Re: [Elecraft] K2 7747 VCO alignment problem
Keith, Not a nice problem to address. I can give you some troubleshooting information if you are willing to hang in there with me. Eliminate the "[Elecraft]" from the subject line and reply to me directly (not to the list). Relay K15 is common on all those bands, but not on 80 and 40m, but that does not explain why 15 meters is OK. Check the resistance between pins 1 and 10 of all 3 relays - that is the coil resistance, and if I recall, it is about 235 ohms. Check that C73 and C74 are the correct values. If that does not reveal the problem, you will have to measure the open/closed state of the relays for the next step. Can you find those relays on the schematic? They are all shown in the reset state. 73, Don W3FPR On 7/13/2020 2:52 PM, Keith Hamilton wrote: I am having trouble with the K2 VCO alignment. I have moved the T5 windings and obtained 6 volts at the left end of R30. I then went on to the chart (table 6-1) to measure the voltages at the listed frequencies. My readings are ok on 80 40 and 15 meters (between 1.5 to 7.5 volts) but on 30,20,17 ,12 and 10 meters the voltage is 8.29 volts and does not change. I have checked the solder connections of T5 and the value of C72 (271). The diodes D21,D22,D23, D24, D25 and D26 are correctly installed. I also went over the solder connections of K13, K14 and K15. __ 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 7747 VCO alignment problem
Thanks for your help Dave! Yes. I was able to get 6 volts on R30 by turning L30. At first the voltage was too high so I adjusted the turns on T5 by spreading the red windings further apart. Then I was able to get to 6 volts. I did a CAL FCTR with the probe on TP1 and the frequency set to 4000, The reading is 8912.22 73 Keith N8CEP On Mon, Jul 13, 2020 at 3:59 PM Dave Van Wallaghen wrote: > Hi Keith, > > Were you able to get 6v on R30 by tuning L30? Did you have to bring the > voltage down or up by moving the windings on T5? > > If you would, set the VFO to 4 MHz and do a CAL FCTR on TP1 and let me > know what the reading is. I'm just looking for a couple of clues before > we proceed. > > 73, > Dave, W8FGU > > > On 7/13/2020 2:52:11 PM, "Keith Hamilton" wrote: > > >I am having trouble with the K2 VCO alignment. I have moved the T5 > windings > >and obtained 6 volts at the left end of R30. I then went on to the chart > >(table 6-1) to measure the voltages at the listed frequencies. My readings > >are ok on 80 40 and 15 meters (between 1.5 to 7.5 volts) but on 30,20,17 > >,12 and 10 meters the voltage is 8.29 volts and does not change. > > > >I have checked the solder connections of T5 and the value of C72 (271). > The > >diodes D21,D22,D23, D24, D25 and D26 are correctly installed. I also went > >over the solder connections of K13, K14 and K15. > > > >Now I'm stuck. Any help will be appreciated. > > > >Keioth Hamilton N8CEP > >__ > >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 d...@w8fgu.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 7747 VCO alignment problem
Hi Keith, Were you able to get 6v on R30 by tuning L30? Did you have to bring the voltage down or up by moving the windings on T5? If you would, set the VFO to 4 MHz and do a CAL FCTR on TP1 and let me know what the reading is. I'm just looking for a couple of clues before we proceed. 73, Dave, W8FGU On 7/13/2020 2:52:11 PM, "Keith Hamilton" wrote: I am having trouble with the K2 VCO alignment. I have moved the T5 windings and obtained 6 volts at the left end of R30. I then went on to the chart (table 6-1) to measure the voltages at the listed frequencies. My readings are ok on 80 40 and 15 meters (between 1.5 to 7.5 volts) but on 30,20,17 ,12 and 10 meters the voltage is 8.29 volts and does not change. I have checked the solder connections of T5 and the value of C72 (271). The diodes D21,D22,D23, D24, D25 and D26 are correctly installed. I also went over the solder connections of K13, K14 and K15. Now I'm stuck. Any help will be appreciated. Keioth Hamilton N8CEP __ 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 d...@w8fgu.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
