I have one of these installed in my Bird 43, from ebay;
Bird 43 Wattmeter PEP Adaptor Kit - Thruline
Work with CD-GS Dielectric-Collins-Drake-Heath & others
Item condition:
New
Time left:
2d 17h (Mar 16, 201219:25:21 PDT)
Price:
US $59.95
Has a 2x and 5x range (adjustable to other multipliers, I have mine setup 2x
& 4 x.
Pep and avg readings too, works v-well and excellent value. Installed mine
over a year ago,
and no issues .
http://www.ebay.com/itm/Bird-43-Wattmeter-PEP-Adaptor-Kit-Thruline-/22097011
3232?pt=LH_DefaultDomain_0
<http://www.ebay.com/itm/Bird-43-Wattmeter-PEP-Adaptor-Kit-Thruline-/2209701
13232?pt=LH_DefaultDomain_0&hash=item3372d858d0#ht_985wt_932>
&hash=item3372d858d0#ht_985wt_932
Adrian . vk4tux
From: Edward R. Cole [via Elecraft]
[mailto:ml-node+s365791n7371108...@n2.nabble.com]
Sent: Wednesday, 14 March 2012 5:59 PM
To: vk4tux
Subject: Re: KX3 and Data modes
OK, I guess I need to repeat what I said. The 25H is SPECIAL order
from Radiodan W7RF
<<mailto:[hidden email]>[hidden email]>, who has the
ability to run NBS traceable calibration on these elements.
Any Bird element can be modified to a different power range (if you
do a search you should find some sites that talk to this). But most
of us do not want to dig into one that far.
I think the wrong impression has been taken of Bird's statement of
accuracy. I doubt the inaccuracy is a fixed amount that is the same
at any reading. More likely Bird does its calibrations at full scale
and this is the accuracy that they will warrantee. Seem more
reasonable that the error is relative to the level of the
reading. The actual adjustment is a variable cap inside the
element. That and a resistor determine the level the element functions at.
But that being said, I have no proof the element in question is any
better than reading 25w +/- 1.25w. Ideally, I would have sent the
meter to Radiodan to be calibrated with the element. Then he could
have specified what the accuracy was for the calibration.
But this is a brand-new element, freshly calibrated. Should I doubt
it in favor of my 35 year old 100H element? Especially since
resolution of reading 12w is much worse on the 100 scale than on the 25
scale.
There is only one way for me to determine what the accuracy
is. That is by observing the waveform across the dummy load with my
scope, calculating Vrms from the peak-peak voltage and using that to
determine power using V^2/R, assuming the load is not reactive. Well
I might do that out of curiosity. That is probably the most
accurate way for most hams to measure power (unless you are very rich
and own a calorimeter). I did power measurement at 500-KHz by using
my scope since I have no elements that work below 2-MHz. My 100w
500-KHz transmitter is equipped with an RF ammeter for
measuring/monitoring power.
For normal daily ham measurements I am willing to assume that the new
element is my most accurate. Will it matter much if I am off
1.25w? BTW it could be better than that. That is the worse-case
specification.
73, Ed - KL7UW, WD2XSH/45
======================================
BP40IQ 500 KHz - 10-GHz www.kl7uw.com
EME: 50-1.1kw?, 144-1.4kw, 432-QRT, 1296-?, 3400-?
DUBUS Magazine USA Rep [hidden email]
"Kits made by KL7UW" http://www.kl7uw.com/kits.htm
======================================
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