[TenTec] Antenna Matching Weirdness

[Alan Bryant]

I realize that by posting this, I'm probably going to look like an idiot, 
but I'm sincere in wanting to know what's going on with something. 
Hopefully someone smarter than I am can provide an intelligent answer. So, 
from the "there are no dumb questions" department...

I use a multiband MFJ vertical for an antenna (it's all I have space and 
neighbor tolerance for), and a small antenna tuner with it to broaden its 
bandwidth. The antenna is designed for 40m through 10m, plus 6m and 2m, 
EXCLUDING the WARC bands.

When I initially set-up my station, the only short coax patch cables I had 
with PL-259s on them were made of RG-58 coax, but since it was only a 
couple of 2' cables, I used them anyway. All seemed to work well enough, 
and the tuner also allowed me to match with low SWR on the WARC bands in 
addition to the others. While I know the antenna is far less than optimal 
on the WARC bands, I've managed to work some DX with this set-up on 12m 
with relative ease.

I recently made new patch cables using RG-8 foam core coax, cut to the 
exact lengths I needed. Not surprisingly, the configuration of the three 
tuner knobs was now different to achieve low SWR. But suddenly, I can no 
longer successfully match on 12m at all. The lowest SWR I can get there is 
about 3:1, when I could get it clear down to 1:1 before.

Understanding that trying to use this antenna on the WARC bands is probably 
dumb to start with, I'm still left wondering why I could match it 
successfully with crappy, inappropriate coax (RG-58), and now I can't when 
using quality coax connections of the proper type (RG-8).

Any thoughts on this are welcome (except those, perhaps, telling me I 
shouldn't expect it to work to begin with).

Thanks.



---
Alan Bryant, WDØEVX
Denver, Colorado
http://www.moonworks.com/wd0evx


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