It's a BIT better on ANT-2, but still faults out on occasion, and I'm not getting a true SWR reading. It is slightly more stable, though, to answer your question.
- pjd -----Original Message----- From: Vic Rosenthal <k2vco....@gmail.com> Sent: Tuesday, June 2, 2020 1:01 AM To: Peter Dougherty <li...@w2irt.net> Cc: Jack Brindle <jackbrin...@me.com>; Elecraft@mailman.qth.net Subject: Re: [Elecraft] NOT the feedline Pardon me if this has already been covered, but do you have the same problem if you connect the antenna to ANT-2 on the KPA? I know you don’t want to do this permanently, but just as a test. Victor 4X6GP > On 2 Jun 2020, at 3:47, Peter Dougherty <li...@w2irt.net> wrote: > > Thanks for the reply, Jack. > > Here's a FULL summary of what is in the line at this moment from the jack on > up. > > PL-259 (soldered, Amphenol 83-1SP as all are) to about 2 feet of RG-213 > feeding into a Ten-Tec Tuner, which is being used only as an antenna switch > and is in bypass. This is needed because the power supply fan noise on the > KPA-1500 is just so overwhelming that I can only power it on when needed. I > am primarily an HF operator, so ANT-1 is reserved for my HF stack. If I put > the 6m antenna on ANT-2, I would need to keep the amp running. So everything > goes out on ANT-1, through the TT-238. From there, one feedline goes to the > HF stack and the other to the 6m output. It gets SLIGHTLY better if I go > directly from the KPA-1500 to the input box, as follows but I still > experience faults. > > From there, a PL-259, and 7 or 8 feet of RG-213. Another PL-259, an Amphenol > barrel connector in the input box, PL259, then approximately 65 or 70 feet of > Commscope-branded LMR-400. PL-259 from that is connected to an Amphenol > SO-239 female-to-N-Male, the choke balun, then the driven loop element to the > antenna. > > As of Tuesday morning this will change as follows. KPA-1500 ANT-1 out, PL-259 > and about 40' of Davis BuryFlex out to the remote antenna switch at the base > of the HF stack. From there, about 25 more feet of BuryFlex, a barrel > connector then the LMR-400 up to the 6m antenna. This will basically just be > an experiment to see if there's any improvement; I'll be bypassing both the > old Ten-Tec tuner/switch and the inlet box, and routing via the HF signal > path and automatic antenna switch. Adding 65' of BuryFlex to the path strikes > me as adding measurable and fairly significant loss to an otherwise really > good, quiet antenna system, but if it lets me operate without having to worry > about hard faults all the time then I'll take that as a tradeoff. > > - pjd > > -----Original Message----- > From: Jack Brindle <jackbrin...@me.com> > Sent: Monday, June 1, 2020 6:09 PM > To: Peter Dougherty <li...@w2irt.net> > Cc: Bob McGraw K4TAX <rmcg...@blomand.net>; elecraft@mailman.qth.net > Subject: Re: [Elecraft] NOT the feedline > > Lets take another try at this. There still isn’t enough information in your > emails to really determine what might be going on. From the amplifier’s > viewpoint, *everything* from the antenna jack on the back of the amplifier is > part of the antenna system. So far we know it consists of some section of > RG213, another of LM400, a balun of some sort, and an antenna. There are > undoubtedly some adapters and couplers in between, and perhaps a few other > things. Knowing exactly what these are is critical in making any suggestions. > > Every few months since we released the KPA500 we have seen emails from folks > who are certain that the amplifier is causing a problem. We all build our > stations for low power, then decide that adding an amplifier is needed, so we > buy one. We then are faced with issues driving a lot more power into the > antenna system. These are caused by deficiencies in that system, which was > sized for much lower power, and almost always will contain at least one > component that cannot handle the power. The last part of the KPA500 before > power goes out is the directional coupler (note: it is after the low pass > filters), the KPA1500 has its ATU after those components. With the KPA1500 > ATU in bypass, the directional coupler becomes the last component. This is > important because the directional coupler will see any problem in the antenna > system, and report it. No amplifier component is in the way to modify things, > we get a true picture of what follows the amplifier. So, when something > glitches in the antenna system (usually an arc in a coupler, or an overheated > toroid in a balun or matching unit), the directional coupler picks it up and > moves to protect the amplifier. > > With this in mind, place the KPA1500 ATU into bypass and perform the test. > When you see the fault occur, you then need to look at the entire antenna > system, starting at the antenna jack on the back of the KPA1500. All of the > components are suspect, even a new part (balun, antenna, etc), which may have > been affected by high power right after installation. Be sure to looks at the > RG213, and at the coupler to the LM400. You have made reference to shack > feed-through, what is that, and does it use components that might have issues? > > As in past cases, find the problem in the overall antenna system, and the > KPA1500 will be much happier, as will you. > > So, before we can help you, we need to know the details of the system. > > 73! > Jack, W6FB > Elecraft Engineering > > >> On Jun 1, 2020, at 2:25 PM, Peter Dougherty <li...