Topband: Vertical choke needed?

[Artek Manuals]

Jim/ K9YC

I am with you 100% on your comments below

my 80/ 160 verticals all run "10 lbs of ferrite" at the feed points but 
that is because I run elevated non resonant radials these days. 5lbs of 
ferrites just got to warm to touch, but that is fodder for a whole 
different thread.� My "jungle" makes running ground mounted radial 
systems unpractical.

Among other things� with my wire T's and L's I also avoid coax runs that 
are multiples of odd 1/4 waves at the frequency of interest which helps 
( how much ?)� didn't measure it a the time, but the Winkeyer stopped 
locking up ......:)

Dave
NR1DX

On 1/1/2021 4:19 AM, Jim Brown wrote:
> On 12/31/2020 5:01 PM, Michael Walker wrote:
>> Hi Ken
>>
>> Chokes at both ends of the feed line are always a good idea.
>
> At the base of the antenna, yes, so that the feedline doesn't become a 
> radial. More are probably wasted money. See my latest Cookbook at 
> k9yc.com/publish.htm
>>
>> I have a similar setup to you but with elevated radials and I have 
>> Mix 31 chokes right at the base of the antenna with an UNUN since I 
>> am using 75 ohm coax and then more chokes at the antenna switch.
>>
>> You can�t use enough chokes.
>
> The only good reasons I've discovered for using chokes on feedlines 
> anywhere but at the feedpoint are 1) to break up the feedline into 
> lengths that won't be parasitic becoming parasitic elements to other 
> verticals; and 2) to prevent noise pickup by a mechanism quantified as 
> the Transfer Impedance of the cable, whereby shield current is 
> converted to a differential voltage inside the cable.
>
> W3LPL has observed that #2 should not be an issue with coax laying on 
> the ground. I am not so optimistic with the CATV RG6 we often use for 
> RX antennas, whose shields are VERY flimsy at MF, but I always value 
> Frank's observations.
>
> As to chokes at the station -- if they solve problems, they're putting 
> a band-aid on badly done (or missing) grounding and bonding. See 
> N0AX's ARRL book on the topic, and/or the slide deck for my talks 
> about it.
>
> http://k9yc.com/GroundingAndAudio.pdf
>
> 73, Jim K9YC
>
>
>
> _________________
> Searchable Archives: http://www.contesting.com/_topband - Topband 
> Reflector

-- 
Dave Manuals at ArtekManuals.com www.ArtekManuals.com


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