Re: [Elecraft] [K2] VCO Not Oscillating
Hey, I wanted to let you guys know that the root cause has been found. I asked Don to look at the radio and the root cause was that I had misplaced a 1pF cap at C68 which was labeled 1D. C68 was supposed to be 10pF. It was a stupid construction mistake after all. Perhaps this can serve as a nice data point for anyone else building the K2 that has a similar problem. I will be getting the radio back soon and hope to finish the kit without incident. Thanks, Joseph KI4ITG -- View this message in context: http://elecraft.365791.n2.nabble.com/K2-VCO-Not-Oscillating-tp7588086p7588948.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
[Elecraft] [K2] VCO Not Oscillating
We did make similar mistakes throught out our hobby. Wrong parts, wrong components at wrong places are always the problems. Even I built the 10th K2, I still made mistakes. 73 Johnny VR2XMC 寄件人︰ Joseph Baxley via Elecraft elecraft@mailman.qth.net 收件人︰ elecraft@mailman.qth.net 傳送日期︰ 2014年05月12日 (週一) 11:59 AM 主題︰ Re: [Elecraft] [K2] VCO Not Oscillating Hey, I wanted to let you guys know that the root cause has been found. I asked Don to look at the radio and the root cause was that I had misplaced a 1pF cap at C68 which was labeled 1D. C68 was supposed to be 10pF. It was a stupid construction mistake after all. Perhaps this can serve as a nice data point for anyone else building the K2 that has a similar problem. I will be getting the radio back soon and hope to finish the kit without incident. Thanks, Joseph KI4ITG -- View this message in context: http://elecraft.365791.n2.nabble.com/K2-VCO-Not-Oscillating-tp7588086p7588948.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net/ Please help support this email list: http://www.qsl.net/donate.html Message delivered to vr2...@yahoo.com.hk __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K2] VCO Not Oscillating
Don, Matt, It is possible that I've mislabeled things, though I was trying to follow the diagram they have before the schematics that describes each part. Really I've not got a lot of experience with electronics beyond a couple of classes in college. It's not something they stressed in the physics department unfortunately. That's part of why I'm building the rig. It's an educational experience :) I did wind up trying another J310 that I lifted out of the KIO2 option board I purchased with no luck. I have also ran over all the components in the synthesizer looking for correct value and orientation. I did not find anything out of the ordinary. At this point I am thinking of asking if the fellows at Elecraft in California will look at it. If I have to pull too many parts I'd be afraid of damaging the RF board. Once I get past this part of assembly, I should be fine to finish the rig. Thanks, Joseph -- View this message in context: http://elecraft.365791.n2.nabble.com/K2-VCO-Not-Oscillating-tp7588086p7588437.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K2] VCO Not Oscillating
P.S. I really would like to thank you all for your help. -- View this message in context: http://elecraft.365791.n2.nabble.com/K2-VCO-Not-Oscillating-tp7588086p7588438.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K2] VCO Not Oscillating
Hi Joseph, Just taking a closer look at the voltages you reported on Q16, Q17 Q18: Q17 should be a 2N7000 MOSFET, but the measurements you provided talk about Base, Emitter and Collector (rather than Gate, Source and Drain). Also, the Drain of Q17 has a DC connection to the Source of Q18. You report the Source of Q18 as being 6.64V, but if there is no oscillation then this isn't consistent with the voltages you reported on Q17. Can you maybe check you have used the right transistors, verify the orientation/pin outs, and recheck that the voltages you are reporting against each transistor and each transistor terminal are correct? Somehow something doesn't quite seem to add up with what you reported below :-) Another obvious thing is to verify is the orientation of ICs U3 and U4. 