Reid,
You asked about the CW80 and your 737, as well as your
ic2kl/at500.
responses in digest issue 27 were all over the lot.
(AB7E's were spot-on, however.)
First hand experience: I've had CW160's @ 120',
multiple CW80's @ 60' & 90', ic2kl's, ic4kl's, pw1's, and
several icom exciters. Presently using an ic2kl & lp CW80
@ 60'.
A half wave, more or less in the clear, will radiate
just fine. What you measure as vswr at the shack end of
the feedline reflects impedance transformation in the
transmission line. Seeing 1:1 at the end of 500' of line
doesn't tell you a damned thing about the antenna match,
or system loss. Nor does 8:1, although that surely raises
questions about what's wrong.
The answer to your "will it match it?" question is...only
you can tell. Local variables prevail. If it doesn't match
with the shortest possible feedline, prepare to add line,
33 or 66' at a time.
Also, prepare to use common mode chokes...or what radioworks
calls 'line isolators', or clip-on ferrites, to hold down
common mode current on the feedline.
I'm presently using a cw80 low profile, @ 60', with an ic2kl,
at500 & my old ic751a. Seems to work fine. I have 10 clip-on
type 73 ferrites on the feeder, near the shack entrance.
Despite comments to the contrary, a half wave dipole is a half
wave dipole. I don't care if it's center fed or off-center fed,
fattened on the ends as a bazooka, or not. There simply isn't
going to be a whole heck of a lot of difference in fundamental
performance between them. The advantage of the OCF dipole is
that it's generally easier to match on multiple bands.
The ONE bit of nonsense that flows through things is the height
of the antenna. A 160m antenna at 130' is a LOW antenna. Identical
to a 10m antenna at 8'. Put it up as an inverted Vee with the apex at
35' and the ends sloping, and you should prepare to harvest worms.
(And ANY system exhibiting 8:1 vswr should be examined for major flaws.)
Contact me off-reflector, if you need further help.
Been there. Done that. Happy to share the experience.
N2EA
Jim Jarvis, President
The Morse Group, LLC
732 548 5573 office
www.themorsegroup.net
results@themorsegroup.net
Strategic Planning and Success Strategies
for Sales Professionals and Entrepreneurs.
Sales Excellence Series beginning October 2, 2007
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|