2 items

1] I have since found that Hustler did not make a 160m coil, but
Pro-Am/Valor makes this item (VAL PHF160 = VALOR 160M 8' 3/8-24 WHP/PHF
160B) that I might be able to substitute in its stead.

2] I live in a Antenna Restricted Retirement Community (NO I CAN'T MOVE),
and I have a 40ft pine tree in my back yard. I thought that I might try the
above mentioned item in conjunction with lets say a "LDG AT-200 Pro"
auto-tuner or equivalent. (Note - I cannot run any wires from the house to
the tree in the air - they have to be buried. Also I do not have any
fencing and my rain gutters are grounded.)

My idea is to strap either a metal or pvc painted pole near the top of the
tree, with a mount bracket for the whip (of course all painted to look like
the tree). I will have to feed it with RG-8x (painted) run down the tree and
buried in a trench to the house.

As far as radials go - They are out of the question. Instead - what do you
think if I should just roll up say 250ft of 13ga or so of single conductor
wire about a foot in diameter, attached at the base of the mounting bracket
(hung in the tree) and use it as a counterpoise? I might be able to hang in
the lower branches of the tree - a waterproof box with a loading coil and
attach the counterpoise there instead?

If I could tune TX/RX with this configuration, then I could possibly use it
to cover all of the HF bands.

Of course, I would like to work DX, but if not possible, then at least
conus.

Comments and suggestions welcomed.

73's Howard, W3CQH

John Doe wrote:
2 items

1] I have since found that Hustler did not make a 160m coil, but
Pro-Am/Valor makes this item (VAL PHF160 = VALOR 160M 8' 3/8-24 WHP/PHF
160B) that I might be able to substitute in its stead.

2] I live in a Antenna Restricted Retirement Community (NO I CAN'T MOVE),
and I have a 40ft pine tree in my back yard. I thought that I might try the
above mentioned item in conjunction with lets say a "LDG AT-200 Pro"
auto-tuner or equivalent. (Note - I cannot run any wires from the house to
the tree in the air - they have to be buried. Also I do not have any
fencing and my rain gutters are grounded.)

My idea is to strap either a metal or pvc painted pole near the top of the
tree, with a mount bracket for the whip (of course all painted to look like
the tree). I will have to feed it with RG-8x (painted) run down the tree and
buried in a trench to the house.

As far as radials go - They are out of the question. Instead - what do you
think if I should just roll up say 250ft of 13ga or so of single conductor
wire about a foot in diameter, attached at the base of the mounting bracket
(hung in the tree) and use it as a counterpoise? I might be able to hang in
the lower branches of the tree - a waterproof box with a loading coil and
attach the counterpoise there instead?

Whoa, quite a conundrum there, John. It seems to me that you're best
bet would be to put up as much vertical wire as possible, (probably some
30 feet, and have a loading coil in the circuit, then have a tank
circuit at the bottom to tune the wicked impedances you'll be looking
at. You'd want at least the equivalent of 1/3 wave. On 80 meters, you'd
be looking at around 70 feet or so. 160 meters is looking for more
inductance yet. If you don't have a real pressing need for 160, it would
be a good one to forgo.

The tank circuit will probably be needed even if you use an autotuner.
It is a simple LC with variable cap and coupling transformer. Attach the
lower part of tank to a ground rod, and give it a shot.

Here is a link from Cebik:

http://www.cebik.com/fdim/fdim4.html

You should be able to get fair performance out of this one - nothing
great mind you, but it is after all a compromise antenna.

- 73 de Mike KB3EIA -

On Aug 27, 10:38 am, "John Doe" wrote:

My idea is to strap either a metal or pvc painted pole near the top of the
tree, with a mount bracket for the whip (of course all painted to look like
the tree). I will have to feed it with RG-8x (painted) run down the tree and
buried in a trench to the house.

As far as radials go - They are out of the question. Instead - what do you
think if I should just roll up say 250ft of 13ga or so of single conductor
wire about a foot in diameter, attached at the base of the mounting bracket
(hung in the tree) and use it as a counterpoise? I might be able to hang in
the lower branches of the tree - a waterproof box with a loading coil and
attach the counterpoise there instead?

