SERVICES POLICE / FIRE SYNTHESIZED RADIO CONVERSION NOTES UPDATED.
CIRCA 1985-86 ..
3.2 14th October 2005
G8EPR BEWDLEY WORCESTERSHIRE
Contactable VIA AMATEUR RADIO 6 METRE REPEATER .
USUALLY LISTENING EVENINGS/WEEKEND
There are six main 143 – 156 MHz wideband
boot mobiles, which have been used by Police & Fire brigades in Great
Britain since approximately 1986 through to the present day. All
with approximately output power of 25 watts. AM or FM switchable.
RC675/07 240 channel 12.5 KHz
spacing AM / FM.
RC675/04 16 channel 12.5 KHz
spacing AM / FM.
P Band 79 – 102 MHz earlier version.
Originally made by GEC McMichael in Slough.
RC690 256 channel 12.5KHz spacing
RC640 99 channel 12.5KHz spacing
400 channel 12.5KHz spacing
AM only set.
BE544MU 400 channel 12.5KHz spacing
AM / FM set.
BE540MU 10 channel 25 KHz spacing
UHF FM repeater set.
400 channel repeater VHF-UHF control
400 channel control box.
2 channel remote control box, waterproof.
256 channel 12.5KHz spacing VHF-UHF AM / FM.
For motorcycle use, using slim line vertically mounted flush green red button
control box. For VHF-UHF talk-through only.
Combined UHF 99 channel talk-through system.
(Circa 1990 plus).
Cleartone CM7000/A4 256 Channel 12.5 KHz spaced VHF-UHF AM/FM.
For vehicle use using horizontally mounted flush green red button control box.
For VHF-UHF Talk-through and UHF-UHF Talk-through.
CM7000RP / CM7500RP
12.5 KHz VHF-UHF & UHF-UHF Repeaters
Desktop mounted VHF-UHF repeaters using
CM7000FS VHF AM/FM mobile unit and two CH650 transmitter-receiver units as
a 5 watt UHF-VHF talk-through unit with fitted internal duplexer. No 2
metre or 70 cms conversion available yet.
Desktop mounted VHF-UHF AM/FM repeaters using CM7000FS VHF AM/FM mobile unit
and two CH650 UHF Tx-Rx units as a 5 watt UHF-VHF talkthrough unit with fitted
internal duplexer. No 2 metre or 70 cms conversion available.
Programming Instructions for Early Cleartone
CM7000-CM7500 VHF-UHF mobiles.
of these sets are now becoming obsolete due to TETRA & trunked public radio
systems coming on line since 2001, starting in Lancashire.
Most recently (November 2000) a large auction took place, organised by
RAMCO of Skegness Lincolnshire, of Metropolitan Police and others VHF-UHF radio
schemes. Several second-hand radio
dealers, e.g. Richard Allport Comms PMR, have been selling large quantities at
radio rallies in England and Wales. This
is only the tip of the iceberg, as other forces and brigades start to
(hopefully) dispose of there analogue VHF-UHF schemes.
Brigade schemes (in England and Wales) are exclusive Low Band. 70.5 - 71.5 MHz
receive. 80.0 - 82.0 MHz transmit.
Using Low Band wideband
versions of the Marconi & Burndept sets.
of the above sets are EPROM'ed
varicap synthesized for wideband frequency 143 – 156 MHz including 2
metres. 70 – 72 MHz and 80
– 82 MHz transmit & receive including 4 metres so to convert them to 2 or
4 metres requires virtually no tuning other than EPROM replacement.
keep a look out for these sets fitted in transportable suitcases, used as
emergency portable base stations and talk through systems. These suitcase
sets are usually in mint condition having not had a policeman’s or fireman’s
boot placed on them! Or fixed
station sets built into RS boxes desk mount.
Marconi RC675/07 143 - 156MHz AM -
FM. Boot mounted mobile 240 channel.
79 MHz – 102 MHz P Band old police band sets look identical to the
version - read the serial plaque carefully.
These are only good for donor bits to mend High Band version.
There are two control
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.
is one EPROM to change to put the set straight on 2 metres AM
& FM switchable 12.5 KHz channels.
Marconi RC690 256channel 143 – 156 MHz & 71 MHz AM only.
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 for use on Low Band.
275 RC690/B3 for the 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
using a 2716 EPROM.
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.
RC640 is a shorter boot mounted set but looks the same as the
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.