73, Matt VK2RQ On 29 Apr 2014, at 10:22 am, Joseph Baxley via Elecraft elecraft@mailman.qth.net wrote: Hi, I've been trying for the last four days to figure out what is wrong with my rig. I'm at Phase 2 Test and Alignment and got to testing the frequency of the VCO. It had a reading of 0. Also the voltage on R30 was 7.87V. This is consistent with the VCO not oscillating. The reference oscillator works fine and was within the expected ranges when I looked at it. What I was able to notice was that U4 on the RF board has two pins with voltage values that are out of spec. Pin 1 has 0.9V and pin 13 has 0V. If I read the table they should be 2.1 and 4V respectively. It also seems that the 0V on pin 13 is causing a 0V reading on pin 6 of U6. Otherwise U6 is in spec. I got out my oscilloscope and got a Vrms of 1.13V on U4 pin 1. There wasn't anything on pins 3 or 6 of U3. The voltages for Q17, Q16, and Q18 are as follows: Q17 E: 0V B: 7.13V C: 0.08V Q16 E: 0V B: 0V C: 7.13V Q18 G: 0.08V S: 6.64V D: 0V I have been measuring and testing voltages and components for the last four days and have run out of things to look at for the moment. If any of you can help me with what my problem is, I would be most grateful. Sincerely, Joseph KI4ITG -- View this message in context: http://elecraft.365791.n2.nabble.com/K2-VCO-Not-Oscillating-tp7588086.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to matt.vk...@gmail.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K2] VCO Not Oscillating
Matt, My reason for asserting that the VCO is not oscillating is two-fold. One, there is no frequency at TP1 when I touch it with the probe, but there is when I touch TP2 and TP3. Both of these test points show a correct oscillation of 4.9MHz and 12.09MHz respectively. Second, when I applied my voltmeter to R30 and tried turn the slug for L30 there was no change in the voltage at R30. I will recheck both of these assertions. I looked over my notes for Q17 and realized that I had them mis-labeled when I wrote the first email in this chain. Looking at the notes I have with me the labeling is S: 0V, G: 7.14V, and D: 0.08V. I will of course check these again when I go back to work on the radio as well as the part types, though I'm fairly certain they are correct. I'm taking the night off though. Also, I did check U3 and U4 over several times and recall them being in the correct orientation. Will look again here as well. The action plan for tomorrow is to double check all components in the VCO for correct value and orientation and then to re-heat the solder joints on them. Hopefully it will be something simple and stupid like a misplaced part or a cold joint. Thanks, Joseph -- View this message in context: http://elecraft.365791.n2.nabble.com/K2-VCO-Not-Oscillating-tp7588086p7588251.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K2] VCO Not Oscillating
Ok, that makes more sense now, although we now have the Drain of Q17 at 0.08V connected to the Source of Q18 at 6.64V via the primary (green) winding of T5. I would hazzard a guess that there is also a clerical error with the Q18 voltages, and that the Source is at 0.08V, same as the Drain of Q17, the Gate of Q18 is at 0V, and the Source of Q18 is at 6.67V. The alternative would be that the T5 primary winding is open circuit, but then the other voltages wouldn't make sense. There is minimal ALC voltage on Q17 Drain, so this supports your conclusion that the VCO is not oscillating, although it could also be that either Q16 or the U3 buffer is not working. An RF probe to pin 3 of the U3 buffer will tell you if there is any signal there. You might check that all the variactor diodes are in the right way (D21-D26) and the right type (D21 D22 are 1SV149, D23 D24 are MV209) and that L30 is ok (no red line, large adjustment slot). You could perhaps try changing bands to toggle the K13/K14/K15 relays to isolate the associated components and see if the VCO starts oscillating. As you say, if any joints look suspect, reflowing them is not a bad idea. Good luck, let us know how you go. 73, Matt VK2RQ The most exciting phrase to hear in science, the one that heralds new discoveries, is not 'Eureka!' but 'That's funny...' -- Isaac Asimov On Thu, May 1, 2014 at 11:59 AM, Joseph Baxley via Elecraft elecraft@mailman.qth.net wrote: Matt, My reason for asserting that the VCO is not oscillating is two-fold. One, there is no frequency at TP1 when I touch it with the probe, but there is when I touch TP2 and TP3. Both of these test points show a correct oscillation of 4.9MHz and 12.09MHz respectively. Second, when I applied my voltmeter to R30 and tried turn the slug for L30 there was no change in the voltage at R30. I will recheck both of these assertions. I looked over my notes for Q17 and realized that I had them mis-labeled when I wrote the first email in this chain. Looking at the notes I have with me the labeling is S: 0V, G: 7.14V, and D: 0.08V. I will of course check these again when I go back to work on the radio as well as the part types, though I'm fairly certain they are correct. I'm taking the night off though. Also, I did check U3 and U4 over several times and recall them being in the correct orientation. Will look again here as well. The action plan for tomorrow is to double check all components in the VCO for correct value and orientation and then to re-heat the solder joints on them. Hopefully it will be something simple and stupid like a misplaced part or a cold joint. Thanks, Joseph -- View this message in context: http://elecraft.365791.n2.nabble.com/K2-VCO-Not-Oscillating-tp7588086p7588251.