Vintage UK Police Wireless
Below is a copy of the original description of what must have been one of the first,
(if not THE first) police wireless schemes in the UK.
It is hoped that the theme of vintage police wireless communications, from the pre-war
days, up to the F.C.P. (Frequency Change Programme) of the mid-1980's, when the
Home Office maintained users moved out of Band II, can be expanded on this site.
But first I need your technical information, stories, pictures etc... So if you have anything
suitable please email me HERE (Netscape users) or HERE (IE4/5 users) and I will
add the information to this site. Thanks !
(Please note: this is a new email addresse...the previous address was closed due to the
build up of enormous amounts of spam, so if you have emailed me any information in
the last couple of years, please try again. Thanks ! ).
BRIGHTON POLICE POCKET WIRELESS SET
The Brighton Police Wireless Scheme was first commenced on 22nd January, 1932, when a 100 Watt
transmitter operating on a frequency of 147.8 metres (2030 Kcs) and manufactured by Plessey was
installed in the Town Hall at Brighton. Various teething troubles were overcome and on 14th September,
1933, the Pocket Wireless Receivers were brought into general use for patrol constables. The pocket
set was of the one valve type consisting of two pieces of apparatus, the receiver and the earphone. The
former contained the dry battery and the accumulator, while the latter incorporated the calling device.
A length of cable to which was attached a plug connected the two parts. The overall weight was under
four pounds.
The receiver was carried in one pocket and the earphone in another. The bell on the earphone unit rang
when the transmitter was switched on. Taking the earphone from the pocket, the constable pressed a
small knob at the side and listened for the voice of the operator. This calling up device was the
important feature of the set as it had the effect of making the instrument like a telephone. The sets were
capable of receiving messages at a distance of about six to seven miles from Headquarters. There were
thirty sets in daily use.
The primary advantage of the pocket radio system was that messages could be passed quickly, thus
enabling the man on the beat to act immediately.
Technical Description
The pocket wireless set was constructed in two parts:-
(1) A bakelite box 6 1/2" by 4 3/4" by 1 3/8" containing the receiver itself and LT and HT.
(2) An aluminium case 6 3/4" by 4 3/4" by 1 15/16" by 1 3/8" containing telephone earpiece, bell
and relay. Attached to this portion was the three wire cable which plugged into the set portion
and "switched on" the receiver. The weight of the complete apparatus was about 3 1/2 pounds.
The receiver had one valve, using a Hivac "XL" filament, consumption .067 Amp. The circuit was
an Armstrong super-regenerative and tuning was by a preset condenser, reaction was adjusted by
varying two coils 3/4" diameter, both aerial and reaction coils wound with 90 turns of 32 gauge
double silk covered wire. The aerial consisted of 8 to 2 turns of 32 gauge D.S.C. or enamelled
wire wound in a shallow groove around the edge of the receiver.
Operation of relay and calling up bell
The bell circuit was connected to the L.T. battery, in parallel with the valve filament and across two
adjustable points in the relay. The anode current flowing through two moving coils in the relay tended
to pull the adjustable contacts apart, they being adjusted to a distance of 1/8". When the transmitter
was switched on, the reception of the carrier wave caused a reduction of anode current (normally
approximately .25 of a milliamp) by about 25%. Due to this reduction, the adjustable contacts in the
relay fell together closing the bell circuit. In order to listen in, the user of the receiver pressed a button
switch which again broke the bell circuit. On the cessation of the transmission, the anode current rose to
its former value, pulling the adjustable relay contacts apart and breaking the bell circuit once more.
The valve was of the bayonet type, connections being soldered to it. This was found to give less trouble
than the pinned type used in a valve holder.
The box portion of the receiver was provided with a lid, secured by four spring clips and was easily
removed for the purpose of changing batteries, examining and repairing the set.
Photos of 1950's and 60's eqpt rooms and mobiles to follow
A few 1950's pics of the 'Police Mobile Column'. If you know anything about
these purpose of these vehicles, please email me. Thanks.
More Photos of 1950's and 60's eqpt rooms and mobiles to follow
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