[K2] No signal at TP1 during Alignment and Test Part 2
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[K2] No signal at TP1 during Alignment and Test Part 2
 
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Hello to the group!
I'm afraid I need to lean on your collective K2 troubleshooting expertise. After a long break I have finally made it to the Alignment and Test Part 2 of my build. Everything was going OK until I got to the VCO Test. I have no signal at TP1. I have tested this with the built in counter as well as an external counter. I have gone through some of the troubleshooting I could find online: The orientation of D13 and D8 look good I have checked the soldering at relays K13, K14 and K15 and the value of C72. I have checked the varactors at D21 through D26 and they are oriented properly I am nearly certain they are all the correct type I tested RFC15 in the circuit and could not get any continuity through it. When I pulled it out of the circuit it tested fine so I put it back in. I'm sure this is something basic I just dont understand. I know there is some more testing I can do with Q17 and Q18 (I did check that they are the right type and orientation I also check all the component values around Q18) Lets set that aside for just a second though... Here is where I think it gets a little weird. Looking at the schematic I followed it back to U4. When I compared the voltage table to what i was actually seeing on U4 I think I may have found my problem. According to the table pin 7 should have 0 Volts but i'm showing 4.8! It also shows that pin 13 should have 4 volts but I'm showing 0. All other pins are normal and match the chart. Following Pin 7 of U4 back to Pin 1 of U5 I see the same 4.8 volts. This is supposed to be a clock line so I'm confused where this sort of voltage would be comming from. I'm still new to alot of this and this is by far the most complex kit I've taken on so any and all help will be appreciated! Thanks and 73, Robert AD0TA -- === I could tell you a UDP joke, but you might not get it. === ______________________________________________________________ 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] |
Re: [K2] No signal at TP1 during Alignment and Test Part 2
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Robert,
Do you have a good signal at TP3? If so, ignore the PLL Reference oscillator and U4 for now. You need to get the VFO operating before doing anything else. Do the DC measurements a Q18. If you do not have a negative voltage at the gate, it is not oscillating. T5 is the most likely problem with the VFO. Make certain it is wound correctly and the leads are well stripped and tinned. If you see a ring around the lead (on the solder side), that lead was not adequately stripped and tinned. Both windings must be wound in the same direction. If all the above is correct, put a temporary jumper across C60 to disable the VFO ALC circuit. If it oscillates with the jumper in place, but not without it, replace Q17. If that still does not correct it, try replacing Q16. Be certain D11 is oriented correctly. Ignore the voltages on U4 pins 5, 6, and 7 - those are digital signals, and the manual lists the voltage for the active signal, not what you would typically measure with a DMM. If you look at them with a 'scope you can see pulses on those lines, and that should be sufficient for proper operation. RFC 15 also needs to be ignored until after you get the VFO operating. Once you get a VFO signal at TP1, then you can investigate the operation of U4. 73, Don W3FPR On 6/6/2017 9:47 PM, Robert Forster wrote: > Hello to the group! > > I'm afraid I need to lean on your collective K2 troubleshooting expertise. > After a long break I have finally made it to the Alignment and Test Part 2 > of my build. Everything was going OK until I got to the VCO Test. I have > no signal at TP1. I have tested this with the built in counter as well as > an external counter. I have gone through some of the troubleshooting I > could find online: > > The orientation of D13 and D8 look good > > I have checked the soldering at relays K13, K14 and K15 and the value of > C72. > > I have checked the varactors at D21 through D26 and they are oriented > properly I am nearly certain they are all the correct type > > I tested RFC15 in the circuit and could not get any continuity through it. > When I pulled it out of the circuit it tested fine so I put it back in. > I'm sure this is something basic I just dont understand. > > I know there is some more testing I can do with Q17 and Q18 (I did check > that they are the right type and