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to matt.vk...@gmail.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K2] VCO Not Oscillating
Joseph, I don't know if you are mislabeling the leads of Q18 or not, but those voltages and the leads do not make sense. The Drain of Q18 is connected to the 8B voltage rail through a 33 ohm resistor and should have almost 8 volts on it. The Gate is biased by the rectification of the RF voltage by D13, and when oscillating should have a negative voltage (the fact that you show no negative voltage says Q18 is not oscillating). The Q18 Source would normally have 2 to 3 volts on it, but since Q18 is not oscillating, there is no VFO RF being applied to D11, and that means Q18 will not conduct - that places the gate of Q17 at a high voltage and saturates the Drain to Source of Q18 which will produce 0 volts at the Q18 Source. Refer to the Schematic Key page in the back of the manual for the proper lead callouts for the J310 transistor. In other words, Q18 is simply not oscillating for you. Look at the schematic for the RF board Sheet 1 in the upper right quadrant. Check each component shown there for proper values and good soldering. Make certain Q18, Q17, and Q16 are oriented correctly and diodes D11, D8 and D13 are oriented correctly (look at the Parts Placement Diagram in the back of the manual). Be certain varactors D21 thru D26 are oriented correctly. If it still does not oscillate, rewind T5 being especially careful to make it look exactly like the diagram in the manual and make certain the leads are well stripped and tinned before installing it onto the board. If all that is correct, it will oscillate at some frequency. If the frequency is not correct, that is a different matter, but if everything above is correct, it will oscillate. You could try another J310 at Q18. There is one that should not be mounted yet in your build which would eventually be used at Q24. If that fixes the VFO, ask pa...@elecraft.com for a replacement J310. 73, Don W3FPR On 4/30/2014 11:44 PM, Matt Maguire wrote: Ok, that makes more sense now, although we now have the Drain of Q17 at 0.08V connected to the Source of Q18 at 6.64V via the primary (green) winding of T5. I would hazzard a guess that there is also a clerical error with the Q18 voltages, and that the Source is at 0.08V, same as the Drain of Q17, the Gate of Q18 is at 0V, and the Source of Q18 is at 6.67V. The alternative would be that the T5 primary winding is open circuit, but then the other voltages wouldn't make sense. There is minimal ALC voltage on Q17 Drain, so this supports your conclusion that the VCO is not oscillating, although it could also be that either Q16 or the U3 buffer is not working. An RF probe to pin 3 of the U3 buffer will tell you if there is any signal there. You might check that all the variactor diodes are in the right way (D21-D26) and the right type (D21 D22 are 1SV149, D23 D24 are MV209) and that L30 is ok (no red line, large adjustment slot). You could perhaps try changing bands to toggle the K13/K14/K15 relays to isolate the associated components and see if the VCO starts oscillating. As you say, if any joints look suspect, reflowing them is not a bad idea. Good luck, let us know how you go. 73, Matt VK2RQ The most exciting phrase to hear in science, the one that heralds new discoveries, is not 'Eureka!' but 'That's funny...' -- Isaac Asimov On Thu, May 1, 2014 at 11:59 AM, Joseph Baxley via Elecraft elecraft@mailman.qth.net wrote: Matt, My reason for asserting that the VCO is not oscillating is two-fold. One, there is no frequency at TP1 when I touch it with the probe, but there is when I touch TP2 and TP3. Both of these test points show a correct oscillation of 4.9MHz and 12.09MHz respectively. Second, when I applied my voltmeter to R30 and tried turn the slug for L30 there was no change in the voltage at R30. I will recheck both of these assertions. I looked over my notes for