Doggone it, Don...I'd seen that presentation before - simply forgot about using
a xfmr to couple unbalanced coax to balanced rcv antenna....good on ya for
sending that on -- need to find a Fair-rite 61 core.....hihi
________________________________
From: Don Kirk <wd8dsb@gmail.com>
Sent: Friday, April 1, 2016 2:02 PM
To: James Rodenkirch
Cc: Top Band Contesting
Subject: Re: Topband: Receive loop observations
Hi Jim,
I know my following info does not directly answer your question, but I do think
it's important regarding feedline isolation.
I suggest you take a look at the recommendations of N6RK regarding the use of a
matching transformer to feed tuned shielded loops as it isolates the feedline
from the antenna (shield of coax not tied directly to the loop). I use the
N6RK matching transformer method on my loops of similar design and think it
makes the most sense regarding feedline isolation, and maintaining proper
balance of the antenna.
Here is a link to his paper, and his matching transformer is shown on page 30
and 33 of his paper.
http://www.n6rk.com/loopantennas/pacificon.pdf
73,
Don (wd8dsb)
73,
Don (wd8dsb)
On Fri, Apr 1, 2016 at 3:04 PM, James Rodenkirch
<Rodenkirch_LLC@msn.com<mailto:Rodenkirch_LLC@msn.com>> wrote:
I have installed a receive loop ( http://www.qsl.net/kc2tx/ ) and finished
measuring and observing...
Measurements:
VSWR --- 1.7 @ 1.830
ZO ----- 77 at 1.830
Observation:
Following ON4UN's comments regarding needing a preamp or not, measured S1 to 2
noise level with antenna connected during mid-day, S0 with dummy load connected.
During evening hours, notice some improvement - S2 drop in noise level when
switching from xmt antenna (inverted U) to the loop - but not hearing much in
the way of receive signals (e.g., hear a fairly strong signal from the west
coast on the xmt antenna, nothing on the loop and I have it oriented east/west).
I'm uncertain if a low noise amp will help my cause (thoughts??)
I do not have a common mode choke installed, yet...will one make that much
difference?
The loop is located about 60' away from the Inverted U and radials.
Comments/suggestions appreciated.
Thank you, in advance, for constructive, relative to what I have now,
replies....non-"constructive" means I can't erect a BOG, Beveridge or Waller
Flag so don't ask why I didn't go that route.
71.5/72 de Jim Rodenkirch K9JWV
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