Herb --
I don't have Beverages, but rather pennant antennas. I think we have potential
problems at both ends of the feedline and need protection at both ends. I use
Fair-Rite 31-material snap-on cores at both ends, and there's a noticeable
difference in the noise level if I remove either one.
I suggest you check out "A Ham's Guide to RFI, Ferrites, Baluns, and Audio
Interfacing," by Jim Brown, K9YC, which can be found at
http://www.k9yc.com/RFI-Ham.pdf. I found it very helpful in understanding that
problem and others, and have been able to do a lot to reduce the amount of
locally-generated noise that finds its way into the shack.
Hope this helps.
Art Delibert
KB3FJO
________________________________
From: Topband <topband-bounces@contesting.com> on behalf of Herbert Schoenbohm
<herbs@vitelcom.net>
Sent: Thursday, December 1, 2016 12:06 PM
To: Topband
Subject: Topband: Beverage Feed-line Noise Pickup
On my Beverage feed-line RG6 runs (some 200 feet) I use multi-turns a
large toroid on each feed-line and the attach each coax to a grounding
block and good ground rods (typical Hume Depot RG-6 variety) then on
the other side of the grounding block before the coax runs about 20 feet
to the Beverage Switch I have another large wound 13 turn toroid. I
have since learned that I probably have all my feed-line noise
suppression stuff in the wrong place and that the equipment side toroids
are probably useless anyway. Now I am told that this noise pickup
suppression stuff needs to be out by the actual Beverage feed and about
20-30 feet away. The reasoning is that the noise pickup by the
feed-line needs to be blocked from coupling into the antenna itself. Is
this true?
I am starting to move the toroid-ground-toriod RG-6 "T" combos out
closer to the antennas. I noticed that DX-Engineering sells an RFCC-1
box designed for Beverage coax runs but suggests it be place about 20 to
30' from the Beverage feed which has it's own separate ground rod. I
bought one and before I put it out near the Beverage feed I thought I
would it in place of the toroid system near the shack on one of the
Beverage feedlines. However when I grounded the unit to the Beverage
ground system near the shack I immediately noticed the noise floor jump
up by about 10 db. I now know it is in the wrong place but this test
with the DXE RFCC-1 may prove something of interest. Please correct my
assumption if it is wrong: Noise pickup from long Beverage feed-lines
flows back toward the Beverage feed point and then it is coupled via
the feed point transformer back down the center conductor to the
receiver. If this is true I will remove all toroids at the house and
put them out near Beverage feed points (about 30 feet away with
separate grounds based on the advice I receive back from this post.
Please let me know what you think about this.
Herb Schoenbohm. KV4FZ
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