Re: [Elecraft] QRO - KPA500 Failure
Hi Jim, thanks for your KPA500 issue update and returning the thread to its original point there. Let us know the results once you gets there. Ahoj, Petr - 73 - Petr, OK1RP "Apple & Elecraft freak" B:http://ok1rp.blogspot.com MeWe: https://bit.ly/2HGPoDx MeWe: https://bit.ly/2FmwvDt -- Sent from: http://elecraft.365791.n2.nabble.com/ __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] QRO - KPA500 Failure
Hello Ed, I don't think that you are in class AB with 80% efficiency, in fact you cannot be. Class B can theoretically achieve 78.5% but this is seldom achieved in practice, especially on VHF. Most likely there is a problem with instrumentation. From: elecraft-boun...@mailman.qth.net on behalf of K9MA Sent: 11 February 2020 17:11 To: elecraft@mailman.qth.net Subject: Re: [Elecraft] QRO - KPA500 Failure That's very high efficiency for a solid-state amplifier. Are they operating in class C? Are there any IMD specs at those output levels? 73, Scott K9MA On 2/11/2020 03:18, Edward R Cole wrote: > I checked the operating specs on two of my QRO amps. Not a KPA500. > > 2m-1500w PA using a MRF1K50 in class AB: > 945w 1398w dc 67% eff 453w disp > 1511w 1888w dc 80% eff 377w disp > > 2m-1200w PA using a MRFE6VP61K25H in class AB: > 566w 1200w dc 47% eff 634w disp > 1133w 1542w dc 73% eff 409w disp > > less heat dissipated when running full power RF ouput. > Both are W6PQL amps. > > 73, Ed - KL7UW > http://www.kl7uw.com > Dubus-NA Business mail: > dubus...@gmail.com > __ > 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 > Message delivered to k...@sdellington.us -- Scott K9MA k...@sdellington.us __ 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 Message delivered to g0...@g0ruz.com __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] QRO - KPA500 Failure
That's very high efficiency for a solid-state amplifier. Are they operating in class C? Are there any IMD specs at those output levels? 73, Scott K9MA On 2/11/2020 03:18, Edward R Cole wrote: I checked the operating specs on two of my QRO amps. Not a KPA500. 2m-1500w PA using a MRF1K50 in class AB: 945w 1398w dc 67% eff 453w disp 1511w 1888w dc 80% eff 377w disp 2m-1200w PA using a MRFE6VP61K25H in class AB: 566w 1200w dc 47% eff 634w disp 1133w 1542w dc 73% eff 409w disp less heat dissipated when running full power RF ouput. Both are W6PQL amps. 73, Ed - KL7UW http://www.kl7uw.com Dubus-NA Business mail: dubus...@gmail.com __ 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 Message delivered to k...@sdellington.us -- Scott K9MA k...@sdellington.us __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] QRO - KPA500 Failure
I checked the operating specs on two of my QRO amps. Not a KPA500. 2m-1500w PA using a MRF1K50 in class AB: 945w 1398w dc 67% eff 453w disp 1511w 1888w dc 80% eff 377w disp 2m-1200w PA using a MRFE6VP61K25H in class AB: 566w 1200w dc 47% eff 634w disp 1133w 1542w dc 73% eff 409w disp less heat dissipated when running full power RF ouput. Both are W6PQL amps. 73, Ed - KL7UW http://www.kl7uw.com Dubus-NA Business mail: dubus...@gmail.com __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] QRO - KPA500 Failure
UPDATE: Jack/W6FB contacted me directly shortly after posting. I sent him my fault log to analyze and a detailed description of my equipment setup. Best guess is a cable or antenna failure causing high SWR sometime in the recent past that stressed the finals. They gave up the ghost when I was running 17m FT8. I'm leaning toward a bad patch cable I found between the KPA500 and KAT500 a few months previous to the failure. A cheap cable that became very costly! His guess was right on, when I was pulling the power transformer out of the amp to make it easier to ship I found the ceramic part of a VRF2933 MOSFET rattling around in the cabinet. The problem is now obvious :( The amp left today to Elecraft for repair. I'll let the group know the results once it gets there. Thanks everyone for your constructive comments and to Jack for reaching out and helping me find the problem. '73... Jim KK1W wrote > Was running about 150W on 18 MHz this afternoon. My KPA 500 made a loud > pop. No more output. Any pointers of where to start looking? > > *Details:* > KPA500 (use with KAT500 and Icom 7610) > Antenna on this band is a SteppIR > Amp has been running FB > KPA Utility 1.13.7.16 > 240V supply > A single loud pop was heard. > Mode remained in OPER > No fault light displayed, nor can I find one in the Fault Table > > *After the failure:* > > *In STBY:* > Radio and antennas work fine. SWR shown to exciter is low, as expected. > Exciter power is displayed on KPA500 power meter. > HV = 78.2 > Works correctly on all bands > > *In OPER:* > HV = 78.2 key up > On key down (input of 15W) the asterisk briefly displays, then display > changes to 18.1, back to HV display on key up. > Zero output, SWR shown to exciter is very high (over 3 to 1) > No power shown on output meter. > Fails *on all bands* with high SWR to the exciter. > No fault indication. > > *Other data:* > Here's the last three entries from the fault table: > 00 PWR ON -- 0007 Power was turned on > 0039 09 REFL HI 80 00F0 Excessive reflected power (high SWR) > 00 PWR ON -- Power was turned on > . > > Apparently only faults get logged, subsequent power cycles have not > changed > the table. > > I power cycled the amp, including removing the mains power. - no change. > I reloaded the last configuration - no change. > I removed the cover and looked for any visible damage or bad odors. > Nothing > stands out. > > Amp is about 4 years old and was a kit model. Before I start to > disassemble > if anyone can offer a likely culprit I'm all ears. > > Thanks, > > Jim/KK1W > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto: > Elecraft@.qth > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to > lists+1215531472858-365791@.nabble -- Sent from: http://elecraft.365791.n2.nabble.com/ __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] QRO - KPA500 Failure
Oh but contraire. I agree that lower dissipation typically reduces
MTBF. Therefore, never plug in your KPA500, leave it in the box and it
should last a very long time.
Sorry folks, I just couldn't resist.
I did not do extensive measurements, but the ones I did show the following:
450 watts out, 819 watts in, for a delta of 369 watts, I presume for
heat or 55% efficiency
210 watts out, 576 watts in, for a delta of 366 watts, I presume for
heat or 37% efficiency {I do work 30M that has a power limit of 200 watts}
Note the difference in heat dissipation between 450 watts out and 210
watts out is only 33 watts but is 240 watts difference in RF output.
