[Hallicrafters] [From Your Hallicrafters Reflector] SR-150 CW and 40 meter Issues

[Walt Cates]

Juan,

Since VOX is working in SSB it is most probable a wiring problem in the function or operation switch.  From the video It sounds like in CW, VOX mode K1 is energized all the time and K2 and K3 are coming in with the key down. Check pin 6 of V19B. In CW mode it should be 250 vdc in key up (receive mode) and drop to about 130 or so with the key down (tx mode). If it is 130 or so in CW, VOX with Key up and down and since it seems to function properly in SSB mode, the fault would most likely be wiring between the function switch and the operation switch. But first turn the DELAY (R155) fully counter clockwise and try it. Check ( operation switch) S6 rear, pins 2, 3, and 4 for continuity, they should all be shorted in VOX and have continuity to ( function switch ) S5 rear pins 2 and 3.

One other thing to check. Some people have added bypass capacitors to V18 pin 8 and pin 3 to increase the gain of the mic amp. Not a good idea. This causes the mic amp to oscillate. In SSB mode it may or may not be detected depending upon the frequency and amplitude of the oscillation. In CW mode it is enough to trigger V19B. Some times it is so bad you can hear it in receive mode as a constant low level tone in the receiver all across the band.

Best Regards, Walt Cates, WD0GOF, http://www.myhamshack.com/WD0GOF/<http://www.myhamshack.com/WD0GOF/>
ISAIAH 5:20

My home town http://www.youtube.com/watch?v=PJk8XIPEDeI<http://www.youtube.com/watch?v=PJk8XIPEDeI>