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[W6UV]

I'm going to treat myself to a complete station upgrade and the two setups I'm considering are the Flex-6600/Power Genius XL combination or the Elecraft K4D/KPA1500 combination.

Anyone have any opinions on the amplifier aspects of this decision? Any "gotchas" with either the PGXL or the KPA1500 that I should be aware of?

Most of my operating is digital (RTTY, etc.) with some CW/SSB as well, so a lot of it is at high duty cycles.

[N2TU]

I have been blessed with both! (It is a long story!)

You can't go wrong with either, though there are benefits with each. They are both nosier than a tube amp but there is nothing like instant on when you are chasing that 'rare one'.

Since I got my PGXL and integrated it into my Flex 6600 station, my KPA is relegated to my standby amp. The ability to switch between multiple slices (VFOs) (4 in the 6600) and have the amp follow immediately is remarkable. Monitor 4 bands and seamlessly switch 1500 watts between them is a dream. The control of the PGXL is integrated into the SSDR program, so you can control and monitor the amp without the need for another app.

The PGXL is a SO2R ready amplifier. Mate the PGXL with a 6600 and you have a legal limit SO2R station.

The KPA is a SO1R amplifier.

The KPA, however, has a built in antenna tuner. The PGXL does not, though Flex offers the TGXL external tuner.

The choice rests with you and your operating style. They are both fine amplifiers.

[W6QW]

A tertiary consideration: because of the integrated power supply on the PGXL, the desk-top weight will be about 70 percent greater and the form-factor will be larger.  Have used both and either one will support your digital needs.

I think the primary consideration may well be your preference for the K4 or the Flex.

[G4AON]

I think the primary consideration may well be your preference for the K4 or the Flex.

”Most of my operating is digital”, well if you want to operate ARQ digital modes, as opposed to RTTY or FT8, then neither transceiver is suitable. I have a K4D and it can be pushed into working if you add a PTT “hold on” board to delay PTT dropping by 18 to 20 mS. It will work (without any add-on) on Vara over 11000 mile paths, tested G to ZL, but probably not as far on Amtor/Pactor.

Whether such modes are relevant to your operating is up to you, but some SDR manufacturers seem to be heading towards pretty lousy latency, which can also mess up QSK CW…

The humble IC-7300 runs rings around both the Flex and K4D in terms of latency. See Rob Sherwood’s list, not that one… this one!
http://nc0b.com/latency/Latency%20tests%20on%20several%20transceivers-11.pdf

That list only shows receive latency, my measurements give TX latency of the K4D at 23 mS, and the IC-7300 at 4.2 mS.

The K4D is still a work in progress, Elecraft are slowly adding features, but progress is painfully slow. I don’t know about Flex.

Check out the K4 Groups.io
https://groups.io/g/Elecraft-K4

73 Dave

[W6UV]

I don’t use ARQ modes, nor do I use QSK CW.