Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)
I had a similar issue with my K3s/KPA 1500 that defied logic. Without going into all the details, I finally sent both the K3s and KPA 1500 back to Elecraft to have them analyze it as a systems problem. It turned out to be a faulty 100W PA on the K3s that would generate very short high level transient pulses that somehow caused the fault. Since having that replaced all has been extremely stable for over 12 months. This problem always happened on 6 meters, sometimes on 10 meters, but never on any lower frequencies. Best of luck. Ned WC4X -- 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] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)
On 6/1/2020 6:37 AM, stephen shearer wrote: Ground loops can be another issue. I was having a "feed back" issue with my KX3/KXPA100 ans solved it eliminating ground/power loops. DANGER, WILL ROBINSON! First, ain't no such thing as a "ground loop." The real cause of problems we BLAME on this fictional condition is failure to do proper bonding within our stations and all other "grounds" in our homes. BY LAW (Electrical Building Codes, usually a version of NEC or based on NEC), ALL grounds in any facility must be bonded together. At a minimum, all equipment plugged into the wall must have its chassis bonded to the green wire in its power cord. In a ham station, every chassis must be directly bonded to the others by short, fat copper, AND all equipment that will be interconnected with the station (rig, computer, audio interface) should get AC power from outlets that share the same green wire back to the breaker panel. Lots of detail on this in http://k9yc.com/GroundingAndAudio.pdf and in N0AX's ARRL book on the topic, on which we collaborated. 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
Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)
I have never driven the amp with 90 Watts. Ever. The 90W figure is what comes out of the K3s *after* the amp has tripped out. With the amp in 'operate' I feed it typically 25-35 Watts. Here are the error codes, as requested (truncated for length--there are MANY more): 441 20-06-01T01:02:22 FLT 90 - PWR REFL freq 50304 inp 13W fwd 1064W refl 198W swr 2.5 23A 32C adc 280 var 198 440 20-05-31T23:45:57 FLT 90 - PWR REFL freq 50008 inp 22W fwd 1356W refl 199W swr 2.2 44A 45C adc 281 var 199 439 20-05-31T23:43:46 OVR 90 - PWR REFL freq 50304 inp 23W fwd 1210W refl 172W swr 2.2 39A 31C adc 257 var 172 438 20-05-31T23:43:39 OVR 90 - PWR REFL freq 50304 inp 23W fwd 1204W refl 172W swr 2.2 39A 28C adc 257 var 172 437 20-05-31T23:43:13 FLT 90 - PWR REFL freq 50304 inp 23W fwd 1298W refl 202W swr 2.3 44A 27C adc 284 var 202 435 20-05-31T02:39:03 OVR 90 - PWR REFL freq 50304 inp 14W fwd 1107W refl 178W swr 2.3 23A 47C adc 262 var 178 434 20-05-31T02:34:03 FLT 90 - PWR REFL freq 50304 inp 15W fwd 1152W refl 198W swr 2.4 28A 33C adc 280 var 198 433 20-05-31T02:25:03 OVR 90 - PWR REFL freq 50304 inp 15W fwd 1130W refl 187W swr 2.3 24A 43C adc 270 var 187 432 20-05-31T02:23:03 FLT 90 - PWR REFL freq 50304 inp 18W fwd 1165W refl 199W swr 2.4 40A 43C adc 281 var 199 431 20-05-31T02:21:33 FLT 90 - PWR REFL freq 50304 inp 20W fwd 1189W refl 201W swr 2.3 46A 48C adc 283 var 201 __ 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] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)
The new full-length LMR-400 cable is about 3 feet longer than the old 2-section coax I had before (old = 3/8” hardline and about 8 feet of RG-213). The entry point is grounded to rod immediately below it, connected by 1.5” braid. - pjd From: Mark Goldberg Sent: Monday, June 1, 2020 12:45 AM To: Peter Dougherty Cc: Adrian ; Paul Baldock ; Elecraft Mailing List Subject: Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues) I haven't seen a discussion of your grounding system or feedline length. 6M can be picky. What does your ground system look like? Do you have any common mode chokes on the feedline? Have you tried adding or subtracting 2-3 feet from the feedline? If it is exactly a multiple of 1/2 wave or 1/4 wave changing the feedline length will move it away from that. Have you tried adding a counterpoise in the shack? That's not the ultimate solution but if it improves things it will tell you something. Can you point an IR thermometer at tuner / balun inductors to see if they are getting hot? Just throwing out ideas. 73, Mark W7MLG On Sun, May 31, 2020 at 9:08 PM Peter Dougherty mailto:li...@w2irt.net> > wrote: New coax and old coax behaved identically. HOWEVER, running into about 80 feet of old RG-213 and into the Cantenna dummy load and it doesn't fault. This is the only condition on 6m where there is no fault. Brand new coax, old coax, brand new antenna, old antenna, with balun, without balun. Always faults except when feeding the pure resistive dummy load. If there's any reactance it trips or gives false SWR info. I would also add, why would a 2:1 SWR trip out the amp at 25 or 30 Watts of drive? On the regular HF bands I can use the internal tuner to take out a 2.5 or 3:1 SWR and it still sends 1400-1450 Watts up the pipe.. - pjd __ 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] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)
That's worth a shot. I have a ~7 foot RG-213 patch cable from the back of the amp to the entry box. I don't have any more LMR-400 so I can't use that, but I do have quite a bit of 213 and will make a new patch cable. That's the only bit of the old system that's still remaining. - pjd -Original Message- From: Vic Rosenthal Sent: Monday, June 1, 2020 12:18 AM To: Peter Dougherty Cc: j...@audiosystemsgroup.com; Elecraft@mailman.qth.net Subject: Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues) Are you using the same output connector on the KPA1500 for the dummy load and the antenna? Perhaps the problem is in one of the SO239s or in the KPA’s switching circuit? Victor 4X6GP > On 1 Jun 2020, at 4:30, Peter Dougherty wrote: > > Many here suggested that it was most likely a feedline issue, and I > figured this was indeed a distinct possibility. > > So this afternoon I replaced the feedline. I now have about 80 feet of > brand new LMR-400, new 83-SP1 connectors (and an Amphenol adaptor at > the balun since I don't have any type-N connectors here). The AA-230 > ZOOM analyzer shows about 1.2:1 at 50.313, with resonance just below > the band. I'll fix that tomorrow, but 1.2 or 1.3:1 should be nothing to the > KPA. > > The TDR screen looks very clean, just a tiny bump where the feedline > goes through the (new) bulkhead connector to get into the house. See: > https://www.dropbox.com/s/izcwvece7nt5f42/2020-05-31%2019.32.44.jpg?dl > =0 > > The SWR chart between 50.000 and 50.500: > https://www.dropbox.com/s/y2xh4l1lihy2ujr/2020-05-31%2021.23.29.jpg?dl > =0 > > Again, I know the antenna is resonant a bit low, but this should NOT > be a factor. So here's what's now going on. > > 1) Into a Cantenna dummy load, with 25W of drive from the M3s, the > KPA-1500 is delivering 1075W and showing 1.4:1. No problem delivering > power and no faults. > > 2) With input power increased, 35W of K3s drive gives 1375W at 1.5 > into the Cantenna. Again, no problem delivering power to the purely resistive > load. > Why a 1.5:1, I don't know, but fine, whatever. I can TX for 15-20 > second periods without issue. > > 3) When I switch over to the live antenna, with25 Watts of drive from > the K3s into the actual antenna and the amp faults out instantly in > bypass. When the amplifier is in bypass and the tuner