>Subject: Re: [Amps] BirdÆ 43 Manual
>
>
>Page 4-1 section 2 of the Bird 43 manual:
>
>"Where appreciable power is reflected, as with an
>antenna, it is necessary to subtract reflected from
>forward power to get load power"
>
>Mark WB8JKR
>
>
>This can easily be demonstrated if you have two dummy loads.
>Connect one to the Bird and run up some RF power to make the
>meter read a convenient value.
> Note forward power and make sure reflected power is zero.
>Remove the RF by un-keying the transmitter; leave the power
>control knob where it is. Connect another load in parallel to
>the existing one. Subtract reflected reading from forward reading
>and the result should be the forward reading you got in step one.
>
>Reflected power is not magically eaten by tank circuits, transistors, or
>tubes. It does what it is named for; it keeps reflecting up and down the
>transmission line.
>
Thanks, Mark and Phil. It might be interesting to compare the calculated
Fwd -Ref power delivered to a 70-ohm load with and without an extra 1/4
wavelength of coax added.
- R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K,
www.vcnet.com/measures.
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