[Elecraft] KPA500 gain variation with serial number

[Andy Durbin]

I have been told that the gain of the KPA500 has increased over the years it has been produced.   "Early" KPA500 are reported to need 35-39 W to produce 500 W out. "Later" KPA500 are reported to need only 20-25 W for full output.  The difference in gain has been attributed to difference in the PA transistors as well as component changes in the LPF.

I'm interested in knowing where my KPA500 serial number falls in the spread of required drive power.  I would like to receive data from KPA500 owners so I can get an idea of what gain can be associated with a serial number range.   To minimize the spread of data I'd like to specify 20 m band,  non reactive 50 ohm load,  key down CW mode.  It would be preferable for drive power and output power to be measured with the same instrument but I'll take what I can get.  If a KAT500 or other tuner is in circuit it should be in Bypass mode.

Requested data:

Serial number;  frequency; drive power; output power (target 500 W); PA voltage (front panel HV); PA current (front panel CUR); power measurement instrument(s).

Only one data point for 20 m band is requested but additional data won't be discarded.   I'll collate any data and share it if here is any interest.

Thanks and 73,
Andy, k3wyc