+++++++++++++++++++ Date: Mon, 12 May 2003 19:05:53 -0400 From: "Carter W. Craigie" To: Elecraft List Members Reply-To: N3AO at comcast.net Subject: [Elecraft] K2/100 Amp problems Hi Elecrafters! After about two months of perfect operation, my K2/100 100-watt option is acting strangely. Here's what happens. In the morning, for instance, I turn on the K2. AT TURN-ON, the fan IMMEDIATELY comes on (on HIGH!). If I tap the paddles I see a PA HOT message on the display screen. If I do nothing, it might just stay there, but more often than not, after about 10-15 minutes, the fan stops, and all is well. At other times, if I tap the paddles a SECOND time, I see a HI REFL PWR message on the display screen; the CW tone is VERY distorted, and I decide not to touch the paddles again. At this point I have turned off the rig, waited a minute or two, and then re-started the rig. Sometimes the fan still comes on running at the high speed. Something else happens too! My receive audio seems to fade away! And it will come back (and I am thankful!) but then it fades out again. And if I am SENDING CW, my side tone sometimes goes so far down I can barely hear it at all! I wonder if I'm putting out ANYTHING AT ALL! Something else: if I try to tune the K2 in the first few minutes after start-up, and my power level is set at 50-90 watts, the tuner will give me a reading up in the 1.7 to 2.0 level!!! But if I reduce my power setting to under 9 watts, the SWR drops IMMEDIATELY to 1.0 or 1.2. Hmmm... What have I done so far to correct this situation? 1. I switched rig top lids, going back to my original K2 lid which holds the battery and automatic antenna tuner for LOW power (Up to 10 watts). Everything worked perfectly! So I believe the basic rig is working just fine; it must be a problem in the 100-watt option. 2. I examined the amp and discovered that the lead of that big black capacitor in the back right corner had come separated from the center pin of the SO-239 50-Ohm antenna connector. Very carefully, I reheated the connection and am now sure I do not have a cold solder joint there. 3. I remembered that during my original assembling I had nearly stripped the delicate screw threads of one side of Q1, one of those big flat transistors; well, sure enough, that screw WAS loose! I removed it, took off its lock washer, and replaced it. THIS time the screw found a tightness, and I quickly let good enough be good enough! 4. I re-assembled the metal plate, and switched in the K2/100 cover. And the rig WORKED! I thought I had fixed my problem. But the next morning I turned on the rig to find the exact same conditions I had before my "repair!" RATZ!! I wonder what I should do now... I am off to Dayton on Thursday, so don't know if I can do much of anything between now and then, but I sure want my good operating rig to work again--as it had for a month or two after completing the option! 73, Carter Craigie N3AO K2/100 S/N 678 K1 S/N 159 Carter W. Craigie 5 Faggs Manor Lane Paoli, PA 19301-1905 (610)993-9623 n3ao at arrl.net or n3ao at comcast.net ++++++++++++++++++ From: "Lee Hopper" To: , "Elecraft reflector" Date: Mon, 12 May 2003 22:53:17 -0700 Subject: [Elecraft] Re: K2/100 Amp problems Carter - Very interesting: I have the exact same problem: fan comes on, PA HOT message comes on as soon as I key the rig or attempt to tune it. This doesn't happen if I turn the power down below 10W. I just did the BFO mod and the 14 matched filter crystals and so far (one evening of testing) it hasn't happened again. My filters have never sounded better, btw. Lee Hopper, NB7F K2 #784, SSB, 100W, KAT100, audio filter, etc. ++++++++++++++++++ Date: Tue, 13 May 2003 08:02:50 -0400 From: JimWMiller at aol.com To: leehopp at msn.com, N3AO at comcast.net, elecraft at mailman.qth.net Cc: kn2x at aol.com Subject: Re: [Elecraft] Re: K2/100 Amp problems I had the same message if and only if I powered up by turning on and off the power supply. If the K2 on/off *switch* was used then all was OK. This was repeatable. Seems like the microprocessor gets confused if it powers up slowly! 73, Jim WA2UMP K2:2679 ++++++++++++++++++ From: "Brian Machesney" To: "'Elecraft List Members'" Subject: RE: [Elecraft] K2/100 Amp problems Date: Tue, 13 May 2003 07:47:06 -0400 I have always had this behavior. I clear it by TUNEing the rig before operating it. I suspected this "just a firmware problem," so I never thought to look for a hardware solution. Brian K1LI K1 269 K2 3070 -----Original Message----- From: elecraft-admin at mailman.qth.net [mailto:elecraft-admin at mailman.qth.net] On Behalf Of Carter W. Craigie Sent: Monday, May 12, 2003 7:06 PM To: Elecraft List Members Subject: [Elecraft] K2/100 Amp problems In the morning, for instance, I turn on the K2. AT TURN-ON, the fan IMMEDIATELY comes on (on HIGH!). If I tap the paddles I see a PA HOT message on the display screen. If I do nothing, it might just stay there, but more