[TowerTalk] 160M Antenna puzzlement

[Wes]

He already has the feedpoint Z. "Measuring the SWR and R/X at the base of the 
antenna with my Rig Experts AA-55 Zoom,"

If he removes the loading inductance and trims the wire for -j25 (and the R 
stays around 30) then a shunt inductor of 5.3 uH will give a near perfect match 
at 1820 kHs.

Wes  N7WS

On 12/19/2021 12:50 PM, Jim Brown wrote:
> On 12/19/2021 10:55 AM, Jeff Blaine wrote:
>> For 160 something around 8+ turns & type-31 are the "right" rule of thumb 
>> answers.
>
> Based on my research, a lot more turns. http://k9yc.com/2018Cookbook.pdf
>
> Pete has received lots of good advice in this thread. I'll add this. Base 
> loading is a bad thing, because it places inductance at the point in the 
> antenna that carries the most current, and should be doing the radiating. 
> Better to remember that SWR is NOT a measure of antenna performance, that as 
> Jeff has noted, feedline loss is pretty low on 160M, and that what matters for 
> moderate values of SWR most is whether you amp can put power into it with the 
> help of a tuner. And if practical, I'd replace that length of RG8X with 
> something the size of RG8. OTOH, doubling the number of radials, realizing 
> that length of on-ground radials is not critical, would probably help TX 
> signal more than replacing that coax, and would change the feedpoint Z a bit.
>
> While adding horizontal length is technically a great idea, sometimes that 
> isn't practical. I like Jeff's suggestion of an L-network at the feedpoint, 
> but the design requires either a lot of cut and try, or a sweep of the 
> feedpoint Z with a good vector analyzer whose data can be ported to design 
> software like SimSmith. I'll bet that Pete has neighbors who can do that. And 
> if Pete can send me a suitable sweep, I'd be happy to do a design.
>
> 73, Jim K9YC
>
>
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