Need Help with XG1
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I have an XG-1 Receiver Test Oscillator which I must have accidentally
zapped with RF somehow (I don't know when) because the output resistors R6-8 were fried. I replaced them, as well as R4 and R5, C4 and the transistor. The slide switch in the output tests ok. When I turn the XG-1 on, I can very faintly hear its signal, so it appears that the oscillator is working, but the output level is nowhere near what it should be. Voltage at the top of C3 is 1.23 volts. Anyone have any ideas where else I could look? Elecraft tech support was helpful but ultimately gave up. 73, Pete N4ZR the World Contest Station Database is back, and updated daily www.conteststations.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Thanks for the idea - I removed both D1 and D2 from the circuit - no
improvement. The signal is quite audible (in the 50 uv switch position, and barely audible in the 1 uV position, but doesn't move an S-meter that was formerly tested with it and registered S9. Anyone else? I know that if I had a scope I could measure the p-p voltage coming out of the oscillator, but I don't. 73, Pete N4ZR At 11:49 AM 1/28/2009, Philip Carter wrote: >See if maybe you shorted the protection led. > > > >--- On Wed, 1/28/09, Pete Smith <[hidden email]> wrote: > > > From: Pete Smith <[hidden email]> > > Subject: [Elecraft] Need Help with XG1 > > To: [hidden email] > > Date: Wednesday, January 28, 2009, 11:19 AM > > I have an XG-1 Receiver Test Oscillator which I must have > > accidentally > > zapped with RF somehow (I don't know when) because the > > output resistors > > R6-8 were fried. I replaced them, as well as R4 and R5, C4 > > and the > > transistor. The slide switch in the output tests ok. > > > > When I turn the XG-1 on, I can very faintly hear its > > signal, so it appears > > that the oscillator is working, but the output level is > > nowhere near what > > it should be. Voltage at the top of C3 is 1.23 volts. > > Anyone have any > > ideas where else I could look? Elecraft tech support was > > helpful but > > ultimately gave up. > > > > 73, Pete N4ZR > > the World Contest Station Database is back, and updated > > daily > > www.conteststations.com > > > > > > _______________________________________________ > > Elecraft mailing list > > Post to: [hidden email] > > You must be a subscriber to post to the list. > > Subscriber Info (Addr. Change, sub, unsub etc.): > > http://mailman.qth.net/mailman/listinfo/elecraft > > > > Help: http://mailman.qth.net/subscribers.htm > > Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Pete Smith N4ZR
I don't have mine in front of me, but it is the SMA device that is on
there that you need to replace. It gets blown out. I'll grab the docs real quick and follow-up. Dave Wilburn NM4M Pete Smith wrote: > I have an XG-1 Receiver Test Oscillator which I must have accidentally > zapped with RF somehow (I don't know when) because the output resistors > R6-8 were fried. I replaced them, as well as R4 and R5, C4 and the > transistor. The slide switch in the output tests ok. > > When I turn the XG-1 on, I can very faintly hear its signal, so it appears > that the oscillator is working, but the output level is nowhere near what > it should be. Voltage at the top of C3 is 1.23 volts. Anyone have any > ideas where else I could look? Elecraft tech support was helpful but > ultimately gave up. > > 73, Pete N4ZR > the World Contest Station Database is back, and updated daily > www.conteststations.com > > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com > Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Pete Smith N4ZR
Have you checked for any damage to the circuit board traces? If
enough power was applied to "fry" those resistors despite D1 & D2 being in the circuit, maybe some of the traces were damaged as well. I would think it would be visually obvious, but maybe not. 73 -- Joe KB8AP On Jan 28, 2009, at 8:19 AM, Pete Smith wrote: > I have an XG-1 Receiver Test Oscillator which I must have accidentally > zapped with RF somehow (I don't know when) because the output > resistors > R6-8 were fried. I replaced them, as well as R4 and R5, C4 and the > transistor. The slide switch in the output tests ok. > > When I turn the XG-1 on, I can very faintly hear its signal, so it > appears > that the oscillator is working, but the output level is nowhere near > what > it should be. Voltage at the top of C3 is 1.23 volts. Anyone have any > ideas where else I could look? Elecraft tech support was helpful but > ultimately gave up. _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by dave.wilburn
It appears I was thinking of another device. I would first suspect Q1.
