Richard Clark wrote:
Now, for the standing individual of average size, that person is
approaching a quarter wave at 10M ...

Unless the individual is grounded at one end, that 1/4WL is
non-resonant. :-) Richard, what is your velocity factor?
--
73, Cecil http://www.qsl.net/w5dxp



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I thought the same thing until I did some field strength measurements. (a
meter/diode/antenna field strength meter - I have an e-field probe now, but
haven't tried it yet)

Get this:
A 2M quarter wave on the roof has much more field strength than a 5/8 on
the trunk! I saw about 20 dB more. I was also surprised that the same
model car with a sun roof had LOWER inside (with the roof 1/4 wave) than
the one without the sun roof. Go figure.
Steve, K;9;D:C:I

"JDer8745" wrote in message
...
Crazy George sed:
"At 15', you are in the near field of any HF antenna. ...
---------------------------------
Kind of rules out mobile operation.

Of course the metal body of the vehicle probably shields the station from
the
effects of the near field. 73 de Jack K9CUN

I don't understand why you say this. In the near field the E to I ratio
just isn't at 377 ohms yet, so you can have either a higher E or H field.
Steve K;9;D;C;I

"JDer8745" wrote in message
...
Crazy George sed:

"At 15', you are in the near field of any HF antenna. You do not want
your
station to be in the near field of the antenna. All kinds of undesirable
and often unpredictable things happen."
---------------------------------

Your long piece of crappy old oxidized coax is excessivly (compared to
your shorter fresh stuff) attenuating the signal towards your antenna,
resulting in less power available at the antenna to be reflected back
towards your VSWR meter, & the power that is reflected is being
attenuated on the way back as well, making your VSWR look even better.

If you bend a section of coax & it makes a crackly noise it's only
good for landfill. Doesn't have to be old used stuff either, I've seen
it bad right from the distributor.

Wanta have some fun someday? Measure your forward & reflected @ your
transmitter, then measure it @ the antenna end of the line. Very
Educational.

Howard.


On Sat, 3 Jan 2004 01:35:51 -0000, "Keven Matthews"
wrote:

I recently moved my shack from an upstairs room to downstairs, much closer
to the garden and antennas. All the antennas previously had a long run of
coax to the old shack. The obvious thing was to have a nice new short run
of coax to my HF vertical which is now only 15' away. So I cut the coax and
since then the antenna is no longer resonant on 40 Metres. Also this week I
was putting up a new HF wire antenna, it was getting dark and raining by the
time I was hoisting it up but so I could just have a listen that night a
grabbed an old (15 years) large coiled up of quantity RG213 coax complete
with rotten oxydized pl259 plugs on each end which had just sat on the
garage wall for years. I just slung the coil down and plugged in at each
end. The plugs looked so rotten it was shameful but it pitch dark by then!
However The SWR was pretty good across the band. Regardless I started my
evening doing a tidy job with some of that nice 5DFB japanese coax all ready
for the following day. Guess what ? I put on the nice new cable and plugs
and the antenna is no longer anywhere near resonant on 80M. So why am I
getting a better result with a long length of still coiled cable sitting on
my patio rather that a much shorter brand new piece. Please could some one
explain to me if the coax length does matter, it has certainly never been a
problem for me in the past on VHF and Six but I am new to HF frequencies.
If you do need to have a certain size run, what can you do with the cable if
you phisically dont need it ?


Many Thanks & 73 for 2004

Keven G7UUD

Hi Kevin,

If you have to cut bits off the coax to get the SWR down, your aerial isn't
resonant on the frequency being used. The coax is acting like part of the
aerial.
Get the aerial resonant and it doesn't matter what length of coax you use as
the SWR will not change.

