The Expo "N" kit has its own clarifier circuit, with a separate varactor diode for each of the two crystals. The green wire is to feed the variable voltage from the clarifier control to the Expo board.
You really need to 'open' the clarifier to use this kit. Not sure how you can use it on SSB
without doing that in the first place.
The clarifier range for normal channels 1-40 will not be all that much. Because of the 'slide' range of the new crystals in the Expo kit, you'll get more slide on upper and lower channels than on the normal 40.
The real kicker with this mod on this radio is getting the clarifier 'centered', with the clarifier knob at 12 o'clock. On the main circuit board, you have a separate trimmer coil each for AM
, USB and LSB. No big deal to get all 3 modes centered on channel for channels 1-40.
The real fun has to do with choosing WHICH of the 3 modes will be used to set the two trimmer caps on the Expo board.
If you set channel center on the trimmer on AM
, you'll find that the channel center on the EXTRA channels is only centered for AM
. Channel center for LSB will be to the left of 12 o'clock, and to the right for USB.
This is because you would need six adjustments on the EXPO board to do the same trick done by the three trimmer coils on the main circuit board. To make all 3 modes line up you would need 3 separate trimmers for upper channels and three more for the lowers. The Galaxy "Viagra" board for their 40-channel radios HAS these separate trimmers. The designer of the EXPO kit left these out, so you can get all 3 modes set to 12 o'clock ONLY on the normal channels 1-40. The "offset" from center on upper and lower channels isn't all that much, and won't keep you from tuning in somebody who is more or less on frequency.
Until the clarifier is cut loose from the stock "receive-only" setup, you'll never get it to work correctly on you new, added channels. It's a pain in the neck, requiring you to cut traces on the front-panel control circuit board, best I can remember. Haven't done one of those in years.
The cheaper radios WITH all those channels get, the less reason there is to install a channel mod this quirky.
The EXPO types "A" and "N" kits are different from the simpler "crystals only" types. These two versions contain both the crystal and oscillator for the extra channel coverage. I learned the hard way to hook up a new "A" or "N" kit to a power supply and counter BEFORE putting it in the radio. More often that not, the trimmer caps won't quite set on frequency. Had to change (or add) a disc cap on more than one of these to make it line up on the clarifier. Much easier to do before it's mounted in the radio. It requires a dual-output supply to do this with the "N" kit. One to power it, one to feed clarifier voltage to it.
Now, don't you wish you'd just bought a Superstar 3900 or Voyage VR-9000 in the first place? Bottom line could have come out cheaper that way. And you'd have that "+10" switch, to boot, once you rewired the "CH9" switch. No "Plus ten" on the PC-122, even after the EXPO "N" is installed.