Dave Wilburn NM4M David Wilburn wrote: > I don't have mine in front of me, but it is the SMA device that is on > there that you need to replace. It gets blown out. I'll grab the > docs real quick and follow-up. > > Dave Wilburn > NM4M > > Pete Smith wrote: >> I have an XG-1 Receiver Test Oscillator which I must have accidentally >> zapped with RF somehow (I don't know when) because the output resistors >> R6-8 were fried. I replaced them, as well as R4 and R5, C4 and the >> transistor. The slide switch in the output tests ok. >> >> When I turn the XG-1 on, I can very faintly hear its signal, so it appears >> that the oscillator is working, but the output level is nowhere near what >> it should be. Voltage at the top of C3 is 1.23 volts. Anyone have any >> ideas where else I could look? Elecraft tech support was helpful but >> ultimately gave up. >> >> 73, Pete N4ZR >> the World Contest Station Database is back, and updated daily >> www.conteststations.com >> >> >> _______________________________________________ >> Elecraft mailing list >> Post to: [hidden email] >> You must be a subscriber to post to the list. >> Subscriber Info (Addr. Change, sub, unsub etc.): >> http://mailman.qth.net/mailman/listinfo/elecraft >> >> Help: http://mailman.qth.net/subscribers.htm >> Elecraft web page: http://www.elecraft.com >> > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com > Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Pete Smith N4ZR
At 10:53 AM 28/01/09, you wrote:
>and barely audible in the 1 uV position, but doesn't move an S-meter that >was formerly tested with it and registered S9. Do you mean you used to get S9 with a 1uV signal? I would think the 1uV signal would be close to the noise level. John k7up _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Pete Smith N4ZR
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In reply to this post by Pete Smith N4ZR
Pete,
Do you have the proper voltage on Q1? Check for 1.22 volts at the cathode of U2. Also check the value of R3 and R3 with your ohmmeter. It sounds like you have replaced everything important, but if you had enough RF to fry the resistors, you may have damaged the switch contacts at the same time. You should be able to determine the resistance through the switch with your ohmmeter. Do that for both poles, and both switch positions. 73, Don W3FPR Pete Smith wrote: > Thanks for the idea - I removed both D1 and D2 from the circuit - no > improvement. The signal is quite audible (in the 50 uv switch position, > and barely audible in the 1 uV position, but doesn't move an S-meter that > was formerly tested with it and registered S9. > > Anyone else? I know that if I had a scope I could measure the p-p voltage > coming out of the oscillator, but I don't. > > 73, Pete N4ZR > > Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Pete Smith N4ZR
>I have an XG-1 Receiver Test Oscillator which I must have accidentally
zapped with RF somehow (I don't know when) because the output resistors R6-8 were fried. I replaced them, as well as R4 and R5, C4 and the transistor. The slide switch in the output tests ok. >When I turn the XG-1 on, I can very faintly hear its signal, so it
appears
that the oscillator is working, but the output level is nowhere near what it should be. Voltage at the top of C3 is 1.23 volts. Anyone have any ideas where else I could look? Elecraft tech support was helpful but ultimately gave up. Pete, try replacing D1 and/or D2. One or both is
probably shorted.
73,
Charlie, N0TT
_______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Don Wilhelm-4
Thanks Don. Unfortunately, all those variables test OK. I've gotta fix my
old scope! I think that voltage must be an indication that the transistor oscillator is at least drawing the right amount of current through R9. I'm going back to recheck all my work on the default output attenuator. Must be something there, particularly since the additional stage of attenuation when I switch in the 1 Uv position seems to be working properly. 73, Pete At 02:30 PM 1/28/2009, Don wrote: >Pete, > >Do you have the proper voltage on Q1? Check for 1.22 volts at the cathode >of U2. Also check the value of R3 and R3 with your ohmmeter. > >It sounds like you have replaced everything important, but if you had >enough RF to fry the resistors, you may have damaged the switch contacts >at the same time. You should be able to determine the resistance through >the switch with your ohmmeter. Do that for both poles, and both switch >positions. > >73, >Don W3FPR > >Pete Smith wrote: >>Thanks for the idea - I removed both D1 and D2 from the circuit - no >>improvement. The signal is quite audible (in the 50 uv switch position, >>and barely audible in the 1 uV position, but doesn't move an S-meter that >>was formerly tested with it and registered S9. >> >>Anyone else? I know that if I had a scope I could measure the p-p >>voltage coming out of the oscillator, but I don't. >> >>73, Pete N4ZR >> _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by John-483
No, sorry - I meant that in the 50uv position it generated an S9
reading. In the 1 UV position it was easily audible, but no S meter deflection at all. 73, Pete At 01:41 PM 1/28/2009, John wrote: >At 10:53 AM 28/01/09, you wrote: > >and barely audible in the 1 uV position, but doesn't move an S-meter that > >was formerly tested with it and registered S9. > >Do you mean you used to get S9 with a 1uV signal? I would think the >1uV signal would be close to the noise level. > >John >k7up > >_______________________________________________ >Elecraft mailing list >Post to: [hidden email] >You must be a subscriber to post to the list. >Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > >Help: http://mailman.qth.net/subscribers.htm >Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Pete Smith N4ZR
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At 12:46 PM 1/29/2009, Ron D'Eau Claire wrote:
