Re: [time-nuts] LPRO101 Lamp Exciter Frequency
rbarri...@msn.com wrote: Date: 26/10/2009 7.54 >Yes, everything I've seen points me to think that the oscillator runs at 140Mhz and not 70. ... > >Please, come back to us when you measure the exciter frequency on your LPRO, thank you. Roberto, I've done the check. Please excuse me for the delay due to the fact that I have my stuff spread across two locations 250 Km apart. Last week-end I fetched a working Rb and brought it here where I have spectrum analyzers. No 70 MHz signal at all, you were right. What I can see is 60 MHz, its 120 MHz harmonic and then the about 145 MHz from the lamp ignition oscillator. Probably PE1FBO was misled by me, and I, on my hand, had accepted the occasional 70 MHz reading (made with an hand held counter !) being biased by the FRS specs. I apologize. 73, Antonio I8IOV ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LPRO101 Lamp Exciter Frequency
Hi I have reading the mail on the rubidium oscillator. I just finished repairing my FRS. The manual for the FRS only gives basic operation. However an older manual for the FRK tells that the lamp should have a current between 125mA and 145mA. This is adjusted with C11, the cap on the lamp board. The wire going to the lamp support board to feed through cap C14 is removed from C14 a 500mA meter is inserted. At power on the voltage should be +22V. After the lamp has ignited and the resonator photo cell has detected the lit lamp the power supply should switch to +17V. The current of the lamp (really it’s the current of the oscillator) is adjusted to the low side of the 125-145mA range with C11. I found out that a 10:1 scope probe connected to a SM and touching the lamp housing I was able to see and measure the 70MHz signal. The FRK manual says to turn C11 to one of the listed frequencies listed, keeping the lamp current as above. These frequencies are 69.5, 71.0, 76.5, 77.5, 78.5, 79.0, 84.5, 87.0, and 91.5MHz. My FRS unit would not lock at 10MHz. I found the problem to be the 70MHz oscillator would have a clean signal, but as the lamp housing warmed up the 70MHz oscillator would go into a parasitic oscillation mode. Once in this mode the resonator photo cell, for some reason can not detect the lamp light, even though it is lit. C11 would tune total range from 69.5 to 91.5MHz, but I could not stop this parasitic oscillation. The only way to fix it was to place a Fe bead on the choke lead L5 (.15uH) connected to the base of Q3 (2n3375) oscillator. I was able to tune C11 to 78.5MHz to obtain 132mA lamp current. At this time the resonator photo cell detected the lamp light and the power supply then switched to +17V. And the 10MHz locked I don’t know if this is the problem but it’s a good place to start. 1) Check the 22/17V power supply switching. 2) Check to see if the lamp is ignited. 3) Check for parasitic oscillation mode of the 70MHz oscillator. If you have any questions, send me an E-MAIL. rchens...@gmail.com On 10/26/09, paul swed wrote: > > I guess the thing I have run into on these is there is a small variable cap > in that circuit. > With age they get noisey and jump around. > That needs to be tweaked. > I have one with this issue and it would be quite troublesome to replace > that > cap. > But maybe one day. > > On Sat, Oct 24, 2009 at 5:24 PM, Bruce Griffiths < > bruce.griffi...@xtra.co.nz > > wrote: > > > Roberto Barrios wrote: > > > Date: Sat, 24 Oct 2009 09:35:03 +1300 > > > From: Bruce Griffiths > > > Subject: Re: [time-nuts] LPRO101 Lamp Exciter Frequency > > > To: Discussion of precise time and frequency measurement > > > > > > Message-ID: <4ae21377.7070...@xtra.co.nz> > > > Content-Type: text/plain; charset=ISO-8859-1 > > > > > > Roberto Barrios wrote: > > > > > >> > > >> > > >> Hi all, > > >> > > >> > > >> > > >> I've got an LPRO101 that refuses to lock and you sure will be of great > > help. These devices are quite cheap but I'm trying to learn in the repair > > process. > > >> > > >> > > >> > > >> I've followed PE1FBO's repair guide and everything noted there seems > ok. > > I could not find a single suspect component. These are some notes I've > taken > > on the unit after a 20 minutes warmup: > > >> > > >> > > >> > > >> - Power input current during warmup is 1.2A and 0.4A after it. > > >> > > >> - 10Mhz out swings between 10.000191 and 9.999875, taking 40s to go up > > and 60s to go down in