[Boatanchors] HT-37 VOX Relay

[Mark K3MSB]

I’m working on an HT-37 transmitter donated to our radio club.



The VOX Relay RY1 wants to close when I change the function switch from
STBY to MOX and I can see it move, but it will not travel far enough to
close the contacts.



R69 Is OK, and I measured the RY1 coil resistance to be 9.5K.   The various
voltage drops across R69 and the coil when the radio is in the MOX position
show a current of 5 Ma.



Specifically, the voltage drop across the 9.5K coil is 52V yielding 5 mA.   I
have no idea if these numbers are correct, but the current seem pretty
small.



The “Relay  Tube” V15B tested good, and I used a replacement with no
difference in relay action.



Measured voltages on VR15-1:  278/196,  and VR15-3  5.6/1.7
(STBY/MOX).   There
are in the ballpark.



I tested all the tubes etc, played musical tubes a while,  cleaned the
relay coil (bottom) with DeOxit,  adjust the screw adjustment on the coil
bottom etc.  Nothing helped the relay to perform as expected.



Also, the 0A2 VR tube will not light.   I tried 2 tubes (tested OK in a
tester) and both show about 150V on pins 1 and 5 as expected.   With the
OA2 removed, pin 5 is 187V.   It looks to be regulating, but I’d expect to
see some glow.



The bias measured at TP-2 is -49V.



Comments welcomed; I’m concerned RY1 is bad.


73 Mark K3MSB