RadioBanter - View Single Post - new question (from "system degradation question")

Ian Jackson[_2_] · May 29th 10, 12:14 PM posted to rec.radio.amateur.antenna

In message
,
writes
On May 24, 12:02*am, "rb" wrote:
I'll be using 100 watts SSB/CW, and have about 75' of twinlead up to
antnenna feedpoint.

You've got me going to do the "system degradation question": * I'll run
twinlead to the shack, in spite of the file cabinet.

Now, yes--I can do just fine manually changing my antenna from ladderline
fed to putting it on 160 by jumping both ends together and letting it work
against ground. * Long counterpoise in place. *Then, putting it back as
twinlead dipole on 80m up.

What's the new question? * *I normally would go from 160m up through 15m.
If I just used the jump both ends together and feed long wire, which ant
will be better?

Basically, it's whether a long hat vertical would be as good as using my
twinlead as dipole on bands including 80m and up.

I can certainly keep the antenna twinlead fed dipole, no problem. * *Just
curious.

On most bands it will operate the best fed normally as a dipole.

Probably, but the real answer is that the performance will be different.
You'll need to try it out. The T-feed might actually be quite good on
the lower frequencies - especially 80m - for long-distance contacts. But
you will need a good ground or counterpoise system. Ideally, your
counterpoise should be around a quarterwave (for all the bands where you
use the antenna as a T), so, if it looks promising, you might like to
try multiple wires.

The main problem with any endfed antenna, when fed directly in the
shack, is that you will have a lot of RF in the shack - and you will
also pick up more 'domestic' QRM and hash, usually from things like
switchmode power supplies and all the other 'non-amateur-friendly'
equipment deemed essential for modern-day living.
--
Ian