[RTTY] QUESTION & ANSWER

[Marijan Miletic, S56A]

AA5AU> For a simple transistor keying circuit to key FSK (and PTT, CW), see:
http://www.aa5au.com/rttyinterface.html

It would be healthy to add another 1 kOhm resistor from base to ground in
order to conform with -5 V max inverse voltage from PC COM port.
Shunt capacitor of 10 nF is also highly recommended at collector output in
order to prevent RF feedback to base and subsequent blocking.
This solves 99% of hamradio problems but it is missing in 99% of schematics!

HNY & UE DE MARIO, S56A, N1YU