Brian Kelly wrote:
I'll have some fairly long runs of coax to HF antennas (21Mhz max) to
Field Day antennas. One of the antennas will be an 80M G5RV with their
usual nasty SWRs so a foam-type cable is indicated.

Hi Brian, what bands will the G5RV be used on? Only 80m?
The SWR is not all that nasty on 80m being about 20:1
on the ladder-line and 2:1 on the coax.

Here's one of my rules-of-thumb for which I am infamous. :-)

Given a 102 ft. Dipole at 40 ft. fed with 450 ohm ladder-line
and used on 3.8 MHz, for a ladder-line length between about
25 ft. and 100 ft., the resistance looking into the ladder-line
is about equal to the length of the ladder-line. Thus for 25 ft.
of ladder-line, the impedance looking into the ladder-line is
about 25+jXL1. For a ladder-line length of 50 ft., the impedance
looking into the ladder-line is about 50+jXL2. For a ladder-line
length of 100 ft., the impedance looking into the ladder-line
is about 100+jXL3. Does that give you any hints on how to match it?

According to EZNEC, the impedance looking into 50 ft. of ladder-line
is about 50+j466. Use two series 180pf caps to neutralize the inductive
reactance and you have a feedpoint impedance of 50 ohms. A dual ganged
300pf variable would be ideal.

A 102 ft dipole 40 feet in the air fed with 50 ft of ladder-line
tuned with a dual-gang variable cap on the antenna side of a balun/
choke and no tuner box. Doesn't that sound like a perfect 75m field
day antenna?
--
73, Cecil, W5DXP

Cecil Moore wrote:
Given a 102 ft. Dipole at 40 ft. fed with 450 ohm ladder-line
and used on 3.8 MHz, for a ladder-line length between about
25 ft. and 100 ft., the resistance looking into the ladder-line
^^^^^^^
is about equal to the length of the ladder-line. Thus for 25 ft.
of ladder-line, the impedance looking into the ladder-line is
about 25+jXL1. For a ladder-line length of 50 ft., the impedance
looking into the ladder-line is about 50+jXL2.

I misspoke above. "100 ft." should have been "50 ft."

For a ladder-line
length of 100 ft., the impedance looking into the ladder-line
is about 100+jXL3.

It is true that the resistance for 100 ft. of ladder-line is about
100 ohms, but it is 100-jXC, not 100+jXL. Sorry for the faulty memory.
--
73, Cecil, W5DXP

Cecil Moore wrote in message

A 102 ft dipole 40 feet in the air fed with 50 ft of ladder-line
tuned with a dual-gang variable cap on the antenna side of a balun/
choke and no tuner box. Doesn't that sound like a perfect 75m field
day antenna?

I hope you are successful in making people think so. :/ It'll be
easier pickings for me and my superior, lower overall loss, radiating
device. I already use the *perfect* 75m field day antenna. It's a
regular old full size coax fed dipole. Why would anyone want to
clutter up low loss perfection? Boggles my mind...:/ But it's ok, like
I said, it's to my advantage on that bug infested night in June. I
hope everyone else is using G5RV's, windoms, isotrons, EH's and other
such things.. Makes it easier for us. . MK

Mark Keith wrote:
Cecil Moore wrote in message

A 102 ft dipole 40 feet in the air fed with 50 ft of ladder-line
tuned with a dual-gang variable cap on the antenna side of a balun/
choke and no tuner box. Doesn't that sound like a perfect 75m field
day antenna?