BE536MU 400 channel AM only 143 – 156 MHz
and 71 MHz. Some 2000 sets bought
BE540/A4 VHF-UHF repeater mobiles. Some
3250 bought circa 1985
BE544MU 400 channel AM / FM
143 – 156 MHz and 71 MHz.
Probably the nicest sets to mod for 2metres.
BE536MU AM only. But
easily modified to FM by adding 10 components to the existing unused FM
discriminator chip and noise limiter IC. Makes
the receiver AM / FM switchable or FM only.
Change two EPROMs IC315 and IC314 for 2716 PROM or 2816-2817A E2 PROMs and it
will come straight onto two metres.
Transmitter easily can be converted to FM by feeding attenuated AM audio
into the synthesized oscillator and hence wobbling it up and down.
As per the standard conversion of a Burndept-DYMAR
M2080 synthesized set
256 channel capability with easy to push up and down flip switches. See
more detailed conversion notes at the end of this article.
AM / FM version 400 channel ***
GOLD STAR RECOMMENDED ***
Identical set to the BE536MU but dual mode AM / FM.
No conversion required. Change the 2 EPROMs or 2764 or reprogram the two
fitted E2 PROMs and it will go straight onto two metres.
Both sets can be used with
the BE540 VHF-UHF talk-through control box, to give a crossband 2 metre / 70 cms
repeater facility. If used with a
Pye w15ut talk-through Westminster UHF or a
20 watt 10 channel crystal controlled Westminster replacement set.
Ideal for RAYNET purposes......
If you have no EPROM’s available to put the set on a 2 metre frequency, you
can fit in the EPROM sockets two 8 way bit switches and switch the address lines
up and down to get the synthesizer on to 2 metres, to test the set and control
box out OK. A toggle switch can be
fitted to switch AM / FM per channel or why not have 128 channels AM and 128
channels FM in pre programmed EPROM’s.
Cleartone MB7000 256 channel AM / FM
VHF/UHF mobile system.
Cleartone CM7000.A4 SAME SET
1990’s boot mounted mobile system. One
of the much later sets based on the CM7000. which comes fitted with two CH650 99
channel portable sets (less batteries) transmitter-receiver units.
One is receive only on UHF 99 channels.
One is transmit only on UHF 99 channels.
And one Cleartone
CM7000 boot mounted set VHF 143 – 156 MHz AM / FM
set. All this in one black crackle
finish enclosure boot mounted set, to give talk-through VHF-UHF and UHF-VHF. 2
metres – 70 cms.
accompanying Control Boxes are very flash in red-green/red white with no
protruding knobs, all flush touch buttons. If
the control box to boot set lead is missing, a standard VGA monitor lead female
to male will work instead.
But BEWARE Pins 6 and 7 may have to be REVERSED in such a lead in order to work
with some CM7000-CM7500 sets. The fault will manifest itself as the set
appearing not to power up properly and lighting up control box all lights
are E2PROM’s to change. One in each
portable set and one in the main set.
CH650 16 CHANN SETS
CAN DONE BY USING
KEYPAD OFF ANOTHER SET PLUGGED INTO THE NON KEYPAD SET.
PM100 Programmer which looks
like a CH650 but has a programming lead that comes out of the external
microphone socket on the side of the set and plugs into the mic socket of the
set to be reprogrammed.
see Picture on the website of this
CH650 99CHAN SETS
CAN ONLY BE DONE WITH
A PM200 Cleartone Programmer which
looks identical to the PM100
All CH650s will also require retuning of the front end and of course the VCO
in order to work on 70cms OK.
I HAVE NOW RUN THE SETS ON 2 & 70 USING some Cleartone software very
CM7000 VHF sets will lock up straight
away upon 2 metre frequencies when entered. But I do find that the
squelch control and set-up pots as shown on the bottom metal plate cover are
very touchy and it seems very difficult to set them up to trip the squelch
Some CM7000-MB7000 VHF or UHF sets can
be reprogrammed using a PM300 Cleartone Field Programmer unit which is
identical inside and outside to a PM200 Programmer. This uses a
CM7000-7500 type microphone plug lead To a CH650 type microphone plug.
So this programs through the
microphone socket but I believe that you can also program through the rear D
type 15pin plug of the sets. This would be the preferred way as some of
the repeaters and base stations have their front CM7000-7500 front panels
missing as they are used as boot sets only.
You cannot plug the PM300 programmer
into the front panel microphone socket of any CM7000RP -CM7500RP or any
Dual Band VHF UHF Cleartone front panel. These sets require the
Programmer to plugged into a temporary front panel plugged onto the internal
front of the CM7000-7500 boot set .
