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TUCoPS :: Radio :: ic22s_4.txt

Icom IC-22S mods


Would you like to convert your IC-22S to receive SSB and CW signals? If you
own a shortwave receiver, or a general-coverage HF rig, you can do it easily,
for less than a dollar!

All you need to do is to take a sample of the 455 KHz IF amplifier signal in
your IC-22S and apply it to your shortwave receiver, tuned on 455 KHz in USB,
LSB or CW.

Connect a 68 K ohms resistor on the collector of Q6 (455 KHz IF amplifier).
It's a 455 KHz IF amplifier, NPN 2SC945; collector is the center pin. Connect
the free end of this resistor on the inner conductor of a coaxial cable.
Connect the shield of this coaxial cable on the ground (-) of the IC-22S.
The other end of this coax is connected on the antenna connector of your
shortwave receiver, with the appropriate connector. This coax could be RG-58U
or shielded speaker wire; the length is according to your convenience.  The
resistor is used to limit loading of the IF amplifier.

The frequency you want to listen is selected on the IC-22S. Your SW receiver
must be tuned on 455 KHz. The mode you want to use (USB, LSB, CW) is selected
on your SW receiver. This modification can NOT be done in transmission,
because too many modifications of the IC-22S are involved. You would need to
change the RF amplifier because it's in class C, which doesn't work in
AM and SSB.


R149 pot: adjusts low power. Reducing R148 increases maximum low power (less
than 10 Watts...) possible with R149 pot.

R73 pot (30K): adjusts TX meter readout. When this pot is connected on D10
instead of D11, the meter indicates SWR. R73 could therefore be used to
calibrate FORWARD reading.

R89 pot (100K): Adjusts SWR feedback, and therefore SWR protection level. 

R132 pot: adjusts Mic. Gain.

R124 & R112 pots: Adjusts Maximun deviation.

R124 pot: Adjusts symmetry of clipping of mic. amplifier.

73. Daniel VE2BAP ' VE2CSC.PQ.CAN.NA


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