[TowerTalk] JK C3S WARC Modifications

[jimlux]

On 11/28/19 9:58 AM, Herbert Schoenbohm wrote:
> I have a C3S tribander which I seldom use except when on WARC bands.  It is
> useable there but not as good as I think it would be modifying it for 24
> and 18Mhz.  I wonder if anyone has tried that?  I don't care about 10 and
> 15.  I think by just changing the dimension, i.e making the 10-meter
> elements longer for 24Mhz  and the 15-meter element shorter to cover 18
> Mhz, would possibly work.  Is there anyone who has done this successfully?
>

This is an excellent use for a modeling code and an optimizer. There's 
no "rule of thumb" that will get the right lengths and coupling between 
the elements.

Get yourself a copy of 4nec2 or EZnec or AC6LA's tools, and have at it.

I can't speak for the latter two, but the first one lets you specify the 
optimization criteria with multiple frequencies, and so forth.

I'd start by not worrying about tapered elements - it might be that with 
the element spacings on the stock antenna, there's nothing that will 
actually work. So you're basically just working with 9 wires - a real 
simple model to enter.