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<p>Some thoughts.....Have you checked the tubes associated with the
tuned circuits that are tuning weirdly? Or better yet done
replacements with known good/new ones? But if this is<i> just</i>
associated with the 10 and 15 meter bands, and as you said, the
coils were damaged, getting a shot--a photo--of a known,
unmolested coil would allow you to perhaps rewind the coils per
spec. At the moment, I don't have any 301's handy to open up, but
if someone else on the list doesn't respond, let me know....I
have, I think two 301's...and I'm not sure of the diff's between
the 301 and 300....I don't have any 300's.....Remember too to
suspect the xtal's as I've had xtal's go bad--10 meter one's
incidentally--on my 303'....and there, I'm afraid, the only
substitute besides one off a donor rig, is one of those synthesis
xtal replacements, which, with the need to power them, are a real
hassle in a vintage rig...<br>
</p>
<p>Guy</p>
<p>WA6OQQ<br>
</p>
<br>
<div class="moz-cite-prefix">On 6/30/2018 1:56 PM, Bob wrote:<br>
</div>
<blockquote type="cite"
cite="mid:861d4989-e212-2223-7a7a-5df629d4353b@frontier.com">I
recently restored a HeathKIt SB-300. The 15 and 10 meter front end
coils were severely damaged. I was able to repair them using
epoxy. The 15 meter circuits now peaks when tuned and the crystal
calibrator signal is an S-9, but I am still having issues with 10
meters. The coils peak but the crystal calibrator signal on 10
meters is on S-3 as best. I replaced the 68pf silver mica cap with
a known good one. Also the peak across the four 10 meter segments
occur at different positions on when peaking the preselector, as
an example 28 MHz peaks with the capacitor almost fully closed,
but the 28.5 peaks with the capacitor almost fully open. The 29
Mhz peaks mid range. Seems odd. I have seen where some are
reporting that on 10 meters they get 20 dB over S-9 using the
calibrator. Also if I leave the 15 meters ant coil peaked I get
oscillation, so I have had to back it off slightly from peak. I
suppose I could install a choke similar to the SB-301.
<br>
<br>
As background I have replaced all resistors, electrolytic caps and
disc/silver mica that I found where open. There is no AC ripple
and all other circuits are operating as designed. When operated on
80-15 the calibrator readings range from 3-20 dB over S9. Any
thoughts very much appreciated. I tried to use SB-301 coils
replace the damaged SB-300 coils, but the 301 coils have different
spacing requirements.
<br>
<br>
Any thoughts on resolving this issue would be appreciated. Also if
you have an SB-300 parts unit I would like to get the coils.
<br>
<br>
73
<br>
<br>
Bob, W8RLC
<br>
<br>
<br>
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</blockquote>
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