+++++++++++++++++++++++++++++++++++ Date: Tue, 3 Jul 2001 10:45:53 -0600 From: "Rod Cerkoney, N0RC" Subject: [Elecraft] some K1 tweaking notes Folks, Finished up 0197 a few days ago, and am already tweaking it. ;-) For me the AGC is just to slow on the K1 so I changed C31 to 1uF, as I did before on 539, but this time I also changed C67 to 1uF. During last night's ARS Sprint I only had C31 changed out, and noticed that strong nearby stations reduced RX gain a bit too much, while working weaker stations. Other "transient event's" also muted a few code elements on the weaker stations. The jury is out on how this C67 mod will change things, I'll have to wait for more crowded and mixed signal conditions. Limited testing, listening to weak sigs, then keying "the Big Rig" into a D/L, shows some promise. Also, during last night's sprint I found the RIT range too wide. Mine came in at about +/- 4kHz, this is a result of changing C2 [now 56pF] to limit tuning range to about 69kHz. Changing C7 to 22pF yielded +/- 2kHz; 15pF yielded +/- 1.3kHz, JUST RIGHT for me. Another mod I made is a piece of felt behind the tuning knob to add some drag. I bumped the main tuning knob a couple of times and got off Freq, the "felt drag" helps to minimize this. 73, Rod N0RC Ft Collins, CO +++++++++++++++++++++++++++++ Date: Tue, 03 Jul 2001 08:14:38 -0700 From: lhlousek Subject: [Elecraft] K1 nr 0808 report. I received K1 kit serial nr 0808 last Thu (my K2 nr is 1818) and made its first QSO at 3:30 PM on Fri. I have 40 and 20 meters and set the tuning range for 80kHz. It took about 14 hrs to build and align. I built and added the KNB1 and KAT1 Fri evening. First DX was OH1SR on 20m Sun. Worked OK1ACF, GM0KWL and F5BBD yesterday. The mojo is good. Before I got it I thought the 3digit LCD and user interface might be problematic. It isn’t. It is very easy to learn to use. I would prefer the first press of XFIL to show the current filter rather than switch to the next and same for the keyer speed. (Same goes for the K2 XFIL too.) Mods (IMO the following should be standard in the kit): Linearize VFO travel: Added a 62K 1/8 watt resistor across terminals 1 and 2 of the 10 turn pot. I was getting 11.4 kHz/rev at the bottom and 4.3kHz/rev at the top. I now get 9.4 at the bottom, 8.2 in the middle and 9.0 at the top. This does not change the tuning range. QSK thump: The thump was very noticeable in headphones on noisy bands. The official Elecraft approved mod helped significantly. (add 220 ohms and 22uF in series to ground from the drain of Q11) KNB1 keying noise: Only noticed this once on 20 meters. Did the official mod (add .01 across pins 1 and 8 of NB U1). Haven’t noticed the noise since but I haven’t looked for it either. Picking nits: The VFO shaft has radial play of about .008”. Doesn’t sound like a lot but it sure feels like a lot, especially with the 10kHz/rev sensitivity of the VFO (compared to 1kHz/rev on the K2). I know the same pot is available with a metal shaft but the official line is that it is no better. Anyone know of a different make or model with less wobble? When working K1s I noticed that some of them drifted. Mine does (says so in the specs). During most QSOs I find myself tweaking the RIT to keep the received sig centered in the filter. I’m sure the op on the other end is tweaking his too. (Perhaps I’d be better off using the VFO so that I’d be correcting the transmitted sig too...assuming I’m the one drifting?) It is also pretty sensitive to magnetic fields. I put it on top of my K2 and the sigs moved about 200 Hz due to the K2’s speaker magnet. AGC speed: The AGC attack is a little slow and the decay is very slow. I plan to reduce C31 to 1.0 or .47 uF to see how this works. The top of the front panel board waggled back and forth and clicked against the upper 3D fasteners when I pressed buttons. I added little pads between the front panel board and the upper 3D fasteners as is standard in the K2 kit. The sharp ridge on the VFO knob is not comfy on the finger or thumb and not conducive to smooth tuning. I chucked the knob up in a