David,
I found your note interesting because the same thing happened on my
TR-7 (S/N 46xx) recently. I did a full alignment on the radio and carefully
followed the instructions (more than once) and the result was the same: the
LED would not go out when I adjusted the predriver control on 10m. W8PU
cautioned me at the time that I should only crack the predriver open about
half a turn or risk instability (at least I think that's what he said at the
time). I ended up reducing the ALC board pot slightly and then the LED
would go off with about a half-turn of predriver. I think my radio is set
for about 125W output. I could run it at 140W or so, but then the LED would
not go off on 10m using the predriver control. I was interested in seeing
what kind of answers you got. My particular radio had a couple of failures
when I got it (pin diode, voltage regulator for the DR-7, and some alignment
issues), so I was concerned at the time that this alignment glitch might
indicate another hidden problem. But in using it, it seems to be okay.
Since I aligned mine, I did find one instance where the radio was
unstable on 40m and pegged the needle in CW mode even with the carrier
control set very low. It only happened once (and was very sudden and very
alarming, I might add). The power started to go up normally as I increased
the carrier control, but suddenly - wham! I don't know what caused it and I
don't believe I reduced either the predriver or ALC settings to fix it. It
has behaved okay recently, so I'll just have to keep an eye on it.
73,
Dave / K8JDC
----- Original Message -----
From: David & Chris Drake
To: [email protected]
Sent: Sunday, February 08, 2009 4:12 PM
Subject: [Drakelist] TR-7 Alignment
Hello,
I decided to go back into my TR-7 this afternoon and do some tweeking to my
previous alignment. (the S meter seemed to read higher than my other radios
by quite a bit). After re-setting the S-meter per the manual, I thought I'd
go back over the transmitter settings and lower the output somewhat. I had
read somewhere that Drake liked to set the ALC board at 120w instead of the
called for 140-150w. The purpose being purity of emissions. I'm using it
mainly with an L4B, so the extra 20-30 watts means little.
Per the manual, I set the carrier fully clockwise on 14mhz, keyed the radio
and set the ALC pot to about 120w. Then went to 28mhz and attempted to
reset the predriver board to get the alc light to go out. No can do. The
pot is fully CCW and no more there. I remember when I did the previous
alignment set at about 145w on 14mhz, and then on 28mhz, the alc light just
started to dim at fully CCW on the predriver.
Any comments as to what I should or should not be doing? PS, its sn 5300 or
so with the version 2 predriver.
Thanks,
David
Wd9cmd
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