is in bypass, > and when the K3s is delivering about 90W in FT8 mode, the front panel > on the KPA-1500 says the SWR is 1.9:1. When I press the TUNE button on > the radio, it's showing an SWR of 1.4:1. > > 4) Amp in bypass, tuner inline, press TUNE button on the K3s and the > front panel of the KPA-1500 is showing a perfect 1.0:1 match. It > SHOULD work fine like this, right? > > 5) Pressing ONLY the OPER/STBY button to put the amp in operate (KPA > tuner in and untouched since step 4), the amp SOMETIMES delivers > power, sometimes faults out, shows an SWR of 1.7:1. Pressing the > OPER/STBY button again to use only exciter power, and touching NOTHING > ELSE, it's back to 1.1:1 with 90W of K3s drive. > > 6) There is basically no rhyme or reason why this is happening and > it's > *somewhat* repeatable. The incredibly frustrating part is if I see a > needed station come up, I'll flick the amp's tuner in line and it says it's > tuned. > Once WSJT-X keys the radio, 90 out of 100 times the amp will > hard-fault. If it doesn't fault on the first transmission, it > absolutely WILL on the second transmission. > > So I'm now at a complete loss to understand what's going on here. Amp > is fine into a resistive load. Brand-new antenna, brand new LMR-400 > feedline, brand new connectors, the KPA-1500 is faulting out the same > as it did on the > 10+ year old 6M5 with a patchwork of feedlines. I can't see how this > 10+ is > anything but a problem in the KPA-1500 (S/N 0398). > > - pjd > > -Original Message- > From: elecraft-boun...@mailman.qth.net > On Behalf Of Jim Brown > Sent: Sunday, May 31, 2020 8:22 PM > To: elecraft@mailman.qth.net > Subject: Re: [Elecraft] KPA-1500 faulting on 6m; SWR issues > >> On 5/31/2020 9:54 AM, Jim Miller wrote: >> Have you vetted your feedline at 1500w? Many times something might be >> good at low power and fail at 1500. > > This is good advice. Guys who do lots of portable setup say to always > check the coax first, which mostly means check for a connector that's > bad or badly installed. > > In general, if it doesn't say Amphenol or isn't stamped with a MIL > spec number, it's very likely to be poor quality. This includes > barrels, adapters, etc. Also make sure that every connector is" wrench > tight." > > The advice to run it straight to a dummy load is right on -- if you > have one big enough. :) > > 73, Jim K9YC > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm
Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)
Ground loops can be another issue. I was having a "feed back" issue with my KX3/KXPA100 ans solved it eliminating ground/power loops. 73, steve WB3LGC On 6/1/20 8:25 AM, David Olean wrote: Hello Peter I suspect RFI as well. I do not have a KPA1500, so my advice is not worth much, but the fact that the fault only occurs when a signal is being radiated sends me a red flag. I had a similar problem here with my SPE amplifier power output. I was measuring it on an LP-100A wattmeter. It turns out that 1.8 MHz energy from the SPE amp radiated from my vertical antenna and was getting into a new wire doublet antenna and coming back down the ladder line into the shack. The ladder line was about 7 inches from the power coupler for the LP-100A. RF caused the readings to go wacky and it looked like my amplifier was going postal! The problem was high rf fields next to the power meter coupler. Ferrite balun heating can be seen with a VSWR meter if you set the power at some intermediate level, key the amp up with a steady carrier, and watch for VSWR creeping up. Loose pins in coax can also be a problem. They can heat up and disconnect or start arcing. Those problems do not typically show VSWR creep. They happen all at once usually. The KPA1500 works fine into a dummy load. (No RFI) That is a big clue. Good luck and I hope you find the problem. Maybe an RF sniffer would detect the ingress point? 73 Dave K1WHS On 6/1/2020 5:24 AM, Eric Norris wrote: Is there any chance RF is getting in to the KPA1500 via an alternative route, like one of your HF antennas, a faulty switch, loose bonding/ground, or even a change in house wiring or wifi router, antenna rotator cable, picking up the RF and radiating/routing it to the KPA1500 from the antenna? It's a shot in the dark, I know, but cut out everything but the direct signal path originating from the K3, pull all the house breakers not used, turn off everything--make only the 6m path active and see what happens if this makes sense to you. I feel your frustration--the same thing in reverse took out my 2m EME station. I replaced every single thing, sent the K3 to Elecraft, the XV144 to Don...GUD LUCK OM! VY 73 Eric WD6DBM On Sun, May 31, 2020, 9:07 PM Peter Dougherty wrote: New coax and old coax behaved identically. HOWEVER, running into about 80 feet of old RG-213 and into the Cantenna dummy load and it doesn't fault. This is the only condition on 6m where there is no fault. Brand new coax, old coax, brand new antenna, old antenna, with balun, without balun. Always faults except when feeding the pure resistive dummy load. If there's any reactance it trips or gives false SWR info. I would also add, why would a 2:1 SWR trip out the amp at 25 or 30 Watts of drive? On the regular HF bands I can use the internal tuner to take out a 2.5 or 3:1 SWR and it still sends 1400-1450 Watts up the pipe.. - pjd -Original Message- From: Adrian Sent: Sunday, May 31, 2020 11:05 PM To: Peter Dougherty ; 'Paul Baldock' < p...@paulbaldock.com>; elecraft@mailman.qth.net Subject: Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues) To remove any doubt, a 1.5kw or close dummy load at the end of the coax to replace antenna, would confirm the amp issue. On 1/6/20 12:27 pm, Peter Dougherty wrote: Paul, please re-read what I wrote. The 90W figure is with the amp IN STANDBY! I wouldn't dream of putting more than about 35W into the KPA-1500. I generally like to run about 1200W on 6m, but even if I turn my K3s drive down to 20 Watts, it will STILL hard-fault regularly. NO AMOUNT OF DRIVE from the K3s will stop these problems. If the amp is set to deliver power it's going to fault on 6m, regardless of what the ATU is set for (bypass or inline), and the KPA will miss-read the SWR of the antenna system. The resistance figure is 50.8 Ohms, and the reactance is -11 according to the AA-230. The only difference between "works reliably" and "faults out all the time" is one is a resistive-only load, the other has a reactive component. - pjd - __ 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 norrislawfi...@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 k1...@metrocast.net __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help:
Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)
Peter, If my antenna system had 2.5 to 3 to 1 SWR, I would not run 1.5 KW. I'd be looking at my antenna... 73, and thanks, Dave (NK7Z) https://www.nk7z.net ARRL Volunteer Examiner ARRL Technical Specialist ARRL Asst. Director, NW Division, Technical Resources On 5/31/20 9:07 PM, Peter Dougherty wrote: I would also add, why would a 2:1 SWR trip out the amp at 25 or 30 Watts of drive? On the regular HF bands I can use the internal tuner to take out a 2.5 or 3:1 SWR and it still sends 1400-1450 Watts up the pipe.. - pjd __ 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] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)
