++++++++++++++++++++++++++++++++++++++++++++++++++++++ From: BobK8RL at aol.com Subject: [Elecraft] Elecraft K1 #228 K1 #228 is fully operational on 40/20m. After building the K2 (#1518), the K1 was very easy. Since I take my time and check my work as I go (I hate to troubleshoot needlessly), it took around 20 hours with the inventory. This also included a few hours trying C2/L1 combos in the VFO. I'm sure "speedsters" could assemble the K1 in much less time. I usually read ahead in the manual and highlight key things. This helps reduce errors. Only two parts were missing -- small caps. I just pulled some from my stock, Since I want the beacons at 14.100 MHz on 20m, I tried to get the tuning range to over 100 kHz. Testing showed 75 pF yielded a tuning range of around 105 kHz for my K1, but it was a little difficult to spread the L1 winding to yield something starting at or just below the bottom edge of the band. I tried one less turn also but that was too far off. Settled on the original 33 turns for L1. For now, I have a 100 pF poly cap in for C2. This provides a tuning tange of 145 kHz. I will choose a combo between 75 pF and 100 pF later. I may locate a 15-turn pot and see if it will fit. Initial display was within 100-200 Hz high on 20m and 5.8 kHz low on 40m. The CAL menu option was easy and quick to do. One resistance check was supposed to be > 100 K but yielded 6.2 K. After a few minutes I concluded it was due to the minor T-R switch mod (2.2 K resistor from RP4 Pin 1 to GND) that I had added a little earlier. I put the resistor in while I remembered to do it and had easy access to the RF board. There are still a few minor nits in the manual. Nothing serious. For example, the diagram that shown the speaker mounting has pan-head screws. Also the order hardware listing in the text should agree with the sequence the mounting hardware is used. When one gets to this level of nit-picking it is obvious the Elecraft reviewers / team has done a good job. I plan to make a small light "mount" to just set the K1 in. The view angle is poor otherwise. (I have tried using it on its side.) As on my K2, since I use a BNC adaptor, there is not enough clearance when the radio is tilted unless the radio is also raised in the back. The temperature-controlled soldering station is a must. The Panavise is not. I spent money on that at the advice of a posting on the reflector. Used it just a few minutes. It is more trouble to use than it is worth, especially for the K1 board -- they are small and easy to hold. The assembly sequence Elecraft used usually places "high" items on the PC boards and these offer support / protection for later more fragile components +++++++++++++++++++++++++++++++++++++++++++++++++++++++ Date: Sat, 31 Mar 2001 13:12:36 -0600 From: Mike Subject: [Elecraft] K1 Mods: QSK, AGC, Tuning Rate Hello All! I've just completed some mods to my K1 that have been recently published on this list, and have some comments. (1) Builder Alert QSK Mod: This mod made a great difference in the QSK thump that was heard when using earphones. Highly recommended. (2) AGC C31 Mod: I'm adding my name to the list of those who have found that changing C31 from 2.2 uF to 1 uF really seems to improve the AGC action. 73, Mike / KK5F ++++++++++++++++++++++++++++++++++++++++++++++++++ Date: Sat, 31 Mar 2001 20:26:19 -0600 From: Mike Subject: [Elecraft] K1 VFO Tuning Rate Revisited alta wrote: > Your BEFORE measurements indicate very rapid tuning at the low end, > and fine tuning at the high end. Is this really what you want, Mike? > > PS - With the 120pf cap and 68K mod, the results: > > Freq Diff > 0 > 15 15 Finer tuning at this end > 29 14 > 43 14 > 58 15 > 75 17 > 93 18 > 112 19 > 131 19 > 150 19 > 170 20 Coarse tuning at this end Hi Reed and All, Actually, your detailed presentation of the kHz/turn data above made me realize I short-cutted and bozo'd my data collection by looking only at what happened on the first and the tenth turns. When I took the time to do it right, I collected data