Jim Leder wrote:

I can read all kinds of info about the 'full sized' G5RV, but I have yet to
find any detailed performance info on the G5RV Jr.

Like:
- The original G5RV was designed mainly for 20 meters, with acceptable
performance on 80/40 and if you are lucky maybe 17. What might be the
optimum band for the Jr., if it has one?

Antennas are scalable with frequency. The full-sized G5RV is a
pretty good performer on 80m, 40m, and 20m (also 12m). The 1/2
sized G5RV will therefore be a pretty good performer on 40m,
20m, and 10m.
--
73, Cecil http://www.qsl.net/w5dxp



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OK, I've seen the responses that the G5RV ,and especially the Jr. variety,
are below average performers. And that a center fed doublet with open line
or at least something like 450 ohm ladder line is a better option as long as
you have a balanced to unbalanced external tuner. I certainly won't argue
that, but suppose I want to be able to use my Kenwood TS450sat's internal
tuner (unbalanced input only), what are my options for a decent, simple
multiband antenna (80/75,40,20,17,etc)? And, I understand that 'fan' dipoles
can be effective (I have an Alpha Delta DXEE for 40/20/15/10, it's poor on
40 BTW). I don't have enough tress for multi element dipole anyway. Can a
'doublet' with 450 ohm ladder line to a 4:1 balun then coax to the tuner be
effective? What would be 'ideal' dimensions for the doublet?
BTW, I did download the 'dipole3' program and my friend with the G5RV Jr.
was VERY disappointed to learn that his Jr. wasn't worth a hoot, even though
he has had fair success with it. Guess in the end it all comes down to what
you have faith in :+)) . Nice little program, thanks for pointing me at it.

Fun to consider these things and ALWAYS to experiment. Cecil, I took to
heart your 'l-loop' and modified one for 30 meters. I have had GREAT luck
with it! Best thing I've tried on 30. Thanks!

"Cecil Moore" wrote in message
...
Jim Leder wrote:

I can read all kinds of info about the 'full sized' G5RV, but I have yet
to find any detailed performance info on the G5RV Jr.

Like:
- The original G5RV was designed mainly for 20 meters, with acceptable
performance on 80/40 and if you are lucky maybe 17. What might be the
optimum band for the Jr., if it has one?

Antennas are scalable with frequency. The full-sized G5RV is a
pretty good performer on 80m, 40m, and 20m (also 12m). The 1/2
sized G5RV will therefore be a pretty good performer on 40m,
20m, and 10m.
--
73, Cecil http://www.qsl.net/w5dxp



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Jim Leder wrote:
Fun to consider these things and ALWAYS to experiment. Cecil, I took to
heart your 'l-loop' and modified one for 30 meters. I have had GREAT luck
with it! Best thing I've tried on 30. Thanks!

For anyone who missed it, here is my previous posting on how to
optimize a full-sized G5RV for each HF band by changing the
length of the "matching section" per band.

These are actual measured values for the resonant lengths of the
series section transformer for all HF bands for my optimized G5RV.

102' dipole, insulated wire. Ladder-line is approximately Z0=380
ohms, VF = 0.9. Coax is RG-213

Freq-MHz ladder-line length
3.8 23 ft. (best with 1000pf in parallel)
7.2 35 ft.
10.125 20 ft.
14.2 29 ft.
18.14 36 ft.
21.3 27 ft.
24.95 29 ft.
28.4 38 ft.
--
73, Cecil http://www.qsl.net/w5dxp



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Jim Leder wrote:

OK, I've seen the responses that the G5RV ,and especially the Jr. variety,
are below average performers. And that a center fed doublet with open line
or at least something like 450 ohm ladder line is a better option as long as
you have a balanced to unbalanced external tuner. I certainly won't argue
that, but suppose I want to be able to use my Kenwood TS450sat's internal
tuner (unbalanced input only), what are my options for a decent, simple
multiband antenna (80/75,40,20,17,etc)? And, I understand that 'fan' dipoles
can be effective (I have an Alpha Delta DXEE for 40/20/15/10, it's poor on
40 BTW). I don't have enough tress for multi element dipole anyway. Can a
'doublet' with 450 ohm ladder line to a 4:1 balun then coax to the tuner be
effective? What would be 'ideal' dimensions for the doublet?
BTW, I did download the 'dipole3' program and my friend with the G5RV Jr.
was VERY disappointed to learn that his Jr. wasn't worth a hoot, even though
he has had fair success with it. Guess in the end it all comes down to what
you have faith in :+)) . Nice little program, thanks for pointing me at it.

Fun to consider these things and ALWAYS to experiment. Cecil, I took to
heart your 'l-loop' and modified one for 30 meters. I have had GREAT luck
with it! Best thing I've tried on 30. Thanks!

"Cecil Moore" wrote in message
...

Jim Leder wrote:


I can read all kinds of info about the 'full sized' G5RV, but I have yet
to find any detailed performance info on the G5RV Jr.

Like:
- The original G5RV was designed mainly for 20 meters, with acceptable
performance on 80/40 and if you are lucky maybe 17. What might be the
optimum band for the Jr., if it has one?

