[Elecraft] Transmit power control problem
Hello there friends, Further to my August 15 message when I asked for help to solve my lack of power control after having solved my Info 80 problem, I am happy to let you know that only this morning I have finally fought the dragon to death and my K2 has overcome its lack of power control. I'll share my quest with you all as it may by of any help to someone sometime. Have received some very interesting advices and have been in touch with Gary at Elecraft who, as usual, has been very helpful. Have made a lot of measurements and tests. Have replaced the D9 diode (an old 1N34A) and changed to a 1N5711 and have also changed R68 to 226 ohm 1% so as to upgrade the RF Output Detector stage to the current standards, but to no avail. I let the matter sleep for some days and yesterday afternoon I resumed my fight again. First of all I removed all the options, namely NB2, KSB2, K160RX and KDSP2, reinstalling the respective jumpers. And ... alas!!. When I pressed TUNE after setting the power to 5 watts, the Dummyload/Watmetter read 5 watts and just a little bit more. That was amazing. The RF control worked. Just then I was called to attention as dinner was ready and I had to leave my fight and clear up all the mess of tools and whatnots I had in my workbench which, as it happens to many of us, is in the kitchen office. This morning I have resumed the fight and the basic CW K2 still controlled the RF output. Then I have installed the KSB2 option and ... yes, you are right; there it was: NO ALC and lack of power control. The KSB2 was the culprit. Resuming, the U1 PIC (F/W 1.08b) was damaged. Have installed an older U1 version (1.07) and the K2 works again. Now I'll have to ask Scott at Elecraft for a replacement KSB2 F/W. BTW. Nobody had mentioned to me that a possible KSB2 failure could be the cause of my troubles and now, browsing N0SS new web site, www.n0ss.net , I have downloaded a PDF file titled Use the Serial Wrong Cable and ... BAD THINGS WILL HAPPEN, by Gary Surrency and Tom Hammond and dated December 25, 2003, where all my K2 ailments and probable causes are commented. A pity I didn't get it earlier, but now I know first hand and have learned a bit more on my K2 inners. My thanks to all of you who have contacted me on the matter. This forum is a deep well of friendliness, companionship and knowledge. Sorry for the bandwidth and thanks for your bearing with me. Best 73 and best wishes to you all from Barcelona Pauli, EA3BLQ K2/100 # 1044 [EMAIL PROTECTED] [EMAIL PROTECTED] URL: www.qsl.net/ea3blq ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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] Transmit power control problem
Hi there friends, Further to my former message asking for your kelp, forgot to tell you that I am having the problem on the bare basic K2, no KPA100 or KAT100 installed, so those two options have nothing to do with my present problem. When making the K2ATOBKT mods, I installed two 12 pF capacitors across C21 and C23 so I had to realign reception and transmission and it's been then when I have become aware that I could not control the transmission power output and that is what's keeping me worried. Not the Hi Cur message, though this can also be part of the problem. Thanks for all the feedback I am already receiving. 73 Pauli, EA3BLQ K2/100 # 1044 [EMAIL PROTECTED] [EMAIL PROTECTED] URL: www.qsl.net/ea3blq ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
Re: [Elecraft] Transmit power control problem
Pauli, Let me restate your symptoms first so you can ignore my answer if no match -- 1). You have over 10 watts of actual power generated into your dummy load. 2). The K2 display shows only a small amount of power output 3). You are getting excessive current draw (HI CUR). If ALL that is correct, the problem is in the VRFDET signal path somewhere. The MPU is not sensing RF being generated and tries to increase the power. Check the components in the RF Output Detector (schematic sheet 3 lower right corner). After that simple voltage divider and diode detector, the signal finds its way to the control board and is present at pin 10 of the AUX I/O header and then goes to pin 2 of U6 (there may be an 820 ohm resistor in series before hitting the MPU pin, depends on your level of the Control Board, the early ones did not have the resistor). Also, if you did the keyclick mod, look carefully at that - it will influence the ALC action, but will not likely produce the symptoms you report. 73, Don W3FPR - Original Message - After having solved my recent Info 80 trouble and since I had upgraded my KPA100 and all the F/W, my K2's configuration got quite disarranged, I decided to implement all the mods to upgrade my K2 rev A to a K2 rev B, before getting into the configuring and aligning task (I had installed some of the mods but not all) so I purchased the K2ATOBKT kit and did a lot of disoldering and soldering. All has run as per the manual but (Why there's always a but? Is it Murphy's Law?) now I have got a transmit power control problem. When I key down (TUNE) the K2 and independently of the value I set in the POWER Control (be it 0.50, 2.00, 5.00 or 10.00 watts) I always get the Hi Cur message and the internal wattmeter drops to 0.3 watts, but the truth is that the power transmitted into a very well calibrated 50 Ohm Dummy Load and RF Power Meter (the QRP RF-Power Meter PM-1300a by SSB-Electronics) always, and I mean always with independence of the K2 POWER Control, reads between 10-14 watts depending of the frequency. Have made the resistance checkings and they are OK ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
