I'm in the middle of a long, slow project to get my Valiant back in
service. I've changed out the bigger power tubes, solid-state replacements
for the 866s, and partially re-capped the rig, specifically the RF power
section.
After finding (expensively) out that 'W' 6146s just don't work, I
replaced the finals with new 'B's and power is now being transferred to
the antenna / dummy load.
Main bug:
On the bands below 20M, however, and getting 'worse' as the frequency
gets lower, the rig "runs away" after 15 - 30 seconds - the plate current
rises fatser and faster and then needs to be shut down, lest another set
of 6146s gets wasted. ;}
I have neutralized the transmitter per the manual, seems ok. Bias also
set per sepc. LV rectifier tubes have been chacked (on a Weston 686) and
seem within spec, though their performance under load is measurable only
in situ.
I left the doorknob cap alone because it's fine electrically and not
cracked or discolored.
Do the sypmtoms sound familiar to anyone? Before I spend a bunch more
hours wearing out the transmit switch, I thought I'd ask those who have a
lot more experience than I do with the Valiant.
I can add more info/observations as needed, specific caps replaced, etc.
Thanks all!
Cheers
John KB6SCO
