Author Topic: Telephone line tap equipment.  (Read 905 times)

Offline dsk

  • **
  • Posts: 3794
Telephone line tap equipment.
« on: February 23, 2012, 12:19:02 PM »
This unit was made for use in the exchanges during the "cold war"
I have a few, probably new and unused ones.

The pictures and wiring diagram tells a lot, but why.

I know a lot of politicians at the left side claimed to be under surveillance, and later this has been confermed by the authorities.

dsk
« Last Edit: February 23, 2012, 12:22:03 PM by d_s_k »

Offline G-Man

  • **
  • Posts: 1957
Re: Telephone line tap equipment.
« Reply #1 on: February 23, 2012, 01:43:44 PM »
This unit was made for use in the exchanges during the "cold war"
I have a few, probably new and unused ones.

The pictures and wiring diagram tells a lot, but why.

I know a lot of politicians at the left side claimed to be under surveillance, and later this has been confermed by the authorities.

dsk

It looks like a standard recorder-coupler that was used for many legitimate purposes.

Here in the states Western Electric and other manufacturers produced almost identical units and were used by radio stations, fire/police emergency lines, dictation, call center customer service monitoring, etc.

Is there any supporting information that this unit was intended for the surreptitious recording of conversations?


Offline dsk

  • **
  • Posts: 3794
Re: Telephone line tap equipment.
« Reply #2 on: February 23, 2012, 02:21:42 PM »
More likely you are right. That spy thing makes it a little more exciting.

I can remember from the radio, the politicians told us, short after ended conversation, the lifted of their receiver for making a new call, and the could listen to a playback of their last conversation.

Rather amateurish, or what?

dsk

Offline Bill

  • **
  • Posts: 594
Re: Telephone line tap equipment.
« Reply #3 on: February 24, 2012, 12:25:13 PM »
Not to hijack the topic, but I've never found that a simple phone-line coupler such as that in the diagram works very well. The problem was always that the outgoing audio level on the line is MUCH higher than the incoming audio level. The incoming audio, of course, has been through all the line losses and switching losses as it travels from the far-end set to the near-end set.

Ralph Meyer's book, and undoubtedly any number of others, discusses this. The phone itself can cope with it, anti-sidetone circuits being one major method. But the fact remains that coupling directly into the line has been a problem when I have tried it. Perhaps I never had an amplifier with a good enough AGC circuit.

I always thought that a better coupling point would be at the earpiece, where the levels have been equalized. Tough to do in a covert manner, of course, but for a simple and legitimate coupler, it might have some advantages.

Anyone done this?

Bill

Offline dpaynter1066

  • *
  • Posts: 128
Re: Telephone line tap equipment.
« Reply #4 on: February 24, 2012, 01:35:25 PM »
just use a suction cup inductive pickup,