Hello Peter I suspect RFI as well. I do not have a KPA1500, so my advice is not worth much, but the fact that the fault only occurs when a signal is being radiated sends me a red flag. I had a similar problem here with my SPE amplifier power output. I was measuring it on an LP-100A wattmeter. It turns out that 1.8 MHz energy from the SPE amp radiated from my vertical antenna and was getting into a new wire doublet antenna and coming back down the ladder line into the shack. The ladder line was about 7 inches from the power coupler for the LP-100A. RF caused the readings to go wacky and it looked like my amplifier was going postal! The problem was high rf fields next to the power meter coupler. Ferrite balun heating can be seen with a VSWR meter if you set the power at some intermediate level, key the amp up with a steady carrier, and watch for VSWR creeping up. Loose pins in coax can also be a problem. They can heat up and disconnect or start arcing. Those problems do not typically show VSWR creep. They happen all at once usually. The KPA1500 works fine into a dummy load. (No RFI) That is a big clue. Good luck and I hope you find the problem. Maybe an RF sniffer would detect the ingress point? 73 Dave K1WHS On 6/1/2020 5:24 AM, Eric Norris wrote: Is there any chance RF is getting in to the KPA1500 via an alternative route, like one of your HF antennas, a faulty switch, loose bonding/ground, or even a change in house wiring or wifi router, antenna rotator cable, picking up the RF and radiating/routing it to the KPA1500 from the antenna? It's a shot in the dark, I know, but cut out everything but the direct signal path originating from the K3, pull all the house breakers not used, turn off everything--make only the 6m path active and see what happens if this makes sense to you. I feel your frustration--the same thing in reverse took out my 2m EME station. I replaced every single thing, sent the K3 to Elecraft, the XV144 to Don...GUD LUCK OM! VY 73 Eric WD6DBM On Sun, May 31, 2020, 9:07 PM Peter Dougherty wrote: New coax and old coax behaved identically. HOWEVER, running into about 80 feet of old RG-213 and into the Cantenna dummy load and it doesn't fault. This is the only condition on 6m where there is no fault. Brand new coax, old coax, brand new antenna, old antenna, with balun, without balun. Always faults except when feeding the pure resistive dummy load. If there's any reactance it trips or gives false SWR info. I would also add, why would a 2:1 SWR trip out the amp at 25 or 30 Watts of drive? On the regular HF bands I can use the internal tuner to take out a 2.5 or 3:1 SWR and it still sends 1400-1450 Watts up the pipe.. - pjd -Original Message- From: Adrian Sent: Sunday, May 31, 2020 11:05 PM To: Peter Dougherty ; 'Paul Baldock' < p...@paulbaldock.com>; elecraft@mailman.qth.net Subject: Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues) To remove any doubt, a 1.5kw or close dummy load at the end of the coax to replace antenna, would confirm the amp issue. On 1/6/20 12:27 pm, Peter Dougherty wrote: Paul, please re-read what I wrote. The 90W figure is with the amp IN STANDBY! I wouldn't dream of putting more than about 35W into the KPA-1500. I generally like to run about 1200W on 6m, but even if I turn my K3s drive down to 20 Watts, it will STILL hard-fault regularly. NO AMOUNT OF DRIVE from the K3s will stop these problems. If the amp is set to deliver power it's going to fault on 6m, regardless of what the ATU is set for (bypass or inline), and the KPA will miss-read the SWR of the antenna system. The resistance figure is 50.8 Ohms, and the reactance is -11 according to the AA-230. The only difference between "works reliably" and "faults out all the time" is one is a resistive-only load, the other has a reactive component. - pjd - __ 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 norrislawfi...@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 k1...@metrocast.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
Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)
On 5/31/2020 7:22 PM, Peter Dougherty wrote: This is a brand-new balun from InnovAntennas, made specifically for this antenna, received this past Thursday. The word "balun" has been used to describe nearly a dozen VERY different physical things, and is thus totally useless as a descriptor of what you used (or what they sold you). Buy me a case of a good single malt Scotch and I'll run down the list. I have extensively studied only one set of those "things," common mode chokes formed by winding a length of transmission line onto a ferrite core that is lossy at the frequency(ies) of interest, forming a parallel resonance in the common mode circuit where the RESISTIVE component of the low-Q parallel resonance is what makes the choke work. A good common mode choke does not interact with a well-designed antenna unless the Zo of the transmission line wound onto the ferrite core is mismatched to the antenna. And I emphatically do NOT call them "baluns" because use of that word obscures understanding of HOW they work. 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
Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)
Is there any chance RF is getting in to the KPA1500 via an alternative route, like one of your HF antennas, a faulty switch, loose bonding/ground, or even a change in house wiring or wifi router, antenna rotator cable, picking up the RF and radiating/routing it to the KPA1500 from the antenna? It's a shot in the dark, I know, but cut out everything but the direct signal path originating from the K3, pull all the house breakers not used, turn off everything--make only the 6m path active and see what happens if this makes sense to you. I feel your frustration--the same thing in reverse took out my 2m EME station. I replaced every single thing, sent the K3 to Elecraft, the XV144 to Don...GUD LUCK OM! VY 73 Eric WD6DBM On Sun, May 31, 2020, 9:07 PM Peter Dougherty wrote: > New coax and old coax behaved identically. HOWEVER, running into about 80 > feet of old RG-213 and into the Cantenna dummy load and it doesn't fault. > This is the only condition on 6m where there is no fault. Brand new coax, > old coax, brand new antenna, old antenna, with balun, without balun. Always > faults except when feeding the pure resistive dummy load. If there's any > reactance it trips or gives false SWR info. > > I would also add, why would a 2:1 SWR trip out the amp at 25 or 30 Watts > of drive? On the regular HF bands I can use the internal tuner to take out > a 2.5 or 3:1 SWR and it still sends 1400-1450 Watts up the pipe.. > > - pjd > > -Original Message- > From: Adrian > Sent: Sunday, May 31, 2020 11:05 PM > To: Peter Dougherty ; 'Paul Baldock' < > p...@paulbaldock.com>; elecraft@mailman.qth.net > Subject: Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR > issues) > > To remove any doubt, a 1.5kw or close dummy load at the end of the coax to > replace antenna, would confirm the amp issue. > > On 1/6/20 12:27 pm, Peter Dougherty wrote: > > Paul, please re-read what I wrote. The 90W figure is with the amp IN > > STANDBY! I wouldn't dream of putting more than about 35W into the > KPA-1500. > > I generally like to run about 1200W on 6m, but even if I turn my K3s > > drive down to 20 Watts, it will STILL hard-fault regularly. NO AMOUNT > > OF DRIVE from the K3s will stop these problems. If the amp is set to > > deliver power it's going to fault on 6m, regardless of what the ATU is > > set for (bypass or inline), and the KPA will miss-read the SWR of the > antenna system. > > > > The resistance figure is 50.8 Ohms, and the reactance is -11 according > > to the AA-230. The only difference between "works reliably" and > > "faults out all the time" is one is a resistive-only load, the other > > has a reactive component. > > > > - pjd > > > > - > > > > __ > 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 norrislawfi...@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] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)