lathe (as opposed to just chucking the knob), removed the ridge, cut down the height of the knob and rounded the edge. Looks good and works much better. I also cut off about .090” of the shaft of the VFO pot so that the knob wouldn’t stick out so far and would sit closer to the front panel. I found that I would often accidentally nudge the FVO off frequency when changing filter widths or hitting the XIT button. This hasn’t happened with new lower profile smooth edged knob (which should also be less vulnerable when transporting the rig). Photos of my K1 and K2 knob jobs at http://home.nvbell.net/lhlousek/K1knobsm.jpg http://home.nvbell.net/lhlousek/knobjob.JPG http://home.nvbell.net/lhlousek/RIT_Pointer_sm.JPG. The speaker sounds amazingly good. Don't know about the smaller speaker used with the battery option (B.O.ed) . I plan to add some grill cloth between the speaker and top panel to help keep crud out. I will also add a switch and a few LEDs to illuminate the LCD tonight. Love this little rig. Can't wait to take it on the road with me. Lou W7DZN ++++++++++++++++++++++++++++++++ Date: Tue, 16 Jul 2002 23:11:23 -0500 From: Mike To: elecraft at mailman.qth.net Subject: [Elecraft] Re-work of K1 #175 I just finished a job on my K1 that I was not much looking forward to, using parts recently received from Elecraft. (1) Pulled the front panel and replaced the AF gain pot, which had become scratchy several months ago. I haven't heard anyone else report K1 scratchy pots, so maybe just mine had a problem. The new pot seems to have significantly less shaft woble than the original pot. I may have to order another one and replace the RIT pot. (2) BIG JOB! Pulled off all 16 of the old problematic ceremic trimmers on the KFL1-4 PCB and replaced them with the "new" blue trimmers. I found it was easy to get the old trimmers off, since there was plenty of room under the old trimmers to get something to pry one end up while desoldering. I didn't even damage them. Getting the residual solder out of the vacated hole, and forming the thicker leads of the new caps to get them on the PCB was another story altogether. I was never able to get the holes so clean that the new caps would slip right in, so I wound up just blowing most of the solder out, then heating the holes alternately while I pressed the new cap down. I did have one problem that I didn't find until I was in the alignment phase. Trimmer C1 adjustment had no effect. I found quickly that the ground connection PCB trace to C1, which was on the top of the PCB and therefore buried under C1, was broken. A short jumper installed below the PCB to the ground side of C5 corrected that. Though I can't honestly say that I enjoyed this task, all in all it wasn't as bad as I had feared. (3) Changed C10 and CK in the 30m/40m portion of the pass band circuits of the KFL1-4 from 3 uuf to 4.7 uuf. Though this was recommended in the KFL1-4 temperature stability bulletin as an alternative to replacing the trimmer caps, that's not why I made this change. I have a 170 kHz VFO span option, but with the KFL1-4 I've never been able to align 40m such that I could get the same power output on both ends of the band. In fact, if I aligned the KFL1-4 for 7 watts out at 7070 kHz, I was lucky to be able to get 2 watts out at 7150 kHz, and 5 watts at 7000 kHz. Changing these two caps now allow my K1 to produce very near maximum power all through the 170 kHz tuning range on 40m. (4) Installed the new RFC9 in the attenuator relay circuit to eliminte pop on switching. (5) Installed the new RFC8 in the 12v supply to the low level transmitter stages, as recommended by Elecraft if an 80m board is to be used. I haven't started on rebuilding an old two band KFL1 for 80m/17m yet, but I have parts now for those bands. I can't think of any reason not to have RFC8 in the circuit, even though the new K1 kits have a jumper installed in its place unless an 80m board is to be used. Anyway, my old K1 is back and better than ever. Great rig! Mike / KK5F ++++++++++++++++++ Date: Wed, 17 Jul 2002 09:10:13 -0500 From: Mike To: Paul Cavnar Cc: elecraft at mailman.qth.net Subject: Re: [Elecraft] Another K1 Comes to Life Paul Cavnar wrote: > I am pleased to announce that K1 #1256 has been born... Congratulations! > Next comes the list of mods that I may do ... Likely, I > will do none. :) If yours is of the latest version (manual revision F), there's *very little* left in the way of significant mods. Just about all the issues and improvements developed since the K1 and the KFL1-4 were introduced have been incorporated in the later units. About the only electrical mods I can think of that aren't are just matters of tailoring a feature or two to one's own personal liking: (1) AGC response time decrease (RF board C31 changed to 1 uF or so). (2) KFL1-4 40m bandpass broadening (C10 and CK to 4.7 uuF) if you have a 150 kHz or greater VFO range and want near full output over that range). (3) RIT range reduction (I've not incorporated this one). (4) Backlighting the LCD (I've not incorporated this one). Beyond that are the minor non-electrical improvements, like: (1) Speaker grill cloth - more important than one might think, to keep crud out of the speaker cone and improve appearance. (2) Felt "washers" behind the tuning knob to create some resistance to rotation - strictly a personal choice, but I've found this to be valuable with my 170 kHz VFO tuning range. (3) At one time, a "resonace rattle" could occur at certain audio frequencies unless the four corners of the front panel PCB had some small amount of foam tape between them and the fastening blocks on the main chassis. I've heard no more about this for over a year, so I guess this has been resolved. (4) At some audio frequencies, a rattle could occur between the speaker magnet and the mounting bracket of the KBT1 internal battery unless a single layer of tape was wrapped around the speaker magnet. I haven't heard anyone mention this as a problem in a long time either. I'm sure there's other mods out there, but if I had a new K1 I personally would do all the above except the RIT mod (I like the RIT range as designed) and the LCD backlight (I don't want the extra current consumption). Every other mod I've done to K1 number 175 in the past 21 months has already been incorporated into the latest units. 73, Mike / KK5F ++++++++++++++++++++ From: "Wallace, Andy" To: elecraft at mailman.qth.net Subject: RE: [Elecraft] Another K1 Comes to Life Date: Thu, 18 Jul 2002 13:49:10 -0400 > -----Original Message----- > From: Mike [mailto:mmorrow at companet.net] > > I'm sure there's other mods out there, but if I had a new K1 I > personally would do all the above except the RIT mod (I like the RIT > range as designed) I modified my K1 with the RIT fine-coarse mod as described in the Archives at: http://www.qsl.net/ve3mcf/elecraft_reflect/K1_mod_RIT_Fine-coarse_Feature.tx t I had previously changed my RIT to have more range for working split, and so my fine-coarse mod used different resistor values. When I get a chance, I'll document and post the way I did it. This mod gives a fine-tuning semi-detent in the center of the pot's range. I think it works pretty well. > and the LCD backlight (I don't want the > extra current > consumption). Is 4 mA too much? I performed the mod as described in: http://www.qsl.net/ve3mcf/elecraft_reflect/K1_Lighted_Display.txt and used a pair of Radio Shack bright-white ($5 each) LEDs. Actual color is sort of bluish. Not unattractive. Limiting resistor is a 1.2K surface mount part mounted by the connector (picking off 12VDC from the front panel). Works as well as it can. Part of the problem is that the K1 LCD is close to the front panel. To illuminate it with regular LEDs from the side, it would help if the display was mounted lower to the board. If I ever build another K1, I might try shortening the LCD spacer to allow this. Sure would be nice if lighting could be a standard thing -- maybe some of those small surface mount LCD illuminator strips? I checked the manufacturer's website and they don't offer the model used in the K1 with an integral backlight. -Andy ++++++++++++++++++++