SENDER No. 9A and 9B

The Sender No. 9 was produced by PYE-TMC and intended as a retrofit for the Public Exchange Manual Switchboards.  Most public exchanges had their dials replaced with this sender.  A  Key-Unit No. 4/1 was plugged into the Sender.

They were also used as a retrofit for the PMBX No. 1 and as a standard fitting on the PMBX No. 11, both used on customers premises.

Sender No. 9A - Public Exchange Operator Switchboards when used with Key-Unit No. 4/1A.
Sender No. 9B - Public Exchange Operator Switchboards when used with Key-Unit No. 4/3A.
Sender No. 9B-1 - PMBX No. 1A and 11 switchboards.

The Sender No. 9A just had terminations.  The Sender No. 9B-1 had a flexible lead with a Plug No. 616A.  This connected to a Jack No. 83A which was wired to the switchboards power and dial terminations.  On the PMBX No. 1A a Voltage Regulator was required and wired into the power connections.

They could work on either 24v or 50v DC powered switchboards.

The Key-Unit No 4/1A, 4/1B or 4/1C was connected the jack on the Sender.

Terminations on the Sender No. 9

Terminal   Function
A - Power *
B - Power *
C - Power *
D - Earth
1 - Dial off normal contact
2 - Dial off normal contact
3 -  
4 - Dial Impulse contact
5 - Dial Impulse contact

* If used on a 25v power supply then A, B and C are all linked together.  On 50v systems only A is connected to power.

Sender No. 9A front view

Sender No. 9A rear view (showing solder terminations)
This picture shows a unit supplied to a non-GPO contact.

Sender No. 9B-1 front view

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Last revised: February 24, 2021