for my K1 with C2 = 120 pF: (1) As designed (no resistor from terminal 1 to 2) (2) 100k ohm resistor from terminal 1 to 2 (3) 220k ohm resistor from terminal 1 to 2. VFO Pot As Designed 100k Resistor 220k Resistor Turn Increment Increment Increment Number kHz/turn kHz/turn kHz/turn 1 17.7 15.9 17.6 2 19.8 15.6 18.0 3 22.1 16.1 18.7 4 23.2 16.6 20.0 5 21.7 18.1 20.2 6 18.2 18.6 18.5 7 13.7 17.5 15.8 8 11.6 16.0 13.6 9 10.5 16.0 13.1 10 10.9 18.4 14.3 As Larry/W1HUE and Don/W3FPR suggested, it turns out that the 100k resistor seems to do a pretty good job of almost linearizing the tuning rate over the whole range. This is what I was most interested in, since I have 40m and 15m filter boards and did not want to degrade one end too much at the expense of the other. I can see why Reed's choice of a lower value (68k) would be best if one wanted more bandspread on the low end. I've chosen to install a 100k resistor. 73, Mike / KK5F +++++++++++++++++++++++++++ From: Thor, n9ik [mailto:n9ik at qsl.net] Sent: Wednesday, January 30, 2002 6:15 PM To: elecraft at mailman.qth.net Cc: DolfinDon at aol.com; rod at n0rc.com Subject: RE: [Elecraft] K2 Tuning Knob - FT100 This morning, following a discussion about using the tuning knob from a Yeasu FT-100 as a replacement on the K2, I posted a question about using the same knob on the K1. I also asked for any other suggestions for improving the "feel" and sensitivity of the K1's tuning Since I posted the question, I've gotten several excellent tips from two very helpful people, and I'll summarize their suggestions below: Don, KD5NDB... ... responded first with two separate emails, his first suggestion to replace the tuning pot with a steel-shaft version. His second email suggested connecting a 100k resistor between pins 1 and 2 of the pot, which will make the VFO more linear end-to-end. Rod, N0RC... ... also responded, letting me know that the shaft sizes on the K1 and K2 differ, so the FT-100's knob probably will not fit on the K1. He also included another mod (apparently compiled from ideas collected from other postings), and even took the time today to put pictures of what he's done up on his web site, which also includes other mods for the K1 that I think deserve a close look. I've taken the liberty of including the link to his web site here: http://www.n0rc.com (I hope you don't mind, Rod!). This mod includes trimming the shaft approx. 2-3mm, inserting a felt ring behind the knob, and finally, adding a rubber ring to the knob, fabricated from a slice of old bicycle inner-tube. ========== 01/31 And Chuck, WA2MXR ... ... feels that simply replacing the pot with a metal shaft version increases touch and sensitivity so much that the felt pad and rubber added to the knob are unnecessary. He also has added the 100k resister to make the tuning more linear. In addition, Chuck had a good suggestion for protecting the voltage regulator, U5, from the stresses of removing the covers to work on the K1. He added a protective 'shield' by trimming part of a CD case and attaching it to the RF PCB. A VERY BIG THANK YOU to All three of you - Don, KD5NDB, Rod, N0RC and Chuck, WA2MXR for your _excellent_ suggestions, and for all of the time and trouble you all have taken to answer my questions! - Thor, N9IK ++++++++++++++++++++++++++++ Date: Thu, 31 Jan 2002 07:33:00 -0800 From: lhlousek Subject: Re: [Elecraft] K1 Tuning Knob - F To: n9ik at qsl.net, elecraft at mailman.qth.net For a photo of another low profile K1 knob job check out http://home.nvbell.net/lhlousek/K1knobsm.jpg This is a modification of the standard K1 knob that removes the sharp ridge and decreases the height of the knob. Shaft is cut down and the pot is set back from the front panel with and additional washer to allow the knob to sit very close to the panel. The pot is the Bourns 3540S series (Mouser 652-3540S-1-104, $13.50) which eliminates shaft wobble and sponginess. The pot is also stronger than the stock pot and can't have it's back pushed out. Lou W7DZN ++++++++++++++++++++