[Amps] Alpha Input SWR

[Steve Thompson]

For a fixed impedance Hardy's comment is correct. Changing the 
feeder length alters the phase but not the SWR (ok, there's 
caveats but they don't apply in an ordinary ham station). If your 
SWR reading changes a lot, it indicates you have lots of harmonics 
or the SWR meter isn't good enough.

With a GG amplifier, especially one with a broadband input 
circuit, think of the coax as part of the cathode circuit rather 
than just the link between rig and amp. There's significant 
harmonic current in the cathode circuit and the length of coax 
affects how it flows to ground. That alters the impedance seen by 
the rig when driving it, so changing the coax length can change 
the SWR the rig sees.

Steve

> Hardy,I do not have Mr. Smith's chart.   All I know is what I see with my own
> eyes. CHANGING THE LENGTH OF THE COAX changes the swr as measured by the
> driver, the radio.  What do you recommend to do when the Smiths of this world
> think they know something and then actual real-world practice shows
> conclusively difference?Charly