Walter, Yes, the UHF connector may be rated at 500V, but in practice they handle >4KV. The voltage limit is set by the air gap between the center pin and the shield. I have not had a PL-259 arc over. 73, N2TK, Tony
-----Original Message----- From: elecraft-boun...@mailman.qth.net <elecraft-boun...@mailman.qth.net> On Behalf Of Walter Underwood Sent: Monday, June 1, 2020 6:32 PM To: Elecraft Reflector <elecraft@mailman.qth.net> Subject: Re: [Elecraft] NOT the feedline Even with a 1:1 SWR, 1000 W is pretty close to the 500 V peak rating for a UHF connector. Type N connectors are rated at 1500 V peak. wunder K6WRU Walter Underwood CM87wj http://observer.wunderwood.org/ (my blog) > On Jun 1, 2020, at 3:17 PM, George Kidder <gkid...@ilstu.edu> wrote: > > One of my antennas is a commercial "G5RV" fed with 33' of 450 ohm ladder > line, terminated in a PL-259 pair, with coax from there to the shack. > Apparently this combination results in very high RF voltage at the PL-259, > and it arcs over at 1000 W (not from an Elecraft amp!). This combo goes wild > when I attempt high power on 80M, although it is stable at 100 W. Just > another thing to watch out for! > > 73 - George, W3HBM > > On 6/1/2020 5:59 PM, Ted Edwards W3TB wrote: >> [This message came from an external source. If suspicious, report to >> ab...@ilstu.edu<mailto:ab...@ilstu.edu>] >> >> I am following this with great interest. >> Like Alan G0GNX, I also use an OCF, RG-8X out to the current balun in >> this case, 300 ohm to the antenna. K3, KPA-500 and KAT-500. >> >> If I am running stations in a contest on 40m and also 80m CW, It "appears" >> that my VSWR rises after a half hour and then the KAT-500 starts to >> try to spontaneously retune. Doesn't happen on 20m and up. This >> past weekend in CQ WPX, I reduced drive so that output was about 300 >> watts and it all became tame. >> >> I had thought that it was a heating of the RG-8X; then I changed my >> mind to the current balun from Radiowavz that is rated for 1.5 KW. I >> think it is the balun just getting hot out there. I had used a W2AU >> 4:1 balun with my OCF, which is a voltage balun but I didn't know >> about that -- for upwards of 40 years and with the Elecraft equipment >> for about 4 years since I got the amp/tuner. I just switched to a >> current balun last year with one that I bought at Dayton. >> >> I would have expected more problem with the voltage balun than with >> the current balun. I could change back to the W2AU if needed. >> >> Interesting stuff, so I am reading along. And my thanks to all of you. >> >> On Mon, Jun 1, 2020 at 4:42 PM Fred Jensen <k6...@foothill.net> wrote: >> >>> Nearly same experience Bob: Sloping V, 135 ft legs, from top of 80 >>> ft tower fed with homemade 600 ohm open wire using a DX Engineering >>> 4:1 "balun" [a strange, usually misunderstood piece of electronic >>> apparatus often used for the wrong reasons] rated at 10 KW. It >>> warmed up noticeably at 1.2 KW RTTY use. It helps to remember that >>> one can saturate a ferrite core [especially when very hot] which >>> creates a racket reminiscent of a non-synchronous spark gap TX. >>> >>> 73, >>> Fred ["Skip"] K6DGW >>> Sparks NV DM09dn >>> Washoe County >>> >>> On 6/1/2020 1:48 PM, Bob McGraw K4TAX wrote: >>>> 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 >>> ______________________________________________________________ >>> 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 >>> w3tb....@gmail.com >> >> >> -- >> 73 de Ted Edwards, W3TB and GØPWW >> >> and thinking about operating CW: >> "Do today what others won't, >> so you can do tomorrow what others can't." >> ______________________________________________________________ >> 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 >> gkid...@ilstu.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 > wun...@wunderwood.org ______________________________________________________________ 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 tony....@verizon.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
