Hello Eric,

1. The back section is fixed by four screws through the side plates. Remove
those screws and bend the back section as far as the wiring allows. You will
see the screw heads when the top and bottom cover of IC490 have been removed.

2. 470 nF = 0.47 æF  The capacitance could be higher, but there are space
limitations inside the rig underneath the IC490 Main Unit print.

For the time being you will not need the connection with varactor D3 for
any satellite, but you may need it for a 9600 baud terrestrial net. It will,
however, be feasible to prepare that connection as well when the AF/FM and
AF/SSB connections are being built.

3.                      +12V ÄÄÂÄÄÄÄ¿ 4.7 k
                               ³    ²
                               ³    ÃÄĺÄÄ> SSB out to 9-pin connector
                         850 k ²    ³ 0.47 æF
   #3/IC3                      ³   /
   SSB in ->ÄĺÄÄ---*cable--ÄÄÄÅÄÄ´ BC337 or similar NPN transistor
            0.47 æF            ³   \
                         150 k ²    ³
                               Á    Á
*cable from 0.47 æF condenser on the Main Unit to the amplifier located
 at an empty spot within the rig

You will need the above amplifier only when SSB signal level at #3/IC3 will
not be sufficient for your TNC. I am not familar with TAPR 1200 baud psk
modem.

4. As you know doppler shifts UO-14 frequency downwards only from rise to
set. Often 435.077 ---> 435.058 MHz. Consequently IC490 needs down commands
only. It will get such a command each time the calculated frequency drops by
1 kHz. My program calculates the current frequency, not doppler shift only.
I initally tune my Rx to the frequency I know UO-14 has, when rising above
horizon. I dont need to hear UO-14 at that moment. In fact I know UO-14
frequency any time without listening, just by looking at the monitor. When I
tune my Rx at that frequency I know that UO-14 is there. The control system
then steps the frequency down as frequency calculation tells it to do.

I think you will not need the diagram for the circuitry since your tracking
program apparently does not tell the above things.


You would find Finnish speaking fellows at the subsidiaries of Finnish
companies, like EPL-Kone Pty, in your country. That would unfortunately not
solve the program problem.

Pate OH2SN @ OH2RBI