freq. > > >> > > >> - Lamp voltage is a steady 6.7V. > > >> > > >> - The lamp glows a few seconds after powering the unit. > > >> > > >> > > >> > > >> Placing a pickup look over the PCB, the analyzer shows peaks all over > > the place up to 2.5Ghz (it's limit), so the thing is alive. > > >> > > >> > > >> > > >> There is one unexpected thing I found... The frequency of the RF power > > going into the lamp is 157.3Mhz, very stable. From the repair guide, it > > should be 70Mhz. I checked it with everything on hand (scope, counter, > spec. > > analyzer) and there is no doubt about it. A clean sine of about 16V peak > to > > peak, at 157.3Mhz can be found at the output (source) of the BF160 > MOSFET. > > >> > > >> > > >> > > >> Could this unexpectedly high exciter frequency cause the inability to > > lock or should I loo
Re: [time-nuts] LPRO101 Lamp Exciter Frequency
I guess the thing I have run into on these is there is a small variable cap in that circuit. With age they get noisey and jump around. That needs to be tweaked. I have one with this issue and it would be quite troublesome to replace that cap. But maybe one day. On Sat, Oct 24, 2009 at 5:24 PM, Bruce Griffiths wrote: > Roberto Barrios wrote: > > Date: Sat, 24 Oct 2009 09:35:03 +1300 > > From: Bruce Griffiths > > Subject: Re: [time-nuts] LPRO101 Lamp Exciter Frequency > > To: Discussion of precise time and frequency measurement > > > > Message-ID: <4ae21377.7070...@xtra.co.nz> > > Content-Type: text/plain; charset=ISO-8859-1 > > > > Roberto Barrios wrote: > > > >> > >> > >> Hi all, > >> > >> > >> > >> I've got an LPRO101 that refuses to lock and you sure will be of great > help. These devices are quite cheap but I'm trying to learn in the repair > process. > >> > >> > >> > >> I've followed PE1FBO's repair guide and everything noted there seems ok. > I could not find a single suspect component. These are some notes I've taken > on the unit after a 20 minutes warmup: > >> > >> > >> > >> - Power input current during warmup is 1.2A and 0.4A after it. > >> > >> - 10Mhz out swings between 10.000191 and 9.999875, taking 40s to go up > and 60s to go down in freq. > >> > >> - Lamp voltage is a steady 6.7V. > >> > >> - The lamp glows a few seconds after powering the unit. > >> > >> > >> > >> Placing a pickup look over the PCB, the analyzer shows peaks all over > the place up to 2.5Ghz (it's limit), so the thing is alive. > >> > >> > >> > >> There is one unexpected thing I found... The frequency of the RF power > going into the lamp is 157.3Mhz, very stable. From the repair guide, it > should be 70Mhz. I checked it with everything on hand (scope, counter, spec. > analyzer) and there is no doubt about it. A clean sine of about 16V peak to > peak, at 157.3Mhz can be found at the output (source) of the BF160 MOSFET. > >> > >> > >> > >> Could this unexpectedly high exciter frequency cause the inability to > lock or should I look somewhere else? > >> > >> > >> > >> The deviation from the expected 70Mhz seems too big to me, but should I > tweak the oscillator tuning capacitor (C901) to try to lower the frequency? > >> > >> > >> > >> > > The oscillator is a Clapp oscillator and the (0.6-4.5pF) series tuning > > cap has a large influence on the frequency. > > Unless the coil has shorted turns or another component has gone open > > circuit its seems likely that the oscillator has been mistuned. > > > >> Thank you all, > >> > >> Roberto EB4EQA > >> > >> > >> > > Bruce > > > > > > Hi Bruce, > > > > > > > > Thank you for taking the time to look at this and answer my message. > Thank you for pointing to the oscillator type, thanks to that, I've made > some calculations. I've measured the inductace of the coil and it turns out > to be 460nH. Given the capacitor values, doing the math, the oscillator is > tunable from about 129Mhz to 310Mhz by adjusting capacitor C901. I've found > that there is about 157pF where the 82pF capacitor is, but that has very > little effect on tuning range. I've tried adjusting C901 and the lower I can > get is 125Mhz, as expected. > > > > > > > > Could the correct frequency be in that range, and not 70Mhz If you > confirm it should be 70Mhz, I'll add some capacitance to 901 to get the > oscillator down again to 70Mhz. About 90pF should do. > > > > > > > > Could this actually be the problem in the unit (the lamp glows...) > > > > > > > > Thank you & best regards, > > > > Roberto, EB4EQA > > > > > > Roberto > > Your lamp exciter differs from the one attached. > Unless a fixed capacitor is faulty you shouldn't need to change it. > > In principle it doesn't matter too much what the lamp excitation > frequency is as long as the coupling coil is suitably proportioned. > If the oscillator operates at a frequency other than the design value > the coupling to the lamp may be reduced. > > It would appear that the design frequency differs from that in the > repair manual (unless the coil is faulty). > > The fact that the 10MHz oscillator frequency ramps up and down suggests > that there is something wrong with the frequency lock circuit. > Try looking at the photocell signal processing chain. > > Is the microwave signal actually being modulated? > > > Bruce > > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LPRO101 Lamp Exciter Frequency
<* previous mails in this thread have been cropped *> > Date: Sun, 25 Oct 2009 22:33:59 +0100 > From: "iova...@inwind\.it" > Subject: Re: [time-nuts] LPRO101 Lamp Exciter Frequency > To: "time-nuts" > Message-ID: > Content-Type: text/plain; charset=iso-8859-1 > > Roberto Barrios wrote: > > >>>>> - 10Mhz out swings between 10.000191 and 9.999875, > taking 40s to go up and 60s to go down in freq. > > Roberto, > > please tell me, does the 10 MHz output swing continuously > between the lower and upper limits, or does it stop at the > lower or upper limit after one or two swings? > > >>>> Everything seems to be fine, it would be great to confirm > if other LPROs work at 70Mhz or actually at 140, like mine. > > Sorry that I can't check at present, I'm away. Actually I've > read both (about) 70 and 140 MHz at least on two units using a > one turn link and depending on its position, and this is not > enough to say that the oscillator works at 70 MHz. I could re- > check maybe next week-end and will let you know if the matter > is not solved in the meantime. > > Antonio I8IOV Hi Antonio, The 10Mhz out does not stop, never. It swings around 10.000.000Mhz continuously, +-150Hz, which is expected. It takes 40s to go up and 60s to go down, which is quite close to what the repair guide says (but with switched times...). This brings a question, since the swing times on my units are exactly opposite as appear in the guide, could it be that the 20Mhz oscillator is responding to control voltage to the wrong way?. That would explain the switched ramp times and also why it does not lock... but I wonder how on earth such a failure could occur. Yes, everything I've seen points me to think that the oscillator runs at 140Mhz and not 70. It would be quite easy to conclude that the oscillator runs at 70 if we pick up the 2nd harmonic and the look at the FRS manual, which says the exciter oscillator is adjustable from 70-100Mhz. I also wonder which is actually the optimum frequency for the exciter, since (in my LPRO) the lamp ignites at all frequencies along the whole range of the tuning capacitor values, but lamp voltage peaks at maximum capacitance. If maximum photocell output was the objetive of tuning the exciter frequency, it should peak somewhere between the tuning limits of the oscillator, not at an extreme. It would be nice to clarify this. Please, come back to us when you measure the exciter frequency on your LPRO, thank you. Regards, Roberto Eb4EQA _ ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LPRO101 Lamp Exciter Frequency
Roberto Barrios wrote: > - 10Mhz out swings between 10.000191 and 9.999875, taking 40s to go up and 60s to go down in freq. Roberto, please tell me, does the 10 MHz output swing continuously between the lower and upper limits, or does it stop at the lower or upper limit after one or two swings? Everything seems to be fine, it would be great to confirm if other LPROs work at 70Mhz or actually at 140, like mine. Sorry that I can't check at present, I'm away. Actually I've read both (about) 70 and 140 MHz at least on two units using a one turn link and depending on its position, and this is not enough to say that the oscillator works at 70 MHz. I could re- check maybe next week-end and will let you know if the matter is not solved in the meantime. Antonio I8IOV ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LPRO101 Lamp Exciter Frequency
