09-21-2021, 10:27 AM
Schematic Here
Did the usual recap, changed the out of tolerance resistors and have it playing strong. However despite my efforts to do an alignment (and even prior to the alignment), the set only receives from the halfway point of the tuning capacitor to the high end.
Meaning when the tuner is open to around where 900 - 950 Khz should be, I receive 620 strong. I receive the rest of the broadcast band from that point up (1470 is right where it should be). When I go below the 620 mark, I can get 540 fairly close to where it should be (just a bit below 620) but then from the half open point to totally meshed I just get static that gradually increases in volume the closer to fully meshed it goes. I can move 1470 up and down with the A5 trimmer, but the A7 trimmer for the lower end does nothing. No increase in signal strength no matter how many turns I move it in or out.
I tried known good 6A7, 75, and 6D6 tubes to no avail. I didn't do the local OSC test with another radio yet but my thought is the OSC must be working somewhat for me to receive all the stations I usually do, just that they only appear from the half way point to fully open on the TC. I've never experienced this phenomenon before and am at a loss as to what to try next. Perhaps some of the very talented and knowledgeable folks here can peruse the schematic and give me an idea of what to zero in on. Or maybe I'm just not understanding the alignment procedure correctly.
Did the usual recap, changed the out of tolerance resistors and have it playing strong. However despite my efforts to do an alignment (and even prior to the alignment), the set only receives from the halfway point of the tuning capacitor to the high end.
Meaning when the tuner is open to around where 900 - 950 Khz should be, I receive 620 strong. I receive the rest of the broadcast band from that point up (1470 is right where it should be). When I go below the 620 mark, I can get 540 fairly close to where it should be (just a bit below 620) but then from the half open point to totally meshed I just get static that gradually increases in volume the closer to fully meshed it goes. I can move 1470 up and down with the A5 trimmer, but the A7 trimmer for the lower end does nothing. No increase in signal strength no matter how many turns I move it in or out.
I tried known good 6A7, 75, and 6D6 tubes to no avail. I didn't do the local OSC test with another radio yet but my thought is the OSC must be working somewhat for me to receive all the stations I usually do, just that they only appear from the half way point to fully open on the TC. I've never experienced this phenomenon before and am at a loss as to what to try next. Perhaps some of the very talented and knowledgeable folks here can peruse the schematic and give me an idea of what to zero in on. Or maybe I'm just not understanding the alignment procedure correctly.
Greg V.
West Bend, WI
Member WARCI.org
