As an update, (for all those following this thread with bated breath) It looks like the problem of being unable to get full power out on the bands below 17M, and the inability to do a TXGain calibration, was due to some issue with the configuration of the ATU. I set ATU to not installed and then back to installed and power output came back up. In addition when the ATU is enabled and used to tune the 50 ohm load, the SWR after tuning is 1:1. (those who are following this will remember that originally tuning made the SWR worse). My idea of a loose connection appears to be wrong.
Now, the remaining problem is that the Current Display does not indicate the current actually drawn. The display 'saturates' somewhere around 3 amps or so. (It appears to read sensibly up to that level, and then flattens out as power is turned up). I'll ask Elecraft Tech support for guidance on this one.... I'm hoping to use the rig in the upcoming CQWW, so if there anything amiss, it's sure to show up then. Mark n2qt -----Original Message----- From: Ian White GM3SEK Sent: Sunday, September 23, 2012 4:54 AM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] K3 power output problems Don Wilhelm wrote: > >There is one possibility of a loose connection in the ground path for >the antenna connectors. > >At the upper right-rear corner of the K3 there is a 2D connector, a >long screw and a standoff is fastened to the threads of that long >screw. The tightness of that standoff is important to the ground path >to the antenna connectors. See page 22 of the K3 Assembly manual. > >To tighten the standoff, you will have to first loosen the screw that >goes into the inside end of that standoff, then tighten the standoff >with pliers (or better yet, a 3/16 inch wrench). Once you have >tightened the standoff against the 2D connector, you can tighten the >screw again. That slender pillar is the main return path for an ampere or more of RF current flowing between the KAT3 board and the rear panel sockets. As someone whose design instincts were developed at VHF, where all RF ground paths must be short, broad and direct, I didn't feel comfortable about that corner of the K3. Yes, we know that "it works" and "it's good enough for HF". But in these days of compulsory EMC testing and microscopically detailed product reviews, even HF designers are coming to realise that bending the rules for good RF grounding will eat into the margins of performance, spurious signal rejection and stability. RF grounding of the KAT3 board is also far too dependent on the tightness of the screws at each end of the pillar and the cleanness of all the contact surfaces. That ground return path can be much improved by connecting the mounting screw of J1 directly to the corner of the KAT3 board, using two solder tags that are overlapped and soldered directly together. My K3 doesn't necessarily work any better, but it does satisfy the instincts of an old VHF hound :-) -- 73 from Ian GM3SEK http://www.ifwtech.co.uk/g3sek ______________________________________________________________ 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 ______________________________________________________________ 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