> Date: Mon, 26 Oct 2009 08:36:49 +1300 > From: Bruce Griffiths > Subject: Re: [time-nuts] LPRO101 Lamp Exciter Frequency > To: Discussion of precise time and frequency measurement > > Message-ID: <4ae4a8d1.5070...@xtra.co.nz> > Content-Type: text/plain; charset=ISO-8859-1 > > Roberto Barrios wrote: > > Date: Sun, 25 Oct 2009 14:42:08 +1300 > > From: Bruce Griffiths > > Subject: Re: [time-nuts] LPRO101 Lamp Exciter Frequency > > To: Discussion of precise time and frequency measurement > > > > Message-ID: <4ae3acf0.3080...@xtra.co.nz> > > Content-Type: text/plain; charset=ISO-8859-1 > > > > Roberto Barrios wrote: > > > >>> Date: Sun, 25 Oct 2009 10:24:38 +1300 > >>> From: Bruce Griffiths > >>> Subject: Re: [time-nuts] LPRO101 Lamp Exciter Frequency > >>> To: Discussion of precise time and frequency measurement > >>> <> > >>> Message-ID: <4ae37096.5030...@xtra.co.nz> > >>> Content-Type: text/plain; charset="iso-8859-1" > >>> > >>> Roberto Barrios wrote: > >>> > >>> > >>>> Date: Sat, 24 Oct 2009 09:35:03 +1300 > >>>> From: Bruce Griffiths > >>>> Subject: Re: [time-nuts] LPRO101 Lamp Exciter Frequency > >>>> To: Discussion of precise time and frequency measurement > >>>> > >>>> Message-ID: <4ae21377.7070...@xtra.co.nz> > >>>> Content-Type: text/plain; charset=ISO-8859-1 > >>>> > >>>> Roberto Barrios wrote: > >>>> > >>>> > >>>> > >>>>> Hi all, > >>>>> > >>>>> > >>>>> > >>>>> I've got an LPRO101 that refuses to lock and you sure will be of great > >>>>> help. These devices are quite cheap but I'm trying to learn in the > >>>>> repair process. > >>>>> > >>>>> > >>>>> > >>>>> I've followed PE1FBO's repair guide and everything noted there seems > >>>>> ok. I could not find a single suspect component. These are some notes > >>>>> I've taken on the unit after a 20 minutes warmup: > >>>>> > >>>>> > >>>>> > >>>>> - Power input current during warmup is 1.2A and 0.4A after it. > >>>>> > >>>>> - 10Mhz out swings between 10.000191 and 9.999875, taking 40s to go up > >>>>> and 60s to go down in freq. > >>>>> > >>>>> - Lamp voltage is a steady 6.7V. > >>>>> > >>>>> - The lamp glows a few seconds after powering the unit. > >>>>> > >>>>> > >>>>> > >>>>> Placing a pickup look over the PCB, the analyzer shows peaks all over > >>>>> the place up to 2.5Ghz (it's limit), so the thing is alive. > >>>>> > >>>>> > >>>>> > >>>>> There is one unexpected thing I found... The frequency of the RF power > >>>>> going into the lamp is 157.3Mhz, very stable. From the repair guide, it > >>>>> should be 70Mhz. I checked it with everything on hand (scope, counter, > >>>>> spec. analyzer) and there is no doubt about it. A clean sine of about > >>>>> 16V peak to peak, at 157.3Mhz can be found at the output (source) of > >>>>> the BF160 MOSFET. > >>>>> > >>>>> > >>>>> > >>>>> Could this unexpectedly high exciter frequency cause the inability to > >>>>> lock or should I look somewhere else? > >>>>> > >>>>> > >>>>> > >>>>> The deviation from the expected 70Mhz seems too big to me, but should I > >>>>> tweak the oscillator tuning capacitor (C901) to try to lower the > >>>>> frequency? > >>>>> > >>>>> > >>>>> > >>>>> > >>>>> > >>>>> > >>>> The oscillator is a Clapp oscillator and the (0.6-4.5pF) series tuning > >>>> cap has a large influence on the frequency. > >>>> Unless the coil has shorted turns or another component has gone open > >>>> circuit its seems likely that the oscillator has been mistuned. > >>>>
Re: [time-nuts] LPRO101 Lamp Exciter Frequency
Doug G4DZU wrote: > Hi, > > One of my LPRO101's also won't lock, you mention a repair guide by PE1FBO. > > I've search the web and can't find a source for this, is it possible you > could advise me of it's location. > > best 73s > Doug > G4DZU > > http://radcomms.net/EFRATOM%20LPRO%20101%20Repair%20Guide.pdf Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LPRO101 Lamp Exciter Frequency
First link with "PE1FBO" on Google : http://radcomms.net/EFRATOM%20LPRO%20101%20Repair%20Guide.pdf ;) -Message d'origine- De : time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] De la part de Doug G4DZU Envoyé : dimanche 25 octobre 2009 21:51 À : Discussion of precise time and frequency measurement Objet : Re: [time-nuts] LPRO101 Lamp Exciter Frequency Hi, One of my LPRO101's also won't lock, you mention a repair guide by PE1FBO. I've search the web and can't find a source for this, is it possible you could advise me of it's location. best 73s Doug G4DZU -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com]on Behalf Of Bruce Griffiths Sent: 25 October 2009 19:37 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] LPRO101 Lamp Exciter Frequency Roberto Barrios wrote: > Date: Sun, 25 Oct 2009 14:42:08 +1300 > From: Bruce Griffiths > Subject: Re: [time-nuts] LPRO101 Lamp Exciter Frequency > To: Discussion of precise time and frequency measurement > > Message-ID: <4ae3acf0.3080...