Q17 and realized that I had them mis-labeled when I wrote the first email in this chain. Looking at the notes I have with me the labeling is S: 0V, G: 7.14V, and D: 0.08V. I will of course check these again when I go back to work on the radio as well as the part types, though I'm fairly certain they are correct. I'm taking the night off though. Also, I did check U3 and U4 over several times and recall them being in the correct orientation. Will look again here as well. The action plan for tomorrow is to double check all components in the VCO for correct value and orientation and then to re-heat the solder joints on them. Hopefully it will be something simple and stupid like a misplaced part or a cold joint. Thanks, Joseph __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K2] VCO Not Oscillating
Don, Matt, I looked at the transformer and have double checked him. I saw that there was electrical continuity between leads 1 2 and 3 4 (i.e. zero Ohm resistance between said leads). Also, 3 4 are the green leads. I checked that the green wires weren't crossing and that they were spaced each turn between the red wires. I did notice that they weren't exactly centered, with more red turns before lead three than after lead four. I pulled the transformer out and rewound the green wires to center them and see if it helped any. No dice. Also I checked the number of turns, 16 red and 4 green. I'm intimately familiar with not having properly stripped the wires. That was a problem building my K1! I'm fairly certain then that the transformer is not the problem. I've been checking things like the diodes that run through the VCO to make sure that I have not put in one backwards. I've also been looking for cold joints or solder bridges. Haven't found one yet. Thanks, Joseph -- View this message in context: http://elecraft.365791.n2.nabble.com/K2-VCO-Not-Oscillating-tp7588086p7588156.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K2] VCO Not Oscillating
Joseph, See if the VFO is oscillating. Check the internal counter probe by plugging it into TP2 and use menu CAL FCTR - you should see a frequency near 4913 kHz (the BFO frequency). If that is good, the counter probe should be working. Then plug the probe into TP1. The frequency should be near the K2 dial frequency plus 4913 kHz. If you see that frequency, all is OK with the VFO. If you instead see all zeros, the VFO is not oscillating, and you will have to figure out why. You have already checked the winding of T5, so there may be something else. Check the orientation of D13 and D8 as starters. Then eliminate the VFO ALC from the picture by placing a short from the drsin og Q17 to ground (a convenient place to do that is to put a temporary solder bridge across the leads of C50). Do you get a VFO frequency reading with that in place? If so check the soldering of the VFO ALC components. Look on the schematic and find on sheet 1 for the RF Board all the components in the area labeled VFO ALC and check the soldering of all those components - remove the solder bridge from C50 and see if it still oscillates. If it does, you should be on your way to success. 73, Don W3FPR On 4/29/2014 9:13 PM, Joseph Baxley via Elecraft wrote: Don, Matt, I looked at the transformer and have double checked him. I saw that there was electrical continuity between leads 1 2 and 3 4 (i.e. zero Ohm resistance between said leads). Also, 3 4 are the green leads. I checked that the green wires weren't crossing and that they were spaced each turn between the red wires. I did notice that they weren't exactly centered, with more red turns before lead three than after lead four. I pulled the transformer out and rewound the green wires to center them and see if it helped any. No dice. Also I checked the number of turns, 16 red and 4 green. I'm intimately familiar with not having properly stripped the wires. That was a problem building my K1! I'm fairly certain then that the transformer is not the problem. I've been checking things like the diodes that run through the VCO to make sure that I have not put in one backwards. I've also been looking for cold joints or solder bridges. Haven't found one yet. Thanks, Joseph -- View this message in context: http://elecraft.365791.n2.nabble.com/K2-VCO-Not-Oscillating-tp7588086p7588156.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to w3...@embarqmail.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K2] VCO Not Oscillating
