Hi Ron....
There's an easy to build circuit using just two MPF102 FET's, one toroidal
input transformer, an optional toroidal output transformer (with slightly
more gain) and a handful of resistors and capacitors and diodes. It's been
in use for years by Top Banders -- I first learned about it from W8LRL and
K1PBW back in the '70s. I'm still using a couple that I built back then.
This can be used either at the feedpoint or in the shack.
An 80-10m version appeared in an ARRL Handbook around 1974 or so. A version
of the 160m model was printed in 73 Magazine, I think it was June 1978.
You could build one up from scratch in a couple of hours. I built several
for use at Beverage feedpoints in small baby-food cans, about the diameter
of a small coffee can and half the length. The plastic lid snaps on for easy
access.
If you (or anyone else on the reflector) can't find the references
mentioned, send me an SASE and I'll send you a copy of the schematic.
Another good preamp often found used and cheap at hamfests is the Ameco PCL
"Nuvistor Cascode Preamplifier". It requires a separate power supply (6.3vac
and 125 vdc) but there was also a version with a supply built (The PCL-P I
think).
73/Jon AA1K
At 12:41 AM 12/28/96 EST, you wrote:
>
>Hello to all,
>
>I put together a shielded receiving loop for 160m a few days ago and
>it seems to be a good candidate for a preamplifier. Can anyone
>point me to a source for a schematic or, perhaps, a ready-made unit?
>
>I found one in QST for August, 1988. It looks good but has a high
>parts count. I have this vague recollection of seeing one built
>around a MAR-4, but I can't find anything in my files. :)
>
>Thanks and Happy New Year to all.
>
>Ron (W8RU).
>
>--
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>
--
FAQ on WWW: http://www.contesting.com/topband.html
Submissions: topband@contesting.com
Administrative requests: topband-REQUEST@contesting.com
Sponsored by Akorn Access, Inc & KM9P
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