@w2irt.net> wrote: >> >> Your point is valid, however the underlying fact in my situation is that the >> new antenna with the new 1:1 current balun (i.e. feedline choke) is >> presenting **identically** to my old antenna that didn't have a balun. >> Neither better nor worse. >> >> - pjd >> >> -----Original Message----- >> From: elecraft-boun...@mailman.qth.net >> <elecraft-boun...@mailman.qth.net> On Behalf Of Bob McGraw K4TAX >> Sent: Monday, June 1, 2020 4:48 PM >> To: elecraft@mailman.qth.net >> Subject: Re: [Elecraft] NOT the feedline >> >> Based on my experience, balun power ratings are for MATCHED conditions. It >> is rare that hams use a balun in a matched condition. Thus a 1:1 balun >> should see 50 ohms on the input and 50 ohms on the output, while a >> 4:1 balun should see 200 ohms on the output and 50 ohms on the input. In the >> case of a resonant folded dipole, a 4:1 balun is typically operating in a >> nearly matched condition. All others combinations are unknown and random. >> >> I run about 500 watts on all bands. My baluns are rated at 5KW! It takes >> 3 or 4 big hunkin' pieces of ferrite to attain this power level. My 6 meter >> balun is a 1/2 wavelength electrically of RG-213. No ferrite! >> >> Buy or build a balun of your choice. Using an IR temperature gun, measure >> the ambient temperature of the core. Run about 1/2 rated power carrier for >> 30 to 60 seconds. Measure the temperature again. If it is warm to hot, >> this is RF producing heat. And likely continuing will produce core >> failure. This is not a good balun for your application. >> >> One of my baluns work between the output of my KAT500 and the balanced feed >> line connected to the center of a 256 ft wire. That antenna works 160M - 6M >> with zero issues. Now, I do run a hybrid balun being a 4:1 Guanella balun >> as a transformer, and it is fed with a 1:1 balun for common mode rejection. >> >> Most single core, i.e. 2 or 3 cores stacked with 2 to 4 windings are not at >> all a proper balun design A Guanella balun will have 2 cores with 2 >> windings and then another 2 separate cores with another 2 windings. These >> are then wired to produce a 4:1 balun with good common mode rejection. >> Most "factory" 4:1 baluns are poorly designed and built junk. >> >> See https://www.dj0ip.de/balun-stuff/ for further references. >> >> 73 >> >> Bob, K4TAX >> >> >>> On 6/1/2020 8:45 AM, Alan - G4GNX wrote: >>> I have a similar issue with ferrite 'balun' heating, although mostly >>> tested on 40 metres. I'm using an OSCFD (Windom) which has a main >>> 4:1 balun at the feed point, but also has a sleeve 'balun' >>> consisting of >>> 8 ferrites wrapped in a plastic sleeve, about 3 feet from the feed >>> point. If I run the K3S at 100W, via the KPA500 in standby, then >>> through the KAT500 tuner, I see no problems. >>> >>> On increasing the power to 200W by using the KPA500 in Operate and >>> about 10W drive from the K3S, during a SSB 'over' the temperature of >>> the KPA500 rises and after a few minutes, the SWR readings on the >>> KPA500 and KAT500 start to rise. One of the Elecraft guys actually >>> very kindly went through my fault log and came to the conclusion >>> that the fault is with the antenna/feeder and I agree with him. What >>> is strange is that if I leave a solid carrier running at 200W, I >>> can't easily reproduce the issue and I wonder if its something being >>> affected by peak excursions with SSB? >>> >>> When things do start to go wrong, I can usually perform a manual >>> tune with the KAT500 and the fault will then not (mostly) be apparent. >>> >>> Anyway, I'm in the process of replacing the entire feeder with >>> Westflex 103 and much bigger ferrites. I will also replace the main >>> balun which is a 400W device for a 1KW device, as I think that >>> running the UK max of 400W may be pushing the spec of a 400W balun. >>> Also, the balun itself or connections to it may be faulty. >>> >>> The point now is that I have discovered some damage to the outer >>> covering of the sleeve 'balun' which may be the result of ferrites >>> overheating or may be the cause of movement of the ferrites thus >>> causing instability. Either way, heftier devices seem to be the >>> order of the day. >>> >>> Although the KPA500 temperature rise is somewhat expected, I feel >>> it's a bit higher over a short period than I would like and may be >>> due to reflected power. >>> >>> 73, >>> >>> Alan. G4GNX >>> >>> >>> ------ Original Message ------ >>> From: "David Olean" <k1...@metrocast.net> >>> To: "Peter Dougherty" <li...@w2irt.net> >>> Cc: elecraft@mailman.qth.net >>> Sent: 01/06/2020 13:25:18 >>> Subject: 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 >>>> >>> >>> ______________________________________________________________ >>> 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 >> 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 >> jackbrin...@me.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 > k2vco....@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