Based on these numbers, there is not a lot of difference in heat to be
dissipated in the upper half of the power rating.
100 watts out, 393 watts in, for a delta of 293 watts, I presume for
heat or 25% efficiency.
73
Bob, K4TAX
On 2/10/2020 1:16 PM, Doug Turnbull wrote:
Thank you Andy,
Bob, if maximum power dissipation occurs at 50% max output power then the
greatest amount of heat should be generated for the shack at half max output
power. Power dissipation is in the form of heat not RF. The subject is
interesting for a number of reasons perhaps most importantly to me is that of
reliability. I believe the chance of failure is reduced as one lowers
dissipation while staying within all other component ratings.
73 Doug EI2CN
-Original Message-
From: elecraft-boun...@mailman.qth.net On
Behalf Of Bob McGraw K4TAX
Sent: Monday 10 February 2020 18:47
To: Andy Durbin
Cc: elecraft@mailman.qth.net
Subject: Re: [Elecraft] QRO - KPA500 Failure
Unless one is concerned about power consumption, the efficiency factor should
be really of no concern. Total heat output will always be greater at maximum
output and less at lower power. Nice for warming the shack on a Winter day.
Bob, K4TAX
Sent from my iPhone
On Feb 10, 2020, at 12:18 PM, Andy Durbin wrote:
"This is probably what folks are thinking of when they assume maximum dissipation
occurs at less than full output."
A possible source of error in my data is that the dummy load is cool at the
start of the power ramp and hot by the time peak power is reached. I recorded
LP-100A data during each test run and can see some change in the load
characteristics. I did not attempt to compensate for this when plotting the
data. I simply reported values of R and X that were about average for each
test run.
One way to find out if the change in load is significant would be to start the
power ramp at maximum power rather than minimum power.
Some time after I ran those tests I expanded the capability of my Arduino
station controller to add a page that displays PA voltage, PA current, PA DC
input, PA dissipation, RF Output, and efficiency. A snapshot of the displayed
data can be sent to the controller's logger output.
I just ran a test which had a brief transmission close to full power and
another brief transmission at half power. This test was performed at 14.01 MHz
using a dummy load. Here are the data:
26:36:36.672 KPA Mon frozen
PA voltage=60.6
PA current=14.1
PA input=854
RF out=495
PA diss=359
PA effic=57
26:37:32.437 KPA Mon frozen
PA voltage=64.6
PA current=10.0
PA input=646
RF out=250
PA diss=396
PA effic=38
Dummy load heating would not have been significant factor in this test but the
results still show higher PA dissipation at 250 W out than at 495 W out.
It's really simple to produce a similar data set and there are lots of KPA500
owners here. If you think my data are invalid please share your test data. I
don't mind being wrong as long as I learn something new.
73,
Andy, k3wyc
__
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 Message delivered to
rmcg...@blomand.net
__
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 Message
delivered to turnb...@net1.ie
__
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
Message delivered to arch...@mail-archive.com
Re: [Elecraft] QRO - KPA500 Failure
Thank you Andy, Bob, if maximum power dissipation occurs at 50% max output power then the greatest amount of heat should be generated for the shack at half max output power. Power dissipation is in the form of heat not RF. The subject is interesting for a number of reasons perhaps most importantly to me is that of reliability. I believe the chance of failure is reduced as one lowers dissipation while staying within all other component ratings. 73 Doug EI2CN -Original Message- From: elecraft-boun...@mailman.qth.net On Behalf Of Bob McGraw K4TAX Sent: Monday 10 February 2020 18:47 To: Andy Durbin Cc: elecraft@mailman.qth.net Subject: Re: [Elecraft] QRO - KPA500 Failure Unless one is concerned about power consumption, the efficiency factor should be really of no concern. Total heat output will always be greater at maximum output and less at lower power. Nice for warming the shack on a Winter day. Bob, K4TAX Sent from my iPhone > On Feb 10, 2020, at 12:18 PM, Andy Durbin wrote: > > > "This is probably what folks are thinking of when they assume maximum > dissipation occurs at less than full output." > > A possible source of error in my data is that the dummy load is cool at the > start of the power ramp and hot by the time peak power is reached. I > recorded LP-100A data during each test run and can see some change in the > load characteristics. I did not attempt to compensate for this when plotting > the data. I simply reported values of R and X that were about average for > each test run. > > One way to find out if the change in load is significant would be to start > the power ramp at maximum power rather than minimum power. > > Some time after I ran those tests I expanded the capability of my Arduino > station controller to add a page that displays PA voltage, PA current, PA DC > input, PA dissipation, RF Output, and efficiency. A snapshot of the > displayed data can be sent to the controller's logger output. > > I just ran a test which had a brief transmission close to full power and > another brief transmission at half power. This test was performed at 14.01 > MHz using a dummy load. Here are the data: > > 26:36:36.672 KPA Mon frozen > PA voltage=60.6 > PA current=14.1 > PA input=854 > RF out=495 > PA diss=359 > PA effic=57 > > 26:37:32.437 KPA Mon frozen > PA voltage=64.6 > PA current=10.0 > PA input=646 > RF out=250 > PA diss=396 > PA effic=38 > > Dummy load heating would not have been significant factor in this test but > the results still show higher PA dissipation at 250 W out than at 495 W out. > > It's really simple to produce a similar data set and there are lots of KPA500 > owners here. If you think my data are invalid please share your test data. > I don't mind being wrong as long as I learn something new. > > 73, > Andy, k3wyc > > > __ > 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 Message delivered to > rmcg...@blomand.net > __ 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 Message delivered to turnb...@net1.ie __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] QRO - KPA500 Failure
