KAT100 Troubleshooting
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Hi All,
I have my KAT100 & KPA100 in a separate EC2 enclosure. And I have been QRP for a while. The feeder to my dipole antenna on the roof was made of two RG-58 cables with BNC connectors. The connection between these two cables was not properly made since I had used ordinary electrical tape instead of volcanic tape. However, then the first snow came this year something went very wrong. I was using my K2 in PSK31 & PSK63 mode in about 40 Watts and the KPA100 get warmer than usual It became so hot so I could actually smell it. But no smoke. After I short while when I tried to tune the KAT100 it sounded 'funny' and the SWR leds went a little crazy. The cable connection was deep in the snow and I have learned from Don, W3FPR, to be aware that snow generated static can cause a large surge on the antenna (just like lightning), which can zap the 1N5711 diodes in the watt meters in the KPA100 and KAT100. Three of four 1N5711 in the SWR Bridges were blown. One in the KAT100 and two in the KAP100. They are now replaced. But something is still wrong. I have tested Relays, Inductors and Capacitors (page 35 in the Manual) and all relays are switching. When tuning in AUTO mode at 10 watts or less the display on the K2 shows the power and 1.0 - 1 for all bands and antennas. When tuning at higher power the display only shows 20 and I have to stop the tuning manually. Sometimes the relays are switching but only SWR led #1 is turned on. I really need some assistance here! Best 73's, Rolf SMØYQC K2 #4979 _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Rolf,
If the diodes were blown, there is a possibility that the op amps connected to them were also blown. In the KAT100 and KPA100 this would be U5 and maybe U6. U5 provides the FWD and REFL power voltages for the SWR measurement and U6 provides the RF level signal VRFDET. If any of these voltages are wrong "funny" things may happen. A blown U6 drove me crazy for about a week, so I am very familiar with this part of the K2. Hope this helps. 73 Logan, KZ6O #1609 -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of TWC Sent: Tuesday, July 15, 2008 7:41 AM To: [hidden email] Subject: [Elecraft] KAT100 Troubleshooting Hi All, I have my KAT100 & KPA100 in a separate EC2 enclosure. And I have been QRP for a while. The feeder to my dipole antenna on the roof was made of two RG-58 cables with BNC connectors. The connection between these two cables was not properly made since I had used ordinary electrical tape instead of volcanic tape. However, then the first snow came this year something went very wrong. I was using my K2 in PSK31 & PSK63 mode in about 40 Watts and the KPA100 get warmer than usual It became so hot so I could actually smell it. But no smoke. After I short while when I tried to tune the KAT100 it sounded 'funny' and the SWR leds went a little crazy. The cable connection was deep in the snow and I have learned from Don, W3FPR, to be aware that snow generated static can cause a large surge on the antenna (just like lightning), which can zap the 1N5711 diodes in the watt meters in the KPA100 and KAT100. Three of four 1N5711 in the SWR Bridges were blown. One in the KAT100 and two in the KAP100. They are now replaced. But something is still wrong. I have tested Relays, Inductors and Capacitors (page 35 in the Manual) and all relays are switching. When tuning in AUTO mode at 10 watts or less the display on the K2 shows the power and 1.0 - 1 for all bands and antennas. When tuning at higher power the display only shows 20 and I have to stop the tuning manually. Sometimes the relays are switching but only SWR led #1 is turned on. I really need some assistance here! Best 73's, Rolf SMØYQC K2 #4979 _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Rolf G
Rolf,
The display of 20 watts is correct - the firmware limits the KPA100 power to 20 watts when tuning at high power. The fact that it appears not to complete the TUNE is a potential problem, but if you have replaced the diodes in the KAT100 and they are still good, *and* it tunes correctly at 10 watts, then I do not believe the problem is in the K2, KPA100 or KAT100. You can test that by tuning into a dummy load at the high power setting - or even into a light bulb used as a dummy load (it does not have to be 50 ohms for this tuner test - likely better if it is not 50 ohms). If the tune completes at the 20 watt level, then declare your Elecraft K2 gear to be OK and look more carefully at your antenna system. Are you getting RF Feedback that is troublesome at 20 watts, but not at 10 watts? Is there something that is arcing over when 20 watts is applied - it is possible that there would be no arcing at 10 watts, but present at 20. Is your coax of the foam dielectric type? If so, be suspicious of it since it was exposed to snow melt. If water gets into coax through even a tiny hole in the outer insulation, the coax will be ruined because the foam soaks up water just like a sponge. Check everything, the problem could be anywhere in the system. 73, Don W3FPR TWC wrote: > > But something is still wrong. > > I have tested Relays, Inductors and Capacitors (page 35 in the Manual) > and all relays are switching. > > When tuning in AUTO mode at 10 watts or less the display on the K2 > shows the power and 1.0 - 1 for all bands > and antennas. When tuning at higher power the display only shows 20 > and I have to stop the tuning manually. > Sometimes the relays are switching but only SWR led #1 is turned on. > Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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