Re: K3 won't power up
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I have a k3 that was working fine but now will not power up.
I had lent the unit to someone to use at Field Day. They reported it would not power up. Going through the unit it appears that a nut and washer has come off of one of the PL259 antenna plates. A thorough internal inspection found a loose washer but no nut. There is nothing evidently wrong inside, no flashing, no sparking, no burning odor. It just won't come on. Fuse did not activate. I am going to call the factory tomorrow but anyone have any ideas? ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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I would look for the missing nut first (possibly stuck to the speaker)
Then I'd take the top and bottom covers of and check traces etc ________________________________ From: George Thornton <[hidden email]> To: Bruce Beford <[hidden email]>; "[hidden email]" <[hidden email]> Sent: Sunday, August 3, 2014 10:51 PM Subject: Re: [Elecraft] K3 won't power up I have a k3 that was working fine but now will not power up. I had lent the unit to someone to use at Field Day. They reported it would not power up. Going through the unit it appears that a nut and washer has come off of one of the PL259 antenna plates. A thorough internal inspection found a loose washer but no nut. There is nothing evidently wrong inside, no flashing, no sparking, no burning odor. It just won't come on. Fuse did not activate. I am going to call the factory tomorrow but anyone have any ideas? ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by George Thornton
Hi George,
A working K3 didn't power up at field day. That probably means that the power leads were reversed and embarrassment causes that information to be withheld. People here on the reflector probably know what gets damaged when power is reversed. Chances are that is very easy to check if you know what you're looking for. 73, Mike K2MK
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".... if you know what you are looking for....."
Hmmmm, given any thought to explaining that mysterious statement? Not everyone knows what you are talking about. However, they would, most likely, like to learn. Bill W2BLC K-Line ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by Mike K2MK
The base K3 is protected from reverse polarity by a series diode as well
as a diode to ground and a resettable fuse. So it will not power up if the power leads are reversed - and normally will recover with no damage when that condition is corrected. The KPA3 is not similarly protected - the diode drop would be too large and a 20 amp diode would be required. The PA depends on the circuit breaker. The one element that is not protected is the RFC in series with the DC input - RFC6. If the power were reversed, it is likely that RFC6 could have opened before the KPA3 circuit breaker tripped - the reaction of the users in the field would be to reset the breaker, so when it returned, the breaker would look OK. A bit of investigation with an ohmmeter following the path from 12V In on the K3 schematic (RF Board sheet 3) will verify whether power can get to the cathode of D6. Speculation on my part, but I would investigate based on that scenario. I doubt the loose nut has anything to do with the problem, but does need to be corrected. 73, Don W3FPR On 8/4/2014 9:49 AM, Mike K2MK wrote: > Hi George, > > A working K3 didn't power up at field day. That probably means that the > power leads were reversed and embarrassment causes that information to be > withheld. People here on the reflector probably know what gets damaged when > power is reversed. Chances are that is very easy to check if you know what > you're looking for. > > 73, > Mike K2MK > > > George Thornton wrote >> I have a k3 that was working fine but now will not power up. >> >> I had lent the unit to someone to use at Field Day. They reported it >> would not power up. >> >> Going through the unit it appears that a nut and washer has come off of >> one of the PL259 antenna plates. A thorough internal inspection found a >> loose washer but no nut. >> >> There is nothing evidently wrong inside, no flashing, no sparking, no >> burning odor. It just won't come on. >> >> Fuse did not activate. >> >> ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by Bill-3
Hi Bill,
Not mysterious. If I knew I would have said. But luckily Don knows what to look for and responded. 73, Mike K2MK
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