[WriteLog] FSK, PTT & CW Interface
Sat, 13 Apr 2002 16:50:38 -0500
Just wanted to say thanks to Don for his pages.
This is the exact same circuit that I built to use one comport for cw, fsk,
I built them into a little plastic (wish it had been metal) box with three
One small note: You may have to play with the value of the pull down
All transistors are not created equal nor are the voltages in the computer
I have built optos and they work well also.
Sure beats the price of those "big" interfaces and gives good old clean FSK.
----- Original Message -----
From: "Don Hill AA5AU" <email@example.com>
To: "RTTY Reflector" <firstname.lastname@example.org>; "WriteLog Reflector"
Sent: Saturday, April 13, 2002 4:16 PM
Subject: [WriteLog] FSK, PTT & CW Interface
> Someone recently asked me what kind of interface I use to key
> FSK for my radio. Every time someone asks me this, I have to
> dig in a drawer to find the schematic. So last night, with a bunch
> of energy after working the P5, I decided to lay it out on my website.
> A lot of people use opto-isolators, but I could never get one to
> work. I suppose the ones I had in my junk box weren't good. So
> I decided to try a simple NPN transistor circuit and it has worked
> great on both of my computer/radios.
> The circuit for FSK is identical to PTT & CW except for the DB 9
> If you are interested, the page is available off my RTTY page:
> or go directly to the interface page at www.aa5au.com/rttyinterface.
> Hope this can help someone. Let me know if you have any questions.
> These circuits should work with WriteLog or any other program that
> requires FSK, PTT or CW from a serial COM port. What's nice is that
> you can build all 3 circuits on a single COM port.
> 73, Don AA5AU
> WriteLog mailing list