Hi Bob,
I went through this exact issue about 26 years ago and could not find the
answer, even from the Bird rep in this area. The result was that I bought a
special 75 Ohm version of the Bird 43 wattmeter with an expensive 75 Ohm 5 KW
element, both brand new since I had never seen a used 75 Ohm version anywhere.
Later, I found a bargain on a used 50 Ohm Bird 43 with several elements and also
bought that. The bottom line is that I could not see any difference in readings
between them when both of them were connected in series with my amplifier
feeding 75 Ohm CATV hardline. This has been my experience up to at least 10
meters. Beyond that, I have no experience.
One other thing I discovered is that you cannot very well get away with using 75
Ohm elements in a 50 Ohm line section and vice versa even though they will fit
together mechanically. Nothing burns up but the readings are noticably
inaccurate when you mix element impedances and line section impedances.
I have no experience with the Coaxial Dynamics instrument.
Stan
w7ni@easystreet.com
Robert Shohet wrote:
> Hi Guys,
>
> I was wondering if anyone out there knows if the Bird 43 wattmeter and
> Coaxial Dynamics peak reading wattmeter work with 75 ohm coax or just 50
> ohm?
>
> If they don't work properly with 75 ohm coax, is there anyway to "offset"
> the mismatch to get more accurate readings?
>
> Are there any wattmeters that can work properly with both 50 & 75 ohm coax?
>
> Thanks for your help.
>
> 73
>
> Bob KQ2M
>
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List Sponsored by AN Wireless: AN Wireless handles Rohn tower systems,
Trylon Titan towers, coax, hardline and more. Also check out our self
supporting towers up to 96 feet for under $1500!! http://www.anwireless.com
-----
FAQ on WWW: http://www.contesting.com/FAQ/towertalk
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