Well, I suppose anything would be better than nothing, but you are
going to be very limited with this setup. The rules of thumb here
are make the radiating part of your antenna as long as possible to
increase the radiation resistance, make the tuning elements as
efficient as possible to avoid losses due to circulating currents.
For verticals, radials allow higher efficiency and although you may be
able to bring the antenna into resonance at the desired operating
frequency without them, your radiated signal will usually benefit from
as many of them as you can manage. Any radials will help, but just
one that is coiled at the bottom of the vertical is not going to make
up for all the compromises you are making with this design. 40 feet
will make a pretty good vertical perhaps down to the 30 Meters but as
you get on 40 meters and below it's getting pretty short.

On the low frequency bands, your vertical will have very narrow
bandwidth are horrid radiation efficiency as you describe it. It may
very well be usable for you, but there may be other options that will
be more effective on the lower frequency bands (40, 80, 160 Meters).

Have you considered transmitting loops for the lower frequency bands?
They have the advantage of being directional which can help you on
both transmit and receive. Their efficiency is pretty bad, but when
matched against a vertical configured as yours, I'd bet they would be
as good or better in most respects. You will likely be power limited
with these antennas, but properly designed and tuned they can work
quite well. Keep the resistance of your loop and the losses in the
matching network as low as possible and you may discover that they are
better solutions for you.

Usually transmitting loops (or magnetic loops as they are sometimes
called) are home grown affairs. I know of a few products available
for this.. I believe that MFJ has some loop tuner products, and Bail
Isotron makes some things that look like loops to me for various low
frequency bands. (These Isotron antennas have very mixed reviews and I
would figure that they work fairly well when tuned correctly, but they
are difficult to tune properly.) Usually the two biggest issues
facing loops is the voltages and currents produced with very low
transmit powers can be very large and finding the matching components
that can handle the currents and voltages while not introducing IR
losses. Making low resistance loops is not that hard, but finding
variable capacitors that can handle the current and voltages produced
in a single turn loop with even 100 Watts can be difficult (and
expensive.) Going for more than 100 watts is possible, but will
almost assure you of having to home grow just about the whole thing.

Loop antennas also present some unique operating challenges as their
operating bandwidth is VERY limited (approaching SSB Bandwidths at
times) so any frequency changes will include a lengthy period of time
to re-tune and because they are usually located very close to the
operator they can be an RF exposure risk. However, if properly built
they are easy to rotate and provide some directional gain which can be
a HUGE benefit over your standard vertical. You may be putting less
power out of the loop, but it is concentrated in some directions so
your effective power towards the intended location can be much higher.

My advice is to concentrate on your 40 foot tree for 30 meters and up
and for 40 meters on down look to other options. The vertical just
isn't going to perform well as you get down to the lower frequency
bands. I'd also pretty much forget 160 meters unless you will be
happy with a very small bandwidth and very poor performance on either
loops or your current vertical idea.

By the way, I am interested in the Isotron antennas because I live in
a very limiting CC&R environment and I have pretty much zero in the
way of trees to hide antennas in. I'm pretty much limited to what I
can hide in my attic. My trap dipole is pretty much junk on anything
over longer than 30 meters, but what can I expect considering that
it's only about 20 feet up, surrounded by the whole house's worth of
electrical wire and furnace ducting while pretty much limited to about
60 feet long. Oh to get the sunspots back soon!

-= Bob =-

"John Doe" wrote in message
. ..
SNIPPED

My idea is to strap either a metal or pvc painted pole near the top of the
tree, with a mount bracket for the whip (of course all painted to look
like the tree). I will have to feed it with RG-8x (painted) run down the
tree and buried in a trench to the house.

As far as radials go - They are out of the question. Instead - what do you
think if I should just roll up say 250ft of 13ga or so of single conductor
wire about a foot in diameter, attached at the base of the mounting
bracket (hung in the tree) and use it as a counterpoise? I might be able
to hang in the lower branches of the tree - a waterproof box with a
loading coil and attach the counterpoise there instead?

If I could tune TX/RX with this configuration, then I could possibly use
it to cover all of the HF bands.

Of course, I would like to work DX, but if not possible, then at least
conus.

Comments and suggestions welcomed.

