[Yaesu] Serial numbers and 6 meter problem

[Mike Andrews W5EGO]

On Wed, Oct 29, 2008 at 05:11:34PM -0700, John Geiger wrote:
> I know that some of the FT857s had terrible audio on 6 meters (I had one) and am wondering when Yaesu fixed that.  Would a 4E serial number FT857D have this problem corrected?
> 
> 73s John AA5JG

The 857 (non-D)[1] that I bought used had a problem on 6 meters: it 
went into runaway oscillations. I burned up the front end of a Fluke 
1953A counter trying to get an idea of where it was oscillating: with 
the power dialed back to 5 watts, it was putting out about 120W in 
runaway mode. I understand that it was cured in later 857 serials 
by putting ferrites on the HF/6 finals among other changes. 

The terrible audio on 6 could be explained by burnt-up finals, so that
you wind up listening to the driver-and-modulators. 

[1]  Kind of like an R-390 (non-A)

-- 
Mike Andrews, W5EGO
mikea at mikea.ath.cx
Tired old sysadmin