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Post by BBB on Dec 15, 2012 13:57:33 GMT -5
My Imperial was of a bit off frequency using channel 13 (27.113) I tried to add a small cap in parallel to the stand alone crystal near the crystal cage. That lowered it to 27.111, so then I swapped the two identical standalone 7500 crystals on the chassis to see what that would do. That brought it up to 27.119. Then I added a small cap to that swapped crystal and got 27.116 but I noticed the power was down a bit. Before I started out, it would key 1.5 watts and swing to 5 watts PEP. Now it only keys 1 watt and swings to 3 watts. Spitfire was kind enough to steer me to the (3) tuning coils on the upright crystal board saying the oscillator section there was probably in need of alignment. Ironically audio reports were great still! Can I simply tune those for highest output (one a little at at time) or is there more going on there that I would mess up? (insert golden butter knife here>>>  |
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Sandbagger
Administrator/The Boss 
Posts: 6,250 
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Post by Sandbagger on Dec 15, 2012 16:39:17 GMT -5
My Imperial was of a bit off frequency using channel 13 (27.113) I tried to add a small cap in parallel to the stand alone crystal near the crystal cage. That lowered it to 27.111, so then I swapped the two identical standalone 7500 crystals on the chassis to see what that would do. That brought it up to 27.119. Then I added a small cap to that swapped crystal and got 27.116 but I noticed the power was down a bit. Before I started out, it would key 1.5 watts and swing to 5 watts PEP. Now it only keys 1 watt and swings to 3 watts. Spitfire was kind enough to steer me to the (3) tuning coils on the upright crystal board saying the oscillator section there was probably in need of alignment. Ironically audio reports were great still! Can I simply tune those for highest output (one a little at at time) or is there more going on there that I would mess up? (insert golden butter knife here>>> I would return to the original crystals, and put the cap in series with the crystal. That will bring the frequency up. As for tuning, you need to peak each coil in the transmit section for max power. Just make sure you don't hit a receiver coil by mistake. |
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Post by BBB on Dec 16, 2012 9:44:37 GMT -5
I'll try putting the crystals back where they were and see if that brings the power back up. Understood on putting the small cap in series with the crystal I try that too.
This is the first tube rig I tried to turn tuning coils and slugs other than modulation, plate and load. Basically I just rocked them to see if they would move at all and they all worked loose. I was able to bring up the receive that was quite weak with just a little tweak. I used a bamboo chop stick that I whittled the end to a hex shape. They make decent screw drivers as well ha-ha. I'll ask for a copy of the Sam's to help me out please/thank you very much 441.
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