Dave, Exactly my point. Doesn't take long to cause the core to go south. High voltage is fast.
73, Bill K9YEQ -----Original Message----- From: [email protected] <[email protected]> On Behalf Of David Gilbert Sent: Wednesday, September 2, 2020 12:37 PM To: [email protected] Subject: Re: [Elecraft] my KPA1500 and 160M No ... overheating doesn't take much time at all. As I stated in my reply to Bill, high power and high VSWR will indeed heat up a ferrite core device ... balun or common mode choke ... and it can do so quite quickly. In my case, I had a 160m Inverted-L that I put up rather hastily for a contest and I didn't trim it for best match. At 100 watts it worked fine because I could tune it at the shack, but at anything above 1,000 watts the ferrite core in the common mode choke would heat up and fault the amplifier (QRO Technologies HF-2500DX tube amp) in less than two seconds. This happened repeatedly, and when I got serious and fixed the antenna for a lower VSWR everything was stable even at 1500 watts and even with the same choke that I luckily hadn't permanently destroyed (although I suspect the core had been compromised for original choking performance). High VSWR is very tough on ferrite cores. Dave AB7E On 9/2/2020 6:07 AM, Adrian wrote: > Overheat is a situation taking time, and usually starts with a good > match, then deteriorating. > > In this case ; "But when I throw the KAP1500 in line, it gets all > pissed off, throws up and faults out. Says SWR is 99:1 !!!" > > indicating an instant issue while the balun is still stone cold... > > The 5kw balun is not the best for your situation, but rather the 4116 > 3KW hybrid > > https://www.balundesigns.com/model-4116-4-1-hybrid-balun-1-5-54mhz-3kw > / > > See ; > https://www.balundesigns.com/blog/baluns-for-multiband-antennas-fed-wi > th-open-wire-or-ladder-line/ > > 73 > > > Adrian Fewster > > > > > > On 2/9/20 10:12 pm, Bill Johnson wrote: >> I would agree that the coil could overheat. The model number is left >> out. The Balun Design coil chosen may not be satisfactory for your >> power despite the 5KW rating. Which Balun are you using? >> >> Bill >> K9YEQ >> >> -----Original Message----- >> From: [email protected] >> <[email protected]> On Behalf Of David Gilbert >> Sent: Tuesday, September 1, 2020 12:28 PM >> To: [email protected] >> Subject: Re: [Elecraft] my KPA1500 and 160M >> >> >> One distinct possibility is that the 4:1 balun is getting hot at 1500 >> watts. Have you tried running the KPA1500 at a lower power? >> >> 73, >> Dave AB7E >> >> > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net Please help support this email > list: http://www.qsl.net/donate.html Message delivered to > [email protected] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
