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-   -   GPO Jack unit 1B and regulator 6B (https://www.vintage-radio.net/forum/showthread.php?t=167151)

Sparks 25th May 2020 11:08 am

GPO Jack unit 1B and regulator 6B
 
Quick questions. Does this regulator do the same job as the reversible regulator in the 706 ?
If not, what exactly is its purpose and is it essential to have it fitted ?

Thankyou.

198 kHz 25th May 2020 5:50 pm

Re: GPO Jack unit 1B and regulator 6B
 
It was to prevent transmitter noise on short exchange lines or PBX extensions.
The jack units in my TRS used them, as we were just across the road from the exchange.
My recollection is that there wouldn't necessarily be noise without it, but without cuent limiting by the 6B the transmitter insert in the headset could 'fry' in the long term.

Sparks 25th May 2020 8:40 pm

Re: GPO Jack unit 1B and regulator 6B
 
Thankyou 198.

198 kHz 26th May 2020 12:21 am

Re: GPO Jack unit 1B and regulator 6B
 
..👍🏽

dagskarlsen 28th May 2020 12:44 pm

Re: GPO Jack unit 1B and regulator 6B
 
Quote:

Originally Posted by 198 kHz (Post 1252038)
It was to prevent transmitter noise on short exchange lines or PBX extensions.
The jack units in my TRS used them, as we were just across the road from the exchange.
My recollection is that there wouldn't necessarily be noise without it, but without cuent limiting by the 6B the transmitter insert in the headset could 'fry' in the long term.

How did that regulator work? Was it just 2 resistors to make voltage and signal loss like a longer line? Never seen that, but I have seen some fried carbon transmitters.

dsk

Sparks 28th May 2020 6:20 pm

Re: GPO Jack unit 1B and regulator 6B
 
1 Attachment(s)
Here's a picture of the regulator. I've taken it out of the unit but it fits between T11 and T17 on the circuit board. It appears to be two similar-looking components soldered to a coil. More than that I really can't say!

Dave Moll 28th May 2020 7:12 pm

Re: GPO Jack unit 1B and regulator 6B
 
Quote:

Originally Posted by Sparks (Post 1253275)
It appears to be two similar-looking components soldered to a coil.

The "two similar-looking components" look like diodes to me - in opposed polarity.

dagskarlsen 28th May 2020 7:36 pm

Re: GPO Jack unit 1B and regulator 6B
 
Quote:

Originally Posted by Dave Moll (Post 1253301)
Quote:

Originally Posted by Sparks (Post 1253275)
It appears to be two similar-looking components soldered to a coil.

The "two similar-looking components" look like diodes to me - in opposed polarity.

Agree, but regular diodes in opposed direction would not be to much help, but as Zener diodes it could give a suitable voltage drop. Things like that makes me wonder how they did figure out the solutions.

dsk

Sparks 28th May 2020 8:53 pm

Re: GPO Jack unit 1B and regulator 6B
 
I'm afraid I haven't a clue. I just put wires and straps and things where the experts tell me. The circuit board in this jack is largely based on that of the 746 telephone, but I've never seen this regulator in a 746, unless it has a different design.

Dave Moll 28th May 2020 9:06 pm

Re: GPO Jack unit 1B and regulator 6B
 
I think that regulator is specific to the Jack 1B. I have a 1B with a similar one. The 700 series 'phones use a regulator of a completely different design.

dagskarlsen 28th May 2020 9:39 pm

Re: GPO Jack unit 1B and regulator 6B
 
Thank you any way, one day we will find it out.

dsk

Pellseinydd 28th May 2020 11:04 pm

Re: GPO Jack unit 1B and regulator 6B
 
Quote:

Originally Posted by Dave Moll (Post 1253357)
I think that regulator is specific to the Jack 1B. I have a 1B with a similar one. The 700 series 'phones use a regulator of a completely different design.

The Vocabulary of Engineering Stores states "only used with Jack Unit 1B (not earlier 1a) and used to stop 'frying noise' when used wit a Headset No 1"

Sparks 29th May 2020 7:56 am

Re: GPO Jack unit 1B and regulator 6B
 
I wonder if the 3T earphone element had a problem with the jack unit ?

OscarFoxtrot 29th May 2020 8:22 am

Re: GPO Jack unit 1B and regulator 6B
 
The 3T was possibly more sensitive.

When used continuously by operators on public exchange switchboards, the receiver may be too loud for comfort. Under these circumstances the sensitivity should be reduced by shunting the receiver with a Resistor, Carbon, No. 4, 150 ohms. When used at PBXs this shunt is not required since an 180 ohm series resistor is provided in the operator's circuit.

jack units for headsets were usually used on Key and Lamps.

https://www.britishtelephones.com/head2.htm
https://www.britishtelephones.com/jackunit1.htm

What we'd do without Mr Freshwater's magnum opus website, I do not know.

Dave Moll 29th May 2020 8:34 am

Re: GPO Jack unit 1B and regulator 6B
 
... and its companion archive of wiring diagrams from Sam Hallas.


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