EZNEC Rohn 25 top loading
115' Rohn 25
4 spoke top hat, 66" x 0.500" tubing
SWR in a 30 ohm system (match 30 ohms to 50 ohms)
1.800 MHz, 2.2:1
1.900 MHz, 1.2:1
2.000 MHz, 2.2:1 KH6AQ (formerly WX7G)
On Fri, May 15, 2020 at 8:13 AM Jim Brown <jim@audiosystemsgroup.com> wrote:
> On 5/15/2020 8:27 AM, donovanf@starpower.net wrote:
> > A more reliable approach is a tuner in your shack. The extra coax
> > cable loss from elevated VSWR is insignificant on topband.
>
> I strongly agree with this.
>
> Another suggestion. Do your best with what you can rig, using as much
> top-loading as practical rather than base loading. Sweep the feedpoint Z
> with a good analyzer, export the data to SimSmith, do a TDR of the
> feedline to find it's electrical length, and compute the match. I
> recently did that for W6GJB's new 630M antenna, and came up with shunt L
> at the base of the antenna and series C in the shack. Every antenna is,
> of course, different.
>
> 73, Jim K9YC
>
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