I hope you are successful in making people think so. :/ It'll be
easier pickings for me and my superior, lower overall loss, radiating
device. I already use the *perfect* 75m field day antenna. It's a
regular old full size coax fed dipole. Why would anyone want to
clutter up low loss perfection? Boggles my mind...:/ But it's ok, like
I said, it's to my advantage on that bug infested night in June. I
hope everyone else is using G5RV's, windoms, isotrons, EH's and other
such things.. Makes it easier for us. . MK

I suspect the above antenna is more efficient than your coax-fed dipole.
There's negligible loss in the 50 ft. of ladder-line and negligible loss
in the series caps. No tuner required, therefore no lossy coil. So where's
the loss? Please be specific and provide data to back it up.
--
73, Cecil, W5DXP



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

Cecil Moore wrote in message

I suspect the above antenna is more efficient than your coax-fed dipole.
There's negligible loss in the 50 ft. of ladder-line and negligible loss
in the series caps. No tuner required, therefore no lossy coil. So where's
the loss? Please be specific and provide data to back it up.

I suspect you would be in for a surprise at field day..
What about your balun/choke connection? I assume you will be running
coax to that choke, and then to 50 ft of ladder line? And the variable
cap on the antenna side of the choke...How convenient... All I can say
is why? There is no way on earth that setup is *more* efficient than a
coax fed dipole. It may be *fairly* efficient, maybe even quite so if
you are real lucky, but it's not going to be as good as the full size
dipole fed with good coax. No way. The only real loss I have is the
loss of the feedline "213", and on 80m, it's about as good as ladder
line.
Dunno...I think complicated gimmicky setups that are inferior to the
ultra simple coax fed dipole are kind of silly. :/ But to each his
own. If it were better, I could see it. But it's not. It's inferior.
If it were not, I would be using one here at the house. Why would
anyone want to do more work, for something a step in the wrong
direction? Boggles me mind...I've never seen why people want to use
smaller or compromise antennas when you have the whole wide outdoors
to string up anything you want. The "average" storebought G5RV is
pitiful on 80m compared to the coax fed dipole. Not even a real
contest.
But everyone ignore what I say. I'm really fibbing, and just messing
with ole Cecils head....I suggest all field day op's on 80m use
G5RV's, windoms, isotrons and EH antennas. If you all follow my
advice, I might be able to mop up quick, and be able to go home early
and get some sleep in my cool, bug free, air conditioned bed.. :/ MK

Mark Keith wrote:
What about your balun/choke connection?

W2DU choke, virtually lossless. The tuning cap is also virtually
lossless, much more so than a tuner with a coil.

The only real loss I have is the
loss of the feedline "213", and on 80m, it's about as good as ladder
line.

It's about as good as open-wire line with a 10:1 SWR. The matched line
losses in 100 ft. of RG-213 are higher than the unmatched line losses
in 100 ft. of open-wire line with a 10:1 SWR on 80m.

According to Wirebook II, the matched line loss for RG-213 is ten
times higher on 80m than the matched line loss for open-wire line.

If it were better, I could see it. But it's not. It's inferior.
If it were not, I would be using one here at the house.

You are so biased, you wouldn't use one if your life depended
on it. :-)

Why would
anyone want to do more work, for something a step in the wrong
direction?

It's a step in the right direction, Mark, toward an all-HF-band
antenna. I modified my G5RV yesterday to work well on all eight
HF bands plus 6m. Field strength measurements indicated it is
virtually identical to my 130 foot dipole on 80m.

The "average" storebought G5RV is
pitiful on 80m compared to the coax fed dipole.

Mine is virtually equal to a resonant dipole. Your "average" storebought
G5RV must be poorly designed - maybe lacking a balun - maybe using RG-58
coax - maybe using the wrong length of the series section transformer.

But everyone ignore what I say. I'm really fibbing, and just messing
with ole Cecils head...

I asked for some scientific proof of what you say. All you responded
with is prejudice and hand-waving. Please take time to calculate
the matched line losses in RG-213 Vs the unmatched line losses for
open-wire line and you will change your mind (if you are rational).
--
73, Cecil, W5DXP



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

Cecil Moore wrote in message ...
Mark Keith wrote:
What about your balun/choke connection?

W2DU choke, virtually lossless. The tuning cap is also virtually
lossless, much more so than a tuner with a coil.

Won't this depend on the match involved? I have trouble seeing that
connection as "virtually lossless".

