= = = William Mutch wrote in message
= = = ll.edu...

I used to think that passive antenna tuners or matching
networks were worthless, but over the weekend I got some
real SWL evidence to the contrary.
My prime RCVR is a Sat800 refurb

hooked to 156 feet of AWG 16 hard drawn stranded, oriented NNW/SSE
up about 40 feet between two large trees and

* This Antenna sounds Long and High Enough.

fed off center at the 1/3 // 2/3 point

* Sounds 'sort-of-like' a WINDOM (52 Ft & 104Ft) Antenna
that is configured with Two un-equal Top Arms 'elements':
+ 156 Feet = 1WL @ 6.4 MHz & 1/2WL @ 3.2 MHz & 1/4WL @ 1.6 MHz
+ 104 Feet = 1WL @ 9.7 MHz & 1/2WL @ 4.8 MHz & 1/4WL @ 2.4 MHz
+ 52 Feet = 1WL @ 19.3 MHz & 1/2WL @ 9.7 MHz & 1/4WL @ 4.8 MHz
http://www.packetradio.com/windom.htm

with twin RG6U which comes down to a 4:1 balun

* Then sounds like a G5RV Down Leg 'elements'.
http://www.qsl.net/aa3px/g5rv.htm

outdoors at a decent ground (copper ground pipe filled
with copper sulfate, steel well casing and cast iron soil
pipe bonded together with coax braid.)

* The Ground sounds solid enough.

* READ: Compilation of "Ground" Messages
http://groups.yahoo.com/group/Shortw...na/message/524

Coax from the balun goes into the house to the RCVR.

* A Coax Feed-in-Line is always a Good Idea )

One thing about the Sat800 has always bothered me...there's no way
to turn the AGC *off*, so the noise floor is always rushing up to blast
you in the headphones when you tune between stations. I'd previously
not been able to receive anything but a couple of local aero beacons on
longwave, nor anything but the Christian megawatt at 3200 on the 90
meter band. I didn't care much about the longwave since the very useful
aviation weather Elmira NY on 385 khz was replaced by better service on
162.40 Mhz vhf.

Last week, just for fun I made a Hi-Q parallel resonant tank
for longwave from a 385 pf variable cap and a 3.850 mh inductor.
(82 turns #24 awg wire on a 1.3" audio toroid core)

* Sounds like a fairly good Tuned Circuit for your targeted
Longwave Frequency Range.

* FWIW: Sounds like what you have may be more of a Longwave
Signal "Pre-Selector" then an 'general' Antenna Tuner.

* Read - Why:: Baluns -v- Antenna Tuner -v- Pre-Selector
-v- Modern Radio/Receivers
http://groups.yahoo.com/group/Shortw...na/message/728

This tunes 520 khz down to 170 khz with a pronounced peak.
I coupled it very loosely (2 1/2 turns) to the coax near the
RCVR and was astounded at the difference in reception.
Around 0500Z I logged 15 different aero beacons at between
260 and 420 khz !

* Again sounds like your basic tuned circuit works for the intended
Longwave Band Area.

The tuned circuit didn't bring the signal levels up...it took
the noise floor DOWN !

* You may have obtained/gain the same Noise Reduction results
by simply using a Lead-in-Line Isolator 1:1 Matching Transformer
between the Coax Cable Feed-in-Line and the Receiver.

* READ - Wellbrook "Low Noise Antenna" 'design concept' using
two components that WellBrook manufactures: the Universal Magnetic
Balun (UMB) and the Antenna Feed Isolator.
ISOLATOR= http://www.wellbrook.uk.com/longwire.html
http://groups.yahoo.com/group/Shortw...na/message/675
NOTE: Please Read Wellbrooks Claims at the bottom of the webpage
concerning how the "Isolator" can 'reduce' Noise at Low Frequencies
by up to 40 dB.

Same thing happened when I picked up a used Barker & Williamson
AT-300 Tee section tuner at a hamfest last weekend.
The peaks are not as pronounced as the longwave tank, but the 90 meter
band yielded a half dozen African stations where previously I'd heard
nothing but QRMN.

On some frequencies the most dramatic improvement came where the
peak in signal strength and the peak in noise came at slightly different
settings of the tuner. This to me is evidence that nearby noise sources,
even when filtered out of the detector and audio in the receiver are
still affecting the AGC line, turning down the effective signal. Seems
like an active preselector will help if you can't get an antenna out in
the clear, but even if you can, some more selectivity *before* the front
end of the receiver can help.
I'm a convert.

iane ~ RHF

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