>Wow, Pete, what a puzzle! > >You might make up a little probe consisting of a wire connected to your rx >antenna input that you can touch to the circuit parts. If it has to be a >long lead, use a bit of coax so random signal pickup won't confuse things. >If your rx input is grounded for d-c, put a small cap in series - anything >from .001 to .1 should be FB - to provide d-c isolation. Then touch it to >the collector of Q1. You should find your S-9 signal. If not remove coupling >cap C4 and try again. > >If you now have signal, there's a ground somewhere in the attenuator that is >killing the signal. If not, you have a defective transistor (although that >is high unlikely given that you've established that the voltage on the >collector is correct.) > >Once you have the signal at the collector, start working through the >attenuator until you lose it. A very neat idea, Ron - I'm going to use this one a lot! I lifted one leg of C4, the output coupling cap, and took a look at the signal level at the collector of the transistor oscillator. It is very, very low. Is it possible that the RF surge somehow damaged the crystal? I'm running out of components to replace here! 73, Pete _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Pete,
Have you measured the emitter resistor (R2)? I would suspect that more than the crystal. Since you do suspect the crystal, do you have any other crystal that you can substitute for it - it can be any fundamental crystal somewhere between 3.5 MHz and 15 MHz as long as you have a receiver that can hear it to evaluate the result. 73, Don W3FPR Pete Smith wrote: > I lifted one leg of C4, the output coupling cap, and took a look at the > signal level at the collector of the transistor oscillator. It is very, > very low. Is it possible that the RF surge somehow damaged the > crystal? I'm running out of components to replace here! > > 73, Pete > > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Regrettably (hi), the emitter resistor is fine - very close to
nominal. wish I had a crystal to substitute, but I don't, so maybe I need to get one from Elecraft - or just hang up the whole thing and get an XG-2. Thanks for thinking about this, Don. I hope people don't mind my continuing this on the list - I thought the archive might be useful to someone facing the same problem later on. 73, Pete N4ZR At 09:28 AM 1/30/2009, Don Wilhelm wrote: >Pete, > >Have you measured the emitter resistor (R2)? I would suspect that more >than the crystal. >Since you do suspect the crystal, do you have any other crystal that you >can substitute for it - it can be any fundamental crystal somewhere >between 3.5 MHz and 15 MHz as long as you have a receiver that can hear >it to evaluate the result. > >73, >Don W3FPR > >Pete Smith wrote: > > I lifted one leg of C4, the output coupling cap, and took a look at the > > signal level at the collector of the transistor oscillator. It is very, > > very low. Is it possible that the RF surge somehow damaged the > > crystal? I'm running out of components to replace here! > > > > 73, Pete > > > > >_______________________________________________ >Elecraft mailing list >Post to: [hidden email] >You must be a subscriber to post to the list. >Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > >Help: http://mailman.qth.net/subscribers.htm >Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Pete Smith N4ZR
If you havn't checked it out already, check out the BNC connector.
Mine had a problem internally and will cause problems. 73, Tony W7GO _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Pete Smith N4ZR-2
Hi Pete,
You are working much too hard. I designed the XG1 for Elecraft and if you send it to me, I'll repair it for you. 73, Bob, N6CM On Fri, Jan 30, 2009 at 6:34 AM, Pete Smith <[hidden email]> wrote: > Regrettably (hi), the emitter resistor is fine - very close to > nominal. wish I had a crystal to substitute, but I don't, so maybe I need > to get one from Elecraft - or just hang up the whole thing and get an XG-2. > > Thanks for thinking about this, Don. I hope people don't mind my > continuing this on the list - I thought the archive might be useful to > someone facing the same problem later on. > > 73, Pete N4ZR > > At 09:28 AM 1/30/2009, Don Wilhelm wrote: >>Pete, >> >>Have you measured the emitter resistor (R2)? I would suspect that more >>than the crystal. >>Since you do suspect the crystal, do you have any other crystal that you >>can substitute for it - it can be any fundamental crystal somewhere >>between 3.5 MHz and 15 MHz as long as you have a receiver that can hear >>it to evaluate the result. >> >>73, >>Don W3FPR >> >>Pete Smith wrote: >> > I lifted one leg of C4, the output coupling cap, and took a look at the >> > signal level at the collector of the transistor oscillator. It is very, >> > very low. Is it possible that the RF surge somehow damaged the >> > crystal? I'm running out of components to replace here! >> > >> > 73, Pete >> > >> > >>_______________________________________________ >>Elecraft mailing list >>Post to: [hidden email] >>You must be a subscriber to post to the list. >>Subscriber Info (Addr. Change, sub, unsub etc.): >> http://mailman.qth.net/mailman/listinfo/elecraft >> >>Help: http://mailman.qth.net/subscribers.htm >>Elecraft web page: http://www.elecraft.com > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com > > Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Pete Smith N4ZR
I had a similar problem with my XG-2 right after assembly, on one of its three frequencies. Measuring voltages etc. did not give a clue, so I finally took a crystal from my junk box and connected its terminals in parallel with the crystal on the board (simply making the Xtal leads touch the points on the back side of the board). This started full scale oscillation, so I determined the XG-2 crystal in question simply was bad. May have been bad all along or become defective during my assembly.
Elecraft sent me a replacement crystal - which I actually haven't put in yet, but this appeared to be the problem. 73 - Kristinn, TF3KX
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