[AMRadio] Re: How much is too much


john johnmb at nc.rr.com
Fri Jan 19 17:18:09 EST 2007


The little Johnson tuner is more than capable of handling 300W of carrier 
into a reasonable mismatch.   Trying to tune it by loading into a horrible 
mismatch while applying power is a decidedly poor idea with any matchbox 
(to say nothing of what the plate dissipation of your PA tubes is while 
doing this).

It would be kind of like whacking a wristwatch with a hammer because it's 
rated as "shockproof"....  it is, but.......

The Heath tuner you mention is a good one, but with high VSWR, and high 
power, any tuner can/will arc.  Be easy on the tubes and tuner, and do the 
tuning at a lower power, and all will be well. Minor excursions in freq 
(and SWR) can be tweaked up during a transmission, but changing bands, or 
ends of 80M you'd be wise to back down the power and protect your rig and 
tuner (and your blood pressure! :-) ).

John K5MO

John K5MO




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