So if you can only program through the
microphone socket, then you need to have a CM7000-7500 Front panel assembly
with microphone socket to plug on to the programmer lead then unplug/remove
this DUMMY front panel after programming is complete.
Please note if you are unlucky enough
to only own either PM200 or PM300 then you can copy the EPROM from one type
and use it in the other type. Or you could possibly using the chip
select pin on the EPROMs then piggy back them in the programmer and switch
between the two devices? I have not tried this so if anyone has done then can
they please let me know.
CM7000 VHF sets using Poli 1.5 or
Poli 1.73 Software can be set for AM-FM per channel by the PM300 Programmer
but CS11 software (which has variable squelch) appears not to be programmable
AM-FM by a PM300 Programmer. This software can be used in a CM7500 UHF
Mobile as UHF is FM only.
To find out what software is fitted
look carefully upon switch on and in the first few seconds the software number
appears in the LCD window of the set.
By using a Computer Cleartone
interface and program software CM7000-CM7500 is another way of tackling the
problem of getting the sets onto the Amateur bands.
CM7500 UHF Sets (after Programming of
70cm channel frequencies with the PM300 Field Programmer) will require
retuning of the VCOs and front end trimmers to lock up and work upon 70cms.
The receiver is easily done by using a scanner and setting a signal generator
or 2 metre portable transmitter with dummy load fitted to RB0 433.000MHZ for
Then tweaking the receiver VCO
trimmer, as marked upon the bottom metal cover of the set until the signal
generator or 2 metre transmitter signal is heard in the loud speaker of the
The transmitter can be set up by using
the scanner to listen to the lowest 70 cm transmitter frequency programmed in
the set, and tweaking the transmitter VCO trimmer until it locks the VCO and
the scanner bursts into receive.
According to the Service Manual both
the transmitter and receiver VCOs should be set for 7 volts DC at the VCO Test
Point as marked upon the bottom metal cover of the sets for both VHF and UHF
Also there are some very clever people
around now who are capable of extracting the E2PROM information out as raw data
and rejigging its program codes to enable all of these above sets, (including
Marconi and Burndept types) to work on 2 metres - 4 metres and 70 cms. I am
however not able to do this and rely other Radio Amateurs to do this for me.
Boxes that stand vertically (not horizontally) are for Motorbike
mounting - MB7000 see pictures.
Note two colour types RED-GREEN and
WHITE-RED but both seem to be identical.
is just the two transmitter-receiver CH650 portables and separate CM7000/A
VHF boot mounted unit with horizontal GREY BUTTON CONTROL BOX or the upgraded
RED-GREEN flush control box for VHF-UHF / UHF-UHF Talk-through and normal VHF or
CM7000/A4/T (ALPHA Numeric Ranger Series
sets) and Cleartone PUMA CH150 200 Channel plus UHF Portables.
All The MB7000 - CM7000 sets above are
channel readout only.
ClearTone sets marked CM7000 A4/T are
Alpha Numeric Display sets which allows text in the display of the Control Box
or front panel so these can be reproggammed with text readout in them per
channel. They also use CLEARTONE PUMA CH150 200 Channel UHF portables in
the VHF-UHF repeater section instead of CH650 Sets. Again using a CLEARTONE
computer interface and software the CH150 can be reproggammed to 70 cms with
ease and a bit of tweaking of the VCO etc.
Pictures of CM7000 VHF FM 256 channel mobile
© Karim SU1KA 2005
prices are approximately
Sets only 15 to 25 Pounds.
Control boxes 5 to 10 Pounds.
Depending on whether complete or not. The
first BE536 released were scrap ones bought at a Leicester Rally in
approximately 1990 from an Burndept engineer who was selling off the prototypes
from the workshop / laboratories of FKI Burndept
At auctions the control leads tend to get split up into stillages and
sold separately to scrap metal dealers etc.
The Burndept/Marconi sets
RC675-RC690-BE536-BE544 all use standard Home
Office 36 pin D type female to male leads which can be easily be made up from
RC640 requires a 15 pin D type female to male lead.
The above sets and control boxes all require an identical facilities 15 pin D
type plug to be made up with audio and PTT straps in it.
are three straps to solder across in the facility plug 15 pin D
Pin 7 to Pin 15
Pin 5 to Pin 13
Pin 4 to Pin 12
must be plugged into both set and control box or audio/PTT won’t work.
The BE536 single Control Box also needs a 8 pin DIN plug at the rear marked LPCU
(Low Profile COntrol Unit) with shorting links.
