Craig Roberts <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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This TR-7 output adjustment thing can be a little tricky, I've learned.
For instance, the other day I complained that my second TR-7 would not
respond properly to the published transmitter alignment instructions.
With R1613 (the pot on the ALC board) cranked up all the way, the
maximum output I could achieve was about 110 to 115 watts on 20 meters
with a mysterious oscillation on 40 meters and some RF "junk" on upper
bands. At the suggestion of several list members, I checked various
components, including power supply regulator, final output transistors,
PIN diodes, and the double balanced mixer.
As it happens, the real problem was me! I had misadjusted R2227 on the
Predriver board and had the ALC efficiently limiting the power output to
115 watts or so while the driver was saturated (at least that's my
theory). Repeating the alignment procedure by first setting R2227 at
mid-range (12 o'clock) allowed me to set the output on 20 meters to 120
watts with plenty of room to spare. Going up to 10 meters, as
instructed, and backing down R2227 to about 10 o'clock gave me nice,
clean ALC action on all bands and a fully stable transmitter.
One of our Drake friends suggested backing the output down even further
to 100 watts. This, he intimated, would "baby" the finals with no
discernable drop in performance. This sounds like a good idea.
Anyway, as usual, I need to first examine my operation before I conclude
that the machine's at fault.
73, y'all and Merry Christmas!
Craig
W3CRR
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