K1 VFO frequency does not change
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K1 VFO frequency does not change
 
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I'm at the VFO range test in building of my K1. I go into the CAL menu, display OSC and see a freq of 3.121 MHz. The frequency does not change when I turn the VFO tuning pot.
I checked the voltage on the VFO POT signal and it goes between 0v and 5.935v. The voltage on D3 goes between 0v and 5.888v. Any suggestions on where I should look to determine why I cannot change VFO frequency ? 73, John W8DE |
Re: K1 VFO frequency does not change
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A missing or not properly soldered C2 would do it.
73 - Mike WA8BXN -------Original Message------- From: W8DE Date: 2/23/2013 9:43:56 PM To: [hidden email] Subject: [Elecraft] K1 VFO frequency does not change I'm at the VFO range test in building of my K1. I go into the CAL menu, Display OSC and see a freq of 3.121 MHz. The frequency does not change when I turn the VFO tuning pot. I checked the voltage on the VFO POT signal and it goes between 0v and 5.935v. The voltage on D3 goes between 0v and 5.888v. Any suggestions on where I should look to determine why I cannot change VFO Frequency ? 73, John W8DE ______________________________________________________________ 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 |
Re: K1 VFO frequency does not change
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I had installed the 68 pF C2. Based on your questioning about C2 I swapped it out for the 120pF C2. Still no change in displayed VFO frequency when I turn the tuning pot.
I have checked the installation of the components in that circuit. They appear to be installed correctly. thanks for the suggestion, John W8DE On Feb 23, 2013, at 10:36 PM, Mike WA8BXN [via Elecraft] <[hidden email]> wrote: > A missing or not properly soldered C2 would do it. > > 73 - Mike WA8BXN > |
Re: K1 VFO frequency does not change
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In reply to this post by John Reed, W8DE
John
Is D3 oriented correctly? Is it well soldered? Is C2 well soldered? Those two components are about the only ones that would prevent the frequency from changing. A faulty D3 is a possibility, although that would be rare. 73, Don W3FPR On 2/23/2013 9:43 PM, W8DE wrote: > I'm at the VFO range test in building of my K1. I go into the CAL menu, > display OSC and see a freq of 3.121 MHz. The frequency does not change when > I turn the VFO tuning pot. > > I checked the voltage on the VFO POT signal and it goes between 0v and > 5.935v. The voltage on D3 goes between 0v and 5.888v. > > Any suggestions on where I should look to determine why I cannot change VFO > frequency ? > > 73, > John W8DE > > > > > -- > View this message in context: http://elecraft.365791.n2.nabble.com/K1-VFO-frequency-does-not-change-tp7570276.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 > ______________________________________________________________ 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 |
Re: K1 VFO frequency does not change
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Don,
C2 and D3 look to be properly installed. I confirmed orientation from a 1SV149 data sheet just in case I mis-read the instructions. I can adjust receive frequency with RIT, so it looks like the D4 control is working. Since the D3 voltage is varying from 0v to 5.888v with the tuning pot, but there is no change in frequency, I'm starting to suspect a bad D3. I don't know of anyway to check it in circuit -- at least with the tools I have. I'll see if I can pick up a 1SV149 locally. I considered swapping it with D6, but I don't think I can remove it without damaging it. 73, John W8DE On Feb 24, 2013, at 8:11 AM, "Don Wilhelm-4 [via Elecraft]" <[hidden email]> wrote: > John > > Is D3 oriented correctly? Is it well soldered? > Is C2 well soldered? > Those two components are about the only ones that would prevent the > frequency from changing. > A faulty D3 is a possibility, although that would be rare. > > 73, > Don W3FPR > On 2/23/2013 9:43 PM, W8DE wrote: > > > I'm at the VFO range test in building of my K1. I go into the CAL menu, > > display OSC and see a freq of 3.121 MHz. The frequency does not change when > > I turn the VFO tuning pot. > > > > I checked the voltage on the VFO POT signal and it goes between 0v and > > 5.935v. The voltage on D3 goes between 0v and 5.888v. > > > > Any suggestions on where I should look to determine why I cannot change VFO > > frequency ? > > > > 73, > > John W8DE > > |
Re: K1 VFO frequency does not change
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John, A couple of things you might try. First, use your ohm meter to check D3. It should show lower R in on direction compared to the other. It is a diode. You could perhaps try replacing it with a 1N4004 ... 1N4007 what ever you can get or have. Assuming you can't easily get the proper diode, any of these will also change the C as voltage across them changes. So you should see some change in frequency. 73 - Mike WA8BXN -------Original Message------- From: John Reed, W8DE Date: 2/24/2013 3:27:25 PM To: [hidden email] Subject: Re: [Elecraft] K1 VFO frequency does not change Don, C2 and D3 look to be properly installed. I confirmed orientation from a 1SV149 data sheet just in case I mis-read the instructions. I can adjust receive frequency with RIT, so it looks like the D4 control is working. Since the D3 voltage is varying from 0v to 5.888v with the tuning pot, but there is no change in frequency, I'm starting to suspect a bad D3. I don't know of anyway to check it in circuit -- at least with the tools I have. I ll see if I can pick up a 1SV149 locally. I considered swapping it with D6, but I don't think I can remove it without damaging it. 73, John W8DE ______________________________________________________________ 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 |
Re: K1 VFO frequency does not change
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Mike,
I used the diode test on my fluke 117. It shows the diode is good; 0.633 v. hmmm…. 73, John W8DE On Feb 24, 2013, at 3:42 PM, "Mike WA8BXN [via Elecraft]" <[hidden email]> wrote: > > > John, > > A couple of things you might try. First, use your ohm meter to check D3. It > should show lower R in on direction compared to the other. It is a diode. > You could perhaps try replacing it with a 1N4004 ... 1N4007 what ever you > can get or have. Assuming you can't easily get the proper diode, any of > these will also change the C as voltage across them changes. So you should > see some change in frequency. > > 73 - Mike WA8BXN > > > |