Antennas are scalable with frequency. The full-sized G5RV is a
pretty good performer on 80m, 40m, and 20m (also 12m). The 1/2
sized G5RV will therefore be a pretty good performer on 40m,
20m, and 10m.
--
73, Cecil http://www.qsl.net/w5dxp



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Hi Jim:

Here's what I've done in the past and it worked well for me. (though I'm
not sure about the tuner in the 450, but it worked fine with my LDG
Z100 auto tuner) Run the best coax you can find.. try to keep it as
short as possible (less than 10' would be good) to the outside of the
building then use a 1:1 Choke balun and convert to open wire (ladder
line) run it to the center of the dipole. then get on the air and use
it, think you'll be happy.

73 Dave Kc1di

KC1DI wrote:
Here's what I've done in the past and it worked well for me. (though I'm
not sure about the tuner in the 450, but it worked fine with my LDG
Z100 auto tuner) Run the best coax you can find.. try to keep it as
short as possible (less than 10' would be good) to the outside of the
building then use a 1:1 Choke balun and convert to open wire (ladder
line) run it to the center of the dipole. then get on the air and use
it, think you'll be happy.

Of course, depending upon the impedance seen by the choke, the
choking function may be virtually non-existent. For instance,
5000 ohms is not an unusual impedance in a system of this sort.
The choke would need about 25,000 ohms of choking impedance. I
don't know where to obtain such a choke. I'm doing good to get
500 ohms of choking impedance. If I ran a system such as above,
I would definitely use a balanced antenna tuner.
--
73, Cecil http://www.qsl.net/w5dxp



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"Cecil Moore" wrote
Of course, depending upon the impedance seen by the choke, the
choking function may be virtually non-existent. For instance,
5000 ohms is not an unusual impedance in a system of this sort.
The choke would need about 25,000 ohms of choking impedance. I
don't know where to obtain such a choke.
==================================

Cec, if the circuit impedance at the location of the choke is so high that
the extra impedance of the choke is ineffective, then the current must be so
small a choke is not needed anyway. So what are you worried about?
---
Reg.

"Reg Edwards" wrote
"Cecil Moore" wrote
Of course, depending upon the impedance seen by the choke, the
choking function may be virtually non-existent. For instance,
5000 ohms is not an unusual impedance in a system of this sort.
The choke would need about 25,000 ohms of choking impedance. I
don't know where to obtain such a choke.
==================================

Cec, if the circuit impedance at the location of the choke is so high that
the extra impedance of the choke is ineffective, then the current must be
so
small a choke is not needed anyway. So what are you worried about?
---
Reg.

===================================
Dear Cec,

Just another comment about your oft-described high-impedance choke problem.

In all these discussions the LOCATION of the choke along the transmission
line is always neglected. Yet its location is as just as critical as its
value. If critical it is!

If a two-wire, unbalanced-to-balanced choke is deemed necessary then it
should be located at a lower impedance point in the system where it is
effective.

On the other hand, because very high impedances occur only on sharply
resonant lines, problems may occur, if they ever do, only at rare sharply
defined locations which can usually be ignored even if a resonant frequency
should occur in an amateur band. An operator would very likely be unaware
of it.

What would be the symptoms? Increased RF in the shack?

The solution of such a rare problem, if it occurs, is just to change the
length of the transmission line by a small amount. But you are accustomed
to doing this anyway to save yourself the cost of a tuner. ;o)

Changing the line length will shift an offending high impedance point away
from the choke location.

This very moment it has just come to my wandering mind that you are in the
habit of deliberately changing line length to bring the impedance down to a
value between 25 and 100 ohms at which a choke is certainly fully effective.

So your worries about obtaining an exraordinary high inductance choke really
don't exist.

( Just to tidy up, the length of wire on the choke should ideally be less
than a quarter-wavelength otherwise funny effects occur. And this places a
limit on its inductance. But that's just another factor which contributors
to the argument seem to be unaware of.)
----
Yours, Reg. G4FGQ

On Tue, 24 Aug 2004 17:40:47 +0000 (UTC), "Reg Edwards"
wrote:

In all these discussions the LOCATION of the choke along the transmission
line is always neglected.

Hi Reggie,

You undoubtedly neglect the discussion, but Roy has posted to this
quite often.

73's
Richard Clark, KB7QHC

Reg Edwards wrote:
So your worries about obtaining an exraordinary high inductance choke really
don't exist.

You're right, Reg, for you and me. But how about all the other
unwashed masses who are incapable of locating the common-mode
current-maximum point on their transmission lines? :-) What is
your advice for them?
--
73, Cecil http://www.qsl.net/w5dxp



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Reg Edwards wrote:
Cec, if the circuit impedance at the location of the choke is so high that
the extra impedance of the choke is ineffective, then the current must be so
small a choke is not needed anyway. So what are you worried about?

If the current is small, the voltage is large and metal microphones
burn holes in my lips. Seriously, I still have a scar on my lip from
the 50's so you might say that's what I'm (still) worried about.
--
73, Cecil http://www.qsl.net/w5dxp



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