Yes, I was wondering why this was so interesting. Chuck Jack Hawley KE9UW Sent from my iPhone, cjack > On Feb 10, 2020, at 12:47 PM, Bob McGraw K4TAX wrote: > > Unless one is concerned about power consumption, the efficiency factor should > be really of no concern. Total heat output will always be greater at > maximum output and less at lower power. Nice for warming the shack on a > Winter day. > > > Bob, K4TAX > > > Sent from my iPhone > >> On Feb 10, 2020, at 12:18 PM, Andy Durbin wrote: >> >> >> "This is probably what folks are thinking of when they assume maximum >> dissipation occurs at less than full output." >> >> A possible source of error in my data is that the dummy load is cool at the >> start of the power ramp and hot by the time peak power is reached. I >> recorded LP-100A data during each test run and can see some change in the >> load characteristics. I did not attempt to compensate for this when >> plotting the data. I simply reported values of R and X that were about >> average for each test run. >> >> One way to find out if the change in load is significant would be to start >> the power ramp at maximum power rather than minimum power. >> >> Some time after I ran those tests I expanded the capability of my Arduino >> station controller to add a page that displays PA voltage, PA current, PA >> DC input, PA dissipation, RF Output, and efficiency. A snapshot of the >> displayed data can be sent to the controller's logger output. >> >> I just ran a test which had a brief transmission close to full power and >> another brief transmission at half power. This test was performed at 14.01 >> MHz using a dummy load. Here are the data: >> >> 26:36:36.672 KPA Mon frozen >> PA voltage=60.6 >> PA current=14.1 >> PA input=854 >> RF out=495 >> PA diss=359 >> PA effic=57 >> >> 26:37:32.437 KPA Mon frozen >> PA voltage=64.6 >> PA current=10.0 >> PA input=646 >> RF out=250 >> PA diss=396 >> PA effic=38 >> >> Dummy load heating would not have been significant factor in this test but >> the results still show higher PA dissipation at 250 W out than at 495 W out. >> >> It's really simple to produce a similar data set and there are lots of >> KPA500 owners here. If you think my data are invalid please share your >> test data. I don't mind being wrong as long as I learn something new. >> >> 73, >> Andy, k3wyc >> >> >> __ >> 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 >> Message delivered to rmcg...@blomand.net >> > > > __ > 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 > Message delivered to c-haw...@illinois.edu __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] QRO - KPA500 Failure
Unless one is concerned about power consumption, the efficiency factor should be really of no concern. Total heat output will always be greater at maximum output and less at lower power. Nice for warming the shack on a Winter day. Bob, K4TAX Sent from my iPhone > On Feb 10, 2020, at 12:18 PM, Andy Durbin wrote: > > > "This is probably what folks are thinking of when they assume maximum > dissipation occurs at less than full output." > > A possible source of error in my data is that the dummy load is cool at the > start of the power ramp and hot by the time peak power is reached. I > recorded LP-100A data during each test run and can see some change in the > load characteristics. I did not attempt to compensate for this when plotting > the data. I simply reported values of R and X that were about average for > each test run. > > One way to find out if the change in load is significant would be to start > the power ramp at maximum power rather than minimum power. > > Some time after I ran those tests I expanded the capability of my Arduino > station controller to add a page that displays PA voltage, PA current, PA DC > input, PA dissipation, RF Output, and efficiency. A snapshot of the > displayed data can be sent to the controller's logger output. > > I just ran a test which had a brief transmission close to full power and > another brief transmission at half power. This test was performed at 14.01 > MHz using a dummy load. Here are the data: > > 26:36:36.672 KPA Mon frozen > PA voltage=60.6 > PA current=14.1 > PA input=854 > RF out=495 > PA diss=359 > PA effic=57 > > 26:37:32.437 KPA Mon frozen > PA voltage=64.6 > PA current=10.0 > PA input=646 > RF out=250 > PA diss=396 > PA effic=38 > > Dummy load heating would not have been significant factor in this test but > the results still show higher PA dissipation at 250 W out than at 495 W out. > > It's really simple to produce a similar data set and there are lots of KPA500 > owners here. If you think my data are invalid please share your test data. > I don't mind being wrong as long as I learn something new. > > 73, > Andy, k3wyc > > > __ > 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 > Message delivered to rmcg...@blomand.net > __ 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 Message delivered to arch...@mail-archive.com
[Elecraft] QRO - KPA500 Failure
"This is probably what folks are thinking of when they assume maximum dissipation occurs at less than full output." A possible source of error in my data is that the dummy load is cool at the start of the power ramp and hot by the time peak power is reached. I recorded LP-100A data during each test run and can see some change in the load characteristics. I did not attempt to compensate for this when plotting the data. I simply reported values of R and X that were about average for each test run. One way to find out if the change in load is significant would be to start the power ramp at maximum power rather than minimum power. Some time after I ran those tests I expanded the capability of my Arduino station controller to add a page that displays PA voltage, PA current, PA DC input, PA dissipation, RF Output, and efficiency. A snapshot of the displayed data can be sent to the controller's logger output. I just ran a test which had a brief transmission close to full power and another brief transmission at half power. This test was performed at 14.01 MHz using a dummy load. Here are the data: 26:36:36.672 KPA Mon frozen PA voltage=60.6 PA current=14.1 PA input=854 RF out=495 PA diss=359 PA effic=57 26:37:32.437 KPA Mon frozen PA voltage=64.6 PA current=10.0 PA input=646 RF out=250 PA diss=396 PA effic=38 Dummy load heating would not have been significant factor in this test but the results still show higher PA dissipation at 250 W out than at 495 W out. It's really simple to produce a similar data set and there are lots of KPA500 owners here. If you think my data are invalid please share your test data. I don't mind being wrong as long as I learn something new. 73, Andy, k3wyc __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] QRO - KPA500 Failure
We should also know the power supply efficiency though as a switcher, I expect 90 plus percent.73 Doug EI2CNSent from my Samsung Galaxy smartphone. Original message From: Andy Durbin Date: 10/02/2020 16:58 (GMT+00:00) To: Doug Turnbull , elecraft@mailman.qth.net Subject: Re: [Elecraft] QRO - KPA500 Failure "I understand that efficiency decreases as one derates from the maximum of 1500W output.It surprises me that the power dissipated would peak at half power output or 750 Watts." I have no test data for the KPA1500 and will not speculate on the shape of the PA dissipation curves. All I have is data for one KPA500. For that one KPA500, and under the conditions tested, it's clear that PA dissipation is greater at half power than at full power. It would be easy to get a pair of data points for the KPA1500. Connect the amplifier to a known good 50 ohm load. Drive the amplifier to steady state 1500 W output Record PA current and voltage Drive the amplifier to steady state 750 W output Record the PA current and voltage Repeat on multiple bands if desired and report the results here. 73, Andy, k3wyc __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] QRO - KPA500 Failure