In an earlier message on a different, but related thread: http://elecraft.365791.n2.nabble.com/K3-SWR-Numerical-Indication-td7643839.html I wrote: "I would be surprised if two garden variety instruments, even placed at the same point, would agree. The directional bridges/couplers in most "(V)SWR" meters that hams routinely use externally or which are built into our radios are not precision instruments. There are a number of error sources in reflection measurements; source match, diode non-linearity, coupler tracking errors and often the most significant, directivity error. In an ideal coupler, (i.e signal separation device) one port measures the forward (incident signal) and another measures the reverse (reflected) signal and there is no coupling between ports in the unwanted direction(s). In other words there is no signal at the reverse port due to the forward signal. In a real world coupler there is some leakage signal appearing at the reverse port due to the forward signal, absent any reflected signal. The "goodness" of a directional coupler in this instance is called "directivity" and the error signal is directivity error. Directivity is usually specified in dB. Really good couplers might have directivities in the 40 dB neighborhood. Really really good directional bridges can be 50 dB, but so-so units might be 25-30 dB. Not ready for prime time units are lower than this. Now I have no way of knowing what the directivities are of the couplers built into K3s, KPA500s, KAT500s, etc. but considering that they have to work over about 5 octaves, I'm going out on a limb and saying that 25 to 30 dB is a fair estimate. If I'm wrong, I'm sure I'll hear about it. For sake of discussion I'm going to use 26.5 dB. What this means is that if I terminate the output spigot of one of these radios with a perfect 50+j0 load, I'm going to measure a leakage signal (directivity error) that is 26.5 dB below the incident value. I'll introduce the concept of return loss here. We hams usually speak in terms of SWR. SWR = (1 + p) / (1 - p) where p is the reflection coefficient. Here the p = the voltage measured at the reflected port and the constant 1 represents the incident signal. In reality both of these quantities are complex numbers, they have both magnitude and phase but SWR measurements are scalar, we throw away the phase (since it's difficult to measure) and just use the magnitude. (In fact the symbol "p", which is really the Greek letter rho, indicates the magnitude of the reflection coefficient in normal usage) We can also express this ratio as return loss, which is -20 * log10(p). So return loss, SWR and reflection coefficient are just different ways to express the same thing; the ratio of incident to reflected signal. Let's return to our example; the coupler with 26.5 dB directivity, which indicates a return loss (RL) of 26.5 dB even with a perfect termination. Doing the math and converting RL = 26.5 dB to SWR we get 1.1:1. Our perfect load measures 1.1:1 with our imperfect instrument. And this assumes that there are no other errors, which there always are. But it gets worse. Let's say that the load we want to measure really is 1.1:1. We now have two (apparent) reflections, 1) the real one and 2) the directivity error and they both have the same magnitude. In our simple detector, they sum together. Now I said earlier that we don't measure phase, only magnitude, but just because we don't, or can't measure the relative phases doesn't mean they aren't there. We will examine two cases to determine the limits of error. Case 1) both reflections are in phase, they add up to p + p or 2p, RL = 20.5 and SWR ~1.21:1. Case 2) they are exactly out of phase, they sum to zero. p = 0, RL is infinite and SWR = 1:1. The possible RL error is then -6 to +infinity dB! In other words, an actual SWR of 1.1:1 can be measured anywhere between 1.0:1 and 1.2:1. Is it any wonder that we often read about concerns that one device measures one thing, while another located at the same, or close location measures something different. Of course all of this is predicated on a directional coupler with 26.5 dB directivity and no other error sources. It's entirely possible that the Elecraft couplers are better than this. They are certainly no better than 40 dB since the internal reference resistors are 51 instead of 50 ohm. Plus the "Tandem Match" configuration is in itself not a great match to the transmitter output.(1) Furthermore, the coupler, at least in a K3 is driven by a LPF, which isn't a great 50 ohm source. Plus the coupler output port isn't connected directly to the coax connector. and so on and so forth (2). All of this creates "uncertainty." In a metrology lab heroic efforts are made to reduce uncertainty but do we, or should we, really care in this situation? In my opinion, no, but everyone is free to differ. Wes N7WS (1) See "An HF In-Line Return Loss And Power Meter" by Paul Kiciak, N2PK.
Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)
What are the error codes when you hard fault? Check them and see if there’s any consistency. I sometimes get hard faults when I’ve moved my rf deck, simply because the PowerPoles on the 12v line from the power supply have moved a bit and aren’t making a good connection. I usually see a 50v warning pop up that alerts me to the issue. Have you made sure that 12v line is secured? I also concur that 90 watts Drive into the amp is way too much. That suggests the amp is the culprit. The innovantenna balun is pretty robust. But if you suspect it, bypass it and test a direct line with pigtailed ends directly into the loop. 73, Lou W0FK -- 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] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)
I haven't seen a discussion of your grounding system or feedline length. 6M can be picky. What does your ground system look like? Do you have any common mode chokes on the feedline? Have you tried adding or subtracting 2-3 feet from the feedline? If it is exactly a multiple of 1/2 wave or 1/4 wave changing the feedline length will move it away from that. Have you tried adding a counterpoise in the shack? That's not the ultimate solution but if it improves things it will tell you something. Can you point an IR thermometer at tuner / balun inductors to see if they are getting hot? Just throwing out ideas. 73, Mark W7MLG On Sun, May 31, 2020 at 9:08 PM Peter Dougherty wrote: > New coax and old coax behaved identically. HOWEVER, running into about 80 > feet of old RG-213 and into the Cantenna dummy load and it doesn't fault. > This is the only condition on 6m where there is no fault. Brand new coax, > old coax, brand new antenna, old antenna, with balun, without balun. Always > faults except when feeding the pure resistive dummy load. If there's any > reactance it trips or gives false SWR info. > > I would also add, why would a 2:1 SWR trip out the amp at 25 or 30 Watts > of drive? On the regular HF bands I can use the internal tuner to take out > a 2.5 or 3:1 SWR and it still sends 1400-1450 Watts up the pipe.. > > - pjd > > __ 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] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)