The only real loss I have is the
loss of the feedline "213", and on 80m, it's about as good as ladder
line.

It's about as good as open-wire line with a 10:1 SWR. The matched line
losses in 100 ft. of RG-213 are higher than the unmatched line losses
in 100 ft. of open-wire line with a 10:1 SWR on 80m.

Sure, but is it enough to notice on the air? I doubt it...

According to Wirebook II, the matched line loss for RG-213 is ten
times higher on 80m than the matched line loss for open-wire line.

If it were better, I could see it. But it's not. It's inferior.
If it were not, I would be using one here at the house.

You are so biased, you wouldn't use one if your life depended
on it. :-)

You got that right. Nothing but the best for me.

Why would
anyone want to do more work, for something a step in the wrong
direction?

It's a step in the right direction, Mark, toward an all-HF-band
antenna.
Who's talking about all band use though? All I've heard mentioned was
80m.

I modified my G5RV yesterday to work well on all eight
HF bands plus 6m. Field strength measurements indicated it is
virtually identical to my 130 foot dipole on 80m.

Virtually huh....

The "average" storebought G5RV is
pitiful on 80m compared to the coax fed dipole.

Mine is virtually equal to a resonant dipole.

Maybe close...
Your "average" storebought
G5RV must be poorly designed -

It was.

maybe lacking a balun -

Nope, it had one. I always considered that choke/balun half the
problem...

maybe using RG-58
coax - maybe using the wrong length of the series section transformer.

No, it was RG-8. The antenna was a common storebought version. I won't
mention names, but it's the most popular version out there.

But everyone ignore what I say. I'm really fibbing, and just messing
with ole Cecils head...

I asked for some scientific proof of what you say. All you responded
with is prejudice and hand-waving. Please take time to calculate
the matched line losses in RG-213 Vs the unmatched line losses for
open-wire line and you will change your mind (if you are rational).

Why? I've already done it. I don't need those numbers to help make up
my mind. I've compared the real antennas. I'll never change my mind.
Nothing but the best for me. Anything less is a waste of my valuable
time. All bands? Who gives a rats rectum about all band use? We have
three tri band yagi's for the higher bands. Will smoke any G5RV used
on those bands...Well, time to unplug..It's lightning time for
nm5k...MK

Mark Keith wrote:

Cecil Moore wrote:
W2DU choke, virtually lossless. The tuning cap is also virtually
lossless, much more so than a tuner with a coil.

Won't this depend on the match involved? I have trouble seeing that
connection as "virtually lossless".

I feed all my antennas at a low resistance current maximum point so the
W2DU choke is indeed virtually lossless and fully functional to boot
because it is seeing its designed-for resistance. You would know that
if you took time off from your prejudice position to actually think. :-)

It's about as good as open-wire line with a 10:1 SWR. The matched line
losses in 100 ft. of RG-213 are higher than the unmatched line losses
in 100 ft. of open-wire line with a 10:1 SWR on 80m.

Sure, but is it enough to notice on the air? I doubt it...

If it's not enough to notice on the air, doesn't your entire point
evaporate into nothingness? If no one notices whether an antenna is
resonant or not or fed with coax or open-wire line, what is the point
of your argument?

Why? I've already done it. I don't need those numbers to help make up
my mind. I've compared the real antennas. I'll never change my mind.

That's pretty obvious and is a trait shared by the Catholic Priests who
condemned Copernicus and Galileo. I believe you will never change your
mind even if you come over to my house and see scientific evidence to the
contrary. It's a good thing human lifespans are so short or else the human
race would never make any technical progress.
--
73, Cecil, W5DXP



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

Cecil Moore wrote in message ...
Brian Kelly wrote:
I'll have some fairly long runs of coax to HF antennas (21Mhz max) to
Field Day antennas. One of the antennas will be an 80M G5RV with their
usual nasty SWRs so a foam-type cable is indicated.