@xtra.co.nz> > Content-Type: text/plain; charset=ISO-8859-1 > > Roberto Barrios wrote: > >>> Date: Sun, 25 Oct 2009 10:24:38 +1300 >>> From: Bruce Griffiths >>> Subject: Re: [time-nuts] LPRO101 Lamp Exciter Frequency >>> To: Discussion of precise time and frequency measurement >>> <> >>> Message-ID: <4ae37096.5030...@xtra.co.nz> >>> Content-Type: text/plain; charset="iso-8859-1" >>> >>> Roberto Barrios wrote: >>> >>> >>>> Date: Sat, 24 Oct 2009 09:35:03 +1300 >>>> From: Bruce Griffiths >>>> Subject: Re: [time-nuts] LPRO101 Lamp Exciter Frequency >>>> To: Discussion of precise time and frequency measurement >>>> >>>> Message-ID: <4ae21377.7070...@xtra.co.nz> >>>> Content-Type: text/plain; charset=ISO-8859-1 >>>> >>>> Roberto Barrios wrote: >>>> >>>> >>>> >>>>> Hi all, >>>>> >>>>> >>>>> >>>>> I've got an LPRO101 that refuses to lock and you sure will be of great help. These devices are quite cheap but I'm trying to learn in the repair process. >>>>> >>>>> >>>>> >>>>> I've followed PE1FBO's repair guide and everything noted there seems ok. I could not find a single suspect component. These are some notes I've taken on the unit after a 20 minutes warmup: >>>>> >>>>> >>>>> >>>>> - Power input current during warmup is 1.2A and 0.4A after it. >>>>> >>>>> - 10Mhz out swings between 10.000191 and 9.999875, taking 40s to go up and 60s to go down in freq. >>>>> >>>>> - Lamp voltage is a steady 6.7V. >>>>> >>>>> - The lamp glows a few seconds after powering the unit. >>>>> >>>>> >>>>> >>>>> Placing a pickup look over the PCB, the analyzer shows peaks all over the place up to 2.5Ghz (it's limit), so the thing is alive. >>>>> >>>>> >>>>> >>>>> There is one unexpected thing I found... The frequency of the RF power going into the lamp is 157.3Mhz, very stable. From the repair guide, it should be 70Mhz. I checked it with everything on hand (scope, counter, spec. analyzer) and there is no doubt about it. A clean sine of about 16V peak to peak, at 157.3Mhz can be found at the output (source) of the BF160 MOSFET. >>>>> >>>>> >>>>> >>>>> Could this unexpectedly high exciter frequency cause the inability to lock or should I look somewhere else? >>>>> >>>>> >>>>> >>>>> The deviation from the expected 70Mhz seems too big to me, but should I tweak the oscillator tuning capacitor (C901) to try to lower the frequency? >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>> The oscillator is a Clapp oscillator and the (0.6-4.5pF) series tuning >>>> cap has a large influence on the frequency. >>>> Unless the coil has shorted turns or another component has gone open >>>> circuit its seems likely that the oscillator has been mistuned. >>>> >>>> >>>> >>>>> Thank you all, >>>>> >>>>> Roberto EB4EQA >>>>> >>>>> >>>>> >>&g
Re: [time-nuts] LPRO101 Lamp Exciter Frequency
Hi, One of my LPRO101's also won't lock, you mention a repair guide by PE1FBO. I've search the web and can't find a source for this, is it possible you could advise me of it's location. best 73s Doug G4DZU -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com]on Behalf Of Bruce Griffiths Sent: 25 October 2009 19:37 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] LPRO101 Lamp Exciter Frequency Roberto Barrios wrote: > Date: Sun, 25 Oct 2009 14:42:08 +1300 > From: Bruce Griffiths > Subject: Re: [time-nuts] LPRO101 Lamp Exciter Frequency > To: Discussion of precise time and frequency measurement > > Message-ID: <4ae3acf0.3080...@xtra.co.nz> > Content-Type: text/plain; charset=ISO-8859-1 > > Roberto Barrios wrote: > >>> Date: Sun, 25 Oct 2009 10:24:38 +1300 >>> From: Bruce Griffiths >>> Subject: Re: [time-nuts] LPRO101 Lamp Exciter Frequency >>> To: Discussion of precise time and frequency measurement >>> <> >>> Message-ID: <4ae37096.5030...@xtra.co.nz> >>> Content-Type: text/plain; charset="iso-8859-1" >>> >>> Roberto Barrios wrote: >>> >>> >>>> Date: Sat, 24 Oct 2009 09:35:03 +1300 >>>> From: Bruce Griffiths >>>> Subject: Re: [time-nuts] LPRO101 Lamp Exciter Frequency >>>> To: Discussion of precise time and frequency measurement >>>> >>>> Message-ID: <4ae21377.7070...