For receive only, don't waste your time changing this antenna.  You will not 
notice any difference.  Kind of like a speaker advertised to have a 
frequency response from 10 hertz to 30 kilohertz but the human ear cant hear 
above 20 kilohertz if you have excellent hearing.

Howard #3

----- Original Message ----- 
From: "Richard B. McDonald" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Sunday, December 13, 2015 8:58 AM
Subject: Report on 10M Loop Project, and Request for Feedback


> Hi!
>
>
>
> I want to report on my 10M full wave loop (FWL) project, and ask for
> feedback on it.  My aim was a resonant antenna at 28.4 MHz for RX only on 
> my
> TS-2000.  I viewed this project as practice for the antenna I *really* 
> want
> to make - an 80M FWL for both RX and TX (inspired by Ron).
>
>
>
> To make my loop, 14 gauge insolated stranded copper wire sits inside 1" 
> PVC
> ~12' atop my wooden shack.  It is in the shape of an octagon.  I measured
> the length of the wire at 1005 / 28.4 = 35.39', which I rounded to 35.5'.
> There is a 25' run of 75 ohm coax (the kind for TV, which I was told is 
> fine
> for RX antenna purposes like this) properly soldered to the ends of the
> wire.
>
>
>
> So, my friend from our ham club measured this antenna with his analyzer. 
> It
> turned out to be resonant at 25.5 MHz : (  Now, only because I am obsessed
> with my project and by way of learning, I should like feedback on the
> following:
>
>
>
> 1)      I am told that one thing affecting resonance is the "velocity
> factor" of the wire.  Apparently, the insulation of both a) the wire 
> itself
> and b) the PVC affects the velocity factor.  I have no idea what "velocity
> factor" is, nor how it affects the calculated length of a wire for a FWL 
> as
> per the above.
>
> 2)      To bring the resonant frequency up to 28.4 MHz, I *think* I need 
> to
> decrease the size of what I have built.  Is that right?  "Decrease" as in
> shorten rather than "increase" as in lengthen?
>
> 3)      To decrease the size of my loop, I plan to cut 6" (0.5') off each 
> of
> the eight sides of the octagons for a total of 4' (including obviously the
> wire therein).  Check my math (reasoning) on this.  28.4 / 25.5 = 1.11;
> meaning I am too big by 11%.  0.11 * 35.5 = 3.9; say 4'.
>
>
>
> Incidentally, even though my loop is a little off, it seems to RX better
> than my 43' vertical does on 10M.  Some have said that for RX only this
> resonance differential is insignificant.  In other words, they say that 
> even
> if I tune my loop precisely to 28.4 MHz, on 10M it would be imperceptible 
> as
> to 25.5 MHz for RX.  What do you think about this?
>
>
>
> 73,
>
> Richard KK6MRH 


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