Are you using the same output connector on the KPA1500 for the dummy load and the antenna? Perhaps the problem is in one of the SO239s or in the KPA’s switching circuit? Victor 4X6GP > On 1 Jun 2020, at 4:30, Peter Dougherty wrote: > > Many here suggested that it was most likely a feedline issue, and I figured > this was indeed a distinct possibility. > > So this afternoon I replaced the feedline. I now have about 80 feet of brand > new LMR-400, new 83-SP1 connectors (and an Amphenol adaptor at the balun > since I don't have any type-N connectors here). The AA-230 ZOOM analyzer > shows about 1.2:1 at 50.313, with resonance just below the band. I'll fix > that tomorrow, but 1.2 or 1.3:1 should be nothing to the KPA. > > The TDR screen looks very clean, just a tiny bump where the feedline goes > through the (new) bulkhead connector to get into the house. See: > https://www.dropbox.com/s/izcwvece7nt5f42/2020-05-31%2019.32.44.jpg?dl=0 > > The SWR chart between 50.000 and 50.500: > https://www.dropbox.com/s/y2xh4l1lihy2ujr/2020-05-31%2021.23.29.jpg?dl=0 > > Again, I know the antenna is resonant a bit low, but this should NOT be a > factor. So here's what's now going on. > > 1) Into a Cantenna dummy load, with 25W of drive from the M3s, the KPA-1500 > is delivering 1075W and showing 1.4:1. No problem delivering power and no > faults. > > 2) With input power increased, 35W of K3s drive gives 1375W at 1.5 into the > Cantenna. Again, no problem delivering power to the purely resistive load. > Why a 1.5:1, I don't know, but fine, whatever. I can TX for 15-20 second > periods without issue. > > 3) When I switch over to the live antenna, with25 Watts of drive from the > K3s into the actual antenna and the amp faults out instantly in bypass. When > the amplifier is in bypass and the tuner is in bypass, and when the K3s is > delivering about 90W in FT8 mode, the front panel on the KPA-1500 says the > SWR is 1.9:1. When I press the TUNE button on the radio, it's showing an SWR > of 1.4:1. > > 4) Amp in bypass, tuner inline, press TUNE button on the K3s and the front > panel of the KPA-1500 is showing a perfect 1.0:1 match. It SHOULD work fine > like this, right? > > 5) Pressing ONLY the OPER/STBY button to put the amp in operate (KPA tuner > in and untouched since step 4), the amp SOMETIMES delivers power, sometimes > faults out, shows an SWR of 1.7:1. Pressing the OPER/STBY button again to > use only exciter power, and touching NOTHING ELSE, it's back to 1.1:1 with > 90W of K3s drive. > > 6) There is basically no rhyme or reason why this is happening and it's > *somewhat* repeatable. The incredibly frustrating part is if I see a needed > station come up, I'll flick the amp's tuner in line and it says it's tuned. > Once WSJT-X keys the radio, 90 out of 100 times the amp will hard-fault. If > it doesn't fault on the first transmission, it absolutely WILL on the second > transmission. > > So I'm now at a complete loss to understand what's going on here. Amp is > fine into a resistive load. Brand-new antenna, brand new LMR-400 feedline, > brand new connectors, the KPA-1500 is faulting out the same as it did on the > 10+ year old 6M5 with a patchwork of feedlines. I can't see how this is > anything but a problem in the KPA-1500 (S/N 0398). > > - pjd > > -Original Message- > From: elecraft-boun...@mailman.qth.net On > Behalf Of Jim Brown > Sent: Sunday, May 31, 2020 8:22 PM > To: elecraft@mailman.qth.net > Subject: Re: [Elecraft] KPA-1500 faulting on 6m; SWR issues > >> On 5/31/2020 9:54 AM, Jim Miller wrote: >> Have you vetted your feedline at 1500w? Many times something might be >> good at low power and fail at 1500. > > This is good advice. Guys who do lots of portable setup say to always check > the coax first, which mostly means check for a connector that's bad or badly > installed. > > In general, if it doesn't say Amphenol or isn't stamped with a MIL spec > number, it's very likely to be poor quality. This includes barrels, > adapters, etc. Also make sure that every connector is" wrench tight." > > The advice to run it straight to a dummy load is right on -- if you have one > big enough. :) > > 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 li...@w2irt.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 k2vco@gmail.com
Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)
New coax and old coax behaved identically. HOWEVER, running into about 80 feet of old RG-213 and into the Cantenna dummy load and it doesn't fault. This is the only condition on 6m where there is no fault. Brand new coax, old coax, brand new antenna, old antenna, with balun, without balun. Always faults except when feeding the pure resistive dummy load. If there's any reactance it trips or gives false SWR info. I would also add, why would a 2:1 SWR trip out the amp at 25 or 30 Watts of drive? On the regular HF bands I can use the internal tuner to take out a 2.5 or 3:1 SWR and it still sends 1400-1450 Watts up the pipe.. - pjd -Original Message- From: Adrian Sent: Sunday, May 31, 2020 11:05 PM To: Peter Dougherty ; 'Paul Baldock' ; elecraft@mailman.qth.net Subject: Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues) To remove any doubt, a 1.5kw or close dummy load at the end of the coax to replace antenna, would confirm the amp issue. On 1/6/20 12:27 pm, Peter Dougherty wrote: > Paul, please re-read what I wrote. The 90W figure is with the amp IN > STANDBY! I wouldn't dream of putting more than about 35W into the KPA-1500. > I generally like to run about 1200W on 6m, but even if I turn my K3s > drive down to 20 Watts, it will STILL hard-fault regularly. NO AMOUNT > OF DRIVE from the K3s will stop these problems. If the amp is set to > deliver power it's going to fault on 6m, regardless of what the ATU is > set for (bypass or inline), and the KPA will miss-read the SWR of the antenna > system. > > The resistance figure is 50.8 Ohms, and the reactance is -11 according > to the AA-230. The only difference between "works reliably" and > "faults out all the time" is one is a resistive-only load, the other > has a reactive component. > > - pjd > > - > __ 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] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)
To remove any doubt, a 1.5kw or close dummy load at the end of the coax to replace antenna, would confirm the amp issue. On 1/6/20 12:27 pm, Peter Dougherty wrote: Paul, please re-read what I wrote. The 90W figure is with the amp IN STANDBY! I wouldn't dream of putting more than about 35W into the KPA-1500. I generally like to run about 1200W on 6m, but even if I turn my K3s drive down to 20 Watts, it will STILL hard-fault regularly. NO AMOUNT OF DRIVE from the K3s will stop these problems. If the amp is set to deliver power it's going to fault on 6m, regardless of what the ATU is set for (bypass or inline), and the KPA will miss-read the SWR of the antenna system. The resistance figure is 50.8 Ohms, and the reactance is -11 according to the AA-230. The only difference between "works reliably" and "faults out all the time" is one is a resistive-only load, the other has a reactive component. - pjd - __ 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] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)
