Electronics archaeology

[N8YX]

A thread in which we bring to light obscure/unknown electronics products then try to identify the manufacturer - and the reason for the device being produced.

My latest acquisitions - a pair of Tek TM500 power modules (a 501 and a 502) with one each "Universal Monitoring Module" mounted in them - fall into this class. The Modules look to be an audio amplifier/tape recorder interface which will accept an unbalanced, microphone-level input and trigger an internal relay if the applied signal rises above a panel-presettable level. High and low-cut filters are provided, each controlled from the front panel. A Headphone Out jack (w/ level adjustment) is provided on the front panel and a Line Out jack with NC/NO relay contacts is installed on the back.

These aren't someone's hacked-together DIY modules, either. They incorporate commercial quality double-sided CCAs and professionally fabricated, silk-screened front panels. Shielding is extremely well executed - better, in fact, than in a lot of Tek's OEM offerings. Yet, there is absolutely no manufacturer data or related information present on any portion of the constructs.

Shown here is the TM501/Module I won; the TM502 was set up for two Modules but only came with one. Any of you BCast Eng types know what these are and who made them?

11019

[Jeff K1NSS]

No clue but cool puzzler!

[kb2vxa]

If it wasn't a relic from the Jersey Shore you wouldn't know. (;->) Then I wouldn't know either but I know a good use for it, monitoring a radio channel and recording transmissions. Now I can do it with my software for programming and operating my scanner, digital audio files are saved to HD time and date stamped so I can "listen" in my sleep.

[K7SGJ]

Could you find anything on them in the catalog I sent you?

[N2NH]

Seems to be 70s-80s vintage. Never had them at any of the facilities I worked at though. Maybe used in a radio station to trigger a reel-to-reel recorder remotely for remotes that had a variable or unknown start time. Sometimes a company name is on the rear panel. Not rack mountable in any case, so it might be portable too.

[N8YX]

Eddie:

Not in the catalog - this wasn't a Tek construct.

John:

They're indeed portable, and the power modules have been modified to include a set of binding post input/output strips on the rear panels.

Interestingly enough, a Radio Shack/Archer alarm module was used in them and it's clearly labeled as such.

[KG4NEL]

Ze missiles will launch in five minutes!

[kb2vxa]

And when they do...

[N8YX]

I got the dual power module fixed, along with the Monitoring Module that came with it.

But there's a problem.

Apparently, whomever designed this thing thought it would be a good idea to couple 115VAC to the "ring" microphone connection at the rear panel of the unit, ostensibly to minimize common-mode AC hum pickup.

That's a right nice way to let the factory smoke out of your other Tek plugins when they're feeding the Monitoring Module with AF energy...yep...

[kb2vxa]

Interesting, back in my CB daze during a repair of a tube set I found someone had wired the PTT to the ring contact on the 1/4" phone jack for the mic, not the original I'm sure. I was wondering what the crackle from the mic was when I plugged it in. Good thing it had a crystal cartridge, a dynamic would have gone POOF.