Can someone identify what this is? Has Gpib and F connector, it's a transmitter! - Page 1
Forum section: electronics / testgear

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: December 19, 2015, 01:48:51 am
content: I picked this up having no idea what it was. I got it for a buck at the thrift shop, I saw a gpib port and F connector, the rest of the box is solid green steel, with a 4 pin power jack and key hole. when I opened it, it turned out to be some sort of transmitter... I cant find any data on it the FCC ID page doesnt even say much except its upper frequency is 845/890mhz. It is also marked audiovox cmt-3000 but is actually a Toshiba product... I thought at first maybe an NTSC transmitter but the frequencies don't match the RF channel list of frequencies.I live near a military base, maybe its something goverment? I have yet to rip the shielding off because If what ever it is works... and is useful I would like to do something with it. Unfortunately I have no idea how much power to feed it or why there is 4 pins, nor do I have a machine with a GPIB port.Any guesses are welcome all I can tell is it takes a key, and there is a duplexer along with a modulation, synths, and transmit section with a ton of Toshiba IC's mounted to the back.EDIT: Not an F connector it is a reverse BNC like on old linksys routers.....

author: knarf180
author_rank: Newbie
timestamp: December 19, 2015, 02:22:39 am
content: It has a model number on it. Audiovox cmt-3000.Its an old car phone. Here is a link to the user manual:http://www.manualslib.com/manual/212232/Audiovox-Cmt-3000.html

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: December 19, 2015, 02:40:01 am
content: That's not a GPIB port. It's just a 36 pin micro ribbon connector, AKA printer port. I also don't see an F or a reversed BNC, just a TNC.

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: December 19, 2015, 02:44:36 am
content: Hmmm well when I looked up the model I found the same thing, old car phone... the problem is not a single image shows a box like the one in my pictures. Sorry Ive never used a connector like that so I did not know what it was called. I had in deeed at first maybe this was the base and the phone plugged in to it... but the manual doesn't show this box at all.Im not saying it is not a piece to the car phone in that manual im just to young to have ever seen something like this, and why would a car phone have a printer port?

author: helius
author_rank: Super Contributor
timestamp: December 19, 2015, 02:55:45 am
content: The frequency range is consistent with an AMPS (or D-AMPS) phone. These services were basically all shut down by 2008. The frequency range is still off-limits to consumer radio receivers, although the proliferation of SDR equipment has made that unenforceable.The CN type plug is for connecting the handset, hands-free microphone, and maybe the car radio as well. It was common for car phone systems to mute the car radio when a call began.

author: TheSteve
author_rank: Unknown
timestamp: December 19, 2015, 02:57:57 am
content: It's just the interface connector they choose, it doesn't connect to a printer.Anyways, it's not test equipment...

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: December 19, 2015, 04:12:07 am
content: Well obviously not lol. I just saw saw what I thought was a Gpib connector and thought I made a cool score. Which I kind of did for some sub ghz RF stuff but not as cool as I thought. Why is there no RX can is it is a cell phone?

author: jitter
author_rank: Frequent Contributor
timestamp: December 19, 2015, 06:12:44 am
content: Quote from: Alex Eisenhut on December 19, 2015, 02:40:01 amOther names for it: "Centronics" and "IEEE 1284", was indeed used on printers of the pre-USB era (among other things).

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: December 19, 2015, 08:06:50 am
content: So basically this thing is just a huge through hole cell phone? The case could be reused but i bet theres a ton of cool RF parts in that thing you cant get anymore! Im still surprised there is no can ror rx.....

author: jitter
author_rank: Frequent Contributor
timestamp: December 19, 2015, 06:42:39 pm
content: Quote from: rwgast_lowlevellogicdesin on December 19, 2015, 08:06:50 amThe right can of the three big ones has "RX" printed below it...

author: helius
author_rank: Super Contributor
timestamp: December 20, 2015, 08:48:00 am
content: You can see a spot for an optional "message board" that would have been used for receiving or sending text messages. The unit precedes the advent of SMS, but schemes for text communication, like pagers, have been around a long time.