Main reason is that the diode detector types of VSWR Meters are very
inaccurate when any VSWR is present

Also I have found that running PA's at 90% gives a much cleaner output
(Usually) so I need a meter that will give reasonable accuracy when making
these adjustments.

Some cheapo VHF VSWR meters are so inaccurate as to be useless.
For Bird -- buy the appropriate slug -- slugs are very inexpensive on the
used market.
Not E-BAy -- hi hi

And Mil Surplus thru line meters are very cheap on the surplus market, Less
than new diode detector types.

--
73 From The Signal In The Noise
Caveat Lector Ya All



Why would a ham operator have a need for such accuracy ?
Isn't consistency enough ? For ensurance of not exceeding
the power output for those who want to equal the max then
a scope would be the way to go. For those that build then
there is a need for accuracy and bragging rights are fully
earned. Seems like this falls into the same catagory of
'I have six elements where you have only five'
Art

On Mon, 15 Sep 2003 15:50:26 -0700, "Caveat Lector"
wrote:

Main reason is that the diode detector types of VSWR Meters are very
inaccurate when any VSWR is present

Also I have found that running PA's at 90% gives a much cleaner output
(Usually) so I need a meter that will give reasonable accuracy when making
these adjustments.

Some cheapo VHF VSWR meters are so inaccurate as to be useless.
For Bird -- buy the appropriate slug -- slugs are very inexpensive on the
used market.
Not E-BAy -- hi hi

And Mil Surplus thru line meters are very cheap on the surplus market, Less
than new diode detector types.

Hi OM,

Art says why buy expensive equipment, and then extols a scope (easily
three to ten times expensive as a new Bird 43). He probably intends
to only measure flat power with perfect sine shape applied to perfect
designs. A CB SWR meter works better with even the slightest hint of
imperfection and just as well when every thing is hunky-dory. If you
want to watch a phosphor glow, get TV or build your meter with a Magic
Eye tube (more range than LEDs suggested elsewhere).

You say
diode detector types of VSWR Meters are very
inaccurate when any VSWR is present
and then extol the Bird or Mil Surplus - which are diode detector
types (what aren't - scopes? WHOOPZ back into that yarn).

Has anyone here actually measured SWR without using a diode? Form a
que here and tell your story. I want to hear the one about your
single device non-linear detector (a way of not saying diode while
still being a diode).

Caveat Reader,
Richard Clark, KB7QHC

Richard Clark wrote:
"Has anyone here actually measured SWR without using a diode?"

I did something similar and could have used the same rig to measure SWR
in a feedline.

I used a wire loop which included a thermoammeter suspended from a
horizontal antenna element. I pulled this along the element to measure
its current distribution using a long tow rope and a telescope.

Pulled along a transmission line wire, this would have produced the
currents at the minima and maxima along the wire. From these we could
calculate SWR.

Best regards, Richard Harrison, KB5WZI

On Wed, 17 Sep 2003 14:08:47 -0500 (CDT),
(Richard Harrison) wrote:

Richard Clark wrote:
"Has anyone here actually measured SWR without using a diode?"

I did something similar and could have used the same rig to measure SWR
in a feedline.

I used a wire loop which included a thermoammeter suspended from a
horizontal antenna element. I pulled this along the element to measure
its current distribution using a long tow rope and a telescope.

Pulled along a transmission line wire, this would have produced the
currents at the minima and maxima along the wire. From these we could
calculate SWR.

Best regards, Richard Harrison, KB5WZI


Bravo Richard!

You response from the wilderness exposes the poverty of experience
within the city of enlightenment. Cake and circus seems to be the
daily fare here.

73's
Richard Clark, KB7QHC

In message ,
Richard Harrison writes
Richard Clark wrote:
"Has anyone here actually measured SWR without using a diode?"

I did something similar and could have used the same rig to measure SWR
in a feedline.

I used a wire loop which included a thermoammeter suspended from a
horizontal antenna element. I pulled this along the element to measure
its current distribution using a long tow rope and a telescope.

Pulled along a transmission line wire, this would have produced the
currents at the minima and maxima along the wire. From these we could
calculate SWR.

This was a common task for the students at Marconi College in the 50's.

The meter was read with binoculars.

Mike
--
M.J.Powell

Mike Powell wrote:
"This was a common task fot the students at Marconi College in the
`50`s."

The student practice had a commercial application. It was in the same
decade but at a different locale. It was during the tune-up of a SW
broadcast curtain array near Lisbon, Portugal.

Best regards, Richard Harrison, KB5WZI

Caveat Lector wrote:
Main reason is that the diode detector types of VSWR Meters are very
inaccurate when any VSWR is present

Why can't the diode be biased to improve the accuracy? Or a class-B
amp be used?
--
73, Cecil http://www.qsl.net/w5dxp



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