Voltages for Q5 and U8?
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I am troubleshooting a K1 that has no output.
The guide says to check Q5 and U8 voltages but I do not find them listed anywhere. The DC voltages table lists U8 pin numbers but no voltages. I see nothing for Q5. If anyone knows what they are or where they are listed I would appreciate a reply. The receiver works ok and all the voltage and resistance measurements listed in the assembly part of the manual and those of U9 Q8 and Q7 are all good. Mike K7MH |
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Mike,
I do not know where those DC voltages are listed. For as long as the K1 has been out, I don't understand why that omission had not been spotted long ago. However, back to your problem - the quickest path to resolution is to go first to page 5 of the manual troubleshooting appendix and build an RF Probe (if you have a 'scope with a 10X probe, it can be used instead). The RF Probe does not have to be pretty, or shielded or anything like that. If necessary, punch the leads of the components through a piece of cardboard to provide support, just connect the leads as indicated. OK, RF Probe in hand, or 'scope (if using a 'scope, the Expected voltages will be shown in peak to peak which are 2.8 times the RMS voltages listed), go to the Transmit Signal Tracing section. What you are looking for is the first stage where the RF voltages are significantly *lower* than the expected value. If the voltages are higher, that is OK, and is normal for a K1 that is not developing any RF output. Once you have identified the failing stage (the one where the output is lower than expected, stop and let us know - we can help with detailed analysis of that stage. 73, Don W3FPR On 9/23/2011 6:29 PM, K7MH wrote: > I am troubleshooting a K1 that has no output. > The guide says to check Q5 and U8 voltages but I do not find them listed > anywhere. > The DC voltages table lists U8 pin numbers but no voltages. I see nothing > for Q5. > If anyone knows what they are or where they are listed I would appreciate a > reply. > The receiver works ok and all the voltage and resistance measurements listed > in the > assembly part of the manual and those of U9 Q8 and Q7 are all good. > > Mike K7MH > > -- > View this message in context: http://elecraft.365791.n2.nabble.com/Voltages-for-Q5-and-U8-tp6825928p6825928.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 |
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With an RF probe, I did not get any reading from the first test point, PRE (premix) nor the latter test points in the manual.
I do get a good reading on pin 4 of P1 on the filter board which should be the premix oscillator signal. I do get the correct voltages on U7 on the RF board when checked per the voltage table instructions. I do not get a reading on pin 6 of P1 on the filter board which should be the premix signal output. Any suggestions would be much appreciated. I will double check some things. Mike K7MH. |
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Since the DC voltages for U7 are correct, and the crystal is
oscillating, you most likely have a problem on the band board - either a soldering problem or if you have the 4 band board, a problem with the lead tinning or positioning on T1 and/or T2. If you do have the 4 band board, did you position the trimmer caps initially with the slots parallel to the long side of the board? If not, do that and check again. 73, Don W3FPR On 9/25/2011 1:36 PM, K7MH wrote: > With an RF probe, I did not get any reading from the first test point, PRE > (premix) nor the latter test points in the manual. > I do get a good reading on pin 4 of P1 on the filter board which should be > the premix oscillator signal. > I do get the correct voltages on U7 on the RF board when checked per the > voltage table instructions. > > I do not get a reading on pin 6 of P1 on the filter board which should be > the premix signal output. > > Any suggestions would be much appreciated. > I will double check some things. > > Mike K7MH. > > -- > View this message in context: http://elecraft.365791.n2.nabble.com/Voltages-for-Q5-and-U8-tp6825928p6829593.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 |
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In reply to this post by K7MH
Hi Mike,
I remember you saying you had taken out the KAT1 for these tests. Did you re-install the RF-DET jumper on J2 after you did that? That is an error I have made myself, and I'm afraid it is my only suggestion. On Sun, Sep 25, 2011 at 10:36 AM, K7MH <[hidden email]> wrote: > I do not get a reading on pin 6 of P1 on the filter board which should be > the premix signal output. > > Any suggestions would be much appreciated. > I will double check some things. -- 73, Byron N6NUL ---- - Northern California Contest Club - CU in the 2011 Cal QSO Party 1-2 Oct 2011 - www.cqp.org ______________________________________________________________ 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 |
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In reply to this post by Don Wilhelm-4
It is the two band board with 40 and 20 meters.
I have looked over the filter board several times and re-soldered some joints just to be sure. I will look over it again. I used the pre-wound coils but will look them over again and make double sure the right one is in the right place. |
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In reply to this post by Byron Servies
I don't have the KAT1. Just the basic K1 with 2 bands and the backlight.
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In reply to this post by K7MH
The problem will be found either in the bandpass filter on the left end
of the 2 band board, or in the connections between the filter board and U7 Check the path between U7 pin 4 and the filter board P1 pin 2 and also between U7 pin 5 and filter board P1 pin 1 - both should have close to zero ohms resistance. If that is not the problem, check the capacitor values for C1 through C10 on the board against the band components chart. You might check for continuity between the junction of C4 and C5 when the band is set to Band1 and between the junction of C9 and C10 when set for Band2 - the relays are latching, so you can set the band and then remove the filter board to check for continuity. Do you have the same problem on both bands? If so, it is probably a connection problem. On only one band, I would suspect a wrong component. 73, Don W3FPR On 9/25/2011 2:20 PM, K7MH wrote: > It is the two band board with 40 and 20 meters. > I have looked over the filter board several times and re-soldered some > joints just to be sure. > I will look over it again. > I used the pre-wound coils but will look them over again and make double > sure the right one is in the right place. > > -- > View this message in context: http://elecraft.365791.n2.nabble.com/Voltages-for-Q5-and-U8-tp6825928p6829688.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 |
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I got it working and finished the K1 this evening. Thanks for all the assistance and suggestions.
I am not certain where the problem was but I re-soldered and touched up a few solder joints on the filter board. I think it may have been C10 as the coating on the cap was down into the via a little ways. After touching it and some other joints, I re-peaked the filters in receive and found that the 2nd premix filter of each band peaked in a different place. In transmit it came alive. Very cool!! Thanks again, Mike K7MH. |
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