Dear OMs, Maybe this is an advantage of the SPE 2KFA amp which has three power levels 2000, 1200 and 600 W output. I have both amps and prefer the KPA 1500. Which I find quieter both acoustically and RFI wise on RX. The KPA 1500 is also happier handling Data modes. The SPE will drop down to 600W for RTTY. 73 Doug EI2CNSent from my Samsung Galaxy smartphone. Original message From: K9MA Date: 10/02/2020 16:29 (GMT+00:00) To: elecraft@mailman.qth.net Subject: Re: [Elecraft] QRO - KPA500 Failure Several others have posted test data for the KPA500 here recently. As I recall, it shows that dissipated power is fairly constant from about 50 percent to full output, at about 500 W, dropping a bit at lower power.If it were an ideal class B amplifier, which no solid state RF amplifier even approaches, the efficiency at full output would be 78.5 percent. It would then dissipate only 141 W at full output, and maximum dissipation would be at some lower output power level. This is probably what folks are thinking of when they assume maximum dissipation occurs at less than full output. REAL RF amplifiers don't behave that way, as the test results show.https://en.wikipedia.org/wiki/Power_amplifier_classes#Class_B73,Scott K9MAOn 2/10/2020 09:23, Doug Turnbull wrote:> Hello Andy,>> I do not have the numbers and also would like them. I understand> that efficiency decreases as one derates from the maximum of 1500W output.> It surprises me that the power dissipated would peak at half power output or> 750 Watts. This may be so. If so then almost certainly the Mean Time> Between Failures or MTBF is worsened. I am not in a position to> determine any of this but maybe some guidance from Elecraft itself would be> helpful for both KPA 500 and 1500.>> 73 Doug EI2CN>> >> From: Andy Durbin > Sent: Monday 10 February 2020 14:04> To: Doug Turnbull ; elecraft@mailman.qth.net> Subject: Re: [Elecraft] QRO - KPA500 Failure>> >> Doug,>> >> "I would like to know if running 2/3, 1/2 or even 1/4 maximum power output> increases reliability and MTBF.">> >> I have no experience of amplifier design but I would expect reliability of> the finals to depend on temperature. Finals temperature will depend on the> power dissipated in the finals (PA dissipation) and the effectiveness of the> cooling design.>> >> To understands finals dissipation one would need to produce one's own test> data or rely on the work of others. My test data for the KPA500 shows PA> dissipation peaks at about half power output. So far no one has disputed> the validity of my test data.>> >> It is my understanding that running an amplifier at reduced power only> reduces PA dissipation if the finals voltage is adjusted give a good load> match for that reduced power condition. The KPA500 has no provision for> adjusting PA voltage for the reduced power case. For reduced power the PA> voltage is actually higher than for full power because the high voltage> supply is not regulated.>> >> As I said, I have no experience in amplifier design and would appreciate> comments from those who do.>> >> 73,>> Andy, k3wyc>> >> >> >> __> 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> Message delivered to k...@sdellington.us-- Scott K9MAk9ma@sdellington.us__Elecraft mailing listHome: http://mailman.qth.net/mailman/listinfo/elecraftHelp: http://mailman.qth.net/mmfaq.htmPost: mailto:elecr...@mailman.qth.netThis list hosted by: http://www.qsl.netPlease help support this email list: http://www.qsl.net/donate.htmlMessage delivered to turnb...@net1.ie __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] QRO - KPA500 Failure
"I understand that efficiency decreases as one derates from the maximum of 1500W output.It surprises me that the power dissipated would peak at half power output or 750 Watts." I have no test data for the KPA1500 and will not speculate on the shape of the PA dissipation curves. All I have is data for one KPA500. For that one KPA500, and under the conditions tested, it's clear that PA dissipation is greater at half power than at full power. It would be easy to get a pair of data points for the KPA1500. Connect the amplifier to a known good 50 ohm load. Drive the amplifier to steady state 1500 W output Record PA current and voltage Drive the amplifier to steady state 750 W output Record the PA current and voltage Repeat on multiple bands if desired and report the results here. 73, Andy, k3wyc __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] QRO - KPA500 Failure
Several others have posted test data for the KPA500 here recently. As I recall, it shows that dissipated power is fairly constant from about 50 percent to full output, at about 500 W, dropping a bit at lower power. If it were an ideal class B amplifier, which no solid state RF amplifier even approaches, the efficiency at full output would be 78.5 percent. It would then dissipate only 141 W at full output, and maximum dissipation would be at some lower output power level. This is probably what folks are thinking of when they assume maximum dissipation occurs at less than full output. REAL RF amplifiers don't behave that way, as the test results show. https://en.wikipedia.org/wiki/Power_amplifier_classes#Class_B 73, Scott K9MA On 2/10/2020 09:23, Doug Turnbull wrote: Hello Andy, I do not have the numbers and also would like them. I understand that efficiency decreases as one derates from the maximum of 1500W output. It surprises me that the power dissipated would peak at half power output or 750 Watts. This may be so.If so then almost certainly the Mean Time Between Failures or MTBF is worsened. I am not in a position to determine any of this but maybe some guidance from Elecraft itself would be helpful for both KPA 500 and 1500. 73 Doug EI2CN From: Andy Durbin Sent: Monday 10 February 2020 14:04 To: Doug Turnbull ; elecraft@mailman.qth.net Subject: Re: [Elecraft] QRO - KPA500 Failure Doug, "I would like to know if running 2/3, 1/2 or even 1/4 maximum power output increases reliability and MTBF." I have no experience of amplifier design but I would expect reliability of the finals to depend on temperature. Finals temperature will depend on the power dissipated in the finals (PA dissipation) and the effectiveness of the cooling design. To understands finals dissipation one would need to produce one's own test data or rely on the work of others. My test data for the KPA500 shows PA dissipation peaks at about half power output. So far no one has disputed the validity of my test data. It is my understanding that running an amplifier at reduced power only reduces PA dissipation if the finals voltage is adjusted give a good load match for that reduced power condition. The KPA500 has no provision for adjusting PA voltage for the reduced power case. For reduced power the PA voltage is actually higher than for full power because the high voltage supply is not regulated. As I said, I have no experience in amplifier design and would appreciate comments from those who do. 73, Andy, k3wyc __ 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 Message delivered to k...@sdellington.us -- Scott K9MA k...@sdellington.us __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] QRO - KPA500 Failure
