[Amps] Re: [Amps] BirdŽ 43 Manual

[Tom Rauch]

> The bird only picks up voltage or current but not both. 

Respectfully Ron, that simply is not true in the least. 

If it were true, the meter could not possibly have directivity. Turning 
the slug around would result in the same reading. The reason is 
simple, current can NOT flow both directions in a conductor at the 
same time.

Also if what you said was actually correct, power would be reduced 
when line impedance increased because current would be reduced. 
That is very clearly not true.

If you open an element, you will find a small inductive pickup that 
forms a current transformer (low frequency slugs actually use a 
transformer with a core), and a capacitive divider formed by a small 
metal plate and/or a trimmer capacitor that samples voltage.

Without sampling both current and voltage it is impossible to make 
a directional coupler. You would only have a non-directional volt 
meter, or current meter. Read the test I performed, or better yet 
make some actual measurements yourself.
73, Tom W8JI
W8JI@contesting.com