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Simple 2400 sig source

Dale, I got the info off Internet; -
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

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
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
> signal as I develop my ao40 system.
> Regards,
> Dale Cavies
> ETSA Utilities
> Information Systems & Telecommunications
> *  84045106
> *  Cavies.Dale@etsa.com.au <mailto:Cavies.Dale@etsa.com.au>

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