@xtra.co.nz> >>>> Content-Type: text/plain; charset=ISO-8859-1 >>>> >>>> Roberto Barrios wrote: >>>> >>>> >>>> >>>>> Hi all, >>>>> >>>>> >>>>> >>>>> I've got an LPRO101 that refuses to lock and you sure will be of great help. These devices are quite cheap but I'm trying to learn in the repair process. >>>>> >>>>> >>>>> >>>>> I've followed PE1FBO's repair guide and everything noted there seems ok. I could not find a single suspect component. These are some notes I've taken on the unit after a 20 minutes warmup: >>>>> >>>>> >>>>> >>>>> - Power input current during warmup is 1.2A and 0.4A after it. >>>>> >>>>> - 10Mhz out swings between 10.000191 and 9.999875, taking 40s to go up and 60s to go down in freq. >>>>> >>>>> - Lamp voltage is a steady 6.7V. >>>>> >>>>> - The lamp glows a few seconds after powering the unit. >>>>> >>>>> >>>>> >>>>> Placing a pickup look over the PCB, the analyzer shows peaks all over the place up to 2.5Ghz (it's limit), so the thing is alive. >>>>> >>>>> >>>>> >>>>> There is one unexpected thing I found... The frequency of the RF power going into the lamp is 157.3Mhz, very stable. From the repair guide, it should be 70Mhz. I checked it with everything on hand (scope, counter, spec. analyzer) and there is no doubt about it. A clean sine of about 16V peak to peak, at 157.3Mhz can be found at the output (source) of the BF160 MOSFET. >>>>> >>>>> >>>>> >>>>> Could this unexpectedly high exciter frequency cause the inability to lock or should I look somewhere else? >>>>> >>>>> >>>>> >>>>> The deviation from the expected 70Mhz seems too big to me, but should I tweak the oscillator tuning capacitor (C901) to try to lower the frequency? >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>> The oscillator is a Clapp oscillator and the (0.6-4.5pF) series tuning >>>> cap has a large influence on the frequency. >>>> Unless the coil has shorted turns or another component has gone open >>>> circuit its seems likely that the oscillator has been mistuned. >>>> >>>> >>>> >>>>> Thank you all, >>>>> >>>>> Roberto EB4EQA >>>>> >>>>> >>>>> >>>>> >>>>> >>>> Bruce >>>> >>>> >>>> Hi Bruce, >>>> >>>> >>>> >>>> Thank you for taking the time to look at this and answer my message. Thank you for pointing to the oscillator type, thanks to that, I've made some calculations. I've measured the inductace of the coil and
Re: [time-nuts] LPRO101 Lamp Exciter Frequency
Roberto Barrios wrote: > Date: Sun, 25 Oct 2009 14:42:08 +1300 > From: Bruce Griffiths > Subject: Re: [time-nuts] LPRO101 Lamp Exciter Frequency > To: Discussion of precise time and frequency measurement > > Message-ID: <4ae3acf0.3080...@xtra.co.nz> > Content-Type: text/plain; charset=ISO-8859-1 > > Roberto Barrios wrote: > >>> Date: Sun, 25 Oct 2009 10:24:38 +1300 >>> From: Bruce Griffiths >>> Subject: Re: [time-nuts] LPRO101 Lamp Exciter Frequency >>> To: Discussion of precise time and frequency measurement >>> <> >>> Message-ID: <4ae37096.5030...@xtra.co.nz> >>> Content-Type: text/plain; charset="iso-8859-1" >>> >>> Roberto Barrios wrote: >>> >>> >>>> Date: Sat, 24 Oct 2009 09:35:03 +1300 >>>> From: Bruce Griffiths >>>> Subject: Re: [time-nuts] LPRO101 Lamp Exciter Frequency >>>> To: Discussion of precise time and frequency measurement >>>> >>>> Message-ID: <4ae21377.7070...@xtra.co.nz> >>>> Content-Type: text/plain; charset=ISO-8859-1 >>>> >>>> Roberto Barrios wrote: >>>> >>>> >>>> >>>>> Hi all, >>>>> >>>>> >>>>> >>>>> I've got an LPRO101 that refuses to lock and you sure will be of great >>>>> help. These devices are quite cheap but I'm trying to learn in the repair >>>>> process. >>>>> >>>>> >>>>> >>>>> I've followed PE1FBO's repair guide and everything noted there seems ok. >>>>> I could not find a single suspect component. These are some notes I've >>>>> taken on the unit after a 20 minutes warmup: >>>>> >>>>> >>>>> >>>>> - Power input current during warmup is 1.2A and 0.4A after it. >>>>> >>>>> - 10Mhz out swings between 10.000191 and 9.999875, taking 40s to go up >>>>> and 60s to go down in freq. >>>>> >>>>> - Lamp voltage is a steady 6.7V. >>>>> >>>>> - The lamp glows a few seconds after powering the unit. >>>>> >>>>> >>>>> >>>>> Placing a pickup look over the PCB, the analyzer shows peaks all over the >>>>> place up to 2.5Ghz (it's limit), so the thing is alive. >>>>> >>>>> >>>>> >>>>> There is one unexpected thing I found... The frequency of the RF power >>>>> going into the lamp is 