Don, Thanks again. I had one question from your last email. Did you mean C60? I couldn't find C50 in the VFO circuit. I shorted C60 which put the drain to ground. Still no help. The BFO is working though, so that's good news. I also checked D13 and D8. They match the outline on the board, so they should be good. I will try again tomorrow when I've had some rest. Sometimes I've found fresh eyes help me see things I missed the night before. Joseph On Tuesday, April 29, 2014 9:15 PM, Don Wilhelm-4 [via Elecraft] ml-node+s365791n7588159...@n2.nabble.com wrote: Joseph, See if the VFO is oscillating. Check the internal counter probe by plugging it into TP2 and use menu CAL FCTR - you should see a frequency near 4913 kHz (the BFO frequency). If that is good, the counter probe should be working. Then plug the probe into TP1. The frequency should be near the K2 dial frequency plus 4913 kHz. If you see that frequency, all is OK with the VFO. If you instead see all zeros, the VFO is not oscillating, and you will have to figure out why. You have already checked the winding of T5, so there may be something else. Check the orientation of D13 and D8 as starters. Then eliminate the VFO ALC from the picture by placing a short from the drsin og Q17 to ground (a convenient place to do that is to put a temporary solder bridge across the leads of C50). Do you get a VFO frequency reading with that in place? If so check the soldering of the VFO ALC components. Look on the schematic and find on sheet 1 for the RF Board all the components in the area labeled VFO ALC and check the soldering of all those components - remove the solder bridge from C50 and see if it still oscillates. If it does, you should be on your way to success. 73, Don W3FPR On 4/29/2014 9:13 PM, Joseph Baxley via Elecraft wrote: Don, Matt, I looked at the transformer and have double checked him. I saw that there was electrical continuity between leads 1 2 and 3 4 (i.e. zero Ohm resistance between said leads). Also, 3 4 are the green leads. I checked that the green wires weren't crossing and that they were spaced each turn between the red wires. I did notice that they weren't exactly centered, with more red turns before lead three than after lead four. I pulled the transformer out and rewound the green wires to center them and see if it helped any. No dice. Also I checked the number of turns, 16 red and 4 green. I'm intimately familiar with not having properly stripped the wires. That was a problem building my K1! I'm fairly certain then that the transformer is not the problem. I've been checking things like the diodes that run through the VCO to make sure that I have not put in one backwards. I've also been looking for cold joints or solder bridges. Haven't found one yet. Thanks, Joseph -- View this message in context: http://elecraft.365791.n2.nabble.com/K2-VCO-Not-Oscillating-tp7588086p7588156.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] If you reply to this email, your message will be added to the discussion below:http://elecraft.365791.n2.nabble.com/K2-VCO-Not-Oscillating-tp7588086p7588159.html To unsubscribe from [K2] VCO Not Oscillating, click here. NAML -- View this message in context: http://elecraft.365791.n2.nabble.com/K2-VCO-Not-Oscillating-tp7588086p7588160.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K2] VCO Not Oscillating
Joseph, Blame it on poor lighting at the computer (and my eyes) - yes, C60 is the appropriate capacitor. So the VFO ALC is not the problem - you will have to discover why the VFO is not oscillating. It could be a problem with Q18 or anything in its circuit. Do check Q18 for the correct FET type (J310) and the orientation of D13 and D8 - refer to the parts placement diagram in the back of the manual for the diode orientation. 73, Don W3FPR On 4/29/2014 10:51 PM, Joseph Baxley via Elecraft wrote: Don, Thanks again. I had one question from your last email. Did you mean C60? I couldn't find C50 in the VFO circuit. I shorted C60 which put the drain to ground. Still no help. The BFO is working though, so that's good news. I also checked D13 and D8. They match the outline on the board, so they should be good. I will try again tomorrow when I've had some rest. Sometimes I've found fresh eyes help me see things I missed the night before. Joseph On Tuesday, April 29, 2014 9:15 PM, Don Wilhelm-4 [via Elecraft] ml-node+s365791n7588159...