Paul, please re-read what I wrote. The 90W figure is with the amp IN STANDBY! I wouldn't dream of putting more than about 35W into the KPA-1500. I generally like to run about 1200W on 6m, but even if I turn my K3s drive down to 20 Watts, it will STILL hard-fault regularly. NO AMOUNT OF DRIVE from the K3s will stop these problems. If the amp is set to deliver power it's going to fault on 6m, regardless of what the ATU is set for (bypass or inline), and the KPA will miss-read the SWR of the antenna system. The resistance figure is 50.8 Ohms, and the reactance is -11 according to the AA-230. The only difference between "works reliably" and "faults out all the time" is one is a resistive-only load, the other has a reactive component. - pjd -Original Message- From: Paul Baldock Sent: Sunday, May 31, 2020 10:06 PM To: Peter Dougherty ; elecraft@mailman.qth.net Subject: Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues) A few things I observe on my KPA 1500: On 6m the KPA1500 reads 1.3/1.4:1 into a perfect load. FYI it reads 1.2:1 in to a perfect load on 10M also, but 1.0:1 on all other bands.Elecraft have various excuses for this. 1500W its really pushing it on 6M. Way to much compression. I run mine at 1100W out with 38W drive. as you state 90W, that's way too much drive. As the amp warms up the output drops (on all bands), but I never exceed 38W drive on 6M. On FT8 I drive it to 500W out only, and the amp stays reasonably cool. On 6M I bypass the tuner as the real antenna SWR is less than 1.5:1, and I ignore what the KP1500 says it is. Try the amp the way I use it and see how it goes. Good luck - Paul KW7Y At 06:29 PM 5/31/2020, you wrote: >Many here suggested that it was most likely a feedline issue, and I >figured this was indeed a distinct possibility. > >So this afternoon I replaced the feedline. I now have about 80 feet of >brand new LMR-400, new 83-SP1 connectors (and an Amphenol adaptor at >the balun since I don't have any type-N connectors here). The AA-230 >ZOOM analyzer shows about 1.2:1 at 50.313, with resonance just below >the band. I'll fix that tomorrow, but 1.2 or 1.3:1 should be nothing to the KPA. > >The TDR screen looks very clean, just a tiny bump where the feedline >goes through the (new) bulkhead connector to get into the house. See: >https://www.dropbox.com/s/izcwvece7nt5f42/2020-05-31%2019.32.44.jpg?dl= >0 > >The SWR chart between 50.000 and 50.500: >https://www.dropbox.com/s/y2xh4l1lihy2ujr/2020-05-31%2021.23.29.jpg?dl= >0 > >Again, I know the antenna is resonant a bit low, but this should NOT be >a factor. So here's what's now going on. > >1) Into a Cantenna dummy load, with 25W of drive from the M3s, the >KPA-1500 is delivering 1075W and showing 1.4:1. No problem delivering >power and no faults. > >2) With input power increased, 35W of K3s drive gives 1375W at 1.5 into >the Cantenna. Again, no problem delivering power to the purely resistive load. >Why a 1.5:1, I don't know, but fine, whatever. I can TX for 15-20 >second periods without issue. > >3) When I switch over to the live antenna, with25 Watts of drive from >the K3s into the actual antenna and the amp faults out instantly in >bypass. When the amplifier is in bypass and the tuner is in bypass, and >when the K3s is delivering about 90W in FT8 mode, the front panel on >the KPA-1500 says the SWR is 1.9:1. When I press the TUNE button on the >radio, it's showing an SWR of 1.4:1. > >4) Amp in bypass, tuner inline, press TUNE button on the K3s and the >front panel of the KPA-1500 is showing a perfect 1.0:1 match. It SHOULD >work fine like this, right? > >5) Pressing ONLY the OPER/STBY button to put the amp in operate (KPA >tuner in and untouched since step 4), the amp SOMETIMES delivers power, >sometimes faults out, shows an SWR of 1.7:1. Pressing the OPER/STBY >button again to use only exciter power, and touching NOTHING ELSE, it's >back to 1.1:1 with 90W of K3s drive. > >6) There is basically no rhyme or reason why this is happening and it's >*somewhat* repeatable. The incredibly frustrating part is if I see a >needed station come up, I'll flick the amp's tuner in line and it says it's tuned. >Once WSJT-X keys the radio, 90 out of 100 times the amp will >hard-fault. If it doesn't fault on the first transmission, it >absolutely WILL on the second transmission. > >So I'm now at a complete loss to understand what's going on here. Amp >is fine into a resistive load. Brand-new antenna, brand new LMR-400 >feedline, brand new connectors, the KPA-1500 is faulting out the same >as it did on the >10+ year old 6M5 with a patchwork of feedlines. I can't see how this is >anything but a problem in the KPA-1500 (S/N 0398). > > - pjd > >-Original Message- >From: elecraft-boun...@mailman.qth.net > On Behalf Of Jim Brown >Sent: Sunday, May 31, 2020 8:22 PM >To: elecraft@mailman.qth.net >Subject: Re: [Elecraft] KPA-1500 faulting on 6m; SWR issues > >On 5/31/2020
Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)
This is a brand-new balun from InnovAntennas, made specifically for this antenna, received this past Thursday. Note that exactly what I described was also occurring on my old setup, on an antenna without a balun feed. Basically everything from the output SO-239 on the KPA-1500 on up to the top of the tower has been replaced with brand new everything. The fault conditions are identical to what was happening beforehand. - pjd -Original Message- From: Jack Brindle Sent: Sunday, May 31, 2020 9:38 PM To: Peter Dougherty Cc: elecraft@mailman.qth.net Subject: Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues) Balun? Is it new? What kind? You have pretty much eliminated the KPA1500 with this test. This sounds like a balun toroid heating up and causing problems. You will see perfect conditions at low power, and the AA230 will also show things in great shape. They are not stressing the system. But 1500 watts sure will. Talk a better look at the antenna system. And the balun. Open it up if possible. And, again describe, in detail the antenna system. There is something there to be found. 73! Jack, W6FB > On May 31, 2020, at 6:29 PM, Peter Dougherty wrote: > > Many here suggested that it was most likely a feedline issue, and I > figured this was indeed a distinct possibility. > > So this afternoon I replaced the feedline. I now have about 80 feet of > brand new LMR-400, new 83-SP1 connectors (and an Amphenol adaptor at > the balun since I don't have any type-N connectors here). The AA-230 > ZOOM analyzer shows about 1.2:1 at 50.313, with resonance just below > the band. I'll fix that tomorrow, but 1.2 or 1.3:1 should be nothing to the KPA. > > The TDR screen looks very clean, just a tiny bump where the feedline > goes through the (new) bulkhead connector to get into the house. See: > https://www.dropbox.com/s/izcwvece7nt5f42/2020-05-31%2019.32.44.jpg?dl > =0 > > The SWR chart between 50.000 and 50.500: > https://www.dropbox.com/s/y2xh4l1lihy2ujr/2020-05-31%2021.23.29.jpg?dl > =0 > > Again, I know the antenna is resonant a bit low, but this should NOT > be a factor. So here's what's now going on. > > 1) Into a Cantenna dummy load, with 25W of drive from the M3s, the > KPA-1500 is delivering 1075W and showing 1.4:1. No problem delivering > power and no faults. > > 2) With input power increased, 35W of K3s drive gives 1375W at 1.5 > into the Cantenna. Again, no problem delivering power to the purely resistive load. > Why a 1.5:1, I don't know, but fine, whatever. I can TX for 15-20 > second periods without issue. > > 3) When I switch over to the live antenna, with25 Watts of drive from > the K3s into the actual antenna and the amp faults out instantly in > bypass. When the amplifier is in bypass and the tuner is in bypass, > and when the K3s is delivering about 90W in FT8 mode, the front panel > on the KPA-1500 says the SWR is 1.9:1. When I press the TUNE button on > the radio, it's showing an SWR of 