[Elecraft] Modifying Wattmeter Slugs for QRP

[Sandy W5TVW]

Bird makes (or made?) a model 4410 wattmeter that will do what you want.
It looks identically to a model 43, except it has a single knob "range" switch
on it.  The "ranges" depend on the slug in use.  Mine has a 1 KW max.
2-30 Mhz slug, which yield ranges from 0-1 watt to 0-1000 watts with
a 1 and 3 scaling scheme. (1-3-10-30-100-300-1000 watts in this case).
Very handy for low power stuff.  VHF/UHF elements are available for it
that go down into milliwatt ranges.  It has a built in solid state amplifier that
is run by a common 9v. transistor radio battery.
They ain't cheap!  When I bought this one years ago it was around $500
less elements.  The elements were around $100 each at that time.
I only have two elements for it. 1 KW 2-30 mhz and 1 kw 144-520 Mhz.
(Both give the 1 watt to 1000 watt full scale ranges as per note above.)
I sure can't afford to buy elements for it now!  (Was using it on the job
when I bought it so it was a "tool" expense for income tax purposes.)
73,
Sandy W5TVW
----- Original Message ----- 
From: "Arthur Delibert" <radio75a3 at msn.com>
To: <elecraft at mailman.qth.net>
Sent: Friday, February 03, 2006 10:26 PM
Subject: [Elecraft] Modifying Wattmeter Slugs for QRP


| I have a Bird wattmeter that I'd like to use with QRP rigs.  As best I can tell, though, Bird did
not make slugs smaller than 50 watts for the 2-30 MHz range.
|
| There is a website that discusses how to open a Bird slug and modify it for a different power
level and/or frequency range.  [http://www.hayseed.net/~jpk5lad/BIRD%20Slugs/birdslug1.htm]
|
| I'm wondering if anyone has tried to modify, say, a 2-30MHz/50-watt slug for 10 watts and if so,
any experience to share?  What was the right resistor value?  How was the linearity of the meter
with the modified slug?
|
| Thanks for any experience or insights.
|
| Art Delibert
| KB3FJO
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