@n2.nabble.com wrote: Joseph, See if the VFO is oscillating. Check the internal counter probe by plugging it into TP2 and use menu CAL FCTR - you should see a frequency near 4913 kHz (the BFO frequency). If that is good, the counter probe should be working. Then plug the probe into TP1. The frequency should be near the K2 dial frequency plus 4913 kHz. If you see that frequency, all is OK with the VFO. If you instead see all zeros, the VFO is not oscillating, and you will have to figure out why. You have already checked the winding of T5, so there may be something else. Check the orientation of D13 and D8 as starters. Then eliminate the VFO ALC from the picture by placing a short from the drsin og Q17 to ground (a convenient place to do that is to put a temporary solder bridge across the leads of C50). Do you get a VFO frequency reading with that in place? If so check the soldering of the VFO ALC components. Look on the schematic and find on sheet 1 for the RF Board all the components in the area labeled VFO ALC and check the soldering of all those components - remove the solder bridge from C50 and see if it still oscillates. If it does, you should be on your way to success. 73, Don W3FPR On 4/29/2014 9:13 PM, Joseph Baxley via Elecraft wrote: Don, Matt, I looked at the transformer and have double checked him. I saw that there was electrical continuity between leads 1 2 and 3 4 (i.e. zero Ohm resistance between said leads). Also, 3 4 are the green leads. I checked that the green wires weren't crossing and that they were spaced each turn between the red wires. I did notice that they weren't exactly centered, with more red turns before lead three than after lead four. I pulled the transformer out and rewound the green wires to center them and see if it helped any. No dice. Also I checked the number of turns, 16 red and 4 green. I'm intimately familiar with not having properly stripped the wires. That was a problem building my K1! I'm fairly certain then that the transformer is not the problem. I've been checking things like the diodes that run through the VCO to make sure that I have not put in one backwards. I've also been looking for cold joints or solder bridges. Haven't found one yet. Thanks, Joseph -- View this message in context: http://elecraft.365791.n2.nabble.com/K2-VCO-Not-Oscillating-tp7588086p7588156.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] If you reply to this email, your message will be added to the discussion below:http://elecraft.365791.n2.nabble.com/K2-VCO-Not-Oscillating-tp7588086p7588159.html To unsubscribe from [K2] VCO Not Oscillating, click here. NAML -- View this message in context: http://elecraft.365791.n2.nabble.com/K2-VCO-Not-Oscillating-tp7588086p7588160.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list:
[Elecraft] [K2] VCO Not Oscillating
Hi, I've been trying for the last four days to figure out what is wrong with my rig. I'm at Phase 2 Test and Alignment and got to testing the frequency of the VCO. It had a reading of 0. Also the voltage on R30 was 7.87V. This is consistent with the VCO not oscillating. The reference oscillator works fine and was within the expected ranges when I looked at it. What I was able to notice was that U4 on the RF board has two pins with voltage values that are out of spec. Pin 1 has 0.9V and pin 13 has 0V. If I read the table they should be 2.1 and 4V respectively. It also seems that the 0V on pin 13 is causing a 0V reading on pin 6 of U6. Otherwise U6 is in spec. I got out my oscilloscope and got a Vrms of 1.13V on U4 pin 1. There wasn't anything on pins 3 or 6 of U3. The voltages for Q17, Q16, and Q18 are as follows: Q17 E: 0V B: 7.13V C: 0.08V Q16 E: 0V B: 0V C: 7.13V Q18 G: 0.08V S: 6.64V D: 0V I have been measuring and testing voltages and components for the last four days and have run out of things to look at for the moment. If any of you can help me with what my problem is, I would be most grateful. Sincerely, Joseph KI4ITG -- View this message in context: http://elecraft.365791.n2.nabble.com/K2-VCO-Not-Oscillating-tp7588086.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K2] VCO Not Oscillating
