.
MAYCOM EM-27 MULTI CHANNEL ADAPTION
Disclaimer:
All information on this page is written to explain how these radios may
have been adapted. It is in no way an encouragement for people to make
their own radio equipment work "outside" what is permitted in the UK.
Also I take no responsibility for the accuracy of this page nor do I offer
any guarantees.
From my experience this is the most common and
widely requested adaption using a 1N4007 diode and a
12v d/p c/o relay. There is a direct way just to wire a
double pole (d/p) switch with wire links to the same
connections with the switch fitted at the rear (spare
hole) but this is the "Funkier" way of doing it.
1/ To start take the speaker side of the case off and locate the jumper pads 2 and 7 as shown in the first picture. In position 2 there is
an "0" ohm resistor (Surface mount) which you need to remove (Basically it's just a link resistor)

2/ Second step using a fine point soldering iron and 4 short pieces of wire (Preferably 2 different colours) solder to these 4 pads
making sure not to solder blob across anything else. One colour wire to 2 and a different to 7.

3/ Step 3 is to solder your 1N4007 diode to the relay as shown making sure to get the annode of this diode the correct way around (see
pic) This can then be shaped then soldered to the board which will also secure the relay in place. Please see pic for this (Click any pic
to enlarge it for a clearer view)

4/ Join the floating wires to the relay. See pics and diagram for this, make sure you do it right... scan down for more instructions
Enlarge
Enlarge
Enlarge
Enlarge
5/ Next you need to make sure it covers the full range of
frequencies by slight adjustments of the two cans shown
to the right (Pic 5)

With function
M1 selected M6 changes bands indicated
as
A B C D E with a + or - above. You also have a split
frequency function, select your TX frequency then press
M7. rpt shows on the screen. Now select your RX
frequency (Used mainly on repeaters)
Enlarge
BAND FREQUENCY CH 1 CH 10 CH 20 CH 40
-D 25.165-25.605 0.5W 2W 3W 4W
-E 26.615-26.055 4W 4W 4W 4.5W
A 26.065-26.505 4.5W 4.5W 5W 5W
B 26.515-26.955 5W 5.5W 5.5W 6W
C 26.965-27.405 6W 6W 6W 6.2W
D 27.415-27.855 6.2W 6.2W 6.5W 6.5W
E 27.865-28.305 6.5W 6.5W 6.2W 6W
+A 28.315-28.755 6W 6W 6W 5.5W
+B 28.765-29.205 5.5W 5W 5W 4W
+C 29.215-29.655 4W 2.5W 1.5W 0.5W
/
.
CB Radio Repairers in the UK
CB Radio History from its early days
.