01-20-2018, 08:38 PM
Jcassity;
I notice that the warm-up time of this radio is extremely long - about 2 minutes (no audio until then, weak at first and growing stronger until volume is full). The audio sounds quite good when it is fully warmed up, but two minutes is too long. The schematic says the grid bias on the output tubes is supposed to be -11VDC. What do you measure on your radio? I did note that the 1st IF tube seems noticeably cooler than the second one. I may have to revisit cleaning the tube sockets. I have some of the dental flossing brushes that I can use to get into the socket contacts along with the Deoxit application. I need to measure the AGC voltage and see if that is changing slowly on warm-up. Right now I have 6V6GT tubes installed in the output sockets. I might try the original 6K6 tubes and see how they warm up by comparison.
The 6V6GT tubes produce more volume than the 6K6 tubes did, so they may not be the issue.
Joe
I notice that the warm-up time of this radio is extremely long - about 2 minutes (no audio until then, weak at first and growing stronger until volume is full). The audio sounds quite good when it is fully warmed up, but two minutes is too long. The schematic says the grid bias on the output tubes is supposed to be -11VDC. What do you measure on your radio? I did note that the 1st IF tube seems noticeably cooler than the second one. I may have to revisit cleaning the tube sockets. I have some of the dental flossing brushes that I can use to get into the socket contacts along with the Deoxit application. I need to measure the AGC voltage and see if that is changing slowly on warm-up. Right now I have 6V6GT tubes installed in the output sockets. I might try the original 6K6 tubes and see how they warm up by comparison.
The 6V6GT tubes produce more volume than the 6K6 tubes did, so they may not be the issue.
Joe
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