe a mod to ensure proper board to board 

Always something to do... the FT-847 problem isn't high on my list 
because it's easy to avoid (using the stock mic or a Heil headset, the 
problem doesn't exist, using any mic with power draw it does... quite 
odd, but at least it's nailed down to a particular circuit... better 
than SOME troubleshooting "fun" I've had over the years).

Nate WY0X

More information about the AMSAT-BB mailing list