Joseph, The first thing to check is T5. The direction of the windings is critical, and the leads must be in the proper holes as shown in the diagrams in the manual. In other words, the sense (direction) of the green wire turns on T5 must be the same as the direction of the red wire winding. If that is correct, the VCO will oscillate, and things usually fall 'into line' after that once L30 is adjusted for the proper voltage at the left end of R30. 73, Don W3FPR On 4/28/2014 8:22 PM, Joseph Baxley via Elecraft wrote: Hi, I've been trying for the last four days to figure out what is wrong with my rig. I'm at Phase 2 Test and Alignment and got to testing the frequency of the VCO. It had a reading of 0. Also the voltage on R30 was 7.87V. This is consistent with the VCO not oscillating. The reference oscillator works fine and was within the expected ranges when I looked at it. What I was able to notice was that U4 on the RF board has two pins with voltage values that are out of spec. Pin 1 has 0.9V and pin 13 has 0V. If I read the table they should be 2.1 and 4V respectively. It also seems that the 0V on pin 13 is causing a 0V reading on pin 6 of U6. Otherwise U6 is in spec. I got out my oscilloscope and got a Vrms of 1.13V on U4 pin 1. There wasn't anything on pins 3 or 6 of U3. The voltages for Q17, Q16, and Q18 are as follows: Q17 E: 0V B: 7.13V C: 0.08V Q16 E: 0V B: 0V C: 7.13V Q18 G: 0.08V S: 6.64V D: 0V I have been measuring and testing voltages and components for the last four days and have run out of things to look at for the moment. If any of you can help me with what my problem is, I would be most grateful. Sincerely, Joseph KI4ITG -- View this message in context: http://elecraft.365791.n2.nabble.com/K2-VCO-Not-Oscillating-tp7588086.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to w3...@embarqmail.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K2] VCO Not Oscillating
Don, Thanks for the reply. I should have mentioned that I checked the windings on T5. Pins 1 and 3 should be coming out of the top of the core, no? That's what I have. I also used the yellow core for the transformer. Thanks, Joseph On Monday, April 28, 2014 8:43 PM, Don Wilhelm-4 [via Elecraft] ml-node+s365791n7588092...@n2.nabble.com wrote: Joseph, The first thing to check is T5. The direction of the windings is critical, and the leads must be in the proper holes as shown in the diagrams in the manual. In other words, the sense (direction) of the green wire turns on T5 must be the same as the direction of the red wire winding. If that is correct, the VCO will oscillate, and things usually fall 'into line' after that once L30 is adjusted for the proper voltage at the left end of R30. 73, Don W3FPR On 4/28/2014 8:22 PM, Joseph Baxley via Elecraft wrote: Hi, I've been trying for the last four days to figure out what is wrong with my rig. I'm at Phase 2 Test and Alignment and got to testing the frequency of the VCO. It had a reading of 0. Also the voltage on R30 was 7.87V. This is consistent with the VCO not oscillating. The reference oscillator works fine and was within the expected ranges when I looked at it. What I was able to notice was that U4 on the RF board has two pins with voltage values that are out of spec. Pin 1 has 0.9V and pin 13 has 0V. If I read the table they should be 2.1 and 4V respectively. It also seems that the 0V on pin 13 is causing a 0V reading on pin 6 of U6. Otherwise U6 is in spec. I got out my oscilloscope and got a Vrms of 1.13V on U4 pin 1. There wasn't anything on pins 3 or 6 of U3. The voltages for Q17, Q16, and Q18 are as follows: Q17 E: 0V B: 7.13V C: 0.08V Q16 E: 0V B: 0V C: 7.13V Q18 G: 0.08V S: 6.64V D: 0V I have been measuring and testing voltages and components for the last four days and have run out of things to look at for the moment. If any of you can help me with what my problem is, I would be most grateful. Sincerely, Joseph KI4ITG -- View this message in context: http://elecraft.365791.n2.nabble.com/K2-VCO-Not-Oscillating-tp7588086.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] If you reply to this email, your message will be added to the discussion below:http://elecraft.365791.n2.nabble.com/K2-VCO-Not-Oscillating-tp7588086p7588092.html To unsubscribe from [K2] VCO Not Oscillating, click here. NAML -- View this message in context: http://elecraft.365791.n2.nabble.com/K2-VCO-Not-Oscillating-tp7588086p7588093.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K2] VCO Not Oscillating
