Topband: Detuning shunt fed towers

[ZR]

Ive never had a quality UHF arc even with a 5:1 VSWR of either sign at 
1200-1500W. Never tried an import.

Carl
KM1H


----- Original Message ----- 
From: "DAVID CUTHBERT" <telegrapher9 at gmail.com>
To: "John Harden, D.M.D." <jhdmd at bellsouth.net>
Cc: <topband at contesting.com>
Sent: Thursday, November 29, 2012 1:30 PM
Subject: Re: Topband: Detuning shunt fed towers


>A UHF connector won't flash over at 1500 watts if the VSWR is low.
>
> Dave WX7G
> On Nov 29, 2012 9:04 AM, "John Harden, D.M.D." <jhdmd at bellsouth.net> 
> wrote:
>
>> I have a 100 ft 45G, shunt fed tower with stacked monobanders for 80 -10
>> meters. This includes a 24 ft mast with 12 feet out the tower top. I do 
>> not
>> even worry about detuning it.
>> The shunt (4 wire) cage only goes up to 30 feet due to monobanders down 
>> to
>> about 35 feet. It requires a 2000 pfd vacuum variable in series and a 
>> 1000
>> pfd vacuum variable to ground (Omega match) to resonate the system. The
>> series capacitor is motor driven by a 1 RPM, 12 VDC motor. The SWR 
>> remains
>> flat over the band measured at the match and in the shack. I have right 
>> at
>> 40 radials on ground. At this point the curve becomes 
>> asymptotic..........
>>
>> With an Amphenol Type "HN" connector there is never any flashover.
>> SO-239's did not cut it. Type "N" is even worse.
>>
>> My Hi-Z 4-8 PRO RX antenna is over 100 feet away and there appears to be
>> little interaction. If you do the math there should be interaction but
>> there is so little "real" interaction that I simply disregard it.... The
>> guys at Hi-Z will tell you there is very little difference between the 
>> 4-8
>> PRO and the 8 el array that is in a 200 ft diameter circle. They have 
>> both
>> up. The decrease in beam width between the two is inconsequential to 
>> me....
>>
>> I can now hear about anything that is on compared to others in my area,
>> and can work it quickly if I can hear it. The Hi-Z array is that good....
>> The waters of the sea have parted for me on top band.
>>
>> 73,
>>
>> John, W4NU
>> K4JAG (1959 to 1998)
>> ______________________________**_________________
>> Topband reflector - topband at contesting.com
>>
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> Topband reflector - topband at contesting.com
>
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