[RTTY] QUESTION & ANSWER

[Tom Homewood]

Adding the base to emitter resistor helped me solve some hang up problems
when going from transmit to receive.

73, Tom, W1TO


----- Original Message ----- 
From: "Marijan Miletic, S56A" <s56a at bit.si>
To: <rtty at contesting.com>
Sent: Thursday, December 30, 2004 6:25 PM
Subject: RE: [RTTY] QUESTION & ANSWER


> 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
>