> The thought occurred to me that I could add a second 500w
> amplifier, and drive each of the two arrays with equal length
> transmission lines. Phasing would be selected at low levels,
> inside, out of the weather. Sounds simple enough, for the
> stack situation.
You'd better consider phase and gain errors in the amplifiers,
especially if the amplifiers have filters in each PA and you
combining after the amplifiers (or driving separate antennas).
You also have to consider SWR induced phase errors on transmission
lines that are not exact multiples of 1/4 wl.
As a general rule, it isn't a good idea to combine amplifiers if they
each have low-pass filters or worse yet tunable networks, unless you
have a way of measuring and adjusting phase and level.
73, Tom W8JI
W8JI@contesting.com
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