Mark Keith wrote:
How many others feed theirs this way?
I don't know and don't much care. The discussion is about your
antenna Vs mine.
How would I know how yours would vary from the "usual G5RV"?
By the length of the series section transformer. It varies from
20 ft on 10.125 MHz to 35 ft on 18.14 MHz providing less than
2:1 SWR on the coax on all HF bands - no tuner required. On 3.8 MHz
with a series section length of 23 ft, the series section feedpoint
impedance is resonant at 25+j0 ohms.
Because I DO notice the difference between a coax fed dipole and either
a G5RV or the usual "windom" that is sold by "eastern state antenna co.
inc"
Theirs are not optimumized - mine is. Why don't you compare your dipole
to an Isotron so you can feel even better. :-)
Other than my ground loss, which will be the same for either types of
antennas, for all practical purposes I have no loss.
I can say exactly the same thing. My 50 ohm SWR is less than 2:1 without
a tuner of any kind. There's simply no places for losses to occur.
You can not detect .4 db difference in the real world on 80m.
So if my antenna is within .4 dB of yours, it's as good as yours?
I wish I had said that. As a matter of fact, the difference between
your antenna and mine is the difference between an SWR of 1:1 and an
SWR of 2:1 on 75m. The ARRL Handbook loss chart says that is 0.12 dB
difference for 100 ft of RG-213 on 75m.
Now, Cecil, do the math.
There it is in the paragraph above. My dipole is 102 ft long. EZNEC sez
it has a maximum gain of 6.04 dBi compared to 6.24 dBi for your dipole.
Including the 0.2 dB reduction in gain and the 0.12 dB of additional
losses in the coax for an SWR of 2:1, that's 0.32 dB modeled difference
between your dipole and my G5RV and you say one cannot detect a 0.4 dB
difference. Doesn't that shoot your own argument down?
How many db difference does it take to measure
2 s units on the average radio? A lot more that .4 db, I can tell you.
I'll bet $100 that your antenna is NOT anywhere near 2 S-units better than
mine on 3.8 MHz. And I'll bet my antenna is 2 S-units better than your coax
fed 80m dipole on most bands between 40m and 10m where it functions as well
or better than it does on 75m.
--
73, Cecil, W5DXP
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