04-04-2024, 09:47 AM
The BC band works just fine, cannot get the SW band to work, no oscillation. When the band switch is turned to SW the voltage on lug 3 & 2 on coil and pin 4 on the 6A7 tube drops about 40 volts. This is the secondary coil. On the 6A7 tube there is continuity between pin 6 & 5 of 50K (R10). When the 300 ohm resistor (R9) is lifted removing ground, there is no ground from pin 5 or pin 6 to ground.
If the lugs 4 & 5 on the coil are shorted the voltages drops, if the cap (10) and lug 1 are shorted of the coil the voltage will drop.
I rewound with new wire the secondary coil, lug 2 & 3 (3.4 ohm), did not change anything.
There are 4 switches on the band switch, the antenna switches do not cause the voltage to drop only the switches on the osc coil.
The B+ voltage is not affected when in SW mode, at the 32K (R14) only after the resistor is there a voltage drop.
I think there may be a problem in the osc coil, but what.
Thanks
If the lugs 4 & 5 on the coil are shorted the voltages drops, if the cap (10) and lug 1 are shorted of the coil the voltage will drop.
I rewound with new wire the secondary coil, lug 2 & 3 (3.4 ohm), did not change anything.
There are 4 switches on the band switch, the antenna switches do not cause the voltage to drop only the switches on the osc coil.
The B+ voltage is not affected when in SW mode, at the 32K (R14) only after the resistor is there a voltage drop.
I think there may be a problem in the osc coil, but what.
Thanks
Jim
Spring Lake MI