Topband: Beverage Feed-line Noise Pickup

[Arthur Delibert]

Bruce --


The coax isn't buried.  A lot of it runs across a concrete pool deck, and then up to a second floor window, so no chance to bury it.  For the 31-material snap-on chokes, I use 8 turns of RG-58-whatever through the center.  See the illustrations in Jim Brown's piece for how to wind them so as to minimize capacitance between the turns, which affects the resonant frequency of the choke.


-- Art, KB3FJO


________________________________
From: K1FZ-Bruce <k1fz at myfairpoint.net>
Sent: Thursday, December 1, 2016 11:50 PM
To: Arthur Delibert
Subject: Re: Topband: Beverage Feed-line Noise Pickup


Art,



Wonder if you have your coax cable buried ?



How many turns are you using thru your Ferite 31 cores?



Many thanks,



Bruce-k1fz.


On Fri, 2 Dec 2016 03:24:30 +0000, Arthur Delibert <radio75a3 at msn.com> wrote:

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 at contesting.com> on behalf of Herbert Schoenbohm <herbs at 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

_________________
Topband Reflector Archives - http://www.contesting.com/_topband
Topband Archives - Contesting Online Home<http://www.contesting.com/_topband>
www.contesting.com
Topband Mailing List Archives. Search String: [How to search] Display: ...


_________________
Topband Reflector Archives - http://www.contesting.com/_topband