Re: K1 VFO frequency does not change
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In reply to this post by John Reed, W8DE
John,
Yes, that would strongly indicate that D3 is faulty. It is good that you confirmed RIT does change the frequency. I don't think you will find one locally, but an email to [hidden email] should bring you one quickly in the mail. Since a bad D3 is a rarity, you might also want to check for board continuity with your DMM. Check to see that you have the same voltage variation on one lead of C2 - that will confirm that D3 is connected to C2. The other lead of C2 cannot be tested with voltage, so use your ohmmeter to check for continuity between the other lead of C2 and L1. Should you find the board has an open trace (also a real rarity), repair it with a wire. Elecraft would send you a new board, but you already have enough work in that board to warrant repairing it with a wire. 73, Don W3FPR On 2/24/2013 3:27 PM, John Reed, W8DE wrote: > Don, > C2 and D3 look to be properly installed. I confirmed orientation from a 1SV149 data sheet just in case I mis-read the instructions. > > I can adjust receive frequency with RIT, so it looks like the D4 control is working. > > Since the D3 voltage is varying from 0v to 5.888v with the tuning pot, but there is no change in frequency, I'm starting to suspect a bad D3. I don't know of anyway to check it in circuit -- at least with the tools I have. I'll see if I can pick up a 1SV149 locally. I considered swapping it with D6, but I don't think I can remove it without damaging 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 |
Re: K1 VFO frequency does not change
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Don,
thanks so much for your advice. The board traces in that area all check out good. I'll email a request to elecraft for a new D3. If it really is bad, it makes me wonder about the 1SV149 diodes in the crystal filter circuit. I don't know how I would tell if those are functioning correctly. 73, John W8DE On Feb 24, 2013, at 4:25 PM, "Don Wilhelm-4 [via Elecraft]" <[hidden email]> wrote: John, |
Re: K1 VFO frequency does not change
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John,
If the other 1SV149 varactors are not behaving correctly, it will show up in your IF filter passband. Download Spectrogram from my website www.w3fpr.com (or use Spectrum Lab or ohters) and feed the K1 audio output to your soundcard. I understand that you may not know what to expect, so send me screenshots of the passband for FL1, FL2 and FL3 and I can let you know if they are as expected. 73, Don W3FPR On 2/24/2013 7:31 PM, John Reed, W8DE wrote: > Don, > thanks so much for your advice. The board traces in that area all check out good. I'll email a request to elecraft for a new D3. > > If it really is bad, it makes me wonder about the 1SV149 diodes in the crystal filter circuit. I don't know how I would tell if those are functioning correctly. > > ______________________________________________________________ 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 |
Re: K1 VFO frequency does not change
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In reply to this post by John Reed, W8DE
John,
While you are waiting for the 1SV149 to arrive, solder a 1N400x diode (X = 1 thru 7) in its place and see if you can achieve any variation in the frequency. Make certain the cathode is oriented to connect to the RP2 pin 2 and C2 junction. It may not give you correct range, but it should shift the frequency. 73, Don W3FPR On 2/24/2013 7:31 PM, John Reed, W8DE wrote: > Don, > thanks so much for your advice. The board traces in that area all check out good. I'll email a request to elecraft for a new D3. > > If it really is bad, it makes me wonder about the 1SV149 diodes in the crystal filter circuit. I don't know how I would tell if those are functioning correctly. > > 73, > John W8DE > > On Feb 24, 2013, at 4:25 PM, "Don Wilhelm-4 [via Elecraft]" <[hidden email]> wrote: > >> John, >> >> Yes, that would strongly indicate that D3 is faulty. It is good that >> you confirmed RIT does change the frequency. >> I don't think you will find one locally, but an email to >> [hidden email] should bring you one quickly in the mail. >> >> Since a bad D3 is a rarity, you might also want to check for board >> continuity with your DMM. Check to see that you have the same voltage >> variation on one lead of C2 - that will confirm that D3 is connected to >> C2. The other lead of C2 cannot be tested with voltage, so use your >> ohmmeter to check for continuity between the other lead of C2 and L1. >> Should you find the board has an open trace (also a real rarity), repair >> it with a wire. Elecraft would send you a new board, but you already >> have enough work in that board to warrant repairing it with a wire. >> >> 73, >> Don W3FPR >> >> On 2/24/2013 3:27 PM, John Reed, W8DE wrote: >>> Don, >>> C2 and D3 look to be properly installed. I confirmed orientation from a 1SV149 data sheet just in case I mis-read the instructions. >>> >>> I can adjust receive frequency with RIT, so it looks like the D4 control is working. >>> >>> Since the D3 voltage is varying from 0v to 5.888v with the tuning pot, but there is no change in frequency, I'm starting to suspect a bad D3. I don't know of anyway to check it in circuit -- at least with the tools I have. I'll see if I can pick up a 1SV149 locally. I considered swapping it with D6, but I don't think I can remove it without damaging it. >>> >>> > > > > -- > View this message in context: http://elecraft.365791.n2.nabble.com/K1-VFO-frequency-does-not-change-tp7570276p7570320.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 > ______________________________________________________________ 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 |
Re: K1 VFO frequency does not change
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With the voltage on D3 changing, but no change in VFO frequency it looked like a bad D3 (1SV149). I installed a replacement and now the frequency changes as it should. I used all the recommended static protection when I originally installed it. I guess it was a bad one.
Don, thanks for your help! 73, John W8DE |
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