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Lostgallifreyan · November 29th 09, 09:22 AM posted to rec.radio.amateur.antenna

K7ITM wrote in news:79a92c5a-d528-46cf-a24f-
:

As one who designs all sorts of RF filters and then builds one-off
versions (if as an aid for my own bench-testing of things like
distortion in receiver circuits) or specifies parts for ones put into
production, I'd probably elect to wind my own such transformer if I
needed one, but I can certainly see the appeal of buying one.
Considering the packaging alone, it's worth it to go that way.

Indeed. I make stuff from acetal and other plastics using a bandsaw and
drilled and threaded holes, it's great for tough enclosures to my own design,
but quickly shows how much saving can be had if I find anything that saves me
a lot of construction work. The cost of that transformer can easily be
recovered elsewhere.

But I
also think it's great that you're looking into postings of folk who
have words of wisdom to offer. I have the strong feeling that you're
plenty bright enough to not simply accept those postings on faith, but
will test what you learn from them against your own experiences, and
thus build your knowledge on a firm foundation.

I hope so.

I read several. I chose John Doty's guidance for two reasons:
he didn't conflict with good advice I was taught several years ago, long
before I had (or built) a computer and found the net, and the other is that
many good things have come out of the MIT and I think this could be in the
same vein. (Sam's LaserFAQ being one of the most memorable guides).

Technical (and semi-technical) books are generally safer sources than
postings, but even they are not infallible. I'm thinking here in
particular about one popular book about design and winding of RF
transformers on ferrite toroidal cores. You can learn a lot from the
book, but it's not 100% accurate.

That's certainly true... I found two commercial books on DIY laser building
that were so incomplete that they amounted to little more than commercial
exploiting of stuff the LaserFAQ offers for free. If I hadn't read as much as
I could handle of the great amount of freely available info, I'd not have
realised the extent of weakness in those two books. On my own, I'd only made
a small improvement in a flashlamp circuit at schematic level but flaws
glared once I learned stuff from the LaserFAQ. Another great and mighty
reference tome turned out to be mostly anecdotal and frequently lacking in
basic reference material, but conversely some small books written by RM
Marston turned out to be references I return to several times a year, finding
them more convenient than any web-sited guidance I know. I think there's a
book by Bernard Babani publishing (maybe by the man himself) on the subject
of ferrite cores. Not sure if that's the one you mean but I can find it
easily.

Best wishes for success in improving your (RF) reception -- and in
learning!

Cheers,
Tom

Thankyou. I'm hoping to catch a nice receiver this very day on eBay (been
watching a few pass by recently), if I'm lucky enough with the price, then
I'll work out what to do for an aerial..