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Old April 8th 14, 06:01 PM posted to,
Michael Black[_2_] Michael Black[_2_] is offline
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First recorded activity by RadioBanter: Mar 2008
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Default Hayward design broadband low noise preamp for loops

On Tue, 8 Apr 2014, Geoffrey S. Mendelson wrote:

I have a copy of the book "Practical Wire Antennas" by Heyes (the first
edition). In it is a schematic for a low noise broadband preamplifier
for loops.

This version uses the BSX20 transistor which at the time the book was
written was far more available in the UK than the 2N5179 used by the
original Hayward design.

The book mentions that it was first published in the ARRL Antenna
Handbook, I can not find it in my copy.

THose things, like the Handbook, change glacially, but unless you had the
right edition, it wouldn't mean a thing.

A "broadband 2N5179" preamp is kind of vague. It might have come from
"SOlid State Design for the Radio Amateur", lots of small schematics in
there, and not all projects. But I can also see some sort of loop in QST
circa 1976, that had a preamp that also might have fit. Though I thought
that article was by someone on the ARRL staff, like Doug DeMaw. But, it
might be attributed to Wes Hayward, since they seemed in constant
correspondence at the time.

I may look in the book later, if I remember and get around to it, see what
might be there.


These days it is much cheaper and easier to order 2N5179

from China on eBay (and probably cheaper to order 10 and pick the best)
than it is for me to order a BSX20.

However without the original schematic or construction article, I am
taking it on faith that it will work with no circuit changes, something
I doubt.

A copy of the schematic and accompanying text would be appreciated.
References to where it appeared or links to pages describing it would be
even better.

The original circuit I was looking at contained 1 transistor, 4 diodes,
6 1/4 watt resistors and 4 disk capacitors. The coil could be wound from
hookup wire on a hunk of ferrite rod, which I have many of.

It's fairly "bulletproof", so high voltages from static, lightening
or nearby transmitters (all three here) won't burn it out like an MMIC.

It's a simple design so that I can build it myself. :-)


Geoffrey S. Mendelson, N3OWJ/4X1GM/KBUH7245/KBUW5379