[Hallicrafters] Copper Caps and the HT-37

[Waldo Magnuson]

    The Copper tops are mostly made for the guitar industry and not 
Boatanchors.  Pin 8 on rectifiers usually goes to the filter circuit 
but in some of the Hallicrafters units pin 2 is connected to the filter 
circuit.  Look at the HT-37 schematic and you will see that for both 
the 5R4 and 5V4 pins 2 and 8 are connected to the power transformer 
winding.  In the 5R4 case pin 8 connection also goes to the filter 
choke but pin 2 for the 5V4 goes to the filter choke.  So what you need 
to do is get the Copper cap output (pin 8) over to pin 2 in the 5V4s 
case.  This is easy to do with a diode - just connect the anode of the 
diode to pin 2 and the cathode (the end of the diode with the bar) to 
pin 8.  A 1n4007 will do the job and it works good.  Be sure to 
disconnect the transformer winding from pins 2 and 8 and tape them.  I 
also put a label inside the chassis in case the next fellow wants to 
restore the 5R4 and 5V4.
73,  Skip  W7WGM