One point to consider is the output network that is used to match the output device impedance to 50 ohms. It is a fixed value or ratio. Thus if designed for rated power then at 1/2 or 1/4 power the value would not seem to provide a proper match for effective transfer of energy. This can attribute to overall efficiency. Bob, K4TAX Sent from my iPhone > On Feb 10, 2020, at 9:38 AM, Doug Turnbull wrote: > > Hello Andy, > > I do not have the numbers and also would like them. I understand > that efficiency decreases as one derates from the maximum of 1500W output. > It surprises me that the power dissipated would peak at half power output or > 750 Watts. This may be so.If so then almost certainly the Mean Time > Between Failures or MTBF is worsened. I am not in a position to > determine any of this but maybe some guidance from Elecraft itself would be > helpful for both KPA 500 and 1500. > > 73 Doug EI2CN > > > > From: Andy Durbin > Sent: Monday 10 February 2020 14:04 > To: Doug Turnbull ; elecraft@mailman.qth.net > Subject: Re: [Elecraft] QRO - KPA500 Failure > > > > Doug, > > > > "I would like to know if running 2/3, 1/2 or even 1/4 maximum power output > increases reliability and MTBF." > > > > I have no experience of amplifier design but I would expect reliability of > the finals to depend on temperature. Finals temperature will depend on the > power dissipated in the finals (PA dissipation) and the effectiveness of the > cooling design. > > > > To understands finals dissipation one would need to produce one's own test > data or rely on the work of others. My test data for the KPA500 shows PA > dissipation peaks at about half power output. So far no one has disputed > the validity of my test data. > > > > It is my understanding that running an amplifier at reduced power only > reduces PA dissipation if the finals voltage is adjusted give a good load > match for that reduced power condition. The KPA500 has no provision for > adjusting PA voltage for the reduced power case. For reduced power the PA > voltage is actually higher than for full power because the high voltage > supply is not regulated. > > > > As I said, I have no experience in amplifier design and would appreciate > comments from those who do. > > > > 73, > > Andy, k3wyc > > > > > > > > __ > 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 > Message delivered to rmcg...@blomand.net > __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] QRO - KPA500 Failure
Hello Andy, I do not have the numbers and also would like them. I understand that efficiency decreases as one derates from the maximum of 1500W output. It surprises me that the power dissipated would peak at half power output or 750 Watts. This may be so.If so then almost certainly the Mean Time Between Failures or MTBF is worsened. I am not in a position to determine any of this but maybe some guidance from Elecraft itself would be helpful for both KPA 500 and 1500. 73 Doug EI2CN From: Andy Durbin Sent: Monday 10 February 2020 14:04 To: Doug Turnbull ; elecraft@mailman.qth.net Subject: Re: [Elecraft] QRO - KPA500 Failure Doug, "I would like to know if running 2/3, 1/2 or even 1/4 maximum power output increases reliability and MTBF." I have no experience of amplifier design but I would expect reliability of the finals to depend on temperature. Finals temperature will depend on the power dissipated in the finals (PA dissipation) and the effectiveness of the cooling design. To understands finals dissipation one would need to produce one's own test data or rely on the work of others. My test data for the KPA500 shows PA dissipation peaks at about half power output. So far no one has disputed the validity of my test data. It is my understanding that running an amplifier at reduced power only reduces PA dissipation if the finals voltage is adjusted give a good load match for that reduced power condition. The KPA500 has no provision for adjusting PA voltage for the reduced power case. For reduced power the PA voltage is actually higher than for full power because the high voltage supply is not regulated. As I said, I have no experience in amplifier design and would appreciate comments from those who do. 73, Andy, k3wyc __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] QRO - KPA500 Failure
Doug, "I would like to know if running 2/3, 1/2 or even 1/4 maximum power output increases reliability and MTBF." I have no experience of amplifier design but I would expect reliability of the finals to depend on temperature. Finals temperature will depend on the power dissipated in the finals (PA dissipation) and the effectiveness of the cooling design. To understands finals dissipation one would need to produce one's own test data or rely on the work of others. My test data for the KPA500 shows PA dissipation peaks at about half power output. So far no one has disputed the validity of my test data. It is my understanding that running an amplifier at reduced power only reduces PA dissipation if the finals voltage is adjusted give a good load match for that reduced power condition. The KPA500 has no provision for adjusting PA voltage for the reduced power case. For reduced power the PA voltage is actually higher than for full power because the high voltage supply is not regulated. As I said, I have no experience in amplifier design and would appreciate comments from those who do. 73, Andy, k3wyc __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] QRO - KPA500 Failure
Andy, Yes, you are right and this applies to both KPA 500 and KPA 1500.The conditions for maximum efficiency are not necessarily those for minimum dissipation or reduced stress.I would like to know if running 2/3, 1/2 or even 1/4 maximum power output increases reliability and MTBF.It would be a considerable surprise to me if this were not the case and it would be good to know the numbers.Improvement in MTBF can be several fold for some devices for a reduction in voltage, current or power of as little as 10%.Good design practice normally means that this is part of the engineering design process. The proof of derating is looked for in design reviews. Too many hams run their amplifiers flat out for very little benefit. Signal cleanliness is still another issue; higher voltage but lower power seems to help here. Using FT8 or WSPR on dead band (160M in daytime or 12M), I sometimes run 20 Watts plus. This can be stressful on the K3 especially for WSPR. I crank the K3 down to a watt or so and drive the KPA 1500.Yes, my total energy consumption is no doubt up but stress on either K3 or KPA is minimal. This however is not my concern, I would like to know if running the KPA at lower power increases reliability. In EI we can run 1500 Watts for contests but outside of contests can only run 400W max. 73 Doug EI2CN -Original Message- From: elecraft-boun...@mailman.qth.net On Behalf Of Andy Durbin Sent: Monday 10 February 2020 01:45 To: elecraft@mailman.qth.net Subject: [Elecraft] QRO - KPA500 Failure "I am seeing a lot of confusion and erroneous conclusions based on the terms 'efficiency', 'dissipation' coupled with 'power output'." Yes, very true. Only a few have actually contributed test data. All the rest is assumption and speculation. Andy, k3wyc __ 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 Message delivered to turnb...@net1.ie __ 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 Message delivered to arch...@mail-archive.com
[Elecraft] QRO - KPA500 Failure
"I am seeing a lot of confusion and erroneous conclusions based on the terms 'efficiency', 'dissipation' coupled with 'power output'." Yes, very true. Only a few have actually contributed test data. All the rest is assumption and speculation. Andy, k3wyc __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] QRO - KPA500 Failure
