ReK2/KPA100 problem
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Hi All,
The K2 appears to work on all bands, albeit only 6 to 8watts out on 15/12/15m, which I presume is ok, but maginal. When I connect up my KPA100, output is 100w plus on the lower bands, but on 15/12/10 m it is very low, and the system is self-oscilating around 100MHz and the frequency is unstable. I would think that there was a problem in the KPA's LPF for those bands, but I can't find anything wrong. I use Toroidguys inductors, and all seems well as far as I can check. Has anyone had a similar experience I wonder. Does the low output from the K2 cause this problem Thanks 73 Bryan G3AKF _______________________________________________ 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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Bryan,
I suggest solving the low power output on 15/12/10 for the base K2. You should be able to achieve at least 10 watts on all bands. I don't believe that is your basic problem with the KPA100. If the the KPA100 is self-oscillating, that is the first problem to tackle. Once you get that under control, other apparent problems may also disappear. I have not had experience with oscillations in the KPA100, so the best advice I can offer is to check all components and all soldering - it is not normal for the KPA100 to self-oscillate, in fact in my experience it is quite stable. Look carefully at the input circuit components and the transformer turns. The LPF is not the most likely culprit. 73, Don W3FPR > -----Original Message----- > > The K2 appears to work on all bands, albeit only 6 to 8watts out > on 15/12/15m, which I presume is ok, but maginal. When I connect > up my KPA100, output is 100w plus on the lower bands, but on > 15/12/10 m it is very low, and the system is self-oscilating > around 100MHz and the frequency is unstable. > > I would think that there was a problem in the KPA's LPF for those > bands, but I can't find anything wrong. I use Toroidguys > inductors, and all seems well as far as I can check. > > Has anyone had a similar experience I wonder. Does the low > output from the K2 cause this problem > > Thanks > > 73 Bryan G3AKF > _______________________________________________ > _______________________________________________ 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 Bryan-47
Hallo Bryan,
I have had a problem with my KPA-100 oscillating around 7 MHz, and I sent of a question to support and go this answer within 6 hours: For oscillation problems when a tuner or reactive antenna is installed, the KPA100 must have the latest engineering changes: 1) KPA100SHLDKT 2) KPA100MODKT 3) New KPA100 f/w version 1.1 (requires 1 and 2 above). 4) All paint must be removed where the 2D fasteners and shield grounding clips contact. 5) All cables must be in good condition. Do not more than 5" of RG-174/U between K2 and KPA100. 6) All screws must be tight. The KPA100 shield must be grounded well by both the 3 spring clips, and 2 solder lugs between the SO-239 antenna connector and corner shield screw. 7) The power supply must not be affected by RF. 8) See the attached KPA100 errata for changes in the KPA100 t-r switch. Be sure to check and do the last 2 steps. This clears up KPA100 kits that do not have sufficient t-r switch isolation at high power on the lower freq. bands. My personal comments on the above list: Ad 4) An absolute must and cannot be emphasized enough. Ad 5) This cable can be shortened down to around 4" without any problems, and you can still install the KPA-100 without removing the sides. Ad 6) An absolute must. If you look at my home page www.qslnet.de/dk1htx you can see some pictures taken during my work, and there you can also see how much paint I have removed from the heatsink. Based on input from Tom Hammond I mounted about 30 toroids on the coaxcable leading to my antenna, and my oscillating (and RFI) problems were gone. Best regards DK1HTX, Henrik Tuxen [hidden email] -----Oprindelig meddelelse----- Fra: [hidden email] [mailto:[hidden email]] På vegne af Bryan Sendt: 11 February 2005 16:20 Til: Elecraft Emne: Re[elecraft] K2/KPA100 problem Hi All, The K2 appears to work on all bands, albeit only 6 to 8watts out on 15/12/15m, which I presume is ok, but maginal. When I connect up my KPA100, output is 100w plus on the lower bands, but on 15/12/10 m it is very low, and the system is self-oscilating around 100MHz and the frequency is unstable. I would think that there was a problem in the KPA's LPF for those bands, but I can't find anything wrong. I use Toroidguys inductors, and all seems well as far as I can check. Has anyone had a similar experience I wonder. Does the low output from the K2 cause this problem Thanks 73 Bryan G3AKF _______________________________________________ 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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