In order for them to pass audio and work properly, the links in the Plug /
LINK PIN 1-2
LINK PIN 3-4
LINK PIN 5-6
Cleartone CM7000 and MB7000 do not require these plugs.
All microphone plugs are 5 pin DIN of the Pye Telecomms type but not the
same connections. All power plugs
are 30 year old 12 volt specification 6 pin
Pye Vanguard type.
retain the AM / FM function on your sets when converted and lets get AM back on
BURNDEPT BE536MU. AM/FM CONVERSION NOTES MAY 2004
Both the BE544MU AM/FM and the BE5365MU AM sets share the same PCBs board layout
as each other. But the BE544 being both FM-AM, has the FM discriminator,
the FM modulator and the AM/FM switching components added. Therefore it
would be possible to convert a BE536 to a BE544 by just the addition of extra
components. The 20 watt - 25 watt PA unit at the back is identical in both
sets and further more is wideband from 143 MHz - 156 MHz. Also the manual
states that it is capable of running 70 watts out.
So here are my modification notes for transmit-receive to FM/AM on the BE536MU..
BE536MU AM 256 CHANNELS 143 MHz - 156 MHz SYNTHESIZED TX/RX RECEIVER
AM/FM SWITCHABLE MODIFICATIONS.
Locate IC2, MC3359P, 2ND mixer IC, on the BE536 RX PCB side.
This is the identical IC used on the BE544 AM/FM SET as the FM
The following components are required to carry out the RX Modification :-
3 off 0.1µF capacitors 25v DC working.
1 off 100pf capacitor.
1 off each 15KΩ -- 68KΩ -- 220KΩ resistors.
1 off 2 pole changeover miniature toggle switch.
Solder a 220KΩ resistor and 100pf capacitor in parallel across PINS 13 and 12
From PIN 12 IC2 Solder one 68KΩ resistor in series with
one 0.1µf capacitor in series with one 15KΩ resistor.
Then the other end of the 15KΩ resistor onto PIN 10 of IC2.
PIN 12 - 0 --- 68K --- 0.1µF --- 15KΩ --- 0 - PIN 10
As above then solder another 0.1µF to earth from the centre connection of the
0.1µF and the 15KΩ resistor.
Solder the 3rd 0.1µF cap from PIN 13 IC2 to the centre pin of one pole of the
Locate the junction of the existing C68 0.1µF and R62 22KΩ, on the PCB and
split this junction apart. Then wire to one side of the Toggle switch, for
AM/FM Switching see diagram
Mount Toggle switch through side of BE536 BOOT SET case and AM-FM Switching of
the receiver per channel can now take place.
The second pole of the toggle switch will be used to switch the AM/FM For the
BE536 TX Modifications to FM .
BE536MU AM /FM TX MODIFICATIONS.
On the TX PCB side of the set locate the Junction point of existing C386 &
Then insert the second pole of the Toggle switch, previously fitted in the RX
On the TX PCB side of the set locate the Junction of existing C322 &
Then insert one 10k Ω resistor, in series and remove C307 -- 0.1µF.
Then solder the new FM modulation line, from the toggle switch pole to the
10KΩ resistor Junction with the C322 on the PCB.
(BE536 COMPONENT NUMBERS ARE MARKED ON THE GREEN PCBs)
retain the AM / FM function on your sets when converted
Lets get AM back on
Kenwood PMR Products K4 Repeater System
Consists of two Kenwood TK809E UHF mobile sets and one TK709 VHF AM-FM set all
in one black boot mount box with a PMR Products control head for switching
repeater VHF-UHF and controlling the VHF & UHF sets together.
On the boot set there is a standard 37 way Home Office D Type socket. At
the control head there is a fifteen pin D Type socket. At the control
head end a fifteen pin D Type plug on a tail lead terminates in a breakout box
that contains both the 15 way cable which taps off the first fifteen 1 to 15
pins of the 37 way lead and feeds these pin for pin onto the 15 way lead.
Also at the breakout box there are two speaker cables to feed VHF and separate
UHF audio out.
These sets have recently been sold by Norfolk Police and have been
decommissioned from the said channels they were on.
The software used in the control head and sets is copyright of PMR Products,
Chepstow , Monmouthshire and Kenwood program software will not work with these
sets so they at this point in time remain unmodified for 2 metres and 70
centimetres unless you install and program three standard Kenwood non-police
mobiles which will reprogram on standard Kenwood software. Then the PMR
Products software will allow the sets to be used on 2 metres and 70 cms.
Unless someone out there knows better, in which case please EMail me with your