John, You are correct. I am seeing a lot of confusion and erroneous conclusions based on the terms 'efficiency', 'dissipation' coupled with 'power output'. As an example, consider that a PA running at 50% efficient at 500 watts will dissipate 500 watts of heat and 500 watts of power out. Input DC power will be 1000 watts. Now back the power down to 250 watts - yes, the efficiency will be less, say 33%. That is 250 watts of power output, but 67% of the total power into the amp would be lost as heat - 417 watts of heat. Input power is less too at 667 watts. That drop in efficiency at lower than max design power is true for any amp designed for their maximum rated power output (as most are). The only ones who should be concerned are those who are monitoring their draw from the AC line and their resulting utility bill. 73, Don W3FPR On 2/7/2020 10:16 AM, j...@kk9a.com wrote: There may be reasons for running at less than the amplifier max such as the US 200 watt 30m band limitation. I have no RF engineering knowledge but after looking at your data I see less heat with lower output wattage which seems to me like it would be less stress on finals. __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] QRO - KPA500 Failure
Jim, maybe it is not your case but check this first: http://ok1rp.blogspot.com/2017/02/elecraft-kpa500-lpf-tr-switch-rework.html?_sm_au_=iQWn28RMHPpHWSZ6cLpsvK618Vf61 - 73 - Petr, OK1RP "Apple & Elecraft freak" B:http://ok1rp.blogspot.com MeWe: https://bit.ly/2HGPoDx MeWe: https://bit.ly/2FmwvDt -- Sent from: http://elecraft.365791.n2.nabble.com/ __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] QRO - KPA500 Failure
There may be reasons for running at less than the amplifier max such as the US 200 watt 30m band limitation. I have no RF engineering knowledge but after looking at your data I see less heat with lower output wattage which seems to me like it would be less stress on finals. John KK9A Bob McGraw K4TAX wrote: I've never seen much if any advantage in running a linear below its rated output. I know the regulation state never run more power than needed for adequate communications or terms like that.The difference between 500 watts and 100 watts is 6.9 dB or about 1 S unit. In fact, most all of the time, running at less than rated output is less efficient. It saves nothing. Same for tube amps where I hear hams say they are running at reduced power to "save the tubes". Nope, not the case. (RF output / DC input) * 100 = % efficiency DC input watts = DC volts x DC amps Do the math and you'll see what I mean. A quick run of the numbers with my KPA500 into a dummy load. Output measured with a Bird 43. DC values taken from the KPA500 display 450 W out, 819 W input, 64 volts @ 12.8 amps for 55% efficiency Drive pwr = 16.5W 14.3 dB gain 819 - 450 = 369 watts = heating factor = 0.88 210 W out, 576 W input, 67 volts @ 8.6 amps for 37% efficiency Drive pwr = 7.0 W 14.7 dB gain 576 - 210 = 366 watts = heating factor = 1.74 100 W out, 393 W input, 69 volts @ 5.7 amps for 25% efficiency Drive pwr = 3.2 W 14.9 dB gain 393 - 100 = 293 watts = heating factor = 2.93 73 Bob, K4TAX __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] QRO - KPA500 Failure
I run my KPA500 output just below the level I feel I can get away with...without lighting up the neighborhood. About 350 watts :) John K7FD > On Feb 6, 2020, at 2:06 PM, Bob McGraw K4TAX wrote: > > I've never seen much if any advantage in running a linear below its rated > output. I know the regulation state never run more power than needed for > adequate communications or terms like that.The difference between 500 > watts and 100 watts is 6.9 dB or about 1 S unit. > > In fact, most all of the time, running at less than rated output is less > efficient. It saves nothing. Same for tube amps where I hear hams say > they are running at reduced power to "save the tubes". Nope, not the case. > > (RF output / DC input) * 100 = % efficiency DC input watts = DC > volts x DC amps > > Do the math and you'll see what I mean. > > A quick run of the numbers with my KPA500 into a dummy load. Output measured > with a Bird 43. DC values taken from the KPA500 display > > 450 W out, 819 W input, 64 volts @ 12.8 amps for 55% efficiency Drive pwr = > 16.5W 14.3 dB gain 819 - 450 = 369 watts = heating factor = 0.88 > > 210 W out, 576 W input, 67 volts @ 8.6 amps for 37% efficiency Drive pwr = > 7.0 W 14.7 dB gain 576 - 210 = 366 watts = heating factor = 1.74 > > 100 W out, 393 W input, 69 volts @ 5.7 amps for 25% efficiency Drive pwr > = 3.2 W 14.9 dB gain 393 - 100 = 293 watts = heating factor = 2.93 > > 73 > > Bob, K4TAX > > >> On 2/6/2020 3:07 PM, Rick Bates, NK7I wrote: >> Running low output power from it, is far less efficient than pushing it hard >> (compare wattages consumed to RF watts output delivered at different output >> levels); which may have stressed the finals. Ideally you run the previous >> stages at low-moderate power for lower IMD, then punch it up with the amp. > > __ > 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 > Message delivered to macymonk...@charter.net __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] QRO - KPA500 Failure
"Basically, based on Bob's measurements, the power dissipated is fairly independent of drive level. So, running at reduced power really isn't stressing anything any more that full output." I have done quite extensive testing of my KPA500 and provided links to my results. My KPA500 PA dissipation is strongly dependent on the PA load but, for any given load, the peak dissipation is at out half power output. Andy, k3wyc __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] QRO - KPA500 Failure
Basically, based on Bob's measurements, the power dissipated is fairly independent of drive level. So, running at reduced power really isn't stressing anything any more that full output. (Unlike an "ideal" class B amplifier.) 73, Scott K9MA On 2/6/2020 16:06, Bob McGraw K4TAX wrote: I've never seen much if any advantage in running a linear below its rated output. I know the regulation state never run more power than needed for adequate communications or terms like that. The difference between 500 watts and 100 watts is 6.9 dB or about 1 S unit. In fact, most all of the time, running at less than rated output is less efficient. It saves nothing. Same for tube amps where I hear hams say they are running at reduced power to "save the tubes". Nope, not the case. (RF output / DC input) * 100 = % efficiency DC input watts = DC volts x DC amps Do the math and you'll see what I mean. A quick run of the numbers with my KPA500 into a dummy load. Output measured with a Bird 43. DC values taken from the KPA500 display 450 W out, 819 W input, 64 volts @ 12.8 amps for 55% efficiency Drive pwr = 16.5W 14.3 dB gain 819 - 450 = 369 watts = heating factor = 0.88 210 W out, 576 W input, 67 volts @ 8.6 amps for 37% efficiency Drive pwr = 7.0 W 14.7 dB gain 576 - 210 = 366 watts = heating factor = 1.74 100 W out, 393 W input, 69 volts @ 5.7 amps for 25% efficiency Drive pwr = 3.2 W 14.9 dB gain 393 - 100 = 293 watts = heating factor = 2.93 73 Bob, K4TAX On 2/6/2020 3:07 PM, Rick Bates, NK7I wrote: Running low output power from it, is far less efficient than pushing it hard (compare wattages consumed to RF watts output delivered at different output levels); which may have stressed the finals. Ideally you run the previous stages at low-moderate power for lower IMD, then punch it up with the amp. __ 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 Message delivered to k...@sdellington.us -- Scott K9MA k...@sdellington.us __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] QRO - KPA500 Failure
