In article , Don Pearce
wrote:
On Wed, 21 Nov 2007 13:53:09 +0000 (GMT), Jim Lesurf
wrote:

In article , Don Pearce
wrote:
[big snip]

Do you use Mathcad?

Just as well I wasn't sipping my orange juice. For a moment I thought you
meant back when I was working on Ted's tuner in c1980. That was in the days
of pen and paper. I did have an HP calculator. The 41 IIRC. ;-

No. I write all my programmes in ANSI 'C'. So all of the results on the
page come from that approach. Means I can define how the computation is
done. I am too old fashioned to take to Mathcad. :-)

I wrote a worksheet to implement the helical filter
design method from Zverev, plus a few bits from elsewhere. You just put
in all the details of frequency, BW, number of sections etc, plus the k
and q values from the appropriate table, and it gives you all the coil
dimensions, tap points, shield heights etc. I used a helical IF in my
super tuner - had to work it all out longhand back then, of course.

Indeed. As above. Alas the drawings for Ted's design were all lost long
ago. When I left the company I took my work on amps, but not any of the
stuff on tuners.

Anyway, you are welcome to a copy if you can make use of it.

Not likely to do any tuner design these days, I'm afraid. Thanks for the
offer, though.

Slainte,

Jim

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