When did they do away with transmitter relays in CB's

[Turbo T]

I've noticed many of the older 23 channel radios had them but some 23 channel units didn't. Don't think I've ever seen a 40 channel radio with a transmitter relay inside of it. The newest Cb I know of that still had the transmitter relay was a Midland I used to have with a build date of July 1974. I'm guessing around 1975 or 1976 they did away with them....anyone know for sure?

 

[RatsoW8]

Those big clunky relays went away with vacuum tubes.

 

[Robb]

The keying transistor took the place of the relay because it is much cheaper and took up far less space on the board . . .

When?
Dunno . . .

 

[mr_fx]

didn't the 858 boards use them?

 

[ExitThirteen]

The relays in the AM/SSB chassis got phased out with the introduction of the MB8719 PLL chassis around 1981. However, I think some revisions of the old Cybernet PLL02A AM/SSB chassis didn't have relays, and those were around in the late 70s.

For the most part, by the early 1980's the relays were a thing of the past.


~Cheers~

 

[KG6YGE]

didn't the 858 boards use them?

Yes, the TRC 457 and 458 realistics have them. Mine was a little sluggish, and had to cycle it a bunch of times to get repeatable receive performance. I think this unit sat for many years on a shelf, bought at a thrift store in Catlett Va. Probably used on a farm, before cell phones.