John, It's not shown on the datasheet. However, the VRF2933 is specified as a communications product (not a repurposed switching device) and is from the same family as the VRF150 (upgraded MRF150) which is specified at -32dBc (-38 dB to ARRL standard). Since the VFR2933 is a higher gain part (20 dB minimum gain) than the MRF150/VRF150, I would guess the IMD performance might be a bit worse at maximum output.
Still, with the VRF2933 rated for 300W minimum - 375 typical at 50V - the KPA-500 is not pushing them at 500W. I'd look for IMD numbers on the mid to high 30's (ARRL spec). 73, ... Joe, W4TV > -----Original Message----- > From: elecraft-boun...@mailman.qth.net > [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of juergen > Sent: Saturday, April 17, 2010 7:50 PM > To: elecraft@mailman.qth.net > Subject: Re: [Elecraft] KPA500 active devices!! > > > > Hi Joe > > Have you seen any IMD data on these devices? > > > John > > > --- On Sat, 4/17/10, Joe Subich, W4TV <li...@subich.com> wrote: > > > From: Joe Subich, W4TV <li...@subich.com> > > Subject: Re: [Elecraft] KPA500 active devices!! > > To: "'Doug Faunt N6TQS +1-510-655-8604'" <fa...@panix.com>, > > elecraft@mailman.qth.net > > Date: Saturday, April 17, 2010, 4:45 PM > > > > The VRF2933 is rated for 300 Watts each according to the data > > sheet on the manufacturer's web site (Microsemi) ... That > > makes > > their use in a 500 W amplifier reasonable from an IMD > > perspective. > > > > The VRF 2933 minimum gain is also 20dB (23 dB typical) so it > > would appear that the KPA-500 should be capable of clean > > operation with 5 W of drive (e.g., K3 in low power mode). > > > > 73, > > > > ... Joe, W4TV > > > > > > > > > > > -----Original Message----- > > > From: elecraft-boun...@mailman.qth.net > > > > > [mailto:elecraft-boun...@mailman.qth.net] > > On Behalf Of Doug > > > Faunt N6TQS +1-510-655-8604 > > > Sent: Saturday, April 17, 2010 6:45 PM > > > To: elecraft@mailman.qth.net > > > Subject: [Elecraft] KPA500 active devices!! > > > > > > > > > There are two VRF2933's in push-pull, so they're not > > 750 > > > watts each, but per pair. There are only three > > amps in > > > existance, and no devices have been destroyed > > (yet). Again, > > > 500 watts is a very conservative rating. It's been > > key-down > > > for 10 minutes withy no problems. > > > > > > 73, doug > > > > > > ______________________________________________________________ > > Elecraft mailing list > > Home: http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/mmfaq.htm > > Post: mailto:Elecraft@mailman.qth.net > > > > This list hosted by: http://www.qsl.net > > Please help support this email list: http://www.qsl.net/donate.html > > > > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
