Cecil Moore wrote:
Mark Keith wrote:
I think it would *still* probably slightly beat your antenna. I'm fairly
certain even your G5RV will not be a complete equal to my coax fed
dipole.
But you, yourself, have admitted that the difference is negligible.
Thats only between mine and yours, and IF your's works as advertised. In
the real world, I have never seen this happen yet. Heck, in theory,
there should be no real difference in using a coax fed 80m dipole, and a
80 dipole fed with my tuner, and ladder line. Using the bare min
inductance of course... In theory, there should not be enough difference
to notice. In theory...So far in the real world, it hasn't worked that
way for me. I saw a noticable difference. Probably about 5 db's worth if
using strong signals in the upper part of an S meters range. Now, in
that case, the loss was quite livable for just average use. It wasn't
near as bad the the G5RV's we used. The feedline loss in THOSE
PARTICULAR G5RV's was quite large on 80m. I actually had quite a bit of
trouble even contacting many other stations. Led to hair loss...
It
is indeed around 0.4 dB according to all my calculations. And the reward
is that one gets eight antennas for the price of one, i.e. 8 HF band coverage.
If you were feeding your 75m dipole with ladder-line, I wouldn't have nearly
as strong an argument.
Myself, I think multiband 102 ft dipoles should be fed only with ladder
line...Why are you not using your cut ladder line method for G5RV's?
Enquiring minds wanna know...:/
Because it is so easy to achieve nearly a 50+j0 ohm feedpoint impedance at
the series section to coax junction. It is actually relatively difficult
to achieve nearly a 50+j0 ohm impedance using my variable length ladder-
line scheme at the operating position with a 102 foot dipole. But it is
easy with a 130 foot dipole. I simply got tired of the bad rap you and
others were giving G5RVs and chopped my 130 foot dipole to 102 feet. Now
you have to suffer the consequences. :-)
How's that? If you change it, it's not quite the usual "g5rv" that I
complain about. It's a different antenna. Actually, I think calling it a
G5RV is silly unless it's used as a 20m monoband antenna as was
originally designed. The G5RV's I saw were really bad on 80m. It's not
just something I'm making up. I was so disgusted with the things after
the 2nd FD, I refused to ever use one again. And I haven't. I bring my
own wire and coax just to make sure I don't get stuck on one. And I
wasn't the only one complaining either...
I won't be suffering with a system efficiency in the mid 90's...
What I am trying to demonstrate
is how series matching section transformers work not just at 1/4WL and
1/2WL but at many other lengths.
Well, thats fine. But I'm trying to tell everyone to live a little! Go
with gusto! You only spin once! Use a full size efficient, resonant,
antenna if you want manly 80m FD results and have the room for it. I
suppose being resonant should not really be an issue, but in this case
it is. It's hard to beat a 50 ohm antenna , fed with 50 ohm line, by a
50 ohm radio. To me, that is the "perfect" setup. It just so happens a
1/2 wave dipole lets all this fall into place. And it just happens that
a 1/2 wave dipole has a near optimum pattern for the usual FD type
operation on 80m. To me, anything else is like sticking a finger on the
perfect painting , and smearing it around before it's dry.. :/
I guess this is what led me to question your choice of the perfect FD
antenna. 80m, being the band of real issue.
Why would someone prefer a G5RV over
your normal 80m size all band ladder line fed antenna for FD on 80m?
Enquiring minds wanna know that too...:}
Many hams cannot string a 130 foot dipole but can manage a 102 foot dipole.
At field day? A lousy 15 more ft a side? Man, they need to find a better
place for field day...
Thats sad....
Here's where we were last
year...
http://bvarc.freeshell.org/images/FD2003/index.html
No trouble stringing up a real dipole around that place..."It's a fire
training facility in Richmond Tx."
Note my portable tower and beam I bring on a motorcycle trailer. Thats
why I fear you not on the upper bands....
BTW...My tower was the
lowest, but the highest scoring...Due mainly to superior operating
skills though...No, not by me...:/ I didn't use it...Blame N5XZ...
There are other beams also... If I were to FD by myself, I'd drive down
to the beach and operate off the salt water.
Probably could just sit in the truck and use the mobile setup...
Wouldn't need to get out and do any actual work... :/
I've pushed the 130 foot dipole for years. Now I'm pushing the 102 foot
dipole. Sorry if that is politically incorrect. I simply cannot stand by
and allow new old wives' tales to take over ham radio.
I like your all ladder line design better from an efficiency
standpoint...But claiming a coax fed dipole is nearly invincable as far
as wire ant/dipole efficiency's go, is hardly a wives tail. MK
--
http://web.wt.net/~nm5k