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If you have not attempted alignment, that would be next. It's possible the adjustments have drifted with age, or got "tweaked" by someone who didn't know what to watch for while twisting them. In particular be on the lookout for any slug-tuned coils that appear to show a peak with the top of the slug DEAD EVEN with the rim of the hole in the top of the can.

If you see this, it's not really a resonant peak. That can has a failed capacitor inside it. The slug position of max inductance occurs with the slug dead even with the rim of the hole. Turning it counterclockwise so it rises above the top of the can will reduce inductance. Likewise turning it clockwise down into the can also decreases its inductance. Since that failed capacitor raises that coil's resonant frequency, maxing out the inductance compensates, but only partway.

Make it appear to "peak" at that position, but it's not really a peak. Just the adjustment's end-of-travel.

Gotta post a video about this someday and just post a link to it.

May or may not have anything to do with your symptom. But it's a common enough fault to at least check for. I'm convinced that long term exposure to high humidity causes this, but don't have proof.

73

<blockquote data-quote="nomadradio" data-source="post: 787590" data-attributes="member: 22">If you have not attempted alignment, that would be next. It&#039;s possible the adjustments have drifted with age, or got &quot;tweaked&quot; by someone who didn&#039;t know what to watch for while twisting them. In particular be on the lookout for any slug-tuned coils that appear to show a peak with the top of the slug DEAD EVEN with the rim of the hole in the top of the can. If you see this, it&#039;s not really a resonant peak. That can has a failed capacitor inside it. The slug position of max inductance occurs with the slug dead even with the rim of the hole. Turning it counterclockwise so it rises above the top of the can will reduce inductance. Likewise turning it clockwise down into the can also decreases its inductance. Since that failed capacitor raises that coil&#039;s resonant frequency, maxing out the inductance compensates, but only partway.Make it appear to &quot;peak&quot; at that position, but it&#039;s not really a peak. Just the adjustment&#039;s end-of-travel. Gotta post a video about this someday and just post a link to it. May or may not have anything to do with your symptom. But it&#039;s a common enough fault to at least check for. I&#039;m convinced that long term exposure to high humidity causes this, but don&#039;t have proof. 73</blockquote>

[QUOTE="nomadradio, post: 787590, member: 22"] If you have not attempted alignment, that would be next. It's possible the adjustments have drifted with age, or got "tweaked" by someone who didn't know what to watch for while twisting them. In particular be on the lookout for any slug-tuned coils that appear to show a peak with the top of the slug DEAD EVEN with the rim of the hole in the top of the can. If you see this, it's not really a resonant peak. That can has a failed capacitor inside it. The slug position of max inductance occurs with the slug dead even with the rim of the hole. Turning it counterclockwise so it rises above the top of the can will reduce inductance. Likewise turning it clockwise down into the can also decreases its inductance. Since that failed capacitor raises that coil's resonant frequency, maxing out the inductance compensates, but only partway. Make it appear to "peak" at that position, but it's not really a peak. Just the adjustment's end-of-travel. Gotta post a video about this someday and just post a link to it. May or may not have anything to do with your symptom. But it's a common enough fault to at least check for. I'm convinced that long term exposure to high humidity causes this, but don't have proof. 73 [/QUOTE]

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