73's Howard, W3CQH



Hello,
I remember reading some years ago about a 160 mtr "snake" antenna made
from a piece of coax that laid on top of the ground. About like a garden
hose might. You could even roll it up on a garden hose reel when not in use.
Part of the theory as I remember, was that on 160 mtr band almost no hams
have their antennas at least a 1/4 wave above ground and that RF ground can
be several feet below ground level depending on soil characteristics,
moisture content etc.
The snake antenna is a length of coax with the braid open at the feed point
and the
center and shield shorted at the far end . High voltages can easily be
generated, so it is a good idea to insulate the coax at the feed point, and
at the
far end 100% silicon caulking moisture.
The coax should NOT be an integral number of 1/2 wavelengths long.
Keep in mind that the "Snake" is a compromise antenna , so don't expect to
set any records with it.

Thinking about the "Snake" antenna reminded me of the "Cobra" antenna
http://www.nonstopsystems.com/radio/...adio_cobra.pdf

73, Ace - WH2T


..

"John Doe" wrote in message
. ..
2 items

1] I have since found that Hustler did not make a 160m coil, but
Pro-Am/Valor makes this item (VAL PHF160 = VALOR 160M 8' 3/8-24 WHP/PHF
160B) that I might be able to substitute in its stead.

2] I live in a Antenna Restricted Retirement Community (NO I CAN'T
MOVE), and I have a 40ft pine tree in my back yard. I thought that I
might try the
above mentioned item in conjunction with lets say a "LDG
AT-200 Pro" auto-tuner or equivalent. (Note - I cannot run any wires from
the house to the tree in the air - they have to be buried. Also I do not
have any fencing and my rain gutters are grounded.)

My idea is to strap either a metal or pvc painted pole near the top of the
tree, with a mount bracket for the whip (of course all painted to look
like the tree). I will have to feed it with RG-8x (painted) run down the
tree and
buried in a trench to the house.

As far as radials go - They are out of the question. Instead - what do you
think if I should just roll up say 250ft of 13ga or so of single conductor
wire about a foot in diameter, attached at the base of the mounting bracket
(hung in the tree) and use it as a counterpoise? I might be able to hang in
the lower branches of the tree - a waterproof box with a loading coil and
attach the counterpoise there instead?

If I could tune TX/RX with this configuration, then I could possibly use
it to cover all of the HF bands.

Of course, I would like to work DX, but if not possible, then at least
conus.

Comments and suggestions welcomed.

73's Howard, W3CQH

1] The 160m whip assy that I originally planned to use is CENTER-LOADED
which I think is better than a base loaded whip?

2] Someone suggested that I should run a length of bare wire up the tree
and use a TOPHAT. If I decide to go with a 30 or 40 foot length of bare
wire up the tree, How long should the TOPHAT wires be?

73's de Howard W3CQH

On Sep 2, 5:52 pm, "John Doe" wrote:

1] The 160m whip assy that I originally planned to use is CENTER-LOADED
which I think is better than a base loaded whip?

Yes it is because the lower (below the load) portion of the antenna
would carry a higher current which increases the radiation
resistance. However, there is no free lunch here, because you must
then provide a larger reactance (More inductance in this case) to
bring the antenna into resonance which is likely to have more loss.
You can push this to extreme too, by doing what you suggest next only
in this case the inductive reactance turns to a capacitor as you pass
the end of the antenna...

2] Someone suggested that I should run a length of bare wire up the tree
and use a TOPHAT. If I decide to go with a 30 or 40 foot length of bare
wire up the tree, How long should the TOPHAT wires be?


Yes, you can add capacitive loading by adding a top hat to the top of
your antenna, thereby reducing the inductance required in your loading
coil. If you can add enough capacitance to your hat, you can eliminate
the inductive loading below, but it can be difficult to get a hat that
large in some cases. Capacitive loading is usually a lot more
efficient than a loading coil and has the added benefit of moving more
of the current up the antenna where it can contribute to the radiation
resistance number (making the antenna more efficient). This "top-hat"
is a set of wires that are roughly horizontal and attached to the top
of your vertical. Make it as big as you can hide in your tree I
suppose and expect to have to add additional inductive loading at your
base to bring it into resonance. Capacitance hats can be hard to hide
though, and difficult to construct.

The ARRL Antenna book would be a very good investment for you I
think. It has a wealth of information about how to figure out how
much your "top-hat" design might lower the resonance of your planned
antenna and how much additional inductive loading you might need. It
also has some nice antenna modeling software that also would help you
with your design ideas. (Instead of having to build and rebuild
possible antennas to find the best performer for your site, you can
model them and weed them down to a few most promising designs to try).

-= bob =-