[Amps] Re: [Amps] Re: [Amps] Bird® 43 Manual

[Gary Schafer]

"wlfuqu00@uky.edu" wrote:


> If the resistance is not 50 ohms the two voltages do
> not null out when the slug is in the reverse direction. And they do when
> the resistance is 50 ohms.
>          Here, prove it to your self that the meter does not only sense
> current.
> What happens when you do not connect any load to the meter on say 80 meters?
> You get a large reverse reading and forward reading. But with no load there
> is no current flowing thru the small section of the transmission line in
> the meter.  You can't say that there is a reflected wave from the output
> connector because the slug is a very small fraction of a wave length away
> from the open connector.  The slug is detecting the voltage at this point
> and not current.

Bill,

What you are saying here is what no one else wants to talk about. This has been the
contention of the discussion from the start. With an open circuit at the output
side of the meter there is no current being picked up from the line because there
isn't any. No current means no power. It is obvious that the meter isn't reading
correct forward or reverse power. In this situation there is no isolation
(directivity) in the meter. The meter reads the same forward power indication as it
does reflected.


So if there is zero isolation with this kind of load we can assume that as you get
further away from the 50 ohm load impedance that the forward reverse isolation gets
worse.

73
Gary  K4FMX