KAT-500 Unreliable Tuning
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Over the past six months my KAT500 autotune function has deteriorated to the point where I am getting frustrated. The KAT tuner is connected to a G5RV via 75' of RG-8 coax and is fed from a KPA-500 which is fed from a Kenwood TS480. I switch between between barefoot and amplified transmissions. Upon application of a 40 watt tune, the tuner appears to find a suitable solution but when the power is raised to over 100W, the amplifier faults to a high SWR, some bands, but not always repeatable. The antenna and feedline have been inspected and all OK. If I change bands sometimes it works at higher powers and sometimes not. Other times it cannot find a solution on some bands and other bands are OK, low power or amplified. If I cycle the power to the KAT500, it is OK for a while and then it has trouble again. The problem appears intermittent. Wondering if anyone has had this same problem.
Thanks de dave WB7ELY ______________________________________________________________ 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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Try your tests using a dummy load to remove the antenna from the troubleshooting effort. Ken WA2LBI LG G6 ------ Original message------From: [hidden email]: Mon, Mar 8, 2021 10:43To: [hidden email];Cc: Subject:[Elecraft] KAT-500 Unreliable TuningOver the past six months my KAT500 autotune function has deteriorated to the point where I am getting frustrated. The KAT tuner is connected to a G5RV via 75' of RG-8 coax and is fed from a KPA-500 which is fed from a Kenwood TS480. I switch between between barefoot and amplified transmissions. Upon application of a 40 watt tune, the tuner appears to find a suitable solution but when the power is raised to over 100W, the amplifier faults to a high SWR, some bands, but not always repeatable. The antenna and feedline have been inspected and all OK. If I change bands sometimes it works at higher powers and sometimes not. Other times it cannot find a solution on some bands and other bands are OK, low power or amplified.
If I cycle the power to the KAT500, it is OK for a while and then it has trouble again. The problem appears intermittent. Wondering if anyone has had this same problem. Thanks de dave WB7ELY ______________________________________________________________ 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 DAVID INGEBRIGHT
I had a similar issue with my KAT500. I opened it up and the problem was obvious: there are two green 12g wire bridges that cross. (You can see them in this image: ([hidden email] <https://cdn.shopify.com/s/files/1/2029/4979/products/kat500_inside_500_530x@...?v=1536760566>. You can see one end of the longer green wire near the big red toroid.) There had been arcing between them. My guess is that they arced at higher power levels. I replaced them with slightly longer wires and bent them to create more clearance. That solved my problem.
I recommend taking taking the cover off and taking a look. The problem may be obvious as it was for me. Raj, N2RD > On Mar 8, 2021, at 10:42 AM, [hidden email] wrote: > > Over the past six months my KAT500 autotune function has deteriorated to the point where I am getting frustrated. The KAT tuner is connected to a G5RV via 75' of RG-8 coax and is fed from a KPA-500 which is fed from a Kenwood TS480. I switch between between barefoot and amplified transmissions. Upon application of a 40 watt tune, the tuner appears to find a suitable solution but when the power is raised to over 100W, the amplifier faults to a high SWR, some bands, but not always repeatable. The antenna and feedline have been inspected and all OK. If I change bands sometimes it works at higher powers and sometimes not. Other times it cannot find a solution on some bands and other bands are OK, low power or amplified. If I cycle the power to the KAT500, it is OK for a while and then it has trouble again. The problem appears intermittent. Wondering if anyone has had this same problem. > Thanks de dave WB7ELY > ______________________________________________________________ > 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 DAVID INGEBRIGHT
I had a similar problem during last weekend's ARRL DX SSB
contest. I would press tune on my K3 and the K3 would come to a good solution using about 5W. Then I tried to transmit at 100W and the SWR went wonky and the power folded back. I traced it to a bad connection between the two sections of coax feeding the antenna. Testing with a dummy load can help narrow the problem down to antenna or other. 73 Bill AE6JV On 3/8/21 at 10:42 AM, [hidden email] wrote: >Over the past six months my KAT500 autotune function has >deteriorated to the point where I am getting frustrated. The >KAT tuner is connected to a G5RV via 75' of RG-8 coax and is >fed from a KPA-500 which is fed from a Kenwood TS480. I switch >between between barefoot and amplified transmissions. Upon >application of a 40 watt tune, the tuner appears to find a >suitable solution but when the power is raised to over 100W, >the amplifier faults to a high SWR, some bands, but not always >repeatable. The antenna and feedline have been inspected and >all OK. If I change bands sometimes it works at higher powers >and sometimes not. Other times it cannot find a solution on >some bands and other bands are OK, low power or amplified. If I >cycle the power to the KAT500, it is OK for a while and then it >has trouble again. The problem appears intermittent. Wondering >if anyone has had this same problem. Thanks de dave WB7ELY Bill Frantz | Privacy is dead, get over | Periwinkle (408)348-7900 | it. | 150 Rivermead Rd #235 www.pwpconsult.com | - Scott McNealy (1999) | Peterborough, NH 03458 ______________________________________________________________ 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 Rajiv Dewan-2
I checked inside my tuner, I only have one green wire instead of two.