The advantage I have is that it doesn't set off my fire alarm. On Thu, 6 Feb 2020, Bob McGraw K4TAX wrote: I've never seen much if any advantage in running a linear below its rated output. I know the regulation state never run more power than needed for adequate communications or terms like that.The difference between 500 watts and 100 watts is 6.9 dB or about 1 S unit. In fact, most all of the time, running at less than rated output is less efficient. It saves nothing. Same for tube amps where I hear hams say they are running at reduced power to "save the tubes". Nope, not the case. (RF output / DC input) * 100 = % efficiency DC input watts = DC volts x DC amps Do the math and you'll see what I mean. A quick run of the numbers with my KPA500 into a dummy load. Output measured with a Bird 43. DC values taken from the KPA500 display 450 W out, 819 W input, 64 volts @ 12.8 amps for 55% efficiency Drive pwr = 16.5W 14.3 dB gain 819 - 450 = 369 watts = heating factor = 0.88 210 W out, 576 W input, 67 volts @ 8.6 amps for 37% efficiency Drive pwr = 7.0 W 14.7 dB gain 576 - 210 = 366 watts = heating factor = 1.74 100 W out, 393 W input, 69 volts @ 5.7 amps for 25% efficiency Drive pwr = 3.2 W 14.9 dB gain 393 - 100 = 293 watts = heating factor = 2.93 73 Bob, K4TAX On 2/6/2020 3:07 PM, Rick Bates, NK7I wrote: Running low output power from it, is far less efficient than pushing it hard (compare wattages consumed to RF watts output delivered at different output levels); which may have stressed the finals. Ideally you run the previous stages at low-moderate power for lower IMD, then punch it up with the amp. __ 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 Message delivered to ht...@twofifty.com -- Hisashi T Fujinaka - ht...@twofifty.com BSEE + BSChem + BAEnglish + MSCS + $2.50 = coffee __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] QRO - KPA500 Failure
When I blew the final on my KPA500 Elecraft diagnosed the problem. I had to make a few meter readings and they figured out the problem. They gave me the option of removing the transformer for shipping (most of the amp weight). They gave me instructions to remove and reassemble when it returned. Saved a lot on shipping. Good luck 73 Joe K2UF __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] QRO - KPA500 Failure
As a follow up to my previous message I measured PA voltage and current for OPER mode not keyed and OPER mode keyed with no RF drive input. PAI not keyed .0, keyed .2 PAV not keyed 80.9, keyed 77.8 Hi reflected power fault can't happen with no drive so won't influence the results. Andy, k3wyc __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] QRO - KPA500 Failure
I've never seen much if any advantage in running a linear below its rated output. I know the regulation state never run more power than needed for adequate communications or terms like that. The difference between 500 watts and 100 watts is 6.9 dB or about 1 S unit. In fact, most all of the time, running at less than rated output is less efficient. It saves nothing. Same for tube amps where I hear hams say they are running at reduced power to "save the tubes". Nope, not the case. (RF output / DC input) * 100 = % efficiency DC input watts = DC volts x DC amps Do the math and you'll see what I mean. A quick run of the numbers with my KPA500 into a dummy load. Output measured with a Bird 43. DC values taken from the KPA500 display 450 W out, 819 W input, 64 volts @ 12.8 amps for 55% efficiency Drive pwr = 16.5W 14.3 dB gain 819 - 450 = 369 watts = heating factor = 0.88 210 W out, 576 W input, 67 volts @ 8.6 amps for 37% efficiency Drive pwr = 7.0 W 14.7 dB gain 576 - 210 = 366 watts = heating factor = 1.74 100 W out, 393 W input, 69 volts @ 5.7 amps for 25% efficiency Drive pwr = 3.2 W 14.9 dB gain 393 - 100 = 293 watts = heating factor = 2.93 73 Bob, K4TAX On 2/6/2020 3:07 PM, Rick Bates, NK7I wrote: Running low output power from it, is far less efficient than pushing it hard (compare wattages consumed to RF watts output delivered at different output levels); which may have stressed the finals. Ideally you run the previous stages at low-moderate power for lower IMD, then punch it up with the amp. __ 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 Message delivered to arch...@mail-archive.com
[Elecraft] QRO - KPA500 Failure
"On key down (input of 15W) the asterisk briefly displays, then display changes to 18.1, back to HV display on key up." Are you saying the "HV" text in the display goes away or that it reads HV 18.1? Normally the HV display continues to read the PA supply voltage regardless of whether the amp is keyed or not. It would normally just change from approx 80 V to approx 60 V when keyed. At face value the results seem to indicate a high voltage supply failure or a fault in the PA that is sucking a very high current. What is the PA current during the brief period the KPA500 remains keyed? What are PA voltage and current when keyed if the 60 V line is disconnected from the PA module? Of course the safe plan would be to send it back but those are some of the test I would try if it were mine. Andy, k3wyc __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] QRO - KPA500 Failure
Elecraft self-insures on outbound shipments (i.e., shipments from Elecraft to customer). That means they accept the responsibility of carrier loss or damage because their history of loss/damage has been low. The fact that they self-insure doesn't cover shipments to them unless the company is paying for the shipping, as is the case with a warranty return, I believe. Their shipping instructions for repair returns out of warranty recommend the customer insure the shipment. I received about a 25% discount from UPS when I shipped my KPA1500 a couple of months ago due to my membership in a professional society. You might check for similar discounts if you have any similar memberships. Jim N7US On Thu, Feb 6, 2020, 3:28 PM Hisashi T Fujinaka wrote: > I'm not sure who asked the question first, but check your email from > Elecraft support about shipping. I was told Elecraft self-insures, so my > shipping of my KPA1500 amp from Portland, OR to the mothership was > around $20. > > On Thu, 6 Feb 2020, Rick Bates, NK7I wrote: > > > While also not cheap in shipping and insurance (ask me how I know?) that > > is often the better choice. > > > > Rick, NK7I > > -- > Hisashi T Fujinaka - ht...@twofifty.com > BSEE + BSChem + BAEnglish + MSCS + $2.50 = coffee > > __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] QRO - KPA500 Failure
They self-insure OUTbound from Elecraft; it falls on the shipper to insure, not the recipient. I had to send in the RF deck (only) of the KPA1500 for factory upgrades and I asked for Elecraft to cover shipping. I waited a few days. An hour after I got back from shipping it UPS from Idaho (the insurance was a killer, total bill ~$180), they approved paying for it. DOH! Ask, then be more patient than me. The worst answer is 'no' and that only costs you time to find out. Rick NK7I On 2/6/2020 1:28 PM, Hisashi T Fujinaka wrote: I'm not sure who asked the question first, but check your email from Elecraft support about shipping. I was told Elecraft self-insures, so my shipping of my KPA1500 amp from Portland, OR to the mothership was around $20. On Thu, 6 Feb 2020, Rick Bates, NK7I wrote: While also not cheap in shipping and insurance (ask me how I know?) that is often the better choice. Rick, NK7I __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] QRO - KPA500 Failure
