Re: LF: RE: FCW keyer...

[Andy Talbot <andy.g4jnt@gmail.com>]

Here's some PIC code for generating DFCW I originally wrote for the GB3SCX and GB3SCC microwave beacons.

http://www.g4jnt.com/dfcwbcn2.zip   There are two .ASM files in there, one uses the obsolete 16F84, and ver 2 is adapted for the 16F627  (also the 628 probably) with a few interface connections swapped around

 

It is based on my standard beacon keyer  http://www.g4jnt.com/BcnKeyer.htm  and lets you change message parameters using an RS232 interface rather than having to get out the PIC programmer to change teh stored message.    All the details are in the .ASM file, and circuit etc is similr to the standard keyer module.

 

 

 

Andy

G4JNT

 

 

2011/5/19 Stefan Schäfer <schaefer@iup.uni-heidelberg.de>

Hello Szigy, LF,

Sorry for my delaied answer. I will further answer in a personal mail.

About DFCW: Yes, the first you may use is Rik's QRS program (which i am using too at the moment). With the two 12 V (up to about 10 mA) levels from the RS232 you can directly steer a NPN transistor or a FET or an optocoupler to push the PTT. The other one is needed for DFCW.
Realising the small frequency shift can be done in several ways of course. It depends on your type of VFO. You told me to have a XTAL VFO. So what you can do is just to pull the XTAL a bit. In my first DFCW generator i did it with a simple NPN transistor (BC548C, just cause it was available) that switches a small C against ground. C is some pF, adjustable to set a proper shift. You can use varicap diodes alternatively but actually it doesn't matter.


73, Stefan/DK7FC

Am 19.05.2011 09:50, schrieb Rik Strobbe:

Szigy,

I can offer you a software solution:

http://www.qsl.net/on7yd/zip/qrs408.zip

73, Rik  ON7YD - OR7T

________________________________________
Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org] namens Szigy [yo2is@9a0tcp.ampr.org]
Verzonden: donderdag 19 mei 2011 9:39
Aan: rsgb_lf_group@blacksheep.org
Onderwerp: LF: FCW keyer...

rom: YO2IS
  Some days ago had a nice random QSO with DK7FC on 137.7 KHz.
 We started in QRSS then he come back with a loong DFCW message.
 Unfortunately had no DFCW keyer capability.
 Have built several PIC (16F84) keyers including the SM6LKM beacon
keyer modified by me for QRSS, but none has the DFCW option.
 Being a H.M. fan am looking for some afordable ideas.
    73&  DX !, Szigy