[Elecraft] [QRO] KPA500 variation of PA current band-by-band

Tony Estep esteptony at gmail.com
Tue Feb 7 22:09:55 EST 2012


> On Tue, Feb 7, 2012 at 3:23 PM, <n5ge at n5ge.com> 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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