I'm not sure who asked the question first, but check your email from Elecraft support about shipping. I was told Elecraft self-insures, so my shipping of my KPA1500 amp from Portland, OR to the mothership was around $20. On Thu, 6 Feb 2020, Rick Bates, NK7I wrote: While also not cheap in shipping and insurance (ask me how I know?) that is often the better choice. Rick, NK7I -- Hisashi T Fujinaka - ht...@twofifty.com BSEE + BSChem + BAEnglish + MSCS + $2.50 = coffee __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] QRO - KPA500 Failure
Hi Rick, I like your call sign! :) 73, and thanks, Dave (NK7Z) https://www.nk7z.net ARRL Volunteer Examiner ARRL Technical Specialist ARRL Asst. Director, NW Division, Technical Resources On 2/6/20 1:07 PM, Rick Bates, NK7I wrote: Since the SWR is still nominal into the amp (as shown on your radio), it's not likely the tuned input circuits (which is confirmed from no output on all bands). This points to the high power module. Running low output power from it, is far less efficient than pushing it hard (compare wattages consumed to RF watts output delivered at different output levels); which may have stressed the finals. Ideally you run the previous stages at low-moderate power for lower IMD, then punch it up with the amp. The "HIGH SWR" fault you saw is then very likely the final signing QRT SK. You can confirm that with Elecraft wizards. That module isn't hard to swap out, but it would be best (slightly more costly) for the entire amp to visit it's parents, so that other updates that may not have been done, can be done. Many of them, really matter. While also not cheap in shipping and insurance (ask me how I know?) that is often the better choice. Rick, NK7I On 2/6/2020 12:54 PM, Michael Walker wrote: Amps making noises like that usually mean you have to take the covers off. They are easy enough to repair if you are so inclined. If not, then you will need to contact Elecraft support and odds are you will have to send it home for a Spa day. Mike va3mw On Thu, Feb 6, 2020 at 3:35 PM Jim Brown wrote: On 2/6/2020 12:15 PM, Jim Mullen wrote: Any pointers of where to start looking? 1) What SWR does the rig see with the amp off? 2) Make notes of any error messages given by the KPA500 display. 3) Call Elecraft Support 73, Jim K9YC __ 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 Message delivered to va...@portcredit.net __ 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 Message delivered to rick.n...@gmail.com __ 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 Message delivered to d...@nk7z.net __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] QRO - KPA500 Failure
Since the SWR is still nominal into the amp (as shown on your radio), it's not likely the tuned input circuits (which is confirmed from no output on all bands). This points to the high power module. Running low output power from it, is far less efficient than pushing it hard (compare wattages consumed to RF watts output delivered at different output levels); which may have stressed the finals. Ideally you run the previous stages at low-moderate power for lower IMD, then punch it up with the amp. The "HIGH SWR" fault you saw is then very likely the final signing QRT SK. You can confirm that with Elecraft wizards. That module isn't hard to swap out, but it would be best (slightly more costly) for the entire amp to visit it's parents, so that other updates that may not have been done, can be done. Many of them, really matter. While also not cheap in shipping and insurance (ask me how I know?) that is often the better choice. Rick, NK7I On 2/6/2020 12:54 PM, Michael Walker wrote: Amps making noises like that usually mean you have to take the covers off. They are easy enough to repair if you are so inclined. If not, then you will need to contact Elecraft support and odds are you will have to send it home for a Spa day. Mike va3mw On Thu, Feb 6, 2020 at 3:35 PM Jim Brown wrote: On 2/6/2020 12:15 PM, Jim Mullen wrote: Any pointers of where to start looking? 1) What SWR does the rig see with the amp off? 2) Make notes of any error messages given by the KPA500 display. 3) Call Elecraft Support 73, Jim K9YC __ 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 Message delivered to va...@portcredit.net __ 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 Message delivered to rick.n...@gmail.com __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] QRO - KPA500 Failure
Amps making noises like that usually mean you have to take the covers off. They are easy enough to repair if you are so inclined. If not, then you will need to contact Elecraft support and odds are you will have to send it home for a Spa day. Mike va3mw On Thu, Feb 6, 2020 at 3:35 PM Jim Brown wrote: > On 2/6/2020 12:15 PM, Jim Mullen wrote: > > Any pointers of where to start looking? > > 1) What SWR does the rig see with the amp off? > 2) Make notes of any error messages given by the KPA500 display. > 3) Call Elecraft Support > > 73, Jim K9YC > __ > 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 > Message delivered to va...@portcredit.net > __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] QRO - KPA500 Failure
On 2/6/2020 12:15 PM, Jim Mullen wrote: Any pointers of where to start looking? 1) What SWR does the rig see with the amp off? 2) Make notes of any error messages given by the KPA500 display. 3) Call Elecraft Support 73, Jim K9YC __ 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 Message delivered to arch...@mail-archive.com
[Elecraft] QRO - KPA500 Failure
Was running about 150W on 18 MHz this afternoon. My KPA 500 made a loud pop. No more output. Any pointers of where to start looking? *Details:* KPA500 (use with KAT500 and Icom 7610) Antenna on this band is a SteppIR Amp has been running FB KPA Utility 1.13.7.16 240V supply A single loud pop was heard. Mode remained in OPER No fault light displayed, nor can I find one in the Fault Table *After the failure:* *In STBY:* Radio and antennas work fine. SWR shown to exciter is low, as expected. Exciter power is displayed on KPA500 power meter. HV = 78.2 Works correctly on all bands *In OPER:* HV = 78.2 key up On key down (input of 15W) the asterisk briefly displays, then display changes to 18.1, back to HV display on key up. Zero output, SWR shown to exciter is very high (over 3 to 1) No power shown on output meter. Fails *on all bands* with high SWR to the exciter. No fault indication. *Other data:* Here's the last three entries from the fault table: 00 PWR ON -- 0007 Power was turned on 0039 09 REFL HI 80 00F0 Excessive reflected power (high SWR) 00 PWR ON -- Power was turned on . Apparently only faults get logged, subsequent power cycles have not changed the table. I power cycled the amp, including removing the mains power. - no change. I reloaded the last configuration - no change. I removed the cover and looked for any visible damage or bad odors. Nothing stands out. Amp is about 4 years old and was a kit model. Before I start to disassemble if anyone can offer a likely culprit I'm all ears. Thanks, Jim/KK1W __ 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 Message delivered to arch...@mail-archive.com
