From 23 to 46 channels
without buying crystals
This mod gives old 23 channel
What you'll need:
The first thing to do is find a 2PDT switch. Hopefully the CB/PA switch
is a 2PDT, if it has 6 pins for wires (3 on each side) like the one in the drawing,
radios using the 12 crystal
arrangement a "low band" of
extra channels
23 channel radio that uses the following crystals:
23.290, 23.340, 23.390, 23.440, 23.490, 23.540
14.950, 14.960, 14.970, 14.990
11.730, 11.275
2PDT switch (6-pin)
Ohm-meter
O.K. now a little about how these old rigs work. Every channel uses 3
crystals at a time for TX and RX. Lets say your on 19. The radio would use
23.490 plus 14.970 (sub-total 38.460), then MINUS 11.275 gives 27.185 RX.
The TX works a little different, it needs the 11.730 instead of the 11.275, because
of the 455 khz I.F. If the 11.730 and the 11.275 are switched around, the I.F.
will still work, it will just be 455khz lower than the RX frequency instead of
being 455khz higher. The fact that the I.F. happens to be 455khz presents a
problem, all of the new channels would end up 5 khz off frequency (example channel
19 low would be 26.730 instead of 26.635) This problem is corrected with small
capacitors, about 10 or 15pf will pull the crystals 5khz off their given value,
making the jump to the low band 460 khz.
then it is a 2PDT. The drawing shows which wires are connected when the switch is out
(out means CB mode, in means PA mode) So to disable the CB/PA switch some wires will
have to be connected in order for the CB to work! You can see that:
wire 1 gets connected to wire 2,
wire 4 gets connected to wire 5
and wires 4 and 6 get removed and
are not connected to anything.
