Kinda depends on what channel you want. Simplest fix is to remove one crystal you won't use, like the channel 1 to 4 crystal (marked 8.1590) and installing the new one there. No extra wiring needed this way. The new crystal will deliver four new channels. It will skip one 10 kHz step betwen channel 3 and 4 on the dial, no matter which crystal is installed on that part of the channel switch. This is called the "RC" skip, and the radio does this to the fourth of every five-channel step, between 3 and 4, 7 and 8, 11 and 12, 15 and 16, 19 and 20. A 23-channel radio also skips two RC channels between 21 and 23. To fill in this skip pattern will take yet another crystal, a switch and added wiring to fill in this blank channel skip pattern.
To add channels 26, 27, 28 and 30, use 8.4590 MHz
Channels 31,32,33 and 35 will need 8.5090 MHz.
Channels 36-40, skipping 39 is 8.5590 MHz.
41 to 45 skipping 44 use 8.6090 MHz.
And that's the pattern for each 5-channel step above channel 45, add 50 kHz to that crystal frequency.
Consider the the higher (or lower) you go, the less transmit power and receive performance you'll get. The radio is aligned for channels 1 to 23, so making it perform way above 23 or below channel 1 will require alignment. It will still be a narrow-banded radio, so optimizing it for upper channels will reduce performance on channels 1 to 23.
Sure must sound like "Five miles to school in the snow barefoot and uphill both ways." Heck, that's what this mod felt like that radio was new.
73
