I am trying to match my TS-50 with an AT-50 to a random length wire of
about 50 to 60 ft. At this point 160 through 20 meters tune up fine
however, on 15 and 10 meters the tuner gives me a failure indication.
My question, is there a optimum wire length? even on a random lenght
antenna.
Thanks for any advice.
Fred
wb6iiq

"Fred" a écrit dans le message de news:
...
I am trying to match my TS-50 with an AT-50 to a random length wire of
about 50 to 60 ft. At this point 160 through 20 meters tune up fine
however, on 15 and 10 meters the tuner gives me a failure indication.
My question, is there a optimum wire length? even on a random lenght
antenna.
Thanks for any advice.
Fred



Tuners have difficulties when the length of the wire is close to 0.5lambda,
lambda, 1.5lambda etc.
73

André

http://f5ad.free.fr/
wb6iiq

"Fred" wrote in message
ups.com...
I am trying to match my TS-50 with an AT-50 to a random length wire of
about 50 to 60 ft. At this point 160 through 20 meters tune up fine
however, on 15 and 10 meters the tuner gives me a failure indication.
My question, is there a optimum wire length? even on a random lenght
antenna.
Thanks for any advice.
Fred
wb6iiq

Fred,
Many years ago I input all the frequencies and wavelengths into an Excel
spreadsheet to find a length of wire which would most closely be resonant on
all amateur bands. As I recall 26.5 metres seemed to be an optimum length
when fed via an ATU. It isn't resonant on any amateur band, but most ATU's
will be able to tune it. It worked for me anyway 160m through to 10m. As for
the performance, well it received well enough and obviously radiated enough
of a signal to work 5000+ miles QRP.
Mike G0ULI

Not only that, but if like Kenwood AT-250, Yaesu
FC-20, ect., these only rated to match a SWR of
3:1, or LESS! Not exactly something that is High
Zo +- J ??? ! Jim NN7K

André wrote:

Tuners have difficulties when the length of the wire is close to 0.5lambda,
lambda, 1.5lambda etc.
73

André

http://f5ad.free.fr/
wb6iiq

"Mike Kaliski" wrote in message
...


Many years ago I input all the frequencies and wavelengths into an Excel
spreadsheet to find a length of wire which would most closely be resonant
on
all amateur bands. As I recall 26.5 metres seemed to be an optimum length
when fed via an ATU. It isn't resonant on any amateur band, but most ATU's
will be able to tune it. It worked for me anyway 160m through to 10m. As
for
the performance, well it received well enough and obviously radiated
enough
of a signal to work 5000+ miles QRP.
Mike G0ULI

I assume that the directionality was frequency-dependent. At higher
half-wave multiples, it would have been a beverage antenna, with strongest
signals off the end(s). Was that your experience? I'm getting ready to try
the same thing, although I don't quite have 26.5 meters to play with unless
I can string part of the wire onto my neighbor's property.

"Sal M. Onella" wrote in message
...

"Mike Kaliski" wrote in message
...


Many years ago I input all the frequencies and wavelengths into an Excel
spreadsheet to find a length of wire which would most closely be
resonant
on
all amateur bands. As I recall 26.5 metres seemed to be an optimum
length
when fed via an ATU. It isn't resonant on any amateur band, but most
ATU's
will be able to tune it. It worked for me anyway 160m through to 10m. As
for
the performance, well it received well enough and obviously radiated
enough
of a signal to work 5000+ miles QRP.
Mike G0ULI

I assume that the directionality was frequency-dependent. At higher
half-wave multiples, it would have been a beverage antenna, with strongest
signals off the end(s). Was that your experience? I'm getting ready to
try
the same thing, although I don't quite have 26.5 meters to play with
unless
I can string part of the wire onto my neighbor's property.


At the time I was fairly newly licensed in amateur radio and just concerned
with putting up any old bit of 'wet string' to get a signal out. My antenna
was orientated East West and probably only 15 feet up in the air. From the
UK I could work QRP into the east coast US and all of Europe with pretty
good success. Of course at QRP power levels you have to pick your
frequencies and operating times:-)

It probably helped that in my early professional career as a Merchant Navy
Radio Officer, I was expected to reliably work the UK directly from on board
ship, from as far as Australia, using 1950's valve equipment putting out
only 100w to a Marconi long wire antenna. It did sometimes take up to four
hours to get message traffic passed, but in those days you stayed on watch
until the job was done; a pretty good incentive!

