SBE 100X microphone

[Smokinone]

Well, I've seen a couple of threads on this, but not seen any real solutions. Trying to wire an old SBE100X to a cobra 4 pin. What I have done, is wired the shield to pin1, the audio to pin2, the TX on pin3, and what would be the RX on pin4. With that configuration, no receive, but do have TX. I've seen one diagram shorting pin 1 & 4...that does give receive, but doesn't drop the RX, when going into TX. It seems that it need a different set of contacts than it has in my microphone, or an extra one somehow. I don't know if there were different configurations of the switching for the 100X or not. I have 2 and they seem the same.




Am I wrong about the need for different contacts? I think these would be a nice sounding microphone, but, has special needs to connect them from what I am running into with this thing. Initially the 4 pin was wired for pin1 open, pin2 audio, pin3 TX and pin4 had the shield and receive tied together. That works great as long as I just want to TX and not RX

Has anyone any ideas?

Thanks

 

[TM86]

IIRC, the SBE 100X was designed for relay switched radios. If you're trying to connect it to an electronically switched radio you're going to need to either modify the microphone or figure out a way to wire up a relay or some other circuit inline to switch between the RX and TX lines being grounded when the PTT button is pressed.

The attached pdf is an illustration of how it could be done. For a 4 pin radio you'd just tie shield and ground together. Where to get the +V for the relay is going to depend on what the coil voltage of the relay you're using is. Of course, this is just off the top of my head, I haven't built or tested that to see what new problems it creates trying to solve the one you've got. Chances are someone here has done something similar and may be able to provide a bit more practical advice.

Oh, and I forgot to put a back EMF prevention diode across the coil leads on the relay. D'oh!

 

[Smokinone]

I think you are correct on the relay switching. I don't have any radios that have that feature. I was kinda hoping there was a magic pill so to speak, as the mic sounds pretty good. I will probably just try and sell the 2 I have to someone who might have a radio that could use them. As it is they're just display units to me.
Thank you TM86

 

[sunbulls]

I can’t remember what particular mic that I applied this mod to years ago. Anyway, I removed the existing contact assemble, and replaced it with a set of similar long bladed contacts taken from and old telephone relay. Those typically had stacks of multiple NO and NC contacts. I removed the individual blades and spacers that were not needed, and recreated my own appropriate assembly. For mounting, a small L bracket was also added.