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Old October 27th 04, 03:29 PM
N8WWM
 
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Here's the mod for more channels on this unit.

The PLL is not modifiable when used in an AM only radio, the only method
that will allow more channels is to disconnect the 15.360 Mhz signal that
is coming from a tripler circuit and replace it with another one depending
on the required freq. range.

Here are the instructions:

Lift one end of C87 (the side closest to IC2), then connect a switch's
common pin to the open pcb hole, connect the "modified" switch position to
a crystal oscillator, then connect the "normal" switch position to C87, all
you need to do is get a crystal to use for the oscillator, the original
frequency is 15.360, you add / subtract the number of channels to / from
the frequency

Say you want 26.515 - 26.955 (the low band) just deduct .450 from the
original freq (450 khz = 1 band of channels), so a crystal of 14.910 Mhz
will give you the low band.

OR to get 27.415 - 27.855 (high band) you will need a 15.810 Mhz crystal.


You may actually use both but the radio may not cover the freq. range (
due to limitations in the tuning circuits for the broadband requirements)


The only hard part is finding a supplier for the crystal, the mod itself
is easy !