orientation I also check all the component > values around Q18) Lets set that aside for just a second though... > > Here is where I think it gets a little weird. Looking at the schematic I > followed it back to U4. When I compared the voltage table to what i was > actually seeing on U4 I think I may have found my problem. According to > the table pin 7 should have 0 Volts but i'm showing 4.8! It also shows > that pin 13 should have 4 volts but I'm showing 0. All other pins are > normal and match the chart. > > Following Pin 7 of U4 back to Pin 1 of U5 I see the same 4.8 volts. > This is supposed to be a clock line so I'm confused where this sort of > voltage would be comming from. > > I'm still new to alot of this and this is by far the most complex kit I've > taken on so any and all help will be appreciated! > > Thanks and 73, > Robert > AD0TA > > > 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] |
Re: [K2] No signal at TP1 during Alignment and Test Part 2
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Hi Don and Group,
I got a bit of time to troubleshoot this evening. I do have a good signal at TP3 so I am ignoring the PLL and U4. I did the DC measurements at Q18 and found some issues. the gate shows as a negative polarity but at -.001 volts Source is .08 Drain is at 6.8 This should lead me to suspect T5 correct? the soldering on the underside of the board for T5 looks ok (no ring for these points but the topside of the board looks rough! I used the USB microscope and took some photos. Here: https://flic.kr/s/aHsm2aNdeG I'm thinking that after the VHF contest I should remove T5 and check the windings and re strip the ends and retin. Does this sound like an apropriate course of action? Oh and just for the hell of it I bypassed C60 with no effect either. Thanks again for all your help! 73, Robert AD0TA On Wed, Jun 7, 2017 at 6:33 AM, Don Wilhelm <[hidden email]> wrote: > Robert, > > Do you have a good signal at TP3? If so, ignore the PLL Reference > oscillator and U4 for now. > > You need to get the VFO operating before doing anything else. > Do the DC measurements a Q18. If you do not have a negative voltage at > the gate, it is not oscillating. > > T5 is the most likely problem with the VFO. Make certain it is wound > correctly and the leads are well stripped and tinned. If you see a ring > around the lead (on the solder side), that lead was not adequately stripped > and tinned. Both windings must be wound in the same direction. > > If all the above is correct, put a temporary jumper across C60 to disable > the VFO ALC circuit. If it oscillates with the jumper in place, but not > without it, replace Q17. If that still does not correct it, try replacing > Q16. Be certain D11 is oriented correctly. > > Ignore the voltages on U4 pins 5, 6, and 7 - those are digital signals, > and the manual lists the voltage for the active signal, not what you would > typically measure with a DMM. If you look at them with a 'scope you can > see pulses on those lines, and that should be sufficient for proper > operation. > > RFC 15 also needs to be ignored until after you get the VFO operating. > Once you get a VFO signal at TP1, then you can investigate the operation of > U4. > > 73, > Don W3FPR > > > On 6/6/2017 9:47 PM, Robert Forster wrote: > >> Hello to the group! >> >> I'm afraid I need to lean on your collective K2 troubleshooting expertise. >> After a long break I have finally made it to the Alignment and Test Part 2 >> of my build. Everything was going OK until I got to the VCO Test. I have >> no signal at TP1. I have tested this with the built in counter as well as >> an external counter. I have gone through some of the troubleshooting I >> could find online: >> >> The orientation of D13 and D8 look good >> >> I have checked the soldering at relays K13, K14 and K15 and the value of >> C72. >> >> I have checked the varactors at D21 through D26 and they are oriented >> properly I am nearly certain they are all the correct type >> >> I tested RFC15 in the circuit and could not get any continuity through it. >> When I pulled it out of the circuit it tested fine so I put it back in. >> I'm sure this is something basic I just dont understand. >> >> I know there is some more testing I can do with Q17 and Q18 (I did check >> that they are the right type and orientation I also check all the >> component >> values around Q18) Lets set that aside for just a second though... >> >> Here is where I think it gets a little weird. Looking at the schematic I >> followed it back to U4. When I compared the voltage table to what i was >> actually seeing on U4 I