157.3Mhz, very stable. From the repair guide, it >>>>> should be 70Mhz. I checked it with everything on hand (scope, counter, >>>>> spec. analyzer) and there is no doubt about it. A clean sine of about 16V >>>>> peak to peak, at 157.3Mhz can be found at the output (source) of the >>>>> BF160 MOSFET. >>>>> >>>>> >>>>> >>>>> Could this unexpectedly high exciter frequency cause the inability to >>>>> lock or should I look somewhere else? >>>>> >>>>> >>>>> >>>>> The deviation from the expected 70Mhz seems too big to me, but should I >>>>> tweak the oscillator tuning capacitor (C901) to try to lower the >>>>> frequency? >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>> The oscillator is a Clapp oscillator and the (0.6-4.5pF) series tuning >>>> cap has a large influence on the frequency. >>>> Unless the coil has shorted turns or another component has gone open >>>> circuit its seems likely that the oscillator has been mistuned. >>>> >>>> >>>> >>>>> Thank you all, >>>>> >>>>> Roberto EB4EQA >>>>> >>>>> >>>>> >>>>> >>>>> >>>> Bruce >>>> >>>> >>>> Hi Bruce, >>>> >>>> >>>> >>>> Thank you for taking the time to look at this and answer my message. Thank >>>> you for pointing to the oscillator type, thanks to that, I've made some >>>> calculations. I've measured the inductace of the coil and it turns out to >>>> be 460nH. Given the capacitor values, doing the math, the oscillato
Re: [time-nuts] LPRO101 Lamp Exciter Frequency
Date: Sun, 25 Oct 2009 14:42:08 +1300 From: Bruce Griffiths Subject: Re: [time-nuts] LPRO101 Lamp Exciter Frequency To: Discussion of precise time and frequency measurement Message-ID: <4ae3acf0.3080...@xtra.co.nz> Content-Type: text/plain; charset=ISO-8859-1 Roberto Barrios wrote: > >> Date: Sun, 25 Oct 2009 10:24:38 +1300 >> From: Bruce Griffiths >> Subject: Re: [time-nuts] LPRO101 Lamp Exciter Frequency >> To: Discussion of precise time and frequency measurement >> <> >> Message-ID: <4ae37096.5030...@xtra.co.nz> >> Content-Type: text/plain; charset="iso-8859-1" >> >> Roberto Barrios wrote: >> >>> Date: Sat, 24 Oct 2009 09:35:03 +1300 >>> From: Bruce Griffiths >>> Subject: Re: [time-nuts] LPRO101 Lamp Exciter Frequency >>> To: Discussion of precise time and frequency measurement >>> >>> Message-ID: <4ae21377.7070...@xtra.co.nz> >>> Content-Type: text/plain; charset=ISO-8859-1 >>> >>> Roberto Barrios wrote: >>> >>> >>>> Hi all, >>>> >>>> >>>> >>>> I've got an LPRO101 that refuses to lock and you sure will be of great >>>> help. These devices are quite cheap but I'm trying to learn in the repair >>>> process. >>>> >>>> >>>> >>>> I've followed PE1FBO's repair guide and everything noted there seems ok. I >>>> could not find a single suspect component. These are some notes I've taken >>>> on the unit after a 20 minutes warmup: >>>> >>>> >>>> >>>> - Power input current during warmup is 1.2A and 0.4A after it. >>>> >>>> - 10Mhz out swings between 10.000191 and 9.999875, taking 40s to go up and >>>> 60s to go down in freq. >>>> >>>> - Lamp voltage is a steady 6.7V. >>>> >>>> - The lamp glows a few seconds after powering the unit. >>>> >>>> >>>> >>>> Placing a pickup look over the PCB, the analyzer shows peaks all over the >>>> place up to 2.5Ghz (it's limit), so the thing is alive. >>>> >>>> >>>> >>>> There is one unexpected thing I found... The frequency of the RF power >>>> going into the lamp is 157.3Mhz, very stable. From the repair guide, it >>>> should be 70Mhz. I checked it with everything on hand (scope, counter, >>>> spec. analyzer) and there is no doubt about it. A clean sine of about 16V >>>> peak to peak, at 157.3Mhz can be found at the output (source) of the BF160 >>>> MOSFET. >>>> >>>> >>>> >>>> Could this unexpectedly high exciter frequency cause the inability to lock >>>> or should I look somewhere else? >>>> >>>> >>>> >>>> The deviation from the expected 70Mhz seems too big to me, but should I >>>> tweak the oscillator tuning capacitor (C901) to try to lower the frequency? >>>> >>>> >>>> >>>> >>>> >>> The oscillator is a Clapp oscillator and the (0.6-4.5pF) series tuning >>> cap has a large influence on the frequency. >>> Unless the coil has shorted turns or another component has gone open >>> circuit its seems likely that the oscillator has been mistuned. >>> >>> >>>> Thank you all, >>>> >>>> Roberto EB4EQA >>>> >>>> >>>> >>>> >>> Bruce >>> >>> >>> Hi Bruce, >>> >>> >>> >>> Thank you for taking the time to look at