[Elecraft] Data mode and filters

[Joe Subich, W4TV]

> You are clearly on a mission to shift the ham world to high voltage
> PAs.

No, I'm on a mission - if that's what you call it - to get the ham
world to stop using devices with output impedance below 2 Ohms.  Most
times those are coupled with 16:1 broadband transformers and one gets
significant peak non-linearity because of impedance mismatch and/or
core saturation problems.

If you want to use 12V systems, use multiple amplifiers in parallel
or use a lower power output.  If you want higher power with only a
single pair of devices, get the voltage/impedance up where they will
operate properly.

 > But a significant part of the ham world wants a radio that runs on
 > 11-14VDC, making it much more versatile for portable and mobile
 > operation, carry-on in luggage for a DX trip, and easy to run from a
 > simple solar power system.

There is nothing sacred about 11-14V for any of those functions.
Simple solar and battery power systems can handle higher voltages -
it's just a matter of design and planning, switching supplies for DX
trips can be made just as physically small in higher/multiple voltages
(particularly since they typically need to handle less than half the
current, and quiet "boost regulators" solve the mobile issue.

12V is only used because it has always been used.  Modern equipment
designers make too many compromises in signal quality to force 12V
operation.  "Boost Regulators" (e.g. vibrator or motor generator
supplies) were used for high voltage PAs even in the *tube* days.

73,

    ... Joe, W4TV


On 2015-05-18 12:36 PM, Jim Brown wrote:
> On Mon,5/18/2015 5:40 AM, Joe Subich, W4TV wrote:
>> You are extrapolating the behavior of the K3 with its open loop ALC
>> and reasonably behaved KPA3 to other rigs.  The results would be
>> very different if you were pushing a "12V" Icom, Kenwood, or Yaesu
>> rig.
>
> No, I'm talking about a K3, which is what I measured. The two Yaesu rigs
> I've measured, both run only on 120/240VAC, and their IMD and occupied
> spectrum do NOT decrease with power level.
>
> You are clearly on a mission to shift the ham world to high voltage PAs.
> But a significant part of the ham world wants a radio that runs on
> 11-14VDC, making it much more versatile for portable and mobile
> operation, carry-on in luggage for a DX trip, and easy to run from a
> simple solar power system.
>
> 73, Jim K9YC
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