WorldwideDX Amateur Radio Forums

broncoman529 · #1 10-11-2005, 06:19 PM

I would like to wire up this beautiful Calrad 500c microphone:

to a standard 4 pin Cobra setup. The microphone has a dual crystal element. It also has a two wire cord, I think?(I will have the microphone in my hands by the weeks end to see for sure). I need to figure out the best way to wire up this microphone to work with my radios. I do not have any idea how to convert a two wire microphone to work with a more modern radio. Please help me.

Thanks,

Larry T.

Sonwatcher · #2 10-15-2005, 10:50 PM

I couldn't find anything but I will take a wild guess. One wire should be audio and the other transmit plus sheild. I would take an ohm meter and find your transmit wire while keying the mic. Then put the aud. and trans. wires on the corresponding pins for your plug for your radio plus the sheild. By the way they are great looking mics ! Let us know if you get it working.

broncoman529 · #3 10-16-2005, 09:51 AM

Well, It is working. I wired it a different way though, What I did was to take an XLR connector and modify it to plug directly into the top of an astatic amplified stand. I do have one problem though, Any ideas on how to fix it would be greatly appreciated. When I key up the microphone transmits a loud hum over the air while I am also modulating, Now if I bunch the microphone cord up in my hand the hum is almost gone as if I am sheiding it from interference. I have tried different wiring configurations and the problem persists no matter what I do. Is it possible the the microphone cord that is plugged into the top of the Astatic stand is to long(almost 4ft.)? Please help me, The microphone has great tone and audio quality exept the hum behind it.

Sonwatcher · #4 10-16-2005, 10:10 AM

I had that problem with a d104 and what was happening was a ground problem. It was leaving when I touched the base of the mic and the rf was going to me ! You might check your ground wire and sheild wire in the mic base or any stray strands in the plug.

broncoman529 · #5 10-16-2005, 10:26 AM

Yeah, there is nothing wrong with the Astatic base. I tried four different Astatic bases on 4 different radios and still I got that hum. If I plug in the original Astatic heads into those bases there is no hum at all, That is why I am steering toward the cord being to long. I do not understand the difference between the two wires coming from the Astatic microphone element and the two wires coming from the Calrad microphone attaching to the same place on the Astatic stand. The only difference between the the attachment point is the extra long wire from the Calrad. Any thoughts?

Sonwatcher · #6 10-16-2005, 10:34 AM

Just a thought because of the age of the mic. If you have a d104 with the E + R switch on the bottom, switch it to R and try it.
I still lean on the side of a ground conflict with the new mic. I have cord extentions I use to make my cords longer but have no hum.

WorldwideDX Amateur Radio Forums

Calrad 500c Pill Microphone?