I did it again. I meant to send this to the group but sent it to Jack direct. Sorry Jack.
"The most recent firmware version is V1.54, releasing in mid December." I went to the software page and it says the most recent beta release is MCU 1.52 Nov 17, 2017 and production release is 1.47. ----------------- 73, Tom - KQ5S On Tue, Jan 16, 2018 at 7:18 PM, Jack Brindle <[email protected]> wrote: > Hey Richard; > > I’m glad you are enjoying our creation. The KPA500 is truly a fine piece > of hardware and firmware > that continues to evolve. The most recent firmware version is V1.54, > releasing in mid December. > > Others have answered many of your questions, let me give my shot at a few. > I usually run my > KPA500 in contests at 600 watts. Briefly lighting the 700 watt LED is not > unusual, but I don’t > consistently leave it lit. The amplifier is quite comfortable at 600 watts > for long periods of time. > Mine is one of the first units and was hand-built, so I can’t claim to > have the original PA Deck > installed (it is still sitting on my work bench however), but my current > PA Deck is one of the > original shipping versions. After about 10 years, it is working just fine > for me. > > As for calibration, we perform the cal at the factory for factory-built > units, but not for kits. > The reason is that we need to marry the front panel board with the PA Deck > to perform these > adjustments, something that is not done until well into assembly. The > adjustment values are > kept in memory on the front panel board’s processor. This also means that > if you swap the > PA Deck you will need to recalibrate the measurements. Feel free to > perform your own > calibration to a known standard. You will probably find that you will need > to vary the values > by some small amount to get really accurate measurements. In general they > are pretty close > to start off with, but won’t be “right on.” > > Enjoy the amplifier, and by all means use it at the power you want. If you > have any questions > or need any help, we are here, just ask. You will find customer support to > be very helpful. > > 73! > > Jack, W6FB > Elecraft Engineering > > > > On Jan 16, 2018, at 3:14 PM, Richard Stutsman <[email protected]> wrote: > > > > I've had my KPA500 for a couple of weeks, now, and I have questions > > relating to its efficiency as a function of power output and band. A > friend > > of mine recommended that I run only 300 watts output most of the time in > > order to preserve the life of the FETs. I told him that I didn't spend > > $2300 on an amp just to get less than 5 dB of gain in my signal (over my > > 100-watt exciter) instead of the 7 or 8 dB I paid for. Am I wrong? > > > > I took a lot of data this morning that indicates that there is an inverse > > relationship between output power and efficiency - to the extent that, > down > > to about 300 watts, I find that the amount of heat the finals have to > > dissipate is less, the higher the power output. This is rather > > anti-intuitive. > > > > And if that is true, then wouldn't it be better for the finals if I > > routinely ran the amp at the higher power, so long as voltage, current, > and > > temperature remain within safe limits? Is it safe to run 600 watts on CW, > > especially on 80 and 160 meters, where the efficiency appears to be so > good > > that the finals run cool at 600 watts - even cooler than at 500 watts? > > > > The following data was taken while transmitting into a dummy load. I > > adjusted the drive power to obtain one of several predefined output power > > levels and then measured input volts and amps and calculated input power > > (HV x Current), power dissipation (Input - Output), and efficiency > > (Input/Output). Each measurement was taken after about one second of key > > down in CW mode. Doing the calculations in between each test allowed the > > finals and dummy load to cool off. I never heard the fan come on. Drive, > > Output, Input and Dissipation are in Watts. I have shown voltages falling > > slightly below 60.0 in red, but I had no problem getting 600 watts output > > with less than 40 watts of drive, even in those cases. > > > > *Band Drive Output Volts Amps Input Dissipation Efficiency* > > > > 1.8 23 500 64.3 10.2 654 154 76% > > 30 600 63.9 10.9 697 97 86% > > > > 3.5 23 500 65.1 9.4 612 112 82% > > 30 600 63.2 10.5 664 64 90% > > > > 5 24 500 63.7 11.2 707 207 71% > > 30 600 62.8 12.0 754 154 80% > > > > 7 27 500 62.3 12.5 779 279 64% > > 35 600 61.2 13.8 845 245 71% > > > > 10 32 500 61.2 13.4 820 320 61% > > 39 600 59.8 14.6 873 273 69% > > > > 14 15 225 63.4 9.6 609 384 37% > > 20 310 62.9 11.5 723 413 43% > > 24 400 61.5 12.8 787 387 51% > > 33 500 59.0 14.3 844 344 59% > > 40 600 58.7 15.8 927 327 65% > > > > 18 26 490 60.6 12.9 782 392 63% > > 33 600 59.6 13.8 822 222 73% > > > > 21 26 500 60.0 13.9 834 334 60% > > 35 600 59.8 15.2 909 309 66% > > > > 24 23 500 61.4 12.4 761 261 66% > > 30 600 61.0 13.5 824 224 73% > > > > 28 22 500 61.4 12.7 780 280 64% > > 27 600 60.6 13.8 836 236 72% > > > > Note that in every case there is lower power dissipation (and therefore > > less heat generated), the higher the power. I decided to test several > lower > > power outputs on 20 meters, and I got the maximum dissipation at 310 > watts, > > and the dissipation at 225 watts was nearly the same as it was at 400 > watts. > > > > I should point out that my HV during standby or idle hovered between 79.5 > > and 80.0 volts. I am using the Red tap wire on the 115-volt input. > > > > And, yes, I know not to use the amp on 60 or 30 meters. > > > > If anybody is going to yell at me for testing a 500-watt amp at 600 > watts – > > and for proposing to use that much power routinely on 80 meter CW – let > me > > know your reasoning and why or how you think that would stress the amp. > > > > Oh, and does anybody know if Elecraft would have adjusted the Power > > calibration (per band) of the KPA500 kit version, as mentioned in the > User > > Manau? I found all the settings to be at their default 100%, FWIW. When > > comparing at 100 watts to a cheap external watt meter (which agreed with > my > > TS-590sg power output setting), I found I had to increase power on almost > > every band to 104 watts to trip the 100-watt indication on the KPA500's > > wattmeters. I decided to leave the settings at their default. > > > > Rick N6IET > > ______________________________________________________________ > > Elecraft mailing list > > Home: http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/mmfaq.htm > > Post: mailto:[email protected] > > > > This list hosted by: http://www.qsl.net > > Please help support this email list: http://www.qsl.net/donate.html > > Message delivered to [email protected] > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [email protected] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
