In an article on portable vertical antennas someone mentioned that a
Portable Laundry Reel,
readily available at most camping goods stores, made an excellent windup
counterpoise. It will easily
hold about 80ft of 18 insulated wire, which when measured and marked can
easily be reeled out
to a desired length, and later quickly reeled up again. They are
manufactured by Coghlans and
very reasonably priced (I paid $3.98 CDN). The reel opens easily (it twists
apart). The unreeled
portion does not seem to affect the RF length. To me, it seems like a very
handy item to
have for my apartment antennas.which require counterpoises.

Like the Yo-Yo antenna, it could easily be used as a random wire, or two
could make a
neat compact dipole.

Time will tell -- but it sounds like a great idea to me.

Irv VE6BP

"Irv Finkleman" wrote in message
...


In an article on portable vertical antennas someone mentioned that a
Portable Laundry Reel,
readily available at most camping goods stores, made an excellent windup
counterpoise. It will easily
hold about 80ft of 18 insulated wire, which when measured and marked can
easily be reeled out
to a desired length, and later quickly reeled up again. They are
manufactured by Coghlans and
very reasonably priced (I paid $3.98 CDN). The reel opens easily (it
twists apart). The unreeled
portion does not seem to affect the RF length. To me, it seems like a
very handy item to
have for my apartment antennas.which require counterpoises.

I have also devised a portable counterpoise, albeit not an adjustable one as
you describe, so I see room for improvement. Thus far, I have made two, one
each for 40 and 20. For each, I took a flimsy, disposable aluminum baking
pan and bolted two quarter-wave wires to it. I then use a 3/8-24 mag-mount
base to pin the baking pan down onto any available heavy steel object. From
there, a Hustler (or other) short, single-band whip threads into the 3/8-24
base. Unless it's really lopsided, the antenna stands up nicely.

My AA-54 analyzer showed an in-band VSWR minimum of 1.5:1. I worked a 20m
mobile in Wyoming yesterday from San Diego at "Operating Day" in the Fry's
parking lot. S-5 noise from nearby power lines prevented multiple other
QSOs, guys I could hear buried in the noise.

Irv, if I get four such laundry reels I can dispense with my flimsy baking
pans. I have enough wire to implement your idea with another set of my
surplus chassis slides.

Request for comments and wisdom: Is it accurate to say that say a vertical
needs at least four radials but will not benefit greatly from more than
eight?

Graphs like http://www.wc7i.com/radial%20efficiency.GIF

inspired this question. (The shape of the curve suggests radials added in
the beginning produce big improvement but not so much, later.) From the
graph, going from 50% efficiency toward 70% is certainly less than a
doubling, under half an S-unit, but it takes 20 more radials to get there,
impractical for portable ops. This graph appears to start at four
radials -- It doesn't consider two radials to be worthy of graphing.
Hm-m-m-m ... I know more today than yesterday.

Thanks,
"Sal"
KD6VKW

I've been doing a lot of reading off websites -- most dealing with small
loaded vertical antennas,
and there seems to be a concensus of opinion that even one radial makes a
difference. Because
my station is located within the confines of a small studio suite, with a
small outside balcony which
due to local regulations, nothing can extend beyond, I may even have to run
the radial
around corners and such. I have seen some interesting setups, and one which
you can Google is called
the 'Spiral Counterpoise' is quite interesting. I am also trying to find
some answers as to whether an
artificial ground or a tuned counterpoise as it is sometimes called, is as
effective as a proper
radial, or if it onlyserves to move the high volrage away from the 'lip
burning' mike! It's all
quite interesting. I like your baking pan setup as well! Will a Kilowatt
allow you to bake brownies!

One generous Ham, W4AFA sent me a Superantenna MP-1 which he found surplus
to his
needs. I was really excited but found I cannot operate it indoors due to
all the metal
framing around the doors and windows, and it seems the windows are made of
some
form of glass which itself is RF resistant to a degree. I am QRP with an
FT-817ND so
a few more DBs of loss probably will only make a small difference!

To operate with the antenna on the balcony I am also faced with the metal
framing of
the building serving as five sides of a metal cage, and the matter of
getting the feed
through the door. I've had a piece of RG-58 in the door for a few weeks now
and it doesn't seem to have suffered much. A small impedance bump never hurt
a QRP'er, but I still want to get as much signal out the door as possible.