Serial #2120. I also have the issue of erratic tuning when applying power, adding an additional common mode choke helped calm things down. Dennis NJ6G On 3/8/2021 09:07, Rajiv Dewan wrote: > I had a similar issue with my KAT500. I opened it up and the problem was obvious: there are two green 12g wire bridges that cross. (You can see them in this image: ([hidden email] <https://cdn.shopify.com/s/files/1/2029/4979/products/kat500_inside_500_530x@...?v=1536760566>. You can see one end of the longer green wire near the big red toroid.) There had been arcing between them. My guess is that they arced at higher power levels. I replaced them with slightly longer wires and bent them to create more clearance. That solved my problem. > > I recommend taking taking the cover off and taking a look. The problem may be obvious as it was for me. > > Raj, N2RD ______________________________________________________________ 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 think you have one of the newer units where Elecraft improved the design by putting one wire above and another below the PC board. Mine was #309 with both wires above the PC board. They had arced.
Raj, N2RD > On Mar 10, 2021, at 12:53 PM, Dennis Moore <[hidden email]> wrote: > > I checked inside my tuner, I only have one green wire instead of two. Serial #2120. > > I also have the issue of erratic tuning when applying power, adding an additional common mode choke helped calm things down. > > Dennis NJ6G > > On 3/8/2021 09:07, Rajiv Dewan wrote: >> I had a similar issue with my KAT500. I opened it up and the problem was obvious: there are two green 12g wire bridges that cross. (You can see them in this image: ([hidden email] <https://cdn.shopify.com/s/files/1/2029/4979/products/kat500_inside_500_530x@...?v=1536760566>. You can see one end of the longer green wire near the big red toroid.) There had been arcing between them. My guess is that they arced at higher power levels. I replaced them with slightly longer wires and bent them to create more clearance. That solved my problem. >> >> I recommend taking taking the cover off and taking a look. The problem may be obvious as it was for me. >> >> Raj, N2RD > ______________________________________________________________ > 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] |
Re: KAT-500 Unreliable Tuning
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That is weird! I have S/N 0221 and I only have the short wire above with the other wire below. I bought it used so maybe the PO had it up graded?
Kim - K7IM Sent from my iPad > On Mar 10, 2021, at 09:58, Rajiv Dewan <[hidden email]> wrote: > > I think you have one of the newer units where Elecraft improved the design by putting one wire above and another below the PC board. Mine was #309 with both wires above the PC board. They had arced. > > Raj, N2RD > >> On Mar 10, 2021, at 12:53 PM, Dennis Moore <[hidden email]> wrote: >> >> I checked inside my tuner, I only have one green wire instead of two. Serial #2120. >> >> I also have the issue of erratic tuning when applying power, adding an additional common mode choke helped calm things down. >> >> Dennis NJ6G >> >>> On 3/8/2021 09:07, Rajiv Dewan wrote: >>> I had a similar issue with my KAT500. I opened it up and the problem was obvious: there are two green 12g wire bridges that cross. (You can see them in this image: ([hidden email] <https://cdn.shopify.com/s/files/1/2029/4979/products/kat500_inside_500_530x@...?v=1536760566>. You can see one end of the longer green wire near the big red toroid.) There had been arcing between them. My guess is that they arced at higher power levels. I replaced them with slightly longer wires and bent them to create more clearance. That solved my problem. >>> >>> I recommend taking taking the cover off and taking a look. The problem may be obvious as it was for me. >>> >>> Raj, N2RD >> ______________________________________________________________ >> 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] 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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