Thread: Bird wattmeter
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Old September 16th 03, 01:58 AM
Caveat Lector
 
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Ah at URL:
http://www.hamradiomarket.com/articles/Wattmeters.htm

The cheapos are called "inexpensive cross needle, putt-putt SWR/wattmeters"
Interesting article

--
73 From The Signal In The Noise
Caveat Lector Ya All
"Caveat Lector" wrote in message
news:33t9b.134831$kP.127157@fed1read03...
Perhaps poor choice of words

Bird meters and monimatch type meters use the capacitive coupling of the
coupled line to couple voltage and magnetic coupling to the coupled line
to couple current. THEN the diode sees the vector sum of the two
couplings.


The cheaper ones - like Radio Shack had just diodes to detect peak V or I
and -- I always called em diode detector types -- what wud u call em

Any way I am sure you know the difference



--
73 From The Signal In The Noise
Caveat Lector Ya All
"Richard Clark" wrote in message
...
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