The antennas were generally directional along the length of the ship, but
the navigating officers always seemed to be reluctant to change course and
steam pointing at the UK so I could send a message. I can't think why.

From a professional basis, the more wire up in the air the better but don't
worry if you have to bend it around corners to fit. Provided the antenna is
20 feet up or so, you can get some good low angle (long distance) radiation
off the antenna and low antenna can also be useful for putting out near
vertical signals to work 500 to 1000 mile distances.

Merchant Navy radio installations always used to be done on the cheap using
the lowest powered equipment available. The antennas were fitted around the
masts wherever they would go without compromising operation of cranes and
cargo loading. Depending on the cargo load, the antenna height could vary
from 40 feet to 70 feet above sea level on a typical cargo ship.

One of the best antenna systems I used had two 30 foot helically wound fibre
glass masts, one main, one emergency antenna. Apart from hosing down the
base insulators once a week with fresh water, these worked pretty well and
were essentially maintenance free.

Wires or whips, the antennas were fed via an ATU for all frequencies from
410 kHz to 22 MHz.

Stick a bit of wire up in the air. If works, great. If it doesn't, try
another arrangement. Antenna modelling software is great and can really help
out when designing a system, but there are so many variables in real life,
that sometimes the craziest ideas work much better than theoretical designs.
Try to use wire lengths that avoid very high or very low impedence matches
at the frequencies you are interested in and don't worry about having to use
an ATU to get a match. ATU's are a lot less hassle than traps and loading
coils for general wide band hopping about on the air. If you find a
particular band that you enjoy working on, then design a more efficient
system just to work that band. Open wire feeder as opposed to coax can also
give some useful extra radiation from the antenna system. All the ship board
stuff was fed around the radio room using copper pipe, feed through
insulators in the bulkhead, and multi stranded bare copper cable for the
external antenna and feeds. When not being used for operating, aerials were
connected to earth through a switch box to minimise equipment damage from
the inevitable lightning strikes, especially in the tropics. I forgot once
and the purple discharge glow and loud bangs in the radio room as lightning
repeatedly hit the aerials and jumped to the nearest earth was truly
spectacular. It took me a good couple of minutes to work up the courage to
snap the switches round to the earth position during a slight lull in the
firework display! Strangely enough, all the equipment escaped unscathed.
That's valves for you :-)

Good luck

Mike G0ULI

"Mike Kaliski" wrote in message
...

At the time I was fairly newly licensed in amateur radio and just
concerned
with putting up any old bit of 'wet string' to get a signal out. My
antenna
was orientated East West and probably only 15 feet up in the air. From the
UK I could work QRP into the east coast US and all of Europe with pretty
good success. Of course at QRP power levels you have to pick your
frequencies and operating times:-)

It probably helped that in my early professional career as a Merchant Navy
Radio Officer, I was expected to reliably work the UK directly from on
board
ship, from as far as Australia, using 1950's valve equipment putting out
only 100w to a Marconi long wire antenna. It did sometimes take up to
four
hours to get message traffic passed, but in those days you stayed on watch
until the job was done; a pretty good incentive!

The antennas were generally directional along the length of the ship, but
the navigating officers always seemed to be reluctant to change course and
steam pointing at the UK so I could send a message. I can't think why.

From a professional basis, the more wire up in the air the better but
don't
worry if you have to bend it around corners to fit. Provided the antenna
is
20 feet up or so, you can get some good low angle (long distance)
radiation
off the antenna and low antenna can also be useful for putting out near
vertical signals to work 500 to 1000 mile distances.

Merchant Navy radio installations always used to be done on the cheap
using
the lowest powered equipment available. The antennas were fitted around
the
masts wherever they would go without compromising operation of cranes and
cargo loading. Depending on the cargo load, the antenna height could vary
from 40 feet to 70 feet above sea level on a typical cargo ship.

One of the best antenna systems I used had two 30 foot helically wound fib
re
glass masts, one main, one emergency antenna. Apart from hosing down the
base insulators once a week with fresh water, these worked pretty well and
were essentially maintenance free.

Wires or whips, the antennas were fed via an ATU for all frequencies from
410 kHz to 22 MHz.

