Topband: Tuning 160M Dipole

[Ulrich Weiss]

hello Bob,
many thanks for the interesting tool calculating dipole dimensions.. it 
would be even more useful if it considered insulated wires as well... 
PVC-insulated wire can have an additional shortening effect of up to 5 
percent (i.e. as much as about 7 ft. one either side on topband)... that may 
well be the reason for Paul's problems...
regards

Uli, DJ2YA

----- Original Message ----- 
From: "Bob K6UJ" <k6uj at pacbell.net>
To: "Topband List" <topband at contesting.com>
Sent: Wednesday, October 31, 2012 12:56 AM
Subject: Re: Topband: Tuning 160M Dipole


> Paul,
>
> Here is a handy on line calculator to help you determine the approx wire 
> length.
> You can play with  putting in different freqs and see how much the wire 
> length changes.
> I believe with frequency changes of 10KHZ the wire length changes by about 
> one foot.
> So if it is resonant at 1.800 and you trim off one foot it will be 
> resonant at 1.810.
> Note that with the calculator,  an inverted V  has different lengths than 
> a horiz dipole
>
> http://www.cdagro.com/dip/dpo.html
>
> If you can find the resonant freq (where the lowest SWR is) then you can 
> see how far you have to move.
> I find this calculator to be in the ball park.  I normally cut the wire 
> lengths long to start with and then prune
> till I bring the resonant freq up to where I want it to be.   It sounds 
> like you are resonant below the band right now
> which is good, prune time !
>
> 73,
> K6UJ
> Bob