TELEPHONE No. 706
Telephone No. 706 Accessories
|Fig 1a - Green cord & Block Terminal No. 30||Fig 1B - Red cord and Block Terminal No. 52A|
The initial cords were three-way to allow an extension bell but no more. For extension plan working a four-way cord was needed and this became standard later. Fig 1a is a three-way cord and Block Terminal No. 30. Fig 1b shows a four-way cord (Cord Instrument 4/88) and the, by now, more common Block Terminal No. 52A. The cord and block terminal were supplied in colours to match the telephone body.
As on the handset the new cordage does away with the need for tie strings by using a moulded grommet glued to the cable sheath. The wrapped wire loops used in the past are replaced by the simpler and cheaper spade tags. Replacing a damaged cord is much quicker with the new type.
It is my opinion that the Post Office
exercised tight quality control over the quality of the plastics used in the
cords and grommets. The ones I have are all between 25 and 45 years
old, yet none have gone slimy and sticky. Some non-PO ones in my
collection have deteriorated like that.
|Fig 2a - Telephone No. 706 with button marked 'Press'|
|Fig 2b - Switch mounting
The switch is mounted in it's own metal mounting which fixes into a slot in the switch hook frame and then finally fixed by the smaller screw located to the left of the dial fixing screw.
Fig 2a shows a Telephone No. 706 with a recall button marked 'Press'. In Fig 2b you can see how it mounts onto the phone and fixed by the screw located to the left of the dial mounting retaining screw.
The button here is labelled 'Press' suitable
for recall or call exchange on a shared service line. A different
option button labelled 'On/ Off' can be used for a bell off function and it
works by having an additional foot to its rear arm. In Fig 3, this
button is show to the lower right and by pressing the 'on' side of the
switch causes the button to tilt sideways, so that it latches in the
operated position. Pressing the 'off' side of the switch causes the
switch to tilt the opposite way, thus releasing the latch and the button
springs back up. Simple and clever.
|Fig 3 - Different press buttons|
|Fig 4a - Additional springset|
|Fig 4b - Springset mounting - the two fixing screws can be easily seen on the switch hook upstand|
There are applications that require more
contacts to be operated when the phone is off-hook than are provided in the
basic circuit. A typical case is on extensions connected to a
Switchboard PMBX 2/.. Fig 4a shows a springset 1/DSP/1252 which has a
single make contact. Fig 4b shows one in situ in a phone that was a
PMBX extension. It fits on the right hand support pillar and operates
in the same way as the main springset on the left hand pillar. Other
springsets with different contacts were produced.
|Fig 5a - Buzzer No 32A-1|
|Fig 5b - Buzzer in situ|
This is a small DC buzzer used, typically, on
extensions on a Plan 105 or 107 to allow the main to buzz the extension on
an intercom call or to transfer the exchange line. It mounts using one
of the bell screws as seen in Fig 5b. It looks like a tight fit, but
there is room to get the case back on again - just.
|Fig 6 - Rectifier Element No. 205A (black item in centre of picture)|
|Fig 7 - Thermistor No. 1A-1 (black and yellow item)|
Rectifier Element No. 205A (Fig 6) consists of two diodes connected back-to-back - that is with the anode of one connected to the cathode of the other. It's purpose is to limit voltage surges to the receiver in order to protect the user against acoustic shock which could damage their hearing. It is fitted directly to terminals 1 and 2 as seen. Initially it was provided as an accessory but later it was fitted as standard as a routine safety measure. The style of construction varied by manufacturer. Some were in hard cases with moulded in spade terminals.
Thermistor No. 1A-1 (Fig 7) was generally used on shared service lines (party lines) to prevent bell tinkle when the other party was using the phone. It was wired in series with the bell, replacing the strap between terminals 16 and 17. The Thermistor has a high initial resistance preventing the bell from ringing. After a short burst of ringing current it warms up so that its resistance reduces sufficiently to allow the bell to ring. It always seemed to be the practice to push the Thermistor into the U-shaped cutout in the regulator to hold it firm.
Please note that the phone in Fig 7 is fitted with the additional springset and so it has an extra wire in the desk cord, coloured orange. The Thermistor is only fitted to show where it would fit - it was not there originally.
Lock No. 23
When this lock is switched on it only allows 999 calls to be dialled. A Dial No. 28 must also be fitted.
|Fig 8a - Wall Conversion kit|
|Fig 8b - Telephone No. 706 hung on wall|
The wall telephone in the 700-series, Telephone No. 711, was not available immediately. As some sort of stopgap this adaptation, right, was issued as Telephone No. 1/706, a rebadged version of Ericsson's N1065. Some private suppliers used the kit shown in Fig 8a to make wall telephones available without increasing their inventory by stocking the Telephone No. 711 separately.
The T-shaped bracket is fixed to the wall. The
Telephone No. 706 has its dial and outer number ring reversed and its feet
removed. The case fixing escutcheons are removed and replaced with the
chromed bracket. The telephone can then be hung from the top of the
T-bracket and fixed with the screw at the bottom.
Several other accessories were available and are listed below and in Diagram N808.
Local battery adapters comprising an inductor and two different extra springsets.
A dial dummy for use on CB and Local battery versions.
Additional connection strips, 6-way and 18-way.
Additional 2µF capacitor.
A watch receiver.
The list is proof, if proof were needed, of the versatility of the 706 design.
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