Stick a bit of wire up in the air. If works, great. If it doesn't, try
another arrangement. Antenna modelling software is great and can really
help
out when designing a system, but there are so many variables in real life,
that sometimes the craziest ideas work much better than theoretical
designs.
Try to use wire lengths that avoid very high or very low impedence matches
at the frequencies you are interested in and don't worry about having to
use
an ATU to get a match. ATU's are a lot less hassle than traps and loading
coils for general wide band hopping about on the air. If you find a
particular band that you enjoy working on, then design a more efficient
system just to work that band. Open wire feeder as opposed to coax can
also
give some useful extra radiation from the antenna system. All the ship
board
stuff was fed around the radio room using copper pipe, feed through
insulators in the bulkhead, and multi stranded bare copper cable for the
external antenna and feeds. When not being used for operating, aerials
were
connected to earth through a switch box to minimise equipment damage from
the inevitable lightning strikes, especially in the tropics. I forgot once
and the purple discharge glow and loud bangs in the radio room as
lightning
repeatedly hit the aerials and jumped to the nearest earth was truly
spectacular. It took me a good couple of minutes to work up the courage to
snap the switches round to the earth position during a slight lull in the
firework display! Strangely enough, all the equipment escaped unscathed.
That's valves for you :-)


That's interesting. Thanks for the tips. At the moment, being new to HF,
I have only a rudimentary antenna consisting of a copper pipe dipole (built
for 10m) laying near the peak of my garage roof. Unmodified, it did 10 and
did 15 with a tuner. Then, I made one element longer with an alligator-clip
lead and about 12 feet of TV-coaxial cable; the garage isn't very long, so
it makes an L-shape in the roof. Call it an "L" antenna if you wish; I
call it an unholy mess, but it gets me on 20 and 40 with the tuner. I have
worked New Zealand, Australia, Estonia and the Ukraine as well as any number
of places in North America. The other hams, who spent their money on good
antennas, made many of my QSO's possible and I thank them.

Speaking of valves, I have hundreds of them. I am restoring an old military
tester and I'll have the valves available in a few months.

snip
That's interesting. Thanks for the tips. At the moment, being new to
HF,
I have only a rudimentary antenna consisting of a copper pipe dipole
(built
for 10m) laying near the peak of my garage roof. Unmodified, it did 10
and
did 15 with a tuner. Then, I made one element longer with an
alligator-clip
lead and about 12 feet of TV-coaxial cable; the garage isn't very long,
so
it makes an L-shape in the roof. Call it an "L" antenna if you wish; I
call it an unholy mess, but it gets me on 20 and 40 with the tuner. I
have
worked New Zealand, Australia, Estonia and the Ukraine as well as any
number
of places in North America. The other hams, who spent their money on good
antennas, made many of my QSO's possible and I thank them.

Speaking of valves, I have hundreds of them. I am restoring an old
military
tester and I'll have the valves available in a few months.

What everyone seems to forget is that modern receivers tend to have signal
gains of 120dB or more when operated with everything turned up full. With
this sort of sensitivity, you only need a couple of watts of radiated signal
to work around the world, given the right band conditions.

With a kilowatt or so and a high gain antenna, it is possible to work just
about anywhere first go. It all rather takes the fun out of operating when
it is that easy.

Interesting you mention using copper pipe for a dipole. Some of my more
successful antennas have been made from aluminium tube. I found they give a
lovely broad bandwidth, generally the fatter the tube, the wider the
bandwidth.

As you say, there are plenty of hams who have spent money on high gain
antennas. Lets give them some signals that allow them to put their expensive
antennas to good use:-)

Having worked passing commercial traffic with high powered equipment, I find
I get much more satisfaction from completing QSO's using QRP equipment and
basic antennas than using the big expensive stuff.

If you do decide to play around with valve final stages, you should find
that they are much easier to tune into virtually any old bit of wire. Just
be careful to monitor the grid current and keep the anode voltages down when
the system is not at resonance. One of my favourite valve matching circuits
was essentially a CLC design with the variable inductance formed as a
goniometer - essentially two concentric tubes with wire coils wound around
them. As the inside tube was rotated, the inductance coupling to the fixed
outer tube varied. This sytem was quite robust and I never had any arcing
problems with the inductors. The capacitors used to flash over in the high
humidity of the tropics on full power sometimes, but reducing power by 25%
usually solved the problem. A modern version could be produced with some
plastic drain pipe and a bit of coiled springy phospor bronze or copper
strip to make the connections to the rotating coil. That way you get
continuously variable capacitance and inductance without any switches or the
intermittant contact problems that modern wound inductors with a contact
wheel suffer from.

All the best with your experiments

Mike G0ULI