+++++++++++++++++++++++++++++++++++++ Date: Fri, 11 May 2001 19:54:59 -0400 From: "Morrow, Michael A." Subject: RE: [Elecraft] K1 VFO problem. Joe, you wrote: > Been getting too little lead in my diet so I am building a K1. But the > display is indicating it is too low. The oscillator is fine, and runs > between 309 and 214. > I don't understand these numbers. The VFO output, from the OPF function, when the pot is fully CCW should be about 3090 (or a little higher). When the VFO pot is fully CW, the VFO output should be about 2925 (or a little lower) if you're using the 165 kHz tuning option, or about 3010 (or a little lower) if you're using the 80 kHz tuning option. > However, when I plug the filter board in the display > reads between 6.774 and 6.869 MHz. 20 meters is the same, 13.xxx. > > Logic suggests the 4.015 crystals are funky. All 6 rocks are marked: > 4.91 - 0195. > The crystals are actually 4.915 kHz or there about. It is unlikely that there is any problem with them. I think you don't have the VFO tuning in the proper range. Try re-doing the adjustments as directed on manual page 38. You'll need to compress the turns on the VFO toroid L1 to lower its frequency. Because your K1 operating frequency is too LOW, the subtractive VFO seems to operating too HIGH. You may also have too few turns on the VFO toroid L1. Just as an aside, it may be of interest for comparison purposes to report the measured frequencies of the various oscillators within my K1 and how they combine to determine the actual operating frequency of the K1. This info will be posted in my next e-mail. 73, Mike / KK5F ++++++++++++++++++++++++++++++++++++++++ Date: Fri, 11 May 2001 19:54:59 -0400 From: "Morrow, Michael A." Subject: RE: [Elecraft] K1 VFO problem. Joe, you wrote: > Been getting too little lead in my diet so I am building a K1. But the > display is indicating it is too low. The oscillator is fine, and runs > between 309 and 214. > I don't understand these numbers. The VFO output, from the OPF function, when the pot is fully CCW should be about 3090 (or a little higher). When the VFO pot is fully CW, the VFO output should be about 2925 (or a little lower) if you're using the 165 kHz tuning option, or about 3010 (or a little lower) if you're using the 80 kHz tuning option. > However, when I plug the filter board in the display > reads between 6.774 and 6.869 MHz. 20 meters is the same, 13.xxx. > > Logic suggests the 4.015 crystals are funky. All 6 rocks are marked: > 4.91 - 0195. > The crystals are actually 4.915 kHz or there about. It is unlikely that there is any problem with them. I think you don't have the VFO tuning in the proper range. Try re-doing the adjustments as directed on manual page 38. You'll need to compress the turns on the VFO toroid L1 to lower its frequency. Because your K1 operating frequency is too LOW, the subtractive VFO seems to operating too HIGH. You may also have too few turns on the VFO toroid L1. Just as an aside, it may be of interest for comparison purposes to report the measured frequencies of the various oscillators within my K1 and how they combine to determine the actual operating frequency of the K1. This info will be posted in my next e-mail. 73, Mike / KK5F ++++++++++++++++++++++++++++++++++++++ Date: Sat, 12 May 2001 01:17:33 +0000 (/etc/localtime) From: Joe Reed Subject: RE: [Elecraft] K1 VFO problem. Thanks, Chalk that one up to operator failure :) Too much time in front of the computer screen and not enough time breathing solder fumes. If the brain was engaged I would have realized it was 3309 not 309. A subsequent "mashing" of the turns on L1 brought it right in line where it ought to be. Funny, the K2 went together without a hitch, but I stumbled on the K1. Live and learn. Joe N9JR On Fri, 11 May 2001, Morrow, Michael A. wrote: > Joe, you wrote: > > > Been getting too little lead in my diet so I am building a K1. But the > > display is indicating it is too low. The oscillator is fine, and runs > > between 309 and 214. > > > I don't understand these numbers. The VFO output, from the OPF function, > when the pot is fully CCW should be about 3090 (or a little higher). When > the VFO pot is fully CW, the VFO output should be about 2925 (or a little > lower) if you're using the 165 kHz tuning option, or about 3010 (or a little > lower) if you're using the 80 kHz tuning option. +++++++++++++++++++++++++++++++++++++++++ Date: Fri, 11 May 2001 22:24:03 -0500 From: "Andy Anderson" Subject: Re: [Elecraft] K1 VFO problem.. Well, I had two sets of numbers. Sri that I erased the first, erroneous set, but here are the ones that put me in the game: VFO Range test (pg 38) Paragraph 2: 3.089 Paragraph 4: Fully CW = 2910; fully CCW = 3093 (I selected 150 KHz option) Difference = 183 VFO Range Adjustment (p. 38): Paragraph 2: Squeezing and spreading L1 did not a number below 3100; it was something like 3105. SO, I pulled L1 and removed 1 turn, then reinstalled it. New reading = 3093 (therefore in limits). NOTE: The readings for the VFO Range test above are *after* I removed the L1 turn and reinstalled. There were