03-02-2013, 07:40 AM
Well.. new revolting developments:
1) I was wrong, it's not working on all 5 bands.. it was just the noise level in my shop getting into the IF's. The top two bands are dead. The LO coils, at least the one for the 4th band, seem to have continuity, but no voltage gets to G2 of the LO (6A8 ). This would seem to leave the front section of the bandswitch as the likely culprit.
2) I found out why the RF section and the antenna terminals wouldn't talk to each other: All five antenna input coils have open primaries! Now, that in itself isn't a huge problem, since even I could rewind those primaries easily enough, but.. the aft section of the bandswitch is fused an immovable, and the shaft spins inside it.. so the entire section will need replacement.
Now, I'm a pretty adventurous soul, but I don't know if I'm up to tearing apart that sled to try to fix both ends of the bandswitch. I might be willing to give it a shot if someone has the parts I can buy from them. Otherwise, I'm open to farming that job out. I already have nearly $500 into this chassis (which as I said is an AWESOME performer, even with the problems it has! I really anticipate someday having it in full bloom!) so another $100-200 for someone to fix the sled is no biggie.
Now for a bit of good news to offset all that: The IF spread is now working 100%, and does an awesome job. It lets me hear the crisp highs that my little AM TX is capable of producing just wonderfully.
Also, changing out that 1uf in the tweeter crossover to a 5uf definately gave a much more balanced range, since the main power amp is designed to punch up the bass.
1) I was wrong, it's not working on all 5 bands.. it was just the noise level in my shop getting into the IF's. The top two bands are dead. The LO coils, at least the one for the 4th band, seem to have continuity, but no voltage gets to G2 of the LO (6A8 ). This would seem to leave the front section of the bandswitch as the likely culprit.
2) I found out why the RF section and the antenna terminals wouldn't talk to each other: All five antenna input coils have open primaries! Now, that in itself isn't a huge problem, since even I could rewind those primaries easily enough, but.. the aft section of the bandswitch is fused an immovable, and the shaft spins inside it.. so the entire section will need replacement.
Now, I'm a pretty adventurous soul, but I don't know if I'm up to tearing apart that sled to try to fix both ends of the bandswitch. I might be willing to give it a shot if someone has the parts I can buy from them. Otherwise, I'm open to farming that job out. I already have nearly $500 into this chassis (which as I said is an AWESOME performer, even with the problems it has! I really anticipate someday having it in full bloom!) so another $100-200 for someone to fix the sled is no biggie.
Now for a bit of good news to offset all that: The IF spread is now working 100%, and does an awesome job. It lets me hear the crisp highs that my little AM TX is capable of producing just wonderfully.
Also, changing out that 1uf in the tweeter crossover to a 5uf definately gave a much more balanced range, since the main power amp is designed to punch up the bass.
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