"Keven Matthews" wrote in message
...
I recently moved my shack from an upstairs room to downstairs, much
closer
to the garden and antennas. All the antennas previously had a long run of
coax to the old shack. The obvious thing was to have a nice new short
run
of coax to my HF vertical which is now only 15' away. So I cut the coax
and
since then the antenna is no longer resonant on 40 Metres. Also this week
I
was putting up a new HF wire antenna, it was getting dark and raining by
the
time I was hoisting it up but so I could just have a listen that night a
grabbed an old (15 years) large coiled up of quantity RG213 coax
complete
with rotten oxydized pl259 plugs on each end which had just sat on the
garage wall for years. I just slung the coil down and plugged in at each
end. The plugs looked so rotten it was shameful but it pitch dark by
then!
However The SWR was pretty good across the band. Regardless I started my
evening doing a tidy job with some of that nice 5DFB japanese coax all
ready
for the following day. Guess what ? I put on the nice new cable and
plugs
and the antenna is no longer anywhere near resonant on 80M. So why am I
getting a better result with a long length of still coiled cable sitting
on
my patio rather that a much shorter brand new piece. Please could some
one
explain to me if the coax length does matter, it has certainly never been
a
problem for me in the past on VHF and Six but I am new to HF frequencies.
If you do need to have a certain size run, what can you do with the cable
if
you phisically dont need it ?


Many Thanks & 73 for 2004

Keven G7UUD

Arrrg! Your making my stomach hurt reading this misinformation...

(They told me all I had to do to become a ham was to memorize these
questions.)


"Mike" wrote in message
...
Hi Kevin,

If you have to cut bits off the coax to get the SWR down, your aerial
isn't
resonant on the frequency being used. The coax is acting like part of the
aerial.
Get the aerial resonant and it doesn't matter what length of coax you use
as
the SWR will not change.

w4jle wrote:
Arrrg! Your making my stomach hurt reading this misinformation...

Well, let's add a few words to make his statement correct.

Get the aerial resonant,

with a 50+j0 ohm feedpoint impedance,

and it doesn't matter what length of coax you use
as the SWR will not change.
--
73, Cecil http://www.qsl.net/w5dxp



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Now you are getting technical, beyond the understanding of most of today's
hams.

(I looked everywhere on my SWR's meter and couldn't find a J knob and isn't
a 50 to 0 SWR kinda high)

"Cecil Moore" wrote in message
...
w4jle wrote:
Arrrg! Your making my stomach hurt reading this misinformation...

Well, let's add a few words to make his statement correct.

Get the aerial resonant,

with a 50+j0 ohm feedpoint impedance,

and it doesn't matter what length of coax you use
as the SWR will not change.
--
73, Cecil http://www.qsl.net/w5dxp



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w4jle wrote:



(They told me all I had to do to become a ham was to memorize these
questions.)



SNIP That's absolutely TRUE if all you want is to "...become a ham..."

However, if you want to install and operate an efficient short wave
radio station you need to learn quite a bit!

DD, W1MCE

Well said Sir!

Even the "appliance operators" of old had to know how the appliance worked.

Were I the FCC, your first transmitter and receiver would be built from
scratch and a minimum of 25 CW contacts confirmed before the use of a
purchased rig would be allowed.

Next no one would be permitted to apply for extra class without 5 years
experience and 250 confirmed contacts.Also participation in a public
service capacity, (i.e. traffic net, weather warning net, charity races etc)
and have elemered 5 new hams.

I have a friend that has an extra and has never been on the air. He took the
exams at a hamfest just to see if he could pass them. He said he studied the
question pools for a couple of days on-line. He spent 20 years in the Navy
as a Chief Radioman, so the code was a joke for him.

"Dave Shrader" wrote in message
news:XnFJb.49405$I07.151812@attbi_s53...
w4jle wrote:



(They told me all I had to do to become a ham was to memorize these
questions.)



SNIP That's absolutely TRUE if all you want is to "...become a ham..."

However, if you want to install and operate an efficient short wave
radio station you need to learn quite a bit!

DD, W1MCE