[Amps] Starting up a NEW Henry amp

[Alek Petkovic]

For what it's worth, I have had terrible problems getting the input 
matching right on several amplifiers using the VNA, yet when using 
normal drive levels, as reccommended in the user/service manuals, tuning 
is a breeze. Therefore, I think that there is some truth in the 
assertion that tuning at low levels does not work properly.

73, Alek VK6APK

On 12/12/2023 7:27 pm, Rob Atkinson wrote:
>> If you try
>> to use the internal auto tuner it will not tune properly as it tunes up at low
>> power and the input impedance of the amp changes as the power increases.
> Power level  should not affect the impedance of a load.  If it does,
> then something is wrong.  A part may be heating up and changing value,
> in which case the matching network should be fixed.  You should be
> able to put a vswr analyzer on the amp input and see the R + X for
> some frequency, and those values should hold for whatever drive power
> you use on the same frequency.
>
> 73
>
> Rob
> K5UJ
>
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