Interface to connect the FRG9600 to a computer

SOME TRANSISTOR EQUIVALENTS

BC507 = NPN, 40V 0,2Amp = BC174, BC182, BC190, BC546 
BC517 = NPN Darlington, 40V 0,4Amp = BC875, BC877, 2SC4017


Thanks to Giovanni, HE9LSA, who supplied me with the drawing for a Circuit Board:







Thanks to Anthony, WB8MLA for the pictures and the modification to the circuit, to make it all fit 
inside a serial connector:














A description for this, by Anthony:

The chip I used is the MAX232ACPE which is available from DigiKey. The part number is # MAX232ACPE-ND
and is about $4.25 U.S. Their phone number is 1-800-344-4539  With this chip, you use little tiny .1 
caps in the exact same place where your 22uF caps were. Also, the .1 caps do not have to be polarized! 
I also can tell you that there is another chip, that doesn't require any capacitors at all, and its 
called the MAX233..(its a little bigger though)  I did some minor changes to your circuit, and am happy
with the results! I used a GE940011 Darlington (a little more gain) rather than the BC517. But, what I 
am most happy about is, I was able to fit all the parts into the DB-25 shell, and no power supply 
necessary! The way I did this was to steal power from the RTS line (pin 4) and the DTR line (pin 20) 
by soldering the anode ends of two 1N914 to each pin, and then TYING the cathode ends (the cathode end 
has the band around it) of both together. This gives me double the current (which is usually about 12 
volts @ 12 ma or so). From there, I feed the squelch transistors collector (about 12 volts!) and, I also
tie the input of the 78L05 regulator here, to get 5 volts out of the other side, which runs the MAX232A 
very nicely! Also, the MAX232A draws less current! 
Even the joystick components are inside the DB-25 shell.. 


WARNING: DO NOT ATTEMPT TO DO THIS IF YOU DO NOT
FEEL CONFIDENT WHEN USING SOLDERING EQUIPMENT.
DO NOT BLAME ME IF YOU SCREW UP YOUR RECEIVER OR DO 
ANY DAMAGE TO ANYTHING YOU ARE USING.


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