[Amps] Maximum tolerable SWR for dual 3-500Z amps

[Joe Isabella]

Good question.  Most Amateurs today are (in my opinion) way too concerned with SWR.  This
undoubtedly stems from today's tranceivers using "three legged fuses" for output finals.  In the
begining, Amateurs just looked for the dip and SWR was not a known term.

As long as you get a dip while adjusting the Plate and the Grid Current stays within limits
(roughly 250mA or less for dual 3-500Zs), it should be okay.  I use mine up to 6 or 7:1 SWR on a
couple bands, and it just chugs along.  If you're using coax, there will be bit of loss, so it's
best to use twin lead and a balun.  It can also cause RF in the shack, so good a ground is
mandatory.  I've done it with coax, so I know it works -- just not the best solution.  One last
thing, you want to start on the high end of your loading C -- if you try to start out with too
little loading, you can get one of those nasty arcs (of course, that's true regardless of the
load's Z).

Joe,
N3JI

--- jsb at digistar.com wrote:
> 
> Is there a rule of thumb for maximum permissible SWR for 3-500Z amps at
> given levels of output power?
> 
> Say, 300 watts for 2:1 SWR or 800 watts for 1.5:1 SWR, etc?  For SSB and
> CW modes?
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