1.4:1. > > 4) Amp in bypass, tuner inline, press TUNE button on the K3s and the > front panel of the KPA-1500 is showing a perfect 1.0:1 match. It > SHOULD work fine like this, right? > > 5) Pressing ONLY the OPER/STBY button to put the amp in operate (KPA > tuner in and untouched since step 4), the amp SOMETIMES delivers > power, sometimes faults out, shows an SWR of 1.7:1. Pressing the > OPER/STBY button again to use only exciter power, and touching NOTHING > ELSE, it's back to 1.1:1 with 90W of K3s drive. > > 6) There is basically no rhyme or reason why this is happening and > it's > *somewhat* repeatable. The incredibly frustrating part is if I see a > needed station come up, I'll flick the amp's tuner in line and it says it's tuned. > Once WSJT-X keys the radio, 90 out of 100 times the amp will > hard-fault. If it doesn't fault on the first transmission, it > absolutely WILL on the second transmission. > > So I'm now at a complete loss to understand what's going on here. Amp > is fine into a resistive load. Brand-new antenna, brand new LMR-400 > feedline, brand new connectors, the KPA-1500 is faulting out the same > as it did on the > 10+ year old 6M5 with a patchwork of feedlines. I can't see how this > 10+ is > anything but a problem in the KPA-1500 (S/N 0398). > > - pjd > > -Original Message- > From: elecraft-boun...@mailman.qth.net > On Behalf Of Jim Brown > Sent: Sunday, May 31, 2020 8:22 PM > To: elecraft@mailman.qth.net > Subject: Re: [Elecraft] KPA-1500 faulting on 6m; SWR issues > > On 5/31/2020 9:54 AM, Jim Miller wrote: >> Have you vetted your feedline at 1500w? Many times something might be >> good at low power and fail at 1500. > > This is good advice. Guys who do lots of portable setup say to always > check the coax first, which mostly means check for a connector that's > bad or badly installed. > > In general, if it doesn't say Amphenol or isn't stamped with a MIL > spec number, it's very likely to
Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)
A few things I observe on my KPA 1500: On 6m the KPA1500 reads 1.3/1.4:1 into a perfect load. FYI it reads 1.2:1 in to a perfect load on 10M also, but 1.0:1 on all other bands.Elecraft have various excuses for this. 1500W its really pushing it on 6M. Way to much compression. I run mine at 1100W out with 38W drive. as you state 90W, that's way too much drive. As the amp warms up the output drops (on all bands), but I never exceed 38W drive on 6M. On FT8 I drive it to 500W out only, and the amp stays reasonably cool. On 6M I bypass the tuner as the real antenna SWR is less than 1.5:1, and I ignore what the KP1500 says it is. Try the amp the way I use it and see how it goes. Good luck - Paul KW7Y At 06:29 PM 5/31/2020, you wrote: Many here suggested that it was most likely a feedline issue, and I figured this was indeed a distinct possibility. So this afternoon I replaced the feedline. I now have about 80 feet of brand new LMR-400, new 83-SP1 connectors (and an Amphenol adaptor at the balun since I don't have any type-N connectors here). The AA-230 ZOOM analyzer shows about 1.2:1 at 50.313, with resonance just below the band. I'll fix that tomorrow, but 1.2 or 1.3:1 should be nothing to the KPA. The TDR screen looks very clean, just a tiny bump where the feedline goes through the (new) bulkhead connector to get into the house. See: https://www.dropbox.com/s/izcwvece7nt5f42/2020-05-31%2019.32.44.jpg?dl=0 The SWR chart between 50.000 and 50.500: https://www.dropbox.com/s/y2xh4l1lihy2ujr/2020-05-31%2021.23.29.jpg?dl=0 Again, I know the antenna is resonant a bit low, but this should NOT be a factor. So here's what's now going on. 1) Into a Cantenna dummy load, with 25W of drive from the M3s, the KPA-1500 is delivering 1075W and showing 1.4:1. No problem delivering power and no faults. 2) With input power increased, 35W of K3s drive gives 1375W at 1.5 into the Cantenna. Again, no problem delivering power to the purely resistive load. Why a 1.5:1, I don't know, but fine, whatever. I can TX for 15-20 second periods without issue. 3) When I switch over to the live antenna, with25 Watts of drive from the K3s into the actual antenna and the amp faults out instantly in bypass. When the amplifier is in bypass and the tuner is in bypass, and when the K3s is delivering about 90W in FT8 mode, the front panel on the KPA-1500 says the SWR is 1.9:1. When I press the TUNE button on the radio, it's showing an SWR of 1.4:1. 4) Amp in bypass, tuner inline, press TUNE button on the K3s and the front panel of the KPA-1500 is showing a perfect 1.0:1 match. It SHOULD work fine like this, right? 5) Pressing ONLY the OPER/STBY button to put the amp in operate (KPA tuner in and untouched since step 4), the amp SOMETIMES delivers power, sometimes faults out, shows an SWR of 1.7:1. Pressing the OPER/STBY button again to use only exciter power, and touching NOTHING ELSE, it's back to 1.1:1 with 90W of K3s drive. 6) There is basically no rhyme or reason why this is happening and it's *somewhat* repeatable. The incredibly frustrating part is if I see a needed station come up, I'll flick the amp's tuner in line and it says it's tuned. Once WSJT-X keys the radio, 90 out of 100 times the amp will hard-fault. If it doesn't fault on the first transmission, it absolutely WILL on the second transmission. So I'm now at a complete loss to understand what's going on here. Amp is fine into a resistive load. Brand-new antenna, brand new LMR-400 feedline, brand new connectors, the KPA-1500 is faulting out the same as it did on the 10+ year old 6M5 with a patchwork of feedlines. I can't see how this is anything but a problem in the KPA-1500 (S/N 0398). - pjd -Original Message- From: elecraft-boun...@mailman.qth.net On Behalf Of Jim Brown Sent: Sunday, May 31, 2020 8:22 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] KPA-1500 faulting on 6m; SWR issues On 5/31/2020 9:54 AM, Jim Miller wrote: > Have you vetted your feedline at 1500w? Many times something might be > good at low power and fail at 1500. This is good advice. Guys who do lots of portable setup say to always check the coax first, which mostly means check for a connector that's bad or badly installed. In general, if it doesn't say Amphenol or isn't stamped with a MIL spec number, it's very likely to be poor quality. This includes barrels, adapters, etc. Also make sure that every connector is" wrench tight." The advice to run it straight to a dummy load is right on -- if you have one big enough. :) 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 li...@w2irt.net __ Elecraft
Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)
