[Amps] bird watts

[Dr. David Kirkby]

Gudguyham at aol.com wrote:
>  
> In a message dated 3/7/2006 6:38:36 A.M. Eastern Standard Time,  
> ka1xo at juno.com writes:
> 
> There  are many different RF Power wattmeters, but the Bird 43
> with a 5 or 10KW  slug connected in-line to the nearby antenna
> is the hands-down final say of  True Power in that group.
> 
> 
> 
> 
> In my circle of HAMS (not CBer's) we call the "Bird wattmeter watts" THE  
> GOSPEL!
>  
> It is our standard by which we honor the "Golden Brick Award:" of which I  
> have held for some years now.  It is the only standard by which the award  can 
> be obtained.  We actually have a committee armed with a BIRD wattmeter  and 
> BIRD dummy load who do the testing.
>  
> Nuff said.  Hi Hi 73 Louie W1QJ

Don't worship the Bird.

The Bird 43's I was testing twenty years ago were rarely within 5% of 
FSD. Most were within 10% of FSD, but still a significant fraction were 
outside of that. (These measurements were made at a government standards 
laboratory.)

Bird 43's are fine for determining if a PA is working, but they are not 
capable of accurate power measurement.

I had a Bird 43 myself and bought a new element that covered 432 MHz. It 
was out of spec the day I got it. I returned it to the UK dealer (Aspen 
Electronics), who adjusted it while I was there to be right at 432 MHz. 
I then checked it again, and it was indeed then within spec at that one 
frequency.