02-17-2007, 05:19 PM
I have noticed that the volune needs to be turned all the way up to hear the low end of the band.
**I haven't had a 37-84 in about 40 years but in looking at the schematic there appears to be only one component that would cause your problem- of course I could be wrong.
It would appear that what you are seeing is weak capacitive coupling which would make it frequency sensitive. The lower the freq, the poorer the coupling. The schematic shows part #3- "Capacity obtained by twisting the ends of two wires" on the grid of the input tube- this is the only part that sees all of the input freqs and is not part of a resonant or feedback circuit. I would look closely at this twisted pair of wires- maybe they have been unwound or run too closely to ground. You could probably replace the twisted wires with perhaps 10 or 20pF of fixed capacitance.
'
**I haven't had a 37-84 in about 40 years but in looking at the schematic there appears to be only one component that would cause your problem- of course I could be wrong.
It would appear that what you are seeing is weak capacitive coupling which would make it frequency sensitive. The lower the freq, the poorer the coupling. The schematic shows part #3- "Capacity obtained by twisting the ends of two wires" on the grid of the input tube- this is the only part that sees all of the input freqs and is not part of a resonant or feedback circuit. I would look closely at this twisted pair of wires- maybe they have been unwound or run too closely to ground. You could probably replace the twisted wires with perhaps 10 or 20pF of fixed capacitance.
'
Pete AI2V
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