Re: [QRO] KPA500 variation of PA current band-by-band

Posted by Tony Estep on Feb 08, 2012; 3:09am
URL: http://elecraft.85.s1.nabble.com/QRO-KPA500-variation-of-PA-current-band-by-band-tp7254807p7264581.html

> On Tue, Feb 7, 2012 at 3:23 PM, <[hidden email]> wrote:
>
>>
>> Is your dummy load absolutely a flat 1.0:1 from 1.0MHz to 30MHz?
================
Suppose that the SWR is 1.2. This means that 0.8% of the power is
reflected (80 milliwatts reflected for 10 forward). If the SWR is 1.1,
the reflected power is 0.2%. A simple coax jumper can sometimes cause
an impedance bump large enough to reflect more power than that. A few
minutes spent on a test bench with even the fanciest precision
equipment will quickly disabuse one of the notion that a dummy load
can be trusted to be "absolutely flat 1.0:1 from 1.0MHz to 30MHz."

Tony KT0NY
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