[Elecraft] [KPA500] Low Power Use Cases

[Fred Jensen]

On 7/18/2013 3:08 PM, Chris Johnson wrote:
> I love my KPA500.  I don't use it enough because of all the low power
> digital I do.   I was wondering if the quality of my signal would
> better if I let the KPA500 produce the output even if the wattage is
> 50 or less watts.   If I drive it with 1 to 5 watts, it produces 10
> to 50 watts.   I like the thought of offloading the thermal load of
> my long JT65 & JT9 duty cycles onto the KPA rather than my main rig
> which is a Flex 6700.

You're likely to stimulate more replies than the "Why is aeronautical 
VHF comm still AM?" did. :-)

I don't know anything about a Flex <anything> but, all amplifiers have 
non-zero distortion figures.  Putting two "in series" will add up at 
least some if not all of them.  The amp in your Flex followed by the 
KPA500 will most likely produce a poorer signal quality than just your 
Flex for the same power output.

Secondly, the KPA500 was designed to produce several hundred watts with 
a few tens of watts drive [500W on any band for me takes between 25 and 
30 watts drive].  That's probably the optimum operating point.  Driving 
it with 5 watts should produce somewhere in the 50+ watts output range.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2013 Cal QSO Party 5-6 Oct 2013
- www.cqp.org