Speedcall DTMF Decoder ?

[WA6OXN]

Hi All,

I came across this Speedcall DTMF decoder and I am looking for a manual, schematic, or information on connecting the unit to power. There doesn't appear to be a model number on it anywhere and there are no markings on the rear terminal strip. I can probably figure it out as far as power and audio, the tricky part is there is some strapping to set some basic logic and relay control.

It's 19" rackmount, has several cards, extender card for servicing, 10 buttons on front marked CH.1 thur CH.10, and a switch marked squelch disable.

Thanks for any assistance! -Steve / WA6OXN

[d119]

While I'm not familiar with the unit, it may be some sort of base station ANI decoder instead of an actual controller.

What are you wanting to do with it?

[WA6OXN]

Here's a quick pic of some of the cards. You can see the analog DTMF PLL portion. There's even a spot on the board for the 4th column of tones. It's kind of similar to those old western electric KTU-247B cards.

I just hate to chuck it in the trash. It looks like it's actually fairly well made. Might make for an interesting interface to something.. I just thought it might jog someone's memory if they've seen one before.

http://i444.photobucket.com/albums/qq16 ... e30c0d.jpg

[Will]

That IS REALLY old... a long long time ago.

Probably a aux receiver or voting panel.

[Bill_G]

Lordy - haven't seen one in years. That is the dispatch decoder unit with no display. All it did was light an LED. It's vintage 80's product. Encoders went in the trucks. Someone would push button 1 (CH 1) in the truck, the encoder would key the radio, spit out four dtmf tones, the base would receive it, and the decoder would spit an ACK back to get the truck encoder to shut up. All you heard over the air was beedledeep ... beedledoop ... boodledoop ... beedledoop. Later versions put a display on so you could encode the truck number as well as the button number.

The buttons were defined by the customer. Cabs (for example) could define button 1 as off duty, button 2 on duty, button 3 driving with fare, button 4 stopped with fare, etc etc. Whatever they want. We used to use dymloabels to mark the boxes. Later on you could get silk screened faces.

The final versions, before Speedcall went under, had serial interfaces to tie to a PC running a DOS app that could display all the vehicle numbers with their current status. The encoders in the vehicles had mute gates to kill the local speaker so the drivers didn't have to listen to the turkey farts all day.

As far as finding service lit on that stuff, that could be tough. We got rid of our manuals several years ago after the last customer pulled their Speedcalls out.

[WA6OXN]

That makes sense, the boards and the front have 7414 marked by dymo labels. So at least that's a good start.

I must be getting old, I remember building (breadboarding) something like this for an old remote base back in the early 80's. Old LC network dtmf decoder.

Thanks for the info... -Steve/WA6OXN

[Bill_G]

It was top of the heap stuff. They had excellent analog dtmf encoders and decoders. Excellent LC networks. Fairly easy to understand and configure. Robust. Took abuse and dirt and vibration. Not too picky about the input power because they had good on board regs. The momentary buttons lasted forever. But again, all they did was send out a string of tones that lit a light at the other end. Pretty straight forward. if you are familiar with cmos ttl and opamps, you can almost reverse engineer them.