hi all,
As I can can see in EZNEC, simple model, Tower 2 Ft over average ground, 242
Ft high,
best and simplest solution is to put sloping Dipole, K8UR style, Arch shape,
from top of the Tower,
Gain in dipole direction can be as much as 3.84 dBi at 17 degrees Vertical
angle,
one Dipole toward EU 60-90 degrees, and maybe other to west 270-300
degrees,
that would cover all 360 degrees , with F-S 90 degrees less then 3 dB
difference, but 90 degrees from HH north is NA, south SA, and thats
close-almost local, so should be no problem...
73 gl, looking forward HH , would be new one 160m hi
dado E74AW
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of Carl
Sent: Wednesday, 26 February, 2014 01:44
To: Gary@ka1j.com; Topband@contesting.com
Subject: Re: Topband: AM broadcast tower and 160m dxpedition
Make them shorter and they will often do well over tidal marshes but not
over open water.
For a 240' tower Id suggest gamma feeding it up at the 1/4 wave point and
use 4 elevated radials. It the AM BCB radials are installed they will make
an excellent ground screen but do not connect them to the 160M feedline.
Carl
KM1H
----- Original Message -----
From: "Charlie Cunningham" <charlie-cunningham@nc.rr.com>
To: <Gary@ka1j.com>; <Topband@contesting.com>
Sent: Tuesday, March 25, 2014 5:24 PM
Subject: Re: Topband: AM broadcast tower and 160m dxpedition
> That's not so surprising Gary !! te Way the Beverages and similar
> slow-wave
> antennas work is that they depend on the lossy GND underneath for their
> operation, so a salt marsh would not be a very beneficial GND structure
> under a Beverage!
>
> 73,
> Charlie, K4OTV
>
> -----Original Message-----
> From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of Gary
> Smith
> Sent: Tuesday, February 25, 2014 5:09 PM
> To: Topband@contesting.com
> Subject: Re: Topband: AM broadcast tower and 160m dxpedition
>
> My Inv-L is on a salt marsh on Long Island Sound in Connecticut & I
> ran two bidirectional 860' beverages over the salt marsh. I had
> terrible results with the beverages, very noisy and hardly any
> improvement over the Inv-L, much of the time the Inv-L was more
> effective on Rx. With that, my experience of beverages & salt marshes
> says to avoid this route.
>
> I ended up with a HI-Z Triangular array for Rx and it works very well
> at the same location.
>
> Gary
> KA1J
>
>> No, I don't believe 240' is too high - especially if the tower has a base
>> insulator! It would be so close to 1/2 wave on 160, that it could be fed
>> very well as a 1/2 wave radiator on 160, either via a parallel tuned tank
> or
>> a 1/4 wave of perhaps 450 oh ladder line. A 1/2 wave radiator wis an
>> excellent transmit antenna, and, because of the high feed-point impedance
>> can be driven against a very modest ground arrangement
>>
>> Like you, though, I believe they would do well to put up some terminated
>> loops, or perhaps a Beverage (or 3?) for receive antennas! A 240'
>> vertical
>> would, I think, be a VERY noisy receive antenna. If they put up a KAZ
>> terminated loop that only requires one overhead support, they could steer
> it
>> around with ropes and weights on the ground. The KAZ is like ON4UN's
> FO0AAA
>> 160 receive loop.
>>
>> 73,
>> Charlie, K4OTV
>>
>> -----Original Message-----
>> From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of
>> Richard
>> Karlquist
>> Sent: Tuesday, February 25, 2014 3:38 PM
>> To: topband@contesting.com
>> Subject: Re: Topband: AM broadcast tower and 160m dxpedition
>>
>> Congratulations on your adventure.
>>
>> In the past, I have seen some of these AM tower efforts
>> ruined by lousy receive conditions. I suggest you
>> get an advance team out to the site to check
>> out the noise level etc. and maybe put up some
>> temporary beverages, loops, whatever and LISTEN
>> on them. Use WWV and WWVH on 2.5 MHz as a beacon.
>>
>> Others can comment on whether 240 feet is too high.
>>
>> Rick N6RK
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>
>
>
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