Re: [Elecraft] [XV432} LO Instability Problem
Hi Ian, I had exactly the same problem with my XV 432 and scratched my head for some time. The outcome was that I had during construction switched the coils to be used for L4 and L19 (the two unshielded coils). This had the effect of not allowing me to set the LO on frequency. it would slide off either side of the wanted frequency and the crystal appeared damped and would stop oscillating. Once I swapped the inductors over and re-aligned it would sit on fequency perfectly once warmed up. I fully recomend the crystal oven and high accuracy crystal and leaving the oven on all the time using the jumpers. 73 Guy G0UKN -- View this message in context: http://elecraft.365791.n2.nabble.com/XV432-LO-Instability-Problem-tp7569117p7570425.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:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] [XV432} LO Instability Problem
Hello Ian, Comments below On Fri, Jan 25, 2013 at 8:48 AM, Ian Greenshields ian.greenshie...@gmail.com wrote: Thanks for all the help and comments received so far, on and off reflector - I have to say the responsiveness and quality of help on this reflector is second to none! To summarise: 1. I have tried detuning L4, along with L3 and L5. L4 is very sensitive as is probably to be expected, L3 and L5 somewhat less so. The most stable point of L4 does seem to coincide with the peak in voltage at TP1, and detuning L3 and L5 doesn't seem to make much difference. The problem is that the voltage at TP1 can easily reach 4v or higher, and the LO is definitely less stable if I detune it to keep the voltage below 3v. 2. Is a voltage well above 3v at TP1 a problem? It seems to be just a detector diode circuit on the output of the LO, so I presume a fair amount of variation is to be expected. This is not a problem. You are correct there can be considerable variation from unit to unit and crystal to crystal. 3. The crystal seems mechanically stable in that tapping it doesn't send the frequency all over the place, but it is highly sensitive to being touched, which I assume is heating effect, Likely correct. The oven will make a very large improvement 4. The biggest single improvement was a suggestion to ground the can of the crystal. This is something very familiar to any K2 builder. I grounded the crystal can, K2 filter style, to the oven -ve pad, which was the closest ground point. Huge improvement. The frequency jumping has gone, although there is still significant drift, even long after warm-up. 5. I then tried readjusting L3, L4 L5 to see if detuning the voltage to about 2.5v at TP1 helped now that the oscillator seemed more stable. This seemed to be a backward step as the LO lurched down about 10kHz in frequency, started to drift back up, but then actually stopped oscillating. Restoring L3, L4 and L5 to the point where the voltage at TP1 peaks - about 4v - seems to be the most stable point the LO starts up fine. From switch on it drifts about 3kHz low, then as it warms up, it starts to drift HF until about 3 or 4kHz above the switch-on point. Tune for a peak 6. If my unit is normal, the oven would seem an essential. As I want to use the transverter on SSB, I can't really live with a drift range of 7kHz! 7. What is the view on grounding the crystal can? It does seem to help tremendously with the stability (and I mean the 'crystal mode' stability, just to differentiate from drift). I would order a second crystal along with the oven and first try it without grounding the can. If it still is necessary to ground the can then do it at the bottom near the pc board so that you can install the oven. I would also utilize the option to leave the oscillator and its oven on continuously. This option is explained in the manual. Bob, N6CM __ 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
Re: [Elecraft] [XV432} LO Instability Problem
Ian, Two possibilities occur to me. First, detune the LO inductors L3, L4 and L5 a bit to give you 3 volts maximum at TP1 and see if it stabilizes. Secondly, try adjusting L4 a bit. It may be that the adjustment of L4 puts the crystal right on the 'hairy' edge of oscillation which would make the frequency unstable. The voltage at TP1 should remain between 1.7 and 3.0 volts. 73, Don W3FPR On 1/25/2013 3:40 AM, Ian Greenshields wrote: The LO on my XV432 transverter seems to be very unstable. I think it's something more than just temperature drift as the frequency will sometimes jump by several kHz. It's almost as if the crystal is hunting between different modes of oscillation. Prodding wiggling the components in the LO circuit doesn't point to any obvious poor connection, although the crystal itself is sensitive to being touched, or heated by a finger. The LO alignment voltage at TP1 peaks at about 3.3V. I don't have the temperature oven for the crystal, although I think it's a requirement. But I'm concerned about the frequency jumping and a frequency drift of almost 10kHz which I would not expect even of a non-temperature controlled crystal oscillator. Any thoughts or pointers as to what could be wrong? TIA, Ian G4FSU __ 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
Re: [Elecraft] [XV432} LO Instability Problem
