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Marconi.
Conversion of Emergency Service Radios
RC675/04
16 channel 12.5 KHz spacing AM / FM.
P Band 79 – 102 MHz earlier version.
Originally made by GEC McMichael in Slough.
RC675/07 240
channel 12.5 KHz spacing AM / FM.
Marconi.
RC640
99 channel 12.5KHz spacing FM only.
RC690
256 channel 12.5KHz spacing AM only.
More information on the Marconi RC640 (including ROM images)
here (Ant
M1FDE's website )
The
Marconi RC675/07 143 - 156MHz AM -
FM.
Boot mounted mobile 240 channel.
Beware! RC675/04
79 – 102 MHz P Band old police band sets look identical to the /07
version...read the serial plaque carefully.
These are only good for donor bits to mend High Band version.
Beware! There are two control
boxes...................
MTR110 is 16 channel only
MTR111 is 240 channel and is noticeable by the extra BCD type switch inserted on
the front panel of the control box labelled 1 to F.
The 16 channel control box can be modified with a 15 way BCD type switch which
can be found surplus at rallies and in junk boxes.
There is one EPROM to change to put the set straight on 2 metres
AM & FM switchable 12.5 KHz channels.
The
Marconi RC690 256channel 143 – 156 MHz & 71 MHz AM only.
Some 9750 RC690/A1 sets for Simplex were bought in 1985 – 1986.
High Band 2500 RC690/A2 Duplex VHF-VHF repeater sets were also bought.
950 RC790/A3 fixed station mobiles High Band & Low Band.
6100 RC690/B1 Fire Brigade Simplex sets bought Low Band.
275 RC690/B3 VHF section of VHF-UHF repeater Low Band .
Marconi RC640 99 channel 143 – 156
MHz FM only. Used by Metropolitan
Police. One internal battery backed
ram memory chip for frequencies, if removed from socket goes blank almost
immediately. An ESQUARED PROM /
EPROM can be put in place to bring set onto 2 metres 12.5 KHz channels with no
other component modifications.
As the RC690 is AM only and its control box is difficult to change channel fast
due to having to press the* button and enter channel number required.
It is a poor set to put on 2 metres.
Marconi RC790 is a RC690 in two base station 19 inch rack trays, which will only
have 99 channel capability. The
second tray holds a 12 volt Switched Mode PSU that powers the RC690 in the first
tray.
The RC640 is a shorter boot mounted set but looks the same as the RC690.
It is FM and channel change on similar control box method to the rc690.
But can only be used on 99 channel 12.5 KHz.
160 channels are required to cover 144 – 146 MHz 12.5 KHz spacing.
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