+++++++++++++++++ Date: Sun, 25 Nov 2001 11:47:24 -0600 From: Mike Subject: [Elecraft] My List of K1 Mods I wrote: > The only electrical mods I've found worthwhile in more than a year > of owning it are: > > (1) QSK thump Application Note > (2) Noise Blanker KNB1 RF Noise Elimination Builder Alert #4 > (Thanks for initially pointing me to that mod, John, even > before the alert was issued. I think this mod is now > incorporated in new KNB1s.) > (3) VFO pot kHz/turn linearization mod (100k resistor from > hot side to wiper). > > Other than that, a few mechanical mods to eliminate speaker vibration > problems (foam pads at the corner of the front panel board, tape around > the speaker magnet for the KBT1) are all I've done to mine. I forgot to list one other *very* useful electrical mod that I did based on info from this Elecraft e-list: (4) Decrease AGC response time by changing C31 on the RF board to 1 uF (from the original 2.2 uF). Also, in the non-electrical mod category: I did what Tom/N0SS recommended about using strips of rubber band between the KAT1 PCB standoffs and mounting screw threads to hold them together during KAT1 removal and replacement. I installed some layers of handcut soft felt "washers" behind the VFO knob to eliminate unintended knob motion when letting go of the VFO knob. I pasted some black cross-stitching cloth under the speaker openings to keep moisture and crud out of the speaker cone, and improve appearance. That, then, is the complete catalog of the very minor mods I've put on my K1. Mike / KK5F ++++++++++++++++ Date: Mon, 31 Dec 2001 18:03:39 -0700 From: "Rod N0RC" To: "Elecraft-list" , "Low Power Amateur Radio Discussion" , Subject: [116618] K1 Mods Revisited Folks, I prepared two web articles about my K1 modifications. AGC I discussed before the detail, now they are posted on the web with audio files to illustrate the effect. PASSBAND MODS I took this one step further by making minor changes to the circuit. This too I posted to the web, with details such as Spectrogram plots, audio files and a photograph. You can access these articles at: http://www.radioactivehams.com/~n0rc/index.html then click the appropriate link. ***Happy Holidays*** 73, Rod N0RC Ft Collins, CO +++++++++++++++++ To: elecraft at mailman.qth.net Date: Sun, 10 Mar 2002 17:27:05 -0600 From: Wayne Rogers Subject: [Elecraft] K1 mods Just made N0RC mods to my K1 and replaced Caps with blue temperature compensated. Made K1 passband and AGC modifications and radio operates and aligns much better. Mods are at www.radioactivehams.com W5KDJ - Wayne Spring, Texas ex-SV0WWW & TF2WJN +++++++++++++++++ From: "Rod N0RC" To: "Wayne Rogers" Sent: Sunday, March 10, 2002 5:34 PM Subject: Re: [Elecraft] K1 mods > Folks, the full link is: http://www.radioactivehams.com/~n0rc/ the > short cut is http://www.n0rc.com > > 73, Rod N0RC > Ft Collins, CO +++++++++++++++++++ Date: Wed, 27 Mar 2002 12:16:16 -0800 From: Wayne Burdick Organization: Elecraft To: Mike Cc: elecraft at mailman.qth.net Subject: [Elecraft] Re: Is info on "revised" K1 details coming soon ??? Hi Mike, Sorry for the delay on this. We're planning to more detailed info (and the new manual) on the web site, but we're a little busy with other projects at the moment, not to mention taxes. Nearly all of the chages were the subject of earlier application notes--we just incorporated some them into the PCB and manual to make construction and alignment easier. In addition to the app note mods, we've made it easier to do TX offset. The way we did this is to put a miniature slide switch on the bottom of the RF board, so if your TX offset is already aligned, you might not want to go to the trouble. Similarly, we added a 3-pin header/jumper in the vicinity of R36, so if you have the KAT1 installed, you don't have to solder/de-solder this resistor to do alignment of new Filter boards. If you do this a lot (most builders don't), rather than use a 3-pin header, you might want to wire a slide switch in here. Wayne N6KR Mike wrote: > > I have been hoping for all of the several weeks since the recently > revised K1 has been shipping that either the manual or a detailed > description of the changes would show up on the Elecraft web site. > > By detailed description, I mean real circuit and component info that > could be used if one wished to backfit some of the mods to an older K1. > > If this info will not be made available from Elecraft in the near > future, has anyone else on the list compared the two circuits and > cataloged the details of the improvements? > > Thanks, > Mike / KK5F +++++++++++++ Date: Wed, 27 Mar 2002 14:32:36 -0600 From: Mike To: elecraft at mailman.qth.net Subject: [Elecraft] Re: Is info on "revised" K1 details coming soon ??? Wayne Burdick wrote: > Nearly all of the chages were the subject of earlier application > notes--we just incorporated some them into the PCB and manual to make > construction and alignment easier. Hi Wayne, Thanks very much for the reply! I also understood that a VFO linearization mod and a ATTENUATOR switching noise reduction mod were incorporated, which I don't think have any existing "official" application notes. I was curious if these mods were incorporated using the same methods as described on this list over the past 18 months, or if new approaches were utilized. I was also wondering if the new K1 incorporated any of the VFO temperature compensation components that were listed on the old K1 as possible future circuit additions. I've really enjoyed my full-house K1 #175, especially with the four-band filter board. It has really no competition as a small well-featured backpack and portable rig. I have likely already incorporated most of the mods that were made in the revised K1, but I wanted to verify with a look at the new circuit diagrams. I'm interested in keeping my K1 as up-to-date as possible with subsequent improvements that are reasonable to backfit. Thanks again! Mike / KK5F +++++++++++++++ Date: Wed, 27 Mar 2002 12:58:00 -0800 From: Wayne Burdick Organization: Elecraft To: Mike Cc: elecraft at mailman.qth.net Subject: [Elecraft] Info on "revised" K1 -- details Mike, You'll find the details you asked for (below). Thanks for your comments on the K1. 