By Carl Solomon W5SU
A couple years ago I heard a guy on 20M talking about using a Bearcat wireless speaker-mic, so I decided to try it. The model number is BC906W and it’s actually intended specifically for Uniden Bearcat CB radios. The receiving/transmitting unit is a cradle that mounts to the wall and has a cable which is terminated with a 6 pin mic plug dedicated to one of the Bearcat CB radios.
I’ve adapted it for my transceiver, a Yaesu FTDX-3000, with a simple interface box, and have used it successfully on HF SSB. It can be used for either HF or VHF/UHF radios. Its’ range is claimed to be up to 100 yards, so I’m able to carry on a QSO while physically away from the radio… either from the sofa in my den, the bedroom, kitchen while having a meal, or even on the front or back yard. It’s even worked from across the street as far as a couple of houses up the block. Still another application is the ability to remotely key the transmitter to put out a carrier while pruning a dipole, checking power or SWR, or making other adjustments while at the antenna.
I’ve gotten good audio reports and, though not perfect, whatever it may lack in quality is more than overcome by the convenience it offers. It even has a volume control.
The cradle receives the audio from the radio’s speaker jack, and transmits it wirelessly to the mic’s speaker. Then when you key the wireless mic, PTT is activated, you speak into it, and your audio is transmitted back to the cradle which inserts that audio into the transmitter.
Rarely do you see ham rigs with 6 pin microphone jacks, so some modification was needed. One option was to cut off the 6 pin connector and replace it with one that would plug directly into my transceiver. But I decided to leave it intact so as to not void the warranty, or in the event I may sell it someday. I also didn’t want to commit its use to only one radio. It also needs a 8VDC voltage source, which is normally provided by the CB radio. With a little research on the Internet, I was able to find the pin-outs for the connector. So I made a little interface box to make it more generic. I used a 7808 solid state regulator chip to get 8 VDC (Fig’s 2 and 3).
The wiring out of the RCA jacks could either go to the ports on the radio’s rear panel for PTT, Transmit Audio and Speaker jack…or else to the appropriate pins on a connector plugged into the mic jack. (Fig 4.) For your particular radio, simply find out which pins on your mic jack are for Audio, PTT, and ground, get received audio from your speaker jack, and find 8V from somewhere, then see that those find their way to pins 1,3,4, 5, and 6 of the connector from the cradle.
The unit is made by Uniden and described as BC906W Wireless CB Microphone. It’s currently available and I’ve seen it online from about $50’s to$90’s. Parts for the interface box cost me $10-15. Oh how I miss Tanner’s! I got my parts at Altex in Carrollton.
