[Fox_Tango] Re: Final Tubes in the FT 101

[Wiley Sanders]

I tried replacing the "green band" finals in my Yaesu FT-101E with NOS GE 
6JS6C's. My "green bands" are down to about 60 to 80 W on 10 and 15, but are 
otherwise OK.

Unlike the procedure described in the  FT-101 home page (and reproduced widely 
on ham pages), I did not replace the 100 pf fixed cap. I did find that the 
setting of the air varible cap was "twitchy" but eventually I found a point 
where the output stage developed full power without seeming to oscillate. Your 
experience may vary.

I encountered some self-oscillation on 10B (and thought I might have fried 
some circuitry - the output tank got really hot! But fortunately no damage was 
done). If you hear a farting noise on receive, with no antenna attached - 
that's self-oscillation! Tweak the plate or loading control immediately to 
detune the oscillation!

Unfortunately, I think I fried the new tubes running PSK31 at 30 to 50W for a 
few weeks, so I went back to the original finals, and I've sworn off PSK31 for 
the time being.

I would still recommend replacing the fixed 100 pf with a 10 pf, but it 
doesn't seem entirely necessary if you are very careful. There was a 
discussion of this some time ago on this list - it won't change the 
capacitance much, but it does make the adjustment less twitchy. The series cap 
is necessary to provide safety in case the air variable cap shorts.

The GE 6JS6Cs seem to develop a little less power than rated, about 100 W on 
80-15 and 80W on 10.

-Wiley KF6IIU