Topband: [Bulk] Re: Anybody?
grants2 at pacbell.net
Fri Jan 1 17:49:59 EST 2016
see N6LF's work on 160m top hats
My guess is that informed the DXE design.
On 1/1/2016 12:07 PM, Richard (Rick) Karlquist wrote:
> On 1/1/2016 8:16 AM, K4OWR wrote:
>> :::: Does anyone recall that I originally asked about this?
>> BILL K4OWR
> I looked at the data sheet on this and my intuition
> told me the top hat didn't make sense either electrically
> or mechanically. I did some quick and dirty
> modeling with EZNEC over perfect ground and
> got a drive impedance around 6-j34 at 1.83 MHz. I
> then deleted the horizontal skirt wires and pulled
> out the 39 foot top loading wires to a 45 degree angle.
> I then got a drive impedance of around 8-j9.
> A rope tied to the guy anchors in the manual works
> perfectly to do this. These hybrid wire/ropes then
> become top guys. Its almost as if this was the original
> design, and then they wanted to make a fancy top
> hat. The data sheet brags about the
> uniform current in the vertical, but this simplified
> version kept the current within +/-7%. Good enough
> for me. I don't have a mechanical modeling program,
> but I don't like the DXE design in that respect either.
> It doesn't lend itself to a falling derrick erection
> method, so you have to use their patented winching
> fixture and bolt it to a concrete base. It seems like
> this is the hard to way to build a vertical.
> I needed an emergency 160 meter vertical a few years
> ago and I made a 60 footer out of 2 30' long
> 3" diameter irrigation pipes with 2 top loading
> wires pulled out. A third pipe was used as a
> falling derrick. Pretty simple and it worked great.
> Rick N6RK
> Topband Reflector Archives - http://www.contesting.com/_topband
More information about the Topband