Hi Brian, what bands will the G5RV be used on? Only 80m?
The SWR is not all that nasty on 80m being about 20:1
on the ladder-line and 2:1 on the coax.

Greetings Cecil: I've been on the road for the past three days and am
just now catching up with my e-mail and such.

The answer to your question is that I intend to use a Van Gordon 80M
G5RV at about 40 ft. on 80/75/40 as a minimum. I'm "ambidextrous", I
motor-mouth and twitch paddles on FD so I need "bandwidth" on 80/75.
I'm building a close-spaced wires duo-band dipole for 20 & 15 which
will be hung at around 25-30 ft. If that antenna doesn't work right
I'll also have to use the G5RV on 20/15 too. In the ideal scenario
both antennas would work and I'll be able to swap antennas around for
20 & 15 depending on the pattern & propagation condx of the moment.
I'll use 8X to feed the G5RV balun which will be 8-10 foot above
ground level to keep the weight on the G5RV down

From there I'll run a length of RG-8 to the operating position. Looks
like a 75 or so foot run. I'll use my LDG-11MP ATU to tame the G5RV.
With all this coax involved the ATU won't have much "work" to do . . .

Here's one of my rules-of-thumb for which I am infamous. :-)

Heh.

Given a 102 ft. Dipole at 40 ft. fed with 450 ohm ladder-line
and used on 3.8 MHz, for a ladder-line length between about
25 ft. and 100 ft., the resistance looking into the ladder-line
is about equal to the length of the ladder-line. Thus for 25 ft.
of ladder-line, the impedance looking into the ladder-line is
about 25+jXL1. For a ladder-line length of 50 ft., the impedance
looking into the ladder-line is about 50+jXL2. For a ladder-line
length of 100 ft., the impedance looking into the ladder-line
is about 100+jXL3. Does that give you any hints on how to match it?

According to EZNEC, the impedance looking into 50 ft. of ladder-line
is about 50+j466. Use two series 180pf caps to neutralize the inductive
reactance and you have a feedpoint impedance of 50 ohms. A dual ganged
300pf variable would be ideal.

A 102 ft dipole 40 feet in the air fed with 50 ft of ladder-line
tuned with a dual-gang variable cap on the antenna side of a balun/
choke and no tuner box. Doesn't that sound like a perfect 75m field
day antenna?

I've read the whole thread thru Tuesday AM, I get your point and it
should work well on 80. I suspect the real advantage of your scheme is
that it might be possible to cover both 80 and 75 with low overall
losses which is difficult to accomplish with a fullsize dipole. Since
you already have the EZNec model on hand how 'bout running a 3.50-3.85
Mhz. sweep to see if it's possible to cover that range with some
single specific length of ladderline and the two-section BC variable
cap? If yes I think you have a real keeper idea.

Davis RF has "RG-213 Economy" cable, whatever that is, for $0.23/foot.
Good enough for Field Day.

Brian w3rv

Brian Kelly wrote:
I've read the whole thread thru Tuesday AM, I get your point and it
should work well on 80. I suspect the real advantage of your scheme is
that it might be possible to cover both 80 and 75 with low overall
losses which is difficult to accomplish with a fullsize dipole. Since
you already have the EZNec model on hand how 'bout running a 3.50-3.85
Mhz. sweep to see if it's possible to cover that range with some
single specific length of ladderline and the two-section BC variable
cap? If yes I think you have a real keeper idea.

Maybe you'll like this one. 110 ft dipole at 40 ft, fed with 110 ft of
450 ohm ladder-line and tuned with a single control dual-gang variable cap,
i.e. no conventional antenna tuner. Such an antenna system covers the entire
75-80m band with a 50 ohm SWR ranging from 1.7 at 3.5 MHz to 1.0 at 4.0 MHz,
according to EZNEC. Full band coverage at the twist of one knob? You likeie?

For a coax fed dipole, EZNEC reports an SWR=2:1 bandwidth of 170 kHz.
--
73, Cecil, W5DXP



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----