Wasn't there some issue with the 78L09 at some point? I seem to recall replacing the low-power versions with standard 7809s .. I'd have to pop them open to check de w1rt/john On Fri, Jan 25, 2013 at 9:01 AM, Don Wilhelm w3...@embarqmail.com wrote: Ian, Two possibilities occur to me. First, detune the LO inductors L3, L4 and L5 a bit to give you 3 volts maximum at TP1 and see if it stabilizes. Secondly, try adjusting L4 a bit. It may be that the adjustment of L4 puts the crystal right on the 'hairy' edge of oscillation which would make the frequency unstable. The voltage at TP1 should remain between 1.7 and 3.0 volts. 73, Don W3FPR On 1/25/2013 3:40 AM, Ian Greenshields wrote: The LO on my XV432 transverter seems to be very unstable. I think it's something more than just temperature drift as the frequency will sometimes jump by several kHz. It's almost as if the crystal is hunting between different modes of oscillation. Prodding wiggling the components in the LO circuit doesn't point to any obvious poor connection, although the crystal itself is sensitive to being touched, or heated by a finger. The LO alignment voltage at TP1 peaks at about 3.3V. I don't have the temperature oven for the crystal, although I think it's a requirement. But I'm concerned about the frequency jumping and a frequency drift of almost 10kHz which I would not expect even of a non-temperature controlled crystal oscillator. Any thoughts or pointers as to what could be wrong? TIA, Ian G4FSU __ 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 __ 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
Re: [Elecraft] [XV432} LO Instability Problem
Not true on any XV series transverter I have worked on. The leads of a 7809 would not fit the board. 73, Don W3FPR On 1/25/2013 9:14 AM, John D'Ausilio wrote: Wasn't there some issue with the 78L09 at some point? I seem to recall replacing the low-power versions with standard 7809s .. I'd have to pop them open to check de w1rt/john __ 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
Re: [Elecraft] [XV432} LO Instability Problem
Ian, Does the LO frequency jump if you tap the crystal's can using a plastic rod such as an alignment tool or pencil? If it does, and if all of the soldered connections in the LO's circuit are sound, the jump and drift are most likely caused by some mechanical fault within the crystal assembly itself. The only cure in such cases is to replace the crystal. 73, Geoff LX2AO On January 25, 2013 at 9:40 AM, Ian Greenshields wrote: The LO on my XV432 transverter seems to be very unstable. I think it's something more than just temperature drift as the frequency will sometimes jump by several kHz. It's almost as if the crystal is hunting between different modes of oscillation. Prodding wiggling the components in the LO circuit doesn't point to any obvious poor connection, although the crystal itself is sensitive to being touched, or heated by a finger. The LO alignment voltage at TP1 peaks at about 3.3V. I don't have the temperature oven for the crystal, although I think it's a requirement. But I'm concerned about the frequency jumping and a frequency drift of almost 10kHz which I would not expect even of a non-temperature controlled crystal oscillator. Any thoughts or pointers as to what could be wrong? TIA, Ian G4FSU __ 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
Re: [Elecraft] [XV432} LO Instability Problem
Thanks for all the help and comments received so far, on and off reflector - I have to say the responsiveness and quality of help on this reflector is second to none! To summarise: 1. I have tried detuning L4, along with L3 and L5. L4 is very sensitive as is probably to be expected, L3 and L5 somewhat less so. The most stable point of L4 does seem to coincide with the peak in voltage at TP1, and detuning L3 and L5 doesn't seem to make much difference. The problem is that the voltage at TP1 can easily reach 4v or higher, and the LO is definitely less stable if I detune it to keep the voltage below 3v. 2. Is a voltage well above 3v at TP1 a problem? It seems to be just a detector diode circuit on the output of the LO, so I presume a fair amount of variation is to be expected. 3. The crystal seems mechanically stable in that tapping it doesn't send the frequency all over the place, but it is highly sensitive to being touched, which I assume is heating effect, 4. The biggest single improvement was a suggestion to ground the can of the crystal. This is something very familiar to any K2 builder. I grounded the crystal can, K2 filter style, to the oven -ve pad, which was the closest ground point. Huge improvement. The frequency jumping has gone, although there is still significant drift, even long after warm-up. 5. I then tried readjusting L3, L4 L5 to see if detuning the voltage to about 2.5v at TP1 helped now that the oscillator seemed more stable. This seemed to be a backward step as the LO lurched down about 10kHz in frequency, started to drift back up, but then actually stopped oscillating. Restoring L3, L4 and L5 to the point where the voltage at TP1 peaks - about 4v - seems to be the most stable point the LO starts up fine. From switch on it drifts about 3kHz low, then as it warms up, it starts to drift HF until about 3 or 4kHz above the switch-on point. 6. If my unit is normal, the oven would seem an essential. As I want to use the transverter on SSB, I can't really live with a drift range of 7kHz! 7. What is the view on grounding the crystal can? It does seem to help tremendously with the stability (and I mean the 'crystal mode' stability, just to differentiate from drift). I think my next step is to order the oven (I'm going to have fun fitting that now I've grounded the can!) possibly another crystal. 73 Ian G4FSU On 25 January 2013 14:01, Don Wilhelm w3...@embarqmail.com wrote: Ian, Two possibilities occur to me. First, detune the LO inductors L3, L4 and L5 a bit to give you 3 volts maximum at TP1 and see if it stabilizes. Secondly, try adjusting L4 a bit. It may be that the adjustment of L4 puts the crystal right on the 'hairy' edge of oscillation which would make the frequency unstable. The voltage at TP1 should remain between 1.7 and 3.0 volts. 73, Don W3FPR __ 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
