[hpsdr] Predistortion and different types of amplifiers?

[John Marvin]

Ken,

I might do what you propose in order to determine whether or not there 
is a benefit prior to enabling the autotuner. That would tell me if I 
find a problem with the autotuner engaged whether the problem is that 
PureSignal can't do a reasonable job with my TX path (Hermes -> driver 
amp -> KXPA100) or the problem is the autotuner. If it is the latter 
then I would have to consider modifying the amp to allow sampling 
between the amp and the internal tuner, as Lyle has mentioned the 
possibility of doing.

Note however that what you propose is really only a possible diagnostic, 
not a solution to enabling PureSignal in my actual operating environment.

Thanks,

John
AC0ZG

On 2/12/2014 5:48 PM, Ken N9VV wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> John, how about using a DUMMY LOAD and turning the AUTO TUNER OFF?
> You should be all set if the Dummy can handle the power output that 
> you intend to use.
>
> rgds,
> N9VV
>
> On 2/12/2014 6:34 PM, John Marvin wrote:
>> ***** High Performance Software Defined Radio Discussion List *****
>>
>> Warren,
>>
>> Thanks. Once calibration is complete, how tolerant is the PureSignal
>> adaptation to changes, i.e. if I switch bands, or just move enough in
>> the current band to cause a change in tuner settings, will PureSignal
>> "catch up" to the change as it might need to do with a change in
>> temperature, or would the tuner change be too significant a change for
>> PureSignal to follow?
>>
>> But you're right, I can probably figure this out from just trying it. My
>> only concern would be PureSignal making things worse due to a possibly
>> more extreme tuner change than I had tested with.
>>
>> Thanks,
>>
>> John
>>
>> On 2/12/2014 5:24 PM, Warren C. Pratt wrote:
>>> ***** High Performance Software Defined Radio Discussion List *****
>>>
>>> Hi John,
>>>
>>> I'd say give it a try and let us know how things go.  My
>>> recommendation would be to let the tuner do its tuning and AFTER THAT
>>> enable AutoCalibrate.  I suspect it will work fine.  You may want to
>>> increase the Amplifier Delay parameter a bit to compensate for the
>>> extra delay through the tuner.  If the tuner begins to tune with
>>> AutoCalibrate ON, you might get some very strange and negative results
>>> because some samples for calibration may be collected at a different
>>> tuner setting than others in the same set.
>>>
>>> 73,
>>> Warren  NR0V
>>>
>>> On 2/12/2014 2:12 PM, John Marvin wrote:
>>>> ***** High Performance Software Defined Radio Discussion List *****
>>>>
>>>> I noticed that the documentation shows that the rf sampler should be
>>>> connected between the power amp output and the antenna tuner. In my
>>>> case I'd like to try seeing what PureSignal can do with an Elecraft
>>>> KXPA100 amplifier. However, the amp has the antenna tuner built into
>>>> it. What effect will having the antenna tuner in the path have? I can
>>>> easily believe I would need to recalibrate each time the tuner
>>>> changes its settings.
>>>>
>>>> Thanks,
>>>>
>>>> John
>>>> AC0ZG
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