Hallicrafters CB-3A restoration help needed!!

[The Shadow]

I'm in the process of restoring an old Hallicrafters CB-3A tube base unit and I've run into a snag. I'm hoping you guys might have the answer for me. I've already recapped it, changed resistors and tubes that needed it and installed good crystals.
It transmits and receives but my problem is with the transmit / receive relay circuit. The relay is not closing on transmit. This has a 2 pin mic jack where one pin goes thru a .001 cap to ground and the other goes to the relay. The mic I'm using is an old 2 pin Heathkit (I think). When I press the ptt on the mic nothing happens with the relay. If I manually push the relay contacts closed while keying the mic I get rf output and modulation. So, something in the circuit is preventing the transmit side of the relay from closing like it should. Now, I've restored many tube receivers but this is the first transceiver I've ever worked on and I'm stumped. I'm hoping one of you guys have worked on one of these sets before. Any and all help will be greatly appreciated and I'll remember you in my will!

Terry

[The Shadow]

Surely one of you gray beards (I have a beard and it's gray so don't be offended, it's a term of respect.) knows the answer to this!?


Terry

[KPF-2487]

I have a hallicrafter cb3a the relay is operated by the mic grounding it. shield braid is ground, one wire is mic to first af, other wire to relay.relay coil OK? It uses filament voltage for power-ac when set up as a base-dc through a 22 ohm resistor when wired for mobile...yes it can do both,it has a vibrator hv circuit...sucks alot of juice.I found a schematic on either cb tricks or BAMA.Good luck with the "hollowstate"electronics.Cool old stuff.

['Doc]

How is that HeathKit mic wired?
- 'Doc

[The Shadow]

I finally figured it out. The problem is mechanical not electronic. One of the 2 contacts on the relay arm that moves up and down is not making contact by a hair. It sits just that much lower than the other contact. I haven't been able to get it adjusted yet though. I get one side adjusted and the other side drops a hair. I'm thinking of soldering a shim on the lower contact to hopefully give it enough extra material to make contact. Otherwise the set sounds great over the air.


Terry