[Amps] Bird wattmeter
garyschafer at comcast.net
Mon May 7 16:58:24 EDT 2007
While I appreciate your input, let's be sure we are all on the same page
Just because a meter has a digital readout dial doesn't make it any more
accurate than a regular analogue type meter. Although I haven't yet looked
at the array solutions meter, they may in fact be a superb instrument. But
to say that they are superior because they "pride themselves on calibration
and military spec instruments says little about them. After all Bird has
been supplying the military many tons of their meters for many years and the
fact that the military no longer only buys mil spec equipment means that
they can buy about anything out there, and I know first hand that they do
buy plenty of non mil spec equipment.
The meter movements for a bird 43 are ALL 30 microamp that I am aware of.
Yes they do use other movements for other wattmeters but let's not confuse
the question about the 43 wattmeter movement.
> -----Original Message-----
> From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
> Behalf Of Harold Mandel
> Sent: Monday, May 07, 2007 6:33 AM
> To: helge.skram at c2i.net; garyschafer at comcast.net; amps at contesting.com
> Cc: EconomyEl at aol.com
> Subject: Re: [Amps] Bird wattmeter
> The Bird 43 wattmeter is fine for trend observations, and as said
> below, will last a long time.
> However, do not see their display results as gospel. If you need
> to know the actual power, use a digital RF Power Meter like
> the kind that is discussed herein made by Array Solutions
> (PowerMaster). That firm prides itself on calibration, and the
> spin-off to the Amateur market of milspec-quality instruments
> leaves the Bird meters far behind.
> The Bird meters have two movements. One is a 30 microamp
> movement and the other is a 100 microamp movement. The slugs
> that drive each meter movement are different. For instance, the
> 50KW slug in my 3-1/8" line section is specifically made for the
> Bird 375 wattmeter with a 100uA movement, and scales calibrated
> for KW, not W.
> If anyone needs a reliable source for slugs, please contact Jerry
> at Economy Electronics, http://www.economyelectronics.com
> at telno 501-676-3234. This business offers all sorts of high power
> RF stuff and is also a certified supplier to our cellular projects
> with heliax, coax, connectors, etc.
> All slugs will give 30uA at indicated power.
> The slugs have a small variable potmeter that can be adjusted for
> calibration. Then you need a good reference and gain access to the pot.
> I check Bird meters as you explained with a 12V source connected to the
> Slug connection via a 470k pot and a multimeter reading microamps.
> I have many slugs where most are purchased seconhand. It is not unusual
> that readings are off by as much as +-10%, comparing slugs or measuring
> with a Narda coupler and HP435 powermeter. With a meter that reads full
> scale with 30uA and new slugs, power is accurate within +-5%. The Bird
> 43 is a nice instrument that last for decades if it's cared for.
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