                           xtalfind 1.2
            by Paolo Cravero, IK1ZYW <ik1zyw@qsl.net>


            See COPYING file for license information.


This software is a very simple bunch of C code that allows you to verify
whether a XTAL (quartz crystal, used in electronic applications) is
suitable for building HAM radio equipment.

Three tests are performed, all of them check if the quartz fits into one
of amateur bands (80 to 10m WARC included, 6m and 2m, according to Italian
frequency allocations). An additional test for a custom IF value is
available as well.

1) CW TX or direct-conversion RX: if you see some output in this section,
your XTAL is, on some harmonic, resonating on a HAM band

2) RX with 455kHz IF: this is successfull if n*XTAL+455kHz (or
-455kHz) fits the HAM bands allocation, where n is between 1 and the
maximum harmonic level you have chosen

3) RX with 10.7MHz IF: this is successfull if n*XTAL+10.7MHz (or
-10.7MHz) fits the HAM bands allocation

4) RX with a custom IF: this is successfull if n*XTAL+IF (or -IF) fits
the HAM bands allocation

Tests above are also performed if the XTAL frequency is mixed with another
known frequency (ie you check if the mix two XTALs is useful). If a mixing
frequency is provided, though.

You can launch the software from any unix command line (previous
re-compiling of the source...). You have to type in at least one of the 
following parameters:

* -q<number> where <number> is an _integer_ greater than 0 representing
             the quartz frequency, in Hz
* -a<number> where <number> is an _integer_ greater than 0 representing
             the harmonics level to consider
* -m<number> where <number> is an _integer_ greater than 0 representing
             the frequency with which to mix the quartz

Additionally, you can specify a custom IF value:

* -i<number> where <number> is an _integer_ greater than 0 representing
             the desired IF frequency, in Hz


Examples:

> xtalfind -q2580000

checks whether a quartz on 2.58 MHz is useful till the default harmonic
level (10).

> xtalfind -q2680000 -m1000000

checks whether a 2.68 MHz quartz is useful. Moreover it is mixed with a 1
MHz oscillation and tests are performed again. Default harmonic level of
2.68 MHz are considered in all tests.

> xtalfind -q4567000 -a100

checks usefulness of 4.567 MHz quartz until its 100th harmonic.

> xtalfind -q22533000 -i4433619

checks whether a 22.533 MHz XTAL can work in a receiver with 4.433619
MHz IF. Useful if you want to build crystal filters with cheap XTALs.

Feel free to modify the frequency allocations found within the C code to
better suits your needs. I wrote this software for my own needs, when I
decided to build a QRP RX/TX for HF bands.

I would appreciate an email to know you have found this software useful
(or not), or a QSL via the buro :)

Have fun de
IK1ZYW Paolo

19 November 2001