Yes, leads 1 3 should come out the top of the core. However, you also need to make sure the windings are in the same direction, like in figure 6-16, otherwise you are applying negative instead of positive feedback, and the VCO won't oscillate. Also, make sure leads 1 2 are both red, and go through the core for 16 turns. Leads 3 4 should both be green, and consist of 4 turns. If you get the windings backwards, then the feedback loop won't have sufficient gain, and the VCO won't oscillate. Finally, the other problem that can occur with toroids is that the insulation on the magnet wire wasn't stripped back enough, and there is a poor joint. If this happens, the VCO won't oscillate :-) There are other reasons why the VCO may not oscillate (eg. loading due to solder bridges, components in backwards etc.), but toroids in particular can be quite tricky and confusing, which is why Don suggests to look there first. 73, Matt VK2RQ On 29 Apr 2014, at 11:56 am, Joseph Baxley via Elecraft elecraft@mailman.qth.net wrote: Don, Thanks for the reply. I should have mentioned that I checked the windings on T5. Pins 1 and 3 should be coming out of the top of the core, no? That's what I have. I also used the yellow core for the transformer. Thanks, Joseph On Monday, April 28, 2014 8:43 PM, Don Wilhelm-4 [via Elecraft] ml-node+s365791n7588092...@n2.nabble.com wrote: Joseph, The first thing to check is T5. The direction of the windings is critical, and the leads must be in the proper holes as shown in the diagrams in the manual. In other words, the sense (direction) of the green wire turns on T5 must be the same as the direction of the red wire winding. If that is correct, the VCO will oscillate, and things usually fall 'into line' after that once L30 is adjusted for the proper voltage at the left end of R30. 73, Don W3FPR On 4/28/2014 8:22 PM, Joseph Baxley via Elecraft wrote: Hi, I've been trying for the last four days to figure out what is wrong with my rig. I'm at Phase 2 Test and Alignment and got to testing the frequency of the VCO. It had a reading of 0. Also the voltage on R30 was 7.87V. This is consistent with the VCO not oscillating. The reference oscillator works fine and was within the expected ranges when I looked at it. What I was able to notice was that U4 on the RF board has two pins with voltage values that are out of spec. Pin 1 has 0.9V and pin 13 has 0V. If I read the table they should be 2.1 and 4V respectively. It also seems that the 0V on pin 13 is causing a 0V reading on pin 6 of U6. Otherwise U6 is in spec. I got out my oscilloscope and got a Vrms of 1.13V on U4 pin 1. There wasn't anything on pins 3 or 6 of U3. The voltages for Q17, Q16, and Q18 are as follows: Q17 E: 0V B: 7.13V C: 0.08V Q16 E: 0V B: 0V C: 7.13V Q18 G: 0.08V S: 6.64V D: 0V I have been measuring and testing voltages and components for the last four days and have run out of things to look at for the moment. If any of you can help me with what my problem is, I would be most grateful. Sincerely, Joseph KI4ITG -- View this message in context: http://elecraft.365791.n2.nabble.com/K2-VCO-Not-Oscillating-tp7588086.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] If you reply to this email, your message will be added to the discussion below:http://elecraft.365791.n2.nabble.com/K2-VCO-Not-Oscillating-tp7588086p7588092.html To unsubscribe from [K2] VCO Not Oscillating, click here. NAML -- View this message in context: http://elecraft.365791.n2.nabble.com/K2-VCO-Not-Oscillating-tp7588086p7588093.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to
Re: [Elecraft] [K2] VCO Not Oscillating
Joseph, Yes, leads 1 and 3 should be coming out of the top of the core, but the leads must look like the illustration on page 56 of the manual, the green wires must not cross over each other, but be wound between the red wires. You can check with the internal counter probe or the RF Probe to see if the VCO is oscillating. Make certain that the leads of T5 have been well stripped and tinned before inserting and soldering the leads. If you look at the solder connections and see a ring around the toroid lead, it was not well tinned and soldered. In other words, the connection should look like a mountain, but not a volcano. 73, Don W3FPR On 4/28/2014 9:56 PM, Joseph Baxley via Elecraft wrote: Don, Thanks for the reply. I should have mentioned that I checked the windings on T5. Pins 1 and 3 should be coming out of the top of the core, no? That's what I have. I also used the yellow core for the transformer. Thanks, Joseph On Monday, April 28, 2014 8:43 PM, Don Wilhelm-4 [via Elecraft] ml-node+s365791n7588092...@n2.nabble.com wrote: Joseph, The first thing to check is T5. The direction of the windings is critical, and the leads must be in the proper holes as shown in the diagrams in the manual. In other words, the sense (direction) of the green wire turns on T5 must be the same as the direction of the red wire winding. If that is correct, the VCO will oscillate, and things usually fall 'into line' after that once L30 is adjusted for the proper voltage at the left end of R30. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
