I agree with you re PL-259s. I follow best practices in this regard. Quarter-turn with channel-locks after finger tight, Amphenol 83-1SP, assembled correctly, with cables swept by a TDR. - pjd
-----Original Message----- From: elecraft-boun...@mailman.qth.net <elecraft-boun...@mailman.qth.net> On Behalf Of Bob McGraw K4TAX Sent: Saturday, February 16, 2019 12:39 PM To: elecraft@mailman.qth.net; wrayplace <wraypl...@bellsouth.net> Subject: Re: [Elecraft] KPA-1500 failed! Do not trust PL-259 connectors installed only "finger tight". Today many of those PL-259 connectors "look good" but are really poor quality connectors. ALWAYS snug the PL-259's with a pair of 4" channel lock pliers. You'd be amazed how many strange issues will go away. Not saying this is or was the cause of failure, but I've seen it and experienced it too many times. Also, for other reasons, I run the ALC from my KPA500 to my K3S. Again, another issue of concern resolved. 73 Bob, K4TAX On 2/16/2019 10:13 AM, Dave wrote: > His radio blew one final while driving the KPA1500 in the fall. > > Now his amp blew one LDMOS. > > I’ve been to Peter’s house and used a TDR to check all of his antennas, > cabling, and switching. Cable connectors replaced last year. > > I agree it is good idea to check everything again. Looking at the amp fault > log today did not show signs of anything arcing > > Dave wo2x > > Sent from my waxed string and tin cans. > >> On Feb 16, 2019, at 11:01 AM, Mark Goldberg <marklgoldb...@gmail.com> wrote: >> >> It's been said there are no coincidences. Have you checked your coaxes / >> connectors? I agree that protection built in should not allow radios to blow >> finals, but this sounds like too much of a coincidence with two different >> radios blowing to not be an external intermittent connection. Try wiggling >> all the cables with low power. Unfortunately, sometimes a problem will only >> show up as arcing at high power. Is there another HAM near you with a >> powerful amp and antenna close to yours? >> >> Best of luck, >> >> Mark >> W7MLG >> >> >>> On Sat, Feb 16, 2019 at 8:50 AM <li...@w2irt.net> wrote: >>> Exact same thing happened to my K3s in October, now my KPA-1500. Yeah, So >>> done here. Once repaired and confirmed working it will be up for sale. Going >>> back to a tube amp after this. >>> >>> - pjd >>> >>> -----Original Message----- >>> From: elecraft-boun...@mailman.qth.net <elecraft-boun...@mailman.qth.net> On >>> Behalf Of Paul Baldock >>> Sent: Saturday, February 16, 2019 10:28 AM >>> To: rocke...@gmail.com; elecraft@mailman.qth.net >>> Subject: Re: [Elecraft] KPA-1500 failed! >>> >>> It sounds like one of the output devices have failed. Half power out is >>> usually the indicator. A number here have reported this happening. >>> It would be nice to know why this problem is occurring and if Elecraft are >>> working on a fix. >>> >>> - Paul >>> >>> At 07:10 AM 2/16/2019, rocke...@gmail.com wrote: >>>> I talked to Peter on the phone. He has no bias current when amp is >>>> transmitting with no power applied (key on SSB without talking. He is >>>> reading 54 volts and has tried power cycling amp from power supply >>>> switch and reseated all cables. Definitely BAD distortion on SSB (we >>>> are close enough to hear each other). Looks like one RF device let >>>> loose and it is dragging down the bias voltage. That is my guess. >>>> >>>> Dave wo2x >>>> >>>> >>>> -----Original Message----- >>>> From: elecraft-boun...@mailman.qth.net >>>> <elecraft-boun...@mailman.qth.net> On Behalf Of Wes >>>> Sent: Saturday, February 16, 2019 9:49 AM >>>> To: elecraft@mailman.qth.net >>>> Subject: Re: [Elecraft] KPA-1500 failed! >>>> >>>> I think a two-tone test is the best evaluation tool.. The generator is >>>> built into the K3 if you have another receiver that you can use to >>>> listen to the amp output. I use an SDR-IQ which is a very nice tool >>>> for this but any other SDR would do. >>>> >>>> Sorry for your pain. >>>> >>>> Wes N7WS >>>> >>>> On 2/16/2019 7:28 AM, li...@w2irt.net wrote: >>>>> I was operating in the ARRL-CW contest this morning and on 20m, with >>>>> a >>>>> 1.2:1 SWR on the Yagi, all of a sudden I saw my power drop to about >>>>> 450-500W with about 40W in. Worked a few stations but not as easily >>>>> as when I turned everything on this morning. Switched over to phone >>>> and made a few contacts. >>>>> Audio is fine barefoot with 100W out of the K3s-which suffered blown >>>>> finals itself during CQWW SSB last fall, but with the amp in I got >>>>> reports that my audio was badly distorted. >>>>> >>>>> Before I send it in, is there anything I should look at or any >>>>> diagnostics I can easily perform? For the cost of this, I'd have >>>>> thought protection would have kicked in to prevent anything untoward >>>>> from happening. I'm in complete disbelief, to be honest. >>>>> >>>>> --------------------------------------------- >>>>> 73 and Good DX >>>>> Peter, W2IRT >>>>> >>>> ______________________________________________________________ >>>> 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 >>>> rocke...@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 >>>> p...@paulbaldock.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 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 marklgoldb...@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 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 arch...@mail-archive.com
