I'd been unhappy with the stiffness of my K2's rotary encoder for a while, so when a replacement unit was provided by Scott, I thought it was time for a makeover of my fully loaded K2/100.
The new rotary encoder was definitely an improvement. The original encoder was stiff to turn, even in the absence of the felt washer friction pad, but the new encoder was so free-running, I had to dig out and install that piece of felt. Thanks a million, Scott, the feel of the rig has been improved immensely. I also took the opportunity to replace the AF gain pot, which had a wobbly knobbly. It had no effect on performance, but every time I moved the AF gain control, I was distracted by the knob's wobble. While the lid was off, I decided to do a complete realignment. Again, I found a good setting of L34 difficult to achieve. For me, Spectrogram, with its ever-changing display, proved unhelpful but very careful listening to a weak signal from my genny on 14MHz found a gentle but significant dip in the background noise. AGC voltage setup range ran up to 3.83v and at ALL settings, the AGC reduced the level of a very weak (S1 or less) signal. Eventually I settled on 3.68v as the one that had least effect on a signal just above the noise floor, but there should have been a point where the AGC action cut off.. It was interesting to note that after several months of use, slight improvements could be made to most settings, either because a "bedding in" had taken place or my values had changed. I was very impressed with the residual carrier suppression on SSB. I used a GC Rx with antenna to monitor the carrier level on SSB when transmitted into another antenna. The antennas were only a few feet apart, but a small adjustment left only a very weak residual carrier on SSB. It was lower than the 1uV level from the Elecraft XG2! I found that the screws on one of the KPA100 PA transistors could be tightened by maybe a little less than 1/8 of a turn. The other was yomped down good and tight. A slight improvement of SWR eedback was achieved and the PA bias setting proved far more docile to adjust than my recollection of it when newly constructed. There was far less "drift" as the transistors warmed up. I then went off the rails. It was my intention to check higher power output against a "reasonable" wattmeter. When I held "Tune", regardless of the higher power setting, I only saw 22W until I moved the power output control. Somewhat bewildered, I took a break to allow my limited mental resource to do a spot of background processing. Sure enough, the back of my mind came up trumps. Tune limits the output to approx, 2W in QRP and 20W in QRO. Press Tune and Display to override. Yep! Another case of RTFM! Doh! I did find one parameter of 8-somethingorother was set to "nor" and not to "hold" as the KPA100 manual instructs, but switching between its original setting and the instructed setting didn't seem to make any difference. Eventually, I went with the manual's recommended setting. Overall, I reckon to have squeezed a little more out of the K2. I haven't been able to get an audio report on the slightly changed SSB filter settings but prior to adjustment, I had good reports on SSB audio, despite my rather deep voice. I've moved the notional baseline of all the filters available in SSB up by 50Hz approx. Time and a co-operative local who knows my voice will tell. Was it worth it. Most definitely YES. Some settings had either drifted slightly or my interpretation had changed. I managed to reduce tuning display inaccuracy from approx 30Hz to less than 10Hz and make improvements to a few more settings. Were they significant? NO, I doubt it, but it DID provide a refresher course and it leaves me satisfied for the time being. It's good to touch base occasionally. As with all home constructed equipment, there's always a nagging feeling that "something" can be improved upon. Is this the eternal treadmill to which we are all consigned? It's an undoubted YES for me. As recommended on my bulletin board, think twice, post once. 73 all, DaveL G3TJP _______________________________________________ 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
