Topband: Air core chokes for 160m

Tom W8JI w8ji at w8ji.com
Tue Sep 4 12:33:18 EDT 2012


Unless the feedline is up in the air, I can't imagine you need anything at 
all except perhaps some decoupling to prevent common mode noise from 
reaching the vertical.

I'm sure even a minimal impedance would be more than enough.

Decoupling is mostly a complex issue with seriously truncated, sparse, or 
elevated systems. Those systems have huge electric fields around the 
counterpoise.  R7 verticals (and similar) are a good example. They will melt 
most common mode chokes, and I've seen them cause an arc through the coaxial 
feedline insulation to ground.


----- Original Message ----- 
From: "LY2KZ" <vytenis.sciucka at gmail.com>
To: "Tom W8JI" <w8ji at w8ji.com>
Cc: <topband at contesting.com>
Sent: Tuesday, September 04, 2012 12:10 PM
Subject: Re: Topband: Air core chokes for 160m


> Hi Tom
> I (we) have 21m height mast with two sloping ~17m length top wires. There 
> are 25 radials each about 25m long. The ground is good. Wetland or fresh 
> water in early spring. 
> http://rk.vdu.lt/images/stories/ly2fn/P2260028_600_x_450.jpg  Its 
> February, CQWW160 SSB 2012
> Feedline is long. ~150..200m RG-213. Measured antenna Zin=23+j4
>
> Vytenis
> ly2kz @ly2w
>
> On 2012.09.04 18:30, Tom W8JI wrote:
>>
>>
>> What ground system, feedline routing, and antenna do you have? Most of 
>> the problems, and the acceptable choice of decoupling, would depend 
>> feedline routing and the particular counterpoise or ground system.
>>
>> 73 Tom
>>
>
> 



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