Hi there I was clearing out some junk in the loft in my grand dads house I found this in the loft he hasn't a clue what it is ,it's been there before he moved in .could anybody tell me what this circuit is used for I'll send pictures it looks years old .the rf module is bgy438/H.any help would be good thanks guys !!!!

 

With the 'code' thumb wheels and crystal section. I would guess it is part of a tone coded radio "party line". They were used like telephones back in the day. The receivers would not unsquelch unless the transmitted signal contained the proper tone codes. So you could radio your ranch hand and the repeater would get it and retransmit the signal, the ranch hands radio would have a tone detector and if you transmit the same low freq audio tone his radio will un-squelch and he will hear your message.

 

With the 'code' thumb wheels and crystal section. I would guess it is part of a tone coded radio "party line". They were used like telephones back in the day. The receivers would not unsquelch unless the transmitted signal contained the proper tone codes. So you could radio your ranch hand and the repeater would get it and retransmit the signal, the ranch hands radio would have a tone detector and if you transmit the same low freq audio tone his radio will un-squelch and he will hear your message.

Ok thanks for your help there .so what frequency does this cover as I can't find anything to do with a bgy438/H rf module .i assume it's out dated ?

 

 

That's the bgy438/H module when you zoom in you'll see it thanks

 

Thumbnail Incase it's to large for you all !!

 

I again offer an educated guess. That unit is a custom IC designed to perform the decoding. We used a "tuned element" in the analog version. Receive the right tone and the element would resonate and create the signal used to open the squelch. That custom IC could be designed to use DTMF or several other decoding schemes. It is pretty much junk if not used for its custom purpose.

 

Ok thanks for your help there .so what frequency does this cover as I can't find anything to do with a bgy438/H rf module .i assume it's out dated ?

Try datasheets.pl

 

I again offer an educated guess. That unit is a custom IC designed to perform the decoding. We used a "tuned element" in the analog version. Receive the right tone and the element would resonate and create the signal used to open the squelch. That custom IC could be designed to use DTMF or several other decoding schemes. It is pretty much junk if not used for its custom purpose.

You know I believe your saying it looks like junk it powers on ok with the red light at the front and heats up the heat sinks so I'm assuming there's life in it .i always say the good old days the stuff work and last longer than any other circuits that are made today so no technically junk .are you meaning were the 4 white circles is thumb wheels are they not called Pll rotate switches ? Just like dip switches but different .so do you mean you used a squelch device that connects to the bgy438/H ? I thrown a power meter on it it gave me 13 watts but dunno what frequency it's on according to the white circles I see 1021 is that 102.1mhz you reckon ?

 

I doing the best I can based on some pictures.
Whatever it is, it has gone to the same place horse buggy whips went. You may get it working, but other than a museum piece whatcha gonna do with it?

 

I currently have found it works on 102.1mhz and found a variable on it the transmitter power went up to 23watts .and its Pll phase locked looped .i also noticed it it tuned on 70-108mhz on the frequency counter I borrowed .then I did more frequencys it covered 144mhz to 200mhz.so it was good to know that it covered all those frequencys for a transmitter that is most likely 20 years old .so I took it to a charity shop and gave it to them for free . They were delighted to have it .