Balun? Is it new? What kind? You have pretty much eliminated the KPA1500 with this test. This sounds like a balun toroid heating up and causing problems. You will see perfect conditions at low power, and the AA230 will also show things in great shape. They are not stressing the system. But 1500 watts sure will. Talk a better look at the antenna system. And the balun. Open it up if possible. And, again describe, in detail the antenna system. There is something there to be found. 73! Jack, W6FB > On May 31, 2020, at 6:29 PM, Peter Dougherty wrote: > > Many here suggested that it was most likely a feedline issue, and I figured > this was indeed a distinct possibility. > > So this afternoon I replaced the feedline. I now have about 80 feet of brand > new LMR-400, new 83-SP1 connectors (and an Amphenol adaptor at the balun > since I don't have any type-N connectors here). The AA-230 ZOOM analyzer > shows about 1.2:1 at 50.313, with resonance just below the band. I'll fix > that tomorrow, but 1.2 or 1.3:1 should be nothing to the KPA. > > The TDR screen looks very clean, just a tiny bump where the feedline goes > through the (new) bulkhead connector to get into the house. See: > https://www.dropbox.com/s/izcwvece7nt5f42/2020-05-31%2019.32.44.jpg?dl=0 > > The SWR chart between 50.000 and 50.500: > https://www.dropbox.com/s/y2xh4l1lihy2ujr/2020-05-31%2021.23.29.jpg?dl=0 > > Again, I know the antenna is resonant a bit low, but this should NOT be a > factor. So here's what's now going on. > > 1) Into a Cantenna dummy load, with 25W of drive from the M3s, the KPA-1500 > is delivering 1075W and showing 1.4:1. No problem delivering power and no > faults. > > 2) With input power increased, 35W of K3s drive gives 1375W at 1.5 into the > Cantenna. Again, no problem delivering power to the purely resistive load. > Why a 1.5:1, I don't know, but fine, whatever. I can TX for 15-20 second > periods without issue. > > 3) When I switch over to the live antenna, with25 Watts of drive from the > K3s into the actual antenna and the amp faults out instantly in bypass. When > the amplifier is in bypass and the tuner is in bypass, and when the K3s is > delivering about 90W in FT8 mode, the front panel on the KPA-1500 says the > SWR is 1.9:1. When I press the TUNE button on the radio, it's showing an SWR > of 1.4:1. > > 4) Amp in bypass, tuner inline, press TUNE button on the K3s and the front > panel of the KPA-1500 is showing a perfect 1.0:1 match. It SHOULD work fine > like this, right? > > 5) Pressing ONLY the OPER/STBY button to put the amp in operate (KPA tuner > in and untouched since step 4), the amp SOMETIMES delivers power, sometimes > faults out, shows an SWR of 1.7:1. Pressing the OPER/STBY button again to > use only exciter power, and touching NOTHING ELSE, it's back to 1.1:1 with > 90W of K3s drive. > > 6) There is basically no rhyme or reason why this is happening and it's > *somewhat* repeatable. The incredibly frustrating part is if I see a needed > station come up, I'll flick the amp's tuner in line and it says it's tuned. > Once WSJT-X keys the radio, 90 out of 100 times the amp will hard-fault. If > it doesn't fault on the first transmission, it absolutely WILL on the second > transmission. > > So I'm now at a complete loss to understand what's going on here. Amp is > fine into a resistive load. Brand-new antenna, brand new LMR-400 feedline, > brand new connectors, the KPA-1500 is faulting out the same as it did on the > 10+ year old 6M5 with a patchwork of feedlines. I can't see how this is > anything but a problem in the KPA-1500 (S/N 0398). > > - pjd > > -Original Message- > From: elecraft-boun...@mailman.qth.net On > Behalf Of Jim Brown > Sent: Sunday, May 31, 2020 8:22 PM > To: elecraft@mailman.qth.net > Subject: Re: [Elecraft] KPA-1500 faulting on 6m; SWR issues > > On 5/31/2020 9:54 AM, Jim Miller wrote: >> Have you vetted your feedline at 1500w? Many times something might be >> good at low power and fail at 1500. > > This is good advice. Guys who do lots of portable setup say to always check > the coax first, which mostly means check for a connector that's bad or badly > installed. > > In general, if it doesn't say Amphenol or isn't stamped with a MIL spec > number, it's very likely to be poor quality. This includes barrels, > adapters, etc. Also make sure that every connector is" wrench tight." > > The advice to run it straight to a dummy load is right on -- if you have one > big enough. :) > > 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 li...@w2irt.net > > __ > Elecraft
Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)
Many here suggested that it was most likely a feedline issue, and I figured this was indeed a distinct possibility. So this afternoon I replaced the feedline. I now have about 80 feet of brand new LMR-400, new 83-SP1 connectors (and an Amphenol adaptor at the balun since I don't have any type-N connectors here). The AA-230 ZOOM analyzer shows about 1.2:1 at 50.313, with resonance just below the band. I'll fix that tomorrow, but 1.2 or 1.3:1 should be nothing to the KPA. The TDR screen looks very clean, just a tiny bump where the feedline goes through the (new) bulkhead connector to get into the house. See: https://www.dropbox.com/s/izcwvece7nt5f42/2020-05-31%2019.32.44.jpg?dl=0 The SWR chart between 50.000 and 50.500: https://www.dropbox.com/s/y2xh4l1lihy2ujr/2020-05-31%2021.23.29.jpg?dl=0 Again, I know the antenna is resonant a bit low, but this should NOT be a factor. So here's what's now going on. 1) Into a Cantenna dummy load, with 25W of drive from the M3s, the KPA-1500 is delivering 1075W and showing 1.4:1. No problem delivering power and no faults. 2) With input power increased, 35W of K3s drive gives 1375W at 1.5 into the Cantenna. Again, no problem delivering power to the purely resistive load. Why a 1.5:1, I don't know, but fine, whatever. I can TX for 15-20 second periods without issue. 3) When I switch over to the live antenna, with25 Watts of drive from the K3s into the actual antenna and the amp faults out instantly in bypass. When the amplifier is in bypass and the tuner is in bypass, and when the K3s is delivering about 90W in FT8 mode, the front panel on the KPA-1500 says the SWR is 1.9:1. When I press the TUNE button on the radio, it's showing an SWR of 1.4:1. 4) Amp in bypass, tuner inline, press TUNE button on the K3s and the front panel of the KPA-1500 is showing a perfect 1.0:1 match. It SHOULD work fine like this, right? 5) Pressing ONLY the OPER/STBY button to put the amp in operate (KPA tuner in and untouched since step 4), the amp SOMETIMES delivers power, sometimes faults out, shows an SWR of 1.7:1. Pressing the OPER/STBY button again to use only exciter power, and touching NOTHING ELSE, it's back to 1.1:1 with 90W of K3s drive. 6) There is basically no rhyme or reason why this is happening and it's *somewhat* repeatable. The incredibly frustrating part is if I see a needed station come up, I'll flick the amp's tuner in line and it says it's tuned. Once WSJT-X keys the radio, 90 out of 100 times the amp will hard-fault. If it doesn't fault on the first transmission, it absolutely WILL on the second transmission. So I'm now at a complete loss to understand what's going on here. Amp is fine into a resistive load. Brand-new antenna, brand new LMR-400 feedline, brand new connectors, the KPA-1500 is faulting out the same as it did on the 10+ year old 6M5 with a patchwork of feedlines. I can't see how this is anything but a problem in the KPA-1500 (S/N 0398). - pjd -Original Message- From: elecraft-boun...@mailman.qth.net On Behalf Of Jim Brown Sent: Sunday, May 31, 2020 8:22 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] KPA-1500 faulting on 6m; SWR issues On 5/31/2020 9:54 AM, Jim Miller wrote: > Have you vetted your feedline at 1500w? Many times something might be > good at low power and fail at 1500. This is good advice. Guys who do lots of portable setup say to always check the coax first, which mostly means check for a connector that's bad or badly installed. In general, if it doesn't say Amphenol or isn't stamped with a MIL spec number, it's very likely to be poor quality. This includes barrels, adapters, etc. Also make sure that every connector is" wrench tight." The advice to run it straight to a dummy load is right on -- if you have one big enough. :) 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 li...@w2irt.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