think I may have found my problem. According to >> the table pin 7 should have 0 Volts but i'm showing 4.8! It also shows >> that pin 13 should have 4 volts but I'm showing 0. All other pins are >> normal and match the chart. >> >> Following Pin 7 of U4 back to Pin 1 of U5 I see the same 4.8 volts. >> This is supposed to be a clock line so I'm confused where this sort of >> voltage would be comming from. >> >> I'm still new to alot of this and this is by far the most complex kit I've >> taken on so any and all help will be appreciated! >> >> Thanks and 73, >> Robert >> AD0TA >> >> >> >> -- === I could tell you a UDP joke, but you might not get it. === ______________________________________________________________ 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] |
Re: [K2] No signal at TP1 during Alignment and Test Part 2
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Robert,
Those voltages say the VFO is oscillating, but the DC voltage at the gate of Q18 indicates that either your DMM is dragging the voltage to a low level, or the oscillation is weak. If that is true, T5 is OK. I would suggest that you build up the RF Probe - parts are supplied with your K2 kit. Then go to Appendix E of the K2 manual and do the checks shown on pages 10 and the first part of page 11. If you have an oscilloscope with a 10X probe, do the same checks but the peak to peak voltage should be 2.8 times the expected RMS voltages. As always with new kits, check the soldering. Inadequate heat to flow the solder is a common source of failure to have circuits work correctly. Also check the value of components in the VFO circuit. I have repaired K2s where the only problem is that the builder did not identify the correct capacitors. For instance, C68 must be a 10pF capacitor. There is a 1pF capacitor in the kit which is marked 1D and can at first glance be interpreted as "10". 73, Don W3FPR On 6/8/2017 10:20 PM, Robert Forster wrote: > Hi Don and Group, > > I got a bit of time to troubleshoot this evening. > > I do have a good signal at TP3 so I am ignoring the PLL and U4. > > I did the DC measurements at Q18 and found some issues. > > the gate shows as a negative polarity but at -.001 volts > Source is .08 > Drain is at 6.8 > > This should lead me to suspect T5 correct? > the soldering on the underside of the board for T5 looks ok (no ring > for these points but the topside of the board looks rough! I used the > USB microscope and took some photos. > Here: https://flic.kr/s/aHsm2aNdeG > > ______________________________________________________________ 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] |
Re: [K2] No signal at TP1 during Alignment and Test Part 2
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In reply to this post by Robert Forster
It looks like classic PTTL (poorly tinned toroid leads) on T5.
Vic 4X6GP > On 9 Jun 2017, at 5:20, Robert Forster <[hidden email]> wrote: > > Hi Don and Group, > > I got a bit of time to troubleshoot this evening. > > I do have a good signal at TP3 so I am ignoring the PLL and U4. > > I did the DC measurements at Q18 and found some issues. > > the gate shows as a negative polarity but at -.001 volts > Source is .08 > Drain is at 6.8 > > This should lead me to suspect T5 correct? > the soldering on the underside of the board for T5 looks ok (no ring for > these points but the topside of the board looks rough! I used the USB > microscope and took some photos. > Here: https://flic.kr/s/aHsm2aNdeG > > I'm thinking that after the VHF contest I should remove T5 and check the > windings and re strip the ends and retin. Does this sound like an > apropriate course of action? > > Oh and just for the hell of it I bypassed C60 with no effect either. > > Thanks again for all your help! > > 73, > Robert > AD0TA > >> On Wed, Jun 7, 2017 at 6:33 AM, Don Wilhelm <[hidden email]> wrote: >> >> Robert, >> >> Do you have a good signal at TP3? If so, ignore the PLL Reference >> oscillator and U4 for now. >> >> You need to get the VFO operating before doing anything else. >> Do the DC measurements a Q18. If you do not have a negative voltage at >> the gate, it is not oscillating. >> >> T5 is the most likely problem with the VFO. Make certain it is wound >> correctly and the leads are well stripped and tinned. If you see a ring >> around the lead (on the solder side), that lead was not adequately stripped >> and tinned. Both windings must be wound in the same direction. >> >> If all the above is correct, put a temporary jumper across C60 to disable >> the VFO ALC circuit. If it oscillates with the jumper in place, but not >> without