often than not, after about 10-15 minutes, the fan stops, and all is well. -- snip -- ++++++++++++++++++ Date: Tue, 13 May 2003 09:41:02 -0400 From: "Carter W. Craigie" To: 'Elecraft List Members' Reply-To: N3AO at comcast.net Subject: [Elecraft] FW: PA problem FIX Hi Ron ZL1TW (and to others who chimed in to help me!) I think you have found the cause of my problems with the PA HOT message upon turn-on! I followed your instructions and found my tPA setting was at 2C. I have now changed it to 20C, my present room temperature (68F). That's a big difference! I am sure things will be better now!!! Many thanks for your help, Ron! And who says that the Internet has ruined ham radio??!! You are in New Zealand, yet you have helped someone in Pennsylvania! What a wonderful world you have demonstrated this one can be! 73/72, Carter Craigie N3AO K2/100 S/N 678 K1 S/N 159 -----Original Message----- From: Ron W [mailto:ron_w at clear.net.nz] Sent: Tuesday, May 13, 2003 5:51 AM To: N3AO at comcast.net Subject: Re: PA problem Hi Carter, Regarding having the fan come on straight away and the PA HOT message.....take a look at the CAL/TPA temperature setting. I will bet it has "readjusted" itself to a high temperature instead of the ambient temperature at turn on. I have that problem occasionally. (see page 45 of the KPA100 manual "Temperature Calibration".) Incidentally the "black capacitor" that is attached to the SO239 terminal is actually a RF choke and it is there to divert static build up to ground. If all else fails after resetting the temp reading the good old "456" reset usually ( Holding in the numbers 4,5,and 6 and turning the rig on again.......then wait for the INFO232 message while the EPROM reloads the defaults, to go away) clears any problems associated with the MCU being upset by static discharges or other "nasties". After that treatment you have to reload your filter parameters again and any other changes you have made to the basic menu. My money would be on the TEMP setting having changed..... Cheers.....Ron ZL1TW +++++++++++++++++ Date: Tue, 13 May 2003 08:04:22 -0400 To: n3ao at comcast.net From: Joe Squarzini Cc: elecraft at mailman.qth.net Subject: [Elecraft] PA HOT Carter, I had the same problem. I found that the PA Temp setting had drifted inexplicably to 256 deg. I reset the parameter to room temp and so far it has not happened again. I suspect RFI. No proof however. My K2/100 is mounted in a separate EC2 enclosure along with the KAT100. Joe Joe Squarzini, Jr. K4AA Home (703) 759-4943 FAX (703) 759-0656 k4aa at verizon.net +++++++++++++++++ Date: Wed, 14 May 2003 06:56:19 -0500 Subject: Re: [Elecraft] PA HOT From: Richard Lim To: Joe Squarzini , Cc: Elecraft Ditto on what Joe has said. I had my fan on continuously and I check CAL tPa and temp wall 200C. Reset it and no problem. Rich KQ9L ++++++++++++++++++ Reply-To: "Dominik Bugmann" From: "Dominik Bugmann" To: , , Date: Wed, 14 May 2003 18:56:15 +0200 Subject: [Elecraft] Re: PA HOT Joe, Rich, I have/had the same issue here and I posted the findings a few weeks ago on this reflector http://mailman.qth.net/pipermail/elecraft/2003-April/053270.html. What I figured out so far is: The temperature meter is Q3 and mounted right next to Q1 and Q2. The voltage drop from B to E is roughly 0.6V and varies over temperature. Fortunately this effect is very limear (over a high temp range) and much better compared to a PTC or NTC. Unfortunately the change is only a few mV/C. As you can see on the page 61 in the manual Q3 is directly connected to U1/PIC16C72 where they measure the voltage of Q3. To measure a very low level (0.6V) directly with an A/D converter is not an easy task and I assume that the reference level within the MCU (U1) is also temperature dependant. When I switch on my KPA100 I read 8C which goes to 20C within a few minutes. Q3, U1, ..the whole KPA100 heats up a bit. Nevermind this is not a big issue for KPA100. Unfortunately there is a softwarebug which occurs as soon as the reading is below 0C. One would expect a negative number but it is represented as e.g. 255C (underflow of an 8 Bit counter). The controll software for the fan and "Hot PA" only looks at this number (e.g. 255C) and concludes it must be hot out there. At least this is my understanding of the whole issue. My workaround so far: Check the tPA reading of the KPA100 and (re-)adjust if needed. 73 de Dominik, HB9CZF >Ditto on what Joe has said. I had my fan on continuously and I check CAL tPa >and temp wall 200C. Reset it and no problem. >Rich >KQ9L +++++++++++++++++ Date: Wed, 14 May 2003 15:37:29 -0400 To: "Dominik Bugmann" , , From: Joe Squarzini Subject: [Elecraft] Re: PA HOT Dominik, thanks. Makes a lot of sense. Looks like Eric and Wayne need to come up with a permanent fix so that we aren't resetting TPA. I received a lot of replies so many others must have seen this problem. Thanks and hope all is well . . .73 Joe +++++++++++++++++