[Elecraft] KPA1500 Linearity

[K9MA]

I'll have to make some more measurements, but Paul's seem to have much less gain compression than mine. (0.6 vs 1.4 dB from 1 kW to 1.5 kW) That's also closer to the specs for a pair of BLF88XR's. 

73,
Scott K9MA 

------

Scott Ellington

 --- via iPad

> On Jun 15, 2018, at 11:24 PM, Paul Baldock <paul at paulbaldock.com> wrote:
> 
> I received my KPA-1500 yesterday (#244) and did some linearity tests today
> 
> 14.2MHz, Dummy Load, ATU Bypassed. Using KPA-1500 internal Power Meter. Continuous carrier.
> 
> 10W drive, Gain = 15.6dB 180W
> 15W drive, Gain = 15.8dB
> 20W drive, Gain = 15.9dB
> 25W drive, Gain = 16.0dB 1.0KW
> 30W drive, Gain = 15.9dB
> 35W drive, Gain = 15.7dB
> 40W drive, Gain = 15.6dB
> 43W drive, Gain = 15.4dB 1.5KW
> 45W drive, Gain = 15.4dB 1.57KW
> 
> Based on this it look like about .6dB compression at 1.5KW. I think that's pretty good for an SS Amp.
> 
> I also measured the gain on all the bands at 1.5KW out. Drive varied from 31W on 80M to 47W on 15M. or 16.8dB to 15.0dB. That amount of variation is rather disappointing.
> 
> I also noted that the internal power meter is pretty inaccurate at low levels. For Example at 50W on 20M it reads 43W. Its pretty close above 300W and right on at 1.5KW where its calibrated.
> 
> I would be interested to see any data that others have collected.
> 
> - Paul  KW7Y
> 
> 
> At 02:26 PM 6/14/2018, K9MA wrote:
>> The gain compression I measured, between 1000 and 1500 W on 40 meters, was 1.4 dB. I used the K3 and KPA1500 power meters.  Factory calibration of the KPA1500. 
>> 
>> Scott K9MA 
>> 
>> ----------
>> 
>> Scott Ellington
>> 
>>  --- via iPad
>> 
>> > On Jun 14, 2018, at 2:51 PM, Paul Baldock <paul at paulbaldock.com> wrote:
>> > 
>> > What you report of compression near the maximum power is certainly true of the amplifiers like the SPE-1.5K that use a single device, but I would have thought this would not be true of the KPA1500 that uses 2 devices. This is the reason I returned my SPE and ordered the KPA. Hopefully the compression is less than 1dB.
>> > 
>> > Has anybody else measured it?
>> > 
>> > - Paul  - KW7Y
>> > 
>> > 
>> > 
>> > At 02:21 PM 6/9/2018, you wrote:
>> >> I recently ran a two-tone test and measured CW power gain. (SN1078)  It doesn't look good.  The two-tone waveform shows distinct "flat-topping", and the power gain drops 25 percent from 1000 to 1500 Watts.  My old 3-500Z amplifier is much better.  Has anyone measured IMD or linearity, or seen any test results? While I'm primarily a CW operator, I'd be very reluctant to use the amplifier on SSB. 73, Scott K9MA -- Scott  K9MA k9ma at sdellington.us ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft at mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to paul at paulbaldock.com
>> > 
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