it, replace Q17. If that still does not correct it, try replacing >> Q16. Be certain D11 is oriented correctly. >> >> Ignore the voltages on U4 pins 5, 6, and 7 - those are digital signals, >> and the manual lists the voltage for the active signal, not what you would >> typically measure with a DMM. If you look at them with a 'scope you can >> see pulses on those lines, and that should be sufficient for proper >> operation. >> >> RFC 15 also needs to be ignored until after you get the VFO operating. >> Once you get a VFO signal at TP1, then you can investigate the operation of >> U4. >> >> 73, >> Don W3FPR >> >> >>> On 6/6/2017 9:47 PM, Robert Forster wrote: >>> >>> Hello to the group! >>> >>> I'm afraid I need to lean on your collective K2 troubleshooting expertise. >>> After a long break I have finally made it to the Alignment and Test Part 2 >>> of my build. Everything was going OK until I got to the VCO Test. I have >>> no signal at TP1. I have tested this with the built in counter as well as >>> an external counter. I have gone through some of the troubleshooting I >>> could find online: >>> >>> The orientation of D13 and D8 look good >>> >>> I have checked the soldering at relays K13, K14 and K15 and the value of >>> C72. >>> >>> I have checked the varactors at D21 through D26 and they are oriented >>> properly I am nearly certain they are all the correct type >>> >>> I tested RFC15 in the circuit and could not get any continuity through it. >>> When I pulled it out of the circuit it tested fine so I put it back in. >>> I'm sure this is something basic I just dont understand. >>> >>> I know there is some more testing I can do with Q17 and Q18 (I did check >>> that they are the right type and orientation I also check all the >>> component >>> values around Q18) Lets set that aside for just a second though... >>> >>> Here is where I think it gets a little weird. Looking at the schematic I >>> followed it back to U4. When I compared the voltage table to what i was >>> actually seeing on U4 I think I may have found my problem. According to >>> the table pin 7 should have 0 Volts but i'm showing 4.8! It also shows >>> that pin 13 should have 4 volts but I'm showing 0. All other pins are >>> normal and match the chart. >>> >>> Following Pin 7 of U4 back to Pin 1 of U5 I see the same 4.8 volts. >>> This is supposed to be a clock line so I'm confused where this sort of >>> voltage would be comming from. >>> >>> I'm still new to alot of this and this is by far the most complex kit I've >>> taken on so any and all help will be appreciated! >>> >>> Thanks and 73, >>> Robert >>> AD0TA >>> >>> >>> >>> > > > -- > === > I could tell you a UDP joke, but you might not get it. > === > ______________________________________________________________ > 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] |
Re: [K2] No signal at TP1 during Alignment and Test Part 2
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In reply to this post by Robert Forster
Robert,
I just now had time to look at your photos. It seems to me that your solder on T5 (and maybe elsewhere) looks like "balls" with convex sides. That is indicitive of a solder connection that has not received enough heat. A good solder connection should have a slight fillet and end up with obvious solder that has flowed out entirely onto the solder pad and also up onto the leads. The edges of the solder should taper out to an almost invisible edge with a concave fillet of solder between the pad and the lead. See the diagrams in the Soldering Tutorial available at the Elecraft website (you may have to search for it). I suggest you remove the solder from any connection that looks like those and re-do them. Do not apply so much solder to "pile it on" - that does no good. Heat the solder pad and lead until you can see the solder flow out onto both. Using a small gauge solder helps. With large diameter solder, by the time you apply 'a little bit', that is already too much. Save the large solder for antenna wires. 73, Don W3FPR On 6/8/2017 10:20 PM, Robert Forster wrote: > > This should lead me to suspect T5 correct? > the soldering on the underside of the board for T5 looks ok (no ring > for these points but the topside of the board looks rough! I used the > USB microscope and took some photos. > Here: https://flic.kr/s/aHsm2aNdeG > > ______________________________________________________________ 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] |
Re: [K2] No signal at TP1 during Alignment and Test Part 2
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I agree with Don's comments on the soldering.
