Craig, Sean & Marc wrote :

>Try linx technologies, the technician there spoke to me a bit
about those.
>They have an 800 number, though I don't have it on hand.
>Good luck.
>Craig Webb

>I'd love to have this information myself, so if you find a good
source,
>please let me know. I think, however, that I have seen this info
in the
>ARRL handbook, available from www.arrl.org, or at your local
library.
>Good luck,
>Sean

>What are you doing? Is this production material or home brew?
>Take Care
>Marc

Thanks to you guys for replying and please accept my apologies
for this delayed repsonse. I've been down with the flu for the
last few days. However, I've been trying to put the lay-up to
good use. There's a reference on the inductance of coils in:
Harnwell, "Electromagnetism", pages 327-330.

I can fiddle with his equations and come up with inductance
values for, say a 2.0cm diam PCB coil that appears to be in the
ball park. At least judging by values of capacitors used in
published circuits. Be real nice to be able to check if I'm on
the right track. Thing is, someone *must* have done something on
this?? Damned if I can find a specific ref on the topic though.

thanks for the tip about Linx, Craig. I'm over in Australia, so I
may FAX them instead of  voice call. If I do find something, I'll
let you know, Sean.

As for Marc, this is a home-brew project. I need a 4-button FOB
switch, like on car keyrings but they only seem to go up to 3
buttons. The Tx is just a trinary encoder driving a Colpitts OSC
in ASK mode. It's working OK but I just don't like the idea of
trial and error with the resonant cct. The project's not so far
off PIC  topics 'cause I'm using a 16C54 at the Rx/decoder end.

Thanks again for your interest, guys.

Regards,

PJH
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