07-07-2013, 01:00 PM
Need some help please. Recapped an 80Jr that was playing originally (at least it pulled in one station when I went to pick it up but I asked the seller to turn it off as soon as I got there ). Also replaced out of spec dogbone resistors. When I power it up now, it is motorboating all across the tuning span. Some voltages:
[Image: https://www.dropbox.com/s/jnru9hgema6p6j....jpg?raw=1] "CORRECTED TABLE"
The strange thing is when I put a test lead on plate of the Det-Osc tube, all the motorboating stops (although I can not tune in any stations). If I put the test lead on the cathode of the Det-Osc tube, it still motorboats, except when I tune it to one strong station we have, which then comes in clearly. Don't have a tube tester but since it was playing originally I'm assuming they are still OK. Any thoughts on what to try next. Thanks!
[Image: https://www.dropbox.com/s/jnru9hgema6p6j....jpg?raw=1] "CORRECTED TABLE"
The strange thing is when I put a test lead on plate of the Det-Osc tube, all the motorboating stops (although I can not tune in any stations). If I put the test lead on the cathode of the Det-Osc tube, it still motorboats, except when I tune it to one strong station we have, which then comes in clearly. Don't have a tube tester but since it was playing originally I'm assuming they are still OK. Any thoughts on what to try next. Thanks!