73, Wayne * * * VFO Linearization: Add a 100 k resistor (R19) from pin 1 to pin 2 of the VFO pot pads (R1) on the Front Panel board. No temperature compensation components have been added. Attenuator on/off audio "pop" elimination: Install miniatore 10 or 15 uH RF choke between pins 3 and 8 of relay K1 on the bottom of the RF board. ++++++++++++++ Date: Tue, 04 Jun 2002 06:59:08 -0500 From: Mike To: Elecraft Subject: [Elecraft] K1 Phone Jack Circuit I wrote about the latest version of the K1: > I would have liked to have seen a simple PCB trace design change in the > new K1 that would allow removal of one jumper to disconnect the ring on > the phone jack, so that mono phones and speakers could be plugged in > without using an external stereo-to-mono adapter. I just looked at the errata sheet for the Rev. F K1 manual at the Elecraft site, and I see that it has an excellent summary of the improvements made in the latest K1s. The change I said I'd like to have seen (above) **IS** incorporated in the latest version. I had earlier looked only at the latest schematic, which does not show a removable jumper in the phone jack circuit. It looks like the K1s now shipping have about everything one could want in a four-band, QRP, compact, and light-weight radio. The only change I would make, were I building a new one, would be to reduce the AGC time constant by changing RF-C31 to 1 uF. Mike / KK5F +++++++++++++++++ From: "Wallace, Andy" To: "'Elecraft'" Date: Tue, 22 Oct 2002 08:42:57 -0400 Subject: [Elecraft] Andy's list of installed K1 mods Here's a list of the mods I've made to my K1 since its birth in January of 2002. 120K resistor between VFO pot pins 1 and 2 to improve linearity. Now 9 kHz/revolution. Added speaker grille cloth and rubber grommets to mounting flange of speaker. Added display lighting: pin 16 (12V) of front panel board to 1.2K resistor, going to a pair of Radio Shack 276-320 3.6V "Bright White" LEDs and back to ground at FP pin 20 (GND). Draws 4 mA. Added shrink tubing around RIT/ATTN LEDs to reduce sidelighting through button holes etc. Changed C9 in audio section from 220 uF to 100 uF to reduce bass response. Added Elecraft QSK-thunk mod: Drain of Q11 goes to 220 Ohm resistor, other end of resistor goes to + lead of 22uF cap, - lead of cap goes to GND at C10 location. Added socket pins and jumper to OFFSET and R36 areas to facilitate alignment in the future. Added 12 uH choke between relay K1 leads 3 and 8 to eliminate attenuator pop. Replaced VFO pot with Bourns metal shaft 3540S-1-104 (DANGER do not use Hybritron 3541H-1-104, frequency jumps and is unstable at end of travel). N0RC mods: changed C31 and C67 to 1 uF to speed up AGC. I like this mod, however I did not like his caps-across filter xtals mod; it worked, but narrowed the passband too much for my ears. Bravo on the AGC mod, though! Added the "RIT coarse-fine" mod found in the mailing list archives at http://www.qsl.net/ve3mcf/elecraft_reflect/K1_mod_RIT_Fine-coarse_Feature.tx t except in my case, I added 47 pF to C7 to increase RIT range; also: instead of 33K resistors across the 10K RIT ones, I used 6.8K. This gives me -7.2 to +9.2 kHz of RIT for chasing split DX. Proceed at your own risk! -Andy ++++++++++++++ Date: Tue, 22 Oct 2002 13:21:58 -0700 From: "John, KI6WX" To: Elecraft Mailing List Subject: [Elecraft] Version 7.0 of Spectrogram is Now Available Version 7.0 of Spectrogram may now be downloaded from http://www.visualizationsoftware.com/gram/gramdl.html I have exchanged several emails with the author of Spectrogram to improve its capability for measuring filter response. This version includes a number of improvements. One of the main ones is the capability of increasing the averaging time so that you may reduce the noise ripple on the plots. The new version allows you to specify the averaging time in seconds and the ripple due to noise fluctuations is significantly reduced. In some testing I did on my K2, I found that an averaging time of 100 seconds could reduce the noise ripple to less than 1 dB peak-to-peak. This makes it very easy to use this tool to accurately measure the actual filter response of the K2 filters. There are a number of other display improvements that allow you to set the displayed frequency range to any desired value and to print much better plots than previously. The program also allows you to calibrate your soundcard to remove any effects from it. Its a definite improvement over the earlier capabilities in Spectrogram. There is a low cost upgrade option for registered users of earlier versions of the program, or you can use it without registration with a 10 minute time limit. -John KI6WX ++++++++++++++++++++