|[AMRadio] A bit of Viking Valiant help|
gkbrown at gwi.net
Sat Aug 27 14:01:25 EDT 2005
Just a wild a-- guess, but I thought that the Valiant used only 6146's, not
the "B" 6146. It is my understanding that sometimes subbing in the "'B" for
the early 6146 just doesn't cut the mustard.
----- Original Message -----
From: "John Lawson" <jpl15 at panix.com>
To: <amradio at mailman.qth.net>
Sent: Saturday, August 27, 2005 1:56 PM
Subject: [AMRadio] A bit of Viking Valiant help
> 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
> 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,
> Thanks all!
> John KB6SCO
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