Hi Guys,
I've had pretty good luck with my inv-L which is about 109' going over a big
Oak tree near my Hytower. I have a large 56uH edge wound inductor that I tap to
get multiple resonance points between 1820-1920 Khz. But I find in contest it
is easier to just use my Palstar AT5K-HP tuner. I use the hytower's radial
field of 60+ mostly 65' radials and have the sloper sloping up from a 4" X 4"
post angling up into the tree and basically going like an upside down 'L' over
the top of the tree. Just starts to come down on the far side of the branches.
I have had very good luck so far with it working ZL2OK last year during the
CQWW160SSB contest. Look out, you are going to be hearing my poor CW more if I
can get anyone to slow down enough to work me going about 15-18 WPM (HI HI).
Had luck with the Austral Is. on 160 meters too but that's not too difficult
being in the NW USA.
If you want you can see it on my qrz.com/ki7m page. Just got up the new 1/2 WL
40 meter dipole on side of tower and 80 meter 4-Square using 1/2 WL slopers.
Hoping to be able to work Europe this year on 80 meter much better.
Terry
KI7M
> On October 5, 2018 at 10:19 AM "john@kk9a.com" <john@kk9a.com> wrote:
>
>
> Excellent summary Jim. I have always used 135' of wire and either matched
> it with a hairpin or lived with the elevated SWR. I am wondering what the
> advantage is to using longer wire and adding capacitance from a signal
> strength and bandwidth perspective? This method is probably easier to
> adjust if using a vacuum variable. What are the suggested voltage and PF
> vacuum variable capacitor specs for tuning a 170' top band inverted L?
>
> John KK9A
>
>
> From: "Jim Thomson"
> Date: Fri, 5 Oct 2018 09:25:39
>
> ## 165-175 feet works good.... BUT you then requires some series C to
> cancel out the XL
> of the aprx now .375 long ant.
>
> ### ~135 feet may well result in less than 50 ohms. No big deal, a
> helical
> hair pin coil across the
> feedpoint will increase the feed Z up to 50 ohms. But the ant has to
> initially be a bit shorter to provide
> for some XC. Its just a step up L network. Then you also have DC
> grounded the ant as well.
> And the ant is a lot shorter than a .375 ant.... which may well be easier to
> install etc.
>
> ## A buddy used a motor driven vac cap in series with his 160m GP,
> which
> has a T top loaded
> capacity hat.. sorta like an inverted vee on top..with the center
> supported on
> a catenary line between 2 x trees.
> Then it tunes the entire band from 1800-2000. Fixed caps, or relay
> switched
> cap assy could also be used.
> In his case, the vert portion is 100 ft tall..with the capacity hat T
> also at
> the 100 ft point, with sloping ends.
>
> ### But if u can only go up say 40-50 ft..... you might not want to go
> horizontal for another 120 ft.... to make the
> .375 ant... along with a series cap. You would end up with a substantial
> Horz polarized component.
>
> Jim VE7RF
>
>
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