[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

Simple 2400 sig source



Dale, I got the info off Internet; -
http://www.havilandtelco.com/homepages/gregwycoff/SOURCE.JPG
Also look at the picture, ... /IMG009.JPG.


Check the 486 board for a small TTL xtal oscillator. It will be a silver
coloured 4 pin package 20 x 12 mm with the frequency marked on top,
could be 20, 24, 25, 33, 50 or even 80 MHz. Not present on every 486 MB
board - I scored 3 out of 4. This is the heart of the unit.
The other bits I got were some Tantalums, .01 disc ceramics, two diodes,
and a couple of 15 pf caps. What I had to buy was a 78L05.
I didn't need a connector on the output so I kludged up a bit of "coax"
using about 2 cm of tubing which fitted over a short section of RG58U and
cut some old 1.5mm house wiring to make a dipole.
The only other bits I needed were some old PC board to make a case, some
more 1.5 mm ex-house wiring wire for L1 & L3, 65 x 5 mm brass strip, a
1000pf feed through and a small ferrite bead I had left over from my VHF
days of yonks ago.
Some will say the parts are critical. I've been chastised for using such an
inadequate diode as a 1N4148 but it works 100%. Should have known better and
used a Schottky diode or something else exotic - not sure why - this works
fine.

Its proved to be invaluable and fired me up - I thought SHF was difficult!

The only recommendation I have is to make the case RF tight. This ensures
you are listening to the 2.4GHz from the dipole and not just the TTL's
harmonics.
Helped with tuning the output circuit. I used some .25 inch copper tape from
the local handcraft shop, soldered it around the inside and folded it over
the top edge to give good contact to the top - worked like a charm!

My second one used an old "Pastilles" lolly tin for the box.

Have fun, Terry - ZL3QL.
----- Original Message -----
From: Cavies, Dale (ETSA) <Cavies.Dale@etsa.com.au>
To: <tcarrell@attglobal.net>
Sent: Tuesday, June 12, 2001 3:49 PM
Subject: Simple 2400 sig source


> Terry
> What is the circuit you used for your cheap 2400 sig source.
> Or what bits did you hack from the old 486. I have one here and want a
test
> signal as I develop my ao40 system.
>
> Regards,
>
> VK5DC
>
> Dale Cavies
> ETSA Utilities
> Information Systems & Telecommunications
>
> *  84045106
> *  Cavies.Dale@etsa.com.au <mailto:Cavies.Dale@etsa.com.au>

----
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org



AMSAT Top AMSAT Home