Mark,
Was wondering about the high noise level. Would you have an opinion
on it's origin?
Alex
________________________________
From: Mark D Mobile <Mark4@xxxxxxxxxxxxxxx>
To: MDXC@xxxxxxxxxxxxxxx; Putrich Greg <gregp@xxxxxxxxx>; DX-IRCA
<irca@xxxxxxxxxxxxxxxx>; "DX @NRC" <am@xxxxxxxxxxx>
Sent: Wednesday, May 9, 2012 5:23 PM
Subject: [IRCA] Beverage Antenna in Utah Part Two
REPORT 2: We concluded our work on Monday 5/7 and 'struck the
set'. SDR recordings had been made over several evenings on both
the elevated Beverage and the BOG (1800 feet). Mike's suggested
antenna azimuth was validated by the high number of stations
received in the corridor: Eastern Washington--Western
Montana. I'll post the catch-list later as we look for the
unlikely Alaska catches. I say unlikely BECAUSE:
In addition to the weather issues we encountered an abnormally high
noise level throughout the weekend. With the bandwidth we used (6
khz), the SDRs were displaying noise around -75 to -80 dbm. (I'm
used to Beverage noise floors below -110.) This was one difficulty
we just couldn't overcome. The noise (certainly QRN) was broadband
and continuous, as opposed to the spiky stuff you hear when it's
primarily atmospherics.
Other measurements involved switching an SDR between the elevated
Bev and the BOG and recording signal levels; both broadband and
narrowband. These results and other data will be published
later. To be determined on further playback is whether the BOG was
performing as an electrically-longer antenna than the elevated...on
this very dry desert floor.
On one occasion when we lit up in daytime we heard a rhythmic
interference spike several db above that dreaded broadband
noise. Of interest is that this noise was greatly reduced when we
switched from the elevated to the BOG.
The single-wire remote beverage terminator worked very well, as
noted earlier.
Further Facts Follow From us Fools in the Field.
Mark Durenberger
On the road
From: Mark D Mobile
Sent: Sunday, May 06, 2012 11:22 AM
.REPORT 1:
My friend Mike and I set up two 1800-foot Beverages in the Eastern Utah
desert...one is a BOG and the other elevated about 3 feet. Beverages
are at
320 degrees; we're looking for Alaska. Counterpoises on the ends are
four
300-foot radials of copper supplemented by ground rods.
The new single-wire remote termination control has proved a great
success.
Even though the DC resistance on our dry-desert-earth path measures
close to
2 megohms (!) the 'current amplifier' works well and drives a Vactrol
for
ideal termination. (Of course "ideal" is only for one frequency but the
SDR
does a nice job of showing the overall front-to-back changes.)
We already know that it's working...those of you who've been in this
area
know how tough it can be to remove KOB 770 in favor of KTTH, and KOKC in
favor of KKXA, without phasing...using only the F-B termination.
Today's work will include measurements (with two SDRs) comparing the
elevated Beverage and the BOG, logging RF levels across the MW band in
various conditions of connectivity. Of particular interest is what we
learn
when the BOG (running directly under the elevated wire) is used as a
counterpoise. Audio reports will appear on DXAS.
The weather has been semi-adverse. Nice temps...but strong winds have
meant
DUST! Today however appears a bit more benign.
We hope to share today's results in the next report.
Mark Durenberger
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