I do have an MFJ-259B which will really help, it does tell you when you are
tuned, but doesn't do anything to help efficiency!

It's winter now, and a little too cold to want to sit outside and operate,
but come
summer I may be able to set up something that will get out. I have
intentions, and
have already collected some of the parts, to build a magnetic loop antenna
which
I can remotely control fairly easily -- a simple matter of tuning a
capacitor with a
small DC motor (I have both of those now). That will mean there is no need
for
a counterpoise!

Did I mention I also have a couple of Slinkys? Am I desperate or what? There
are enough guys running them with a degree of success as well -- I have only
got to try it.

In the meantime I am determined to get the MP-1 running -- it is not a great
performer without radials which is what led to the Clothesline device. My
stubborn self want's to get it going on 75M -- if I moved up to 20M and
higher I could probably be making contacts by now.

In any event, I am keeping horribly busy doing what I call 'Offline
Hamming' -- off
the air, but having fun studying and planning which way to turn next! My
new
motto has become "RADIATE OR DIE TRYING!"

IRV VE6BP



"Sal" salmonella@food poisoning.org wrote in message
...

"Irv Finkleman" wrote in message
...


In an article on portable vertical antennas someone mentioned that a
Portable Laundry Reel,
readily available at most camping goods stores, made an excellent windup
counterpoise. It will easily
hold about 80ft of 18 insulated wire, which when measured and marked can
easily be reeled out
to a desired length, and later quickly reeled up again. They are
manufactured by Coghlans and
very reasonably priced (I paid $3.98 CDN). The reel opens easily (it
twists apart). The unreeled
portion does not seem to affect the RF length. To me, it seems like a
very handy item to
have for my apartment antennas.which require counterpoises.

I have also devised a portable counterpoise, albeit not an adjustable one
as you describe, so I see room for improvement. Thus far, I have made
two, one each for 40 and 20. For each, I took a flimsy, disposable
aluminum baking pan and bolted two quarter-wave wires to it. I then use a
3/8-24 mag-mount base to pin the baking pan down onto any available heavy
steel object. From there, a Hustler (or other) short, single-band whip
threads into the 3/8-24 base. Unless it's really lopsided, the antenna
stands up nicely.

My AA-54 analyzer showed an in-band VSWR minimum of 1.5:1. I worked a 20m
mobile in Wyoming yesterday from San Diego at "Operating Day" in the Fry's
parking lot. S-5 noise from nearby power lines prevented multiple other
QSOs, guys I could hear buried in the noise.

Irv, if I get four such laundry reels I can dispense with my flimsy baking
pans. I have enough wire to implement your idea with another set of my
surplus chassis slides.

Request for comments and wisdom: Is it accurate to say that say a
vertical needs at least four radials but will not benefit greatly from
more than eight?

Graphs like http://www.wc7i.com/radial%20efficiency.GIF

inspired this question. (The shape of the curve suggests radials added in
the beginning produce big improvement but not so much, later.) From the
graph, going from 50% efficiency toward 70% is certainly less than a
doubling, under half an S-unit, but it takes 20 more radials to get there,
impractical for portable ops. This graph appears to start at four
radials -- It doesn't consider two radials to be worthy of graphing.
Hm-m-m-m ... I know more today than yesterday.

Thanks,
"Sal"
KD6VKW

"Irv Finkleman" wrote in message
...

snip

I like your baking pan setup as well! Will a Kilowatt
allow you to bake brownies!


Laugh


Did I mention I also have a couple of Slinkys? Am I desperate or what?

Eh, the slinky concept may not be so desperate in its most serious
application(s). Some years ago when my company was equiping a new Navy test
facility along the Pacific Coast in San Diego, we met a designer who
demonstrated a vertical antenna that the Navy was already buying.

It used a compact log spiral counterpoise of multiple wires. The vertical
radiatior was a "Slinky" element which was raised or lowered within its
(35'?) housing by a motor-driven reel and a nylon rope. It had programmable
memory tuning or, screwdriver-style, you could just run the slinky up or
down to hit the spot you wanted. That day, I recall hearing WWV on more
different frequencies than ever before.

$10,000 in the 1980's.

"Sal"