originally different numbers, but I erased them and started over after the adjustment was not within limits. Anyway, I ended up with 32, not 33, turns on L1. After tightening L1 nylon screw, the reading changed to 3094 -- still well within limits. My crystals have the same marking. I was very careful (per the book) not to expose the xtal covers to more than 5 seconds of the iron when installing the ground wires. Hope this helps. Andy Anderson W5VCJ +++++++++++++++++++++++++++++++++++++++++++++++ Date: Sun, 03 Jun 2001 09:41:33 -0500 From: jjbbl at bellsouth.net Subject: [Elecraft] K1/L1 VFO problem To anyone: Help ! I have been stumped with the VFO range test for two weeks. I can not get the freq to adjust to the range in the manual. My readings with R1 fully CW are 4.117 to fully CCW 4.124Mhz. I have done all of the obvious at least three times. I've checked component placement, cold/no solder connections and adjusted the turns on L1 every which a way. Ive added two turns; removed a turn, compressed turns.....No Luck!! I have checked R1 linearity out of circuit and it's fine. I have the Bourns 3590S blue 10 turn pot and am using the ammendum sheet for wiring.The pot has several "dips" in it when tuning CW to CCW. The pot has several "dips" in it when tuning CW to CCW. Everyone of the voltage/resistance checks have passed except on pg 29, P1 pin 8 to grd. I read 5K, but after following the schematic this is not related. I'm getting very discouraged and I'm beginning to wonder if I should use this K1 for an aquarium ornament ! Can someone please help and talk me out of it !. Tnx, John, KD5EJA ++++++++++++++++++++++++++++++++++++++++++++++ Date: Sun, 3 Jun 2001 12:09:43 -0400 From: "John J. McDonough" Subject: Re: [Elecraft] K1/L1 VFO problem John If you think about what's going on, either you have too little capacitance or too little inductance. This could be a result of a soft varactor, a slightly off core for L1 or some similar problem, or the varactor is not seeing an appropriate voltage range. The narrow range you report makes the varactor very suspect. But other caps in the circuit could affect both the frequency and the range if they were way off. The first thing I would do is make sure that the voltage at RP2 pin 1 goes from 0 to 6 volts as the 10 turn pot is moved from end to end. If it doesn't, then find out why. I don't know exactly what the range should be for pin 2 of RP2, but it should also change with turning the VFO pot, and over almost as wide a range. If all this checks out, I'd replace C2 on the theory that it could be the problem (not real likely, tho, IMO), you probably have something in the 68-120pF range, or can get it real easily. I'd also look at C7 and C5 as potentials. Radio Shack has a package of ceramics over a pretty wide range for a couple of bucks. I wouldn't leave these in the circuit, but they would be adequate to tell if one of those caps is way off. (Disk ceramics are prone to microphonics and the VFO is exactly where you don't want this!) If all else fails, it's probably a bad varactor. You can't get one of these at the local Radio Shack though, so if you're as impatient as I am, you would probably try almost anything else first. Hope this helps 72/73 de WB8RCR http://members.home.com/wb8rcr/index.htm didileydadidah QRP-L #1446 Code Warriors #35 +++++++++++++++++++++++++++++++++++++ Date: Sat, 10 Nov 2001 08:49:52 -0800 From: lhlousek Subject: [Elecraft] K1 10 turn VFO pot The VFO knob on my K1 rocked and wobbled and it got worse with use. It had no significant effect on the performance but it certainly did not convey a level of refinement or quality commensurate with what lay behind the knob. The 10 turn pot supplied with the K1 is the Bourns plastic shaft/bushing 3590 series ($11.08). Bourns also makes a metal shaft/bushing version of the 3590 ($12.98). The radial play specification for the shaft is the same for both versions and I have heard that they have about the same subjective degree of wobble. The Bourns 3540S series ($13.50) has a metal shaft/bushing with about 1/2 the specified radial play of the 3590 series pots. I have one of these on my K1 and it feels like it has about the same play and wobble as the rotary encoder on the K2, i.e. very little. An additional benefit is that inward axial loads are supported by a retaining ring on the shaft that bears against the front of the bushing unlike in the 3590 where the load is borne by the rear of the housing. At least one K1 owner has had the back of the pot get punched out when the VFO knob was pushed or bumped while being transported in baggage. The 3540S should be much stronger. This pot seems to have a slightly greater "wirewound" feel to it than the 3590 series. That is, you can feel the wires through the knob a little more and hear the wiper as it rides over of the windings of the resistive element a little easier. IMO this is an acceptable tradeoff for the much more solid feeling knob. The prices above are single piece prices from the Mouser catalog. The Mouser stock number is 652-3540S-1-104. Lou W7DZN +++++++++++++++++++