I am not familiar with the kit, but if you had to wind the torroid yourself, were you sure to remove ALL the insulation from the wire ends before soldering them to the board? 73, Ron WA2EIO On 6/9/2017 10:41 AM, Don Wilhelm wrote: > Robert, > > I just now had time to look at your photos. It seems to me that your > solder on T5 (and maybe elsewhere) looks like "balls" with convex > sides. That is indicitive of a solder connection that has not > received enough heat. > A good solder connection should have a slight fillet and end up with > obvious solder that has flowed out entirely onto the solder pad and > also up onto the leads. The edges of the solder should taper out to > an almost invisible edge with a concave fillet of solder between the > pad and the lead. > See the diagrams in the Soldering Tutorial available at the Elecraft > website (you may have to search for it). > > I suggest you remove the solder from any connection that looks like > those and re-do them. Do not apply so much solder to "pile it on" - > that does no good. Heat the solder pad and lead until you can see the > solder flow out onto both. > > Using a small gauge solder helps. With large diameter solder, by the > time you apply 'a little bit', that is already too much. Save the > large solder for antenna wires. > > 73, > Don W3FPR > > On 6/8/2017 10:20 PM, Robert Forster wrote: >> >> This should lead me to suspect T5 correct? >> the soldering on the underside of the board for T5 looks ok (no ring >> for these points but the topside of the board looks rough! I used the >> USB microscope and took some photos. >> Here: https://flic.kr/s/aHsm2aNdeG >> >> > > ______________________________________________________________ > 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] |
Re: [K2] No signal at TP1 during Alignment and Test Part 2
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Well it was T5! Sorry to take so long to get back but free time has been
short lately. Lead 4 of the transformer was poorly stripped as expected. I also think I need to run a little more heat when I'm soldering from this point forward to make sure i get good connections made. Thank you to everyone who responded. After I finish my happy dance I think I'll go make a cocktail! 73, Robert AD0TA On Fri, Jun 9, 2017 at 8:48 AM, Ron Manfredi <[hidden email]> wrote: > I agree with Don's comments on the soldering. > > I am not familiar with the kit, but if you had to wind the torroid > yourself, were you sure to remove ALL the insulation from the wire ends > before soldering them to the board? > > > 73, > > Ron WA2EIO > > > > > On 6/9/2017 10:41 AM, Don Wilhelm wrote: > >> Robert, >> >> I just now had time to look at your photos. It seems to me that your >> solder on T5 (and maybe elsewhere) looks like "balls" with convex sides. >> That is indicitive of a solder connection that has not received enough heat. >> A good solder connection should have a slight fillet and end up with >> obvious solder that has flowed out entirely onto the solder pad and also up >> onto the leads. The edges of the solder should taper out to an almost >> invisible edge with a concave fillet of solder between the pad and the lead. >> See the diagrams in the Soldering Tutorial available at the Elecraft >> website (you may have to search for it). >> >> I suggest you remove the solder from any connection that looks like those >> and re-do them. Do not apply so much solder to "pile it on" - that does no >> good. Heat the solder pad and lead until you can see the solder flow out >> onto both. >> >> Using a small gauge solder helps. With large diameter solder, by the >> time you apply 'a little bit', that is already too much. Save the large >> solder for antenna wires. >> >> 73, >> Don W3FPR >> >> On 6/8/2017 10:20 PM, Robert Forster wrote: >> >>> >>> This should lead me to suspect T5 correct? >>> the soldering on the underside of the board for T5 looks ok (no ring for >>> these points but the topside of the board looks rough! I used the USB >>> microscope and took some photos. >>> Here: https://flic.kr/s/aHsm2aNdeG >>> >>> >>> >> ______________________________________________________________ >> 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] >> >> > -- === I could tell you a UDP joke, but you might not get it. === ______________________________________________________________ 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] |
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