[TowerTalk] Vertical balun

[Jan Erik Holm]

Again, why a balun? StepIR should know better.
If there are RF currents on the braid of the
feedline you need to cut the braid, that is from
an RF point of view. That you do with forexample
ferrite beads, as you correctly point out below.
I would put them as close to the feedpoint as
possible, if that doesnt solve the problem I
would move them.
Why complicate things with unneeded stuff, keep
it correct and simple and it will pay of in the
long run.

Jim SM2EKM

----------------------------------------------------

Tom Champlin wrote:

> Well, for instance, I just bought a Big SteppIR vertical. The company 
> recommends a balun in some cases. They said it was to keep the RF from 
> coming down the coax. They also sell this balun. Not being a purist, I often 
> like to use the term balun meaning an RF choke as well as a 1:1 matching 
> device. Balanced to unbalanced.
> I normally just use a string of large ferrite beads at the feed point. I 
> haven't modeled this with EZNEC yet, but I would bet that the radials will 
> couple some RF to the coax shield, hence my question as to where to place 
> the beads, balun, or whatever one wants to call it.
> 
> Best regards,
> 
> Tom W0HH
> 
> 
> ----- Original Message ----- 
> From: "Jan Erik Holm" <sm2ekm at telia.com>
> To: <towertalk at contesting.com>
> Sent: Thursday, December 18, 2003 10:45 PM
> Subject: Re: [TowerTalk] Vertical balun
> 
> 
> 
>>Why a balun?
>>
>>73 Jim SM2EKM
>>--------------
>>
>>Don Havlicek wrote:
>>
>>>Tom,
>>>Good question!
>>>I never used a balun on the 80m vertical, but might when I replace the
>>>coax this Spring.
>>>I'll be interested in reading the responses to your query.
>>>Don
>>>N8DE
>>>
>>>Tom Champlin wrote:
>>>
>>>
>>>>The recent discussion of ground radials has been a big help for me.
>>>>There is just one other thing that bothers me. Most hams would
>>>>probably either run buried PVC to put the feed line in, which would of
>>>>necessity be parallel with the nearest buried radials. Even if
>>>>everything was above ground, my question would be the same. Assuming
>>>>it would be desirable to use some kind of balun on the coax before or
>>>>at the vertical feed point, possibly a W1JR toroid type, or some
>>>>ferrite beads. The object being to keep RF from running back to the
>>>>shack on the coax braid.
>>>>So, would one want to place this balun past the radial field but
>>>>before the feed line gets close to the house or right at the antenna,
>>>>or does it matter?
>>>>Tom W0HH
>>>>_______________________________________________
>>>>
>>>>See: http://www.mscomputer.com  for "Self Supporting Towers",
>>>>"Wireless Weather Stations", and lot's more.  Call Toll Free,
>>>>1-800-333-9041 with any questions and ask for Sherman, W2FLA.
>>>>
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>>>>
>>>
>>>
>>>_______________________________________________
>>>
>>>See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless
>>>Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with
>>>any questions and ask for Sherman, W2FLA.
>>>
>>>_______________________________________________
>>>TowerTalk mailing list
>>>TowerTalk at contesting.com
>>>http://lists.contesting.com/mailman/listinfo/towertalk
>>>
>>
>>
>>_______________________________________________
>>
>>See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless 
>>Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with 
>>any questions and ask for Sherman, W2FLA.
>>
>>_______________________________________________
>>TowerTalk mailing list
>>TowerTalk at contesting.com
>>http://lists.contesting.com/mailman/listinfo/towertalk
>>
> 
>