this and answer my message. Thank >>> you for pointing to the oscillator type, thanks to that, I've made some >>> calculations. I've measured the inductace of the coil and it turns out to >>> be 460nH. Given the capacitor values, doing the math, the oscillator is >>> tunable from about 129Mhz to 310Mhz by adjusting capacitor C901. I've found >>> that there is about 157pF where the 82pF capacitor is, but that has very >>> little effect on tuning range. I've tried adjusting C901 and the lower I >>> can get is 125Mhz, as expected. >>> >>> >>> >>> Could the correct frequency be in that range, and not 70Mhz If you >>> confirm it should be 70Mhz, I'll add some capacitance to 901 to get the >>> oscillator down again to 70Mhz. About 90pF should do. >>&g
Re: [time-nuts] LPRO101 Lamp Exciter Frequency
Roberto Barrios wrote: > >> Date: Sun, 25 Oct 2009 10:24:38 +1300 >> From: Bruce Griffiths >> Subject: Re: [time-nuts] LPRO101 Lamp Exciter Frequency >> To: Discussion of precise time and frequency measurement >> <> >> Message-ID: <4ae37096.5030...@xtra.co.nz> >> Content-Type: text/plain; charset="iso-8859-1" >> >> Roberto Barrios wrote: >> >>> Date: Sat, 24 Oct 2009 09:35:03 +1300 >>> From: Bruce Griffiths >>> Subject: Re: [time-nuts] LPRO101 Lamp Exciter Frequency >>> To: Discussion of precise time and frequency measurement >>> >>> Message-ID: <4ae21377.7070...@xtra.co.nz> >>> Content-Type: text/plain; charset=ISO-8859-1 >>> >>> Roberto Barrios wrote: >>> >>> >>>> Hi all, >>>> >>>> >>>> >>>> I've got an LPRO101 that refuses to lock and you sure will be of great >>>> help. These devices are quite cheap but I'm trying to learn in the repair >>>> process. >>>> >>>> >>>> >>>> I've followed PE1FBO's repair guide and everything noted there seems ok. I >>>> could not find a single suspect component. These are some notes I've taken >>>> on the unit after a 20 minutes warmup: >>>> >>>> >>>> >>>> - Power input current during warmup is 1.2A and 0.4A after it. >>>> >>>> - 10Mhz out swings between 10.000191 and 9.999875, taking 40s to go up and >>>> 60s to go down in freq. >>>> >>>> - Lamp voltage is a steady 6.7V. >>>> >>>> - The lamp glows a few seconds after powering the unit. >>>> >>>> >>>> >>>> Placing a pickup look over the PCB, the analyzer shows peaks all over the >>>> place up to 2.5Ghz (it's limit), so the thing is alive. >>>> >>>> >>>> >>>> There is one unexpected thing I found... The frequency of the RF power >>>> going into the lamp is 157.3Mhz, very stable. From the repair guide, it >>>> should be 70Mhz. I checked it with everything on hand (scope, counter, >>>> spec. analyzer) and there is no doubt about it. A clean sine of about 16V >>>> peak to peak, at 157.3Mhz can be found at the output (source) of the BF160 >>>> MOSFET. >>>> >>>> >>>> >>>> Could this unexpectedly high exciter frequency cause the inability to lock >>>> or should I look somewhere else? >>>> >>>> >>>> >>>> The deviation from the expected 70Mhz seems too big to me, but should I >>>> tweak the oscillator tuning capacitor (C901) to try to lower the frequency? >>>> >>>> >>>> >>>> >>>> >>> The oscillator is a Clapp oscillator and the (0.6-4.5pF) series tuning >>> cap has a large influence on the frequency. >>> Unless the coil has shorted turns or another component has gone open >>> circuit its seems likely that the oscillator has been mistuned. >>> >>> >>>> Thank you all, >>>> >>>> Roberto EB4EQA >>>> >>>> >>>> >>>> >>> Bruce >>> >>> >>> Hi Bruce, >>> >>> >>> >>> Thank you for taking the time to look at this and answer my message. Thank >>> you for pointing to the oscillator type, thanks to that, I've made some >>> calculations. I've measured the inductace of the coil and it turns out to >>> be 460nH. Given the capacitor values, doing the math, the oscillator is >>> tunable from about 129Mhz to 310Mhz by adjusting capacitor C901. I've found >>> that there is about 157pF where the 82pF capacitor is, but that has very >>> little effect on tuning range. I've tried adjusting C901 and the lower I >>> can get is 125Mhz, as expected. >>> >>> >>> >>> Could the correct frequency be in that range, and not 70Mhz If you >>> confirm it should be 70Mhz, I'll add some capacitance to 901 to get the >>> oscillator down again to 70Mhz. About 90pF should do. >>> >>> >>> >>> Could this actually be the problem in the unit (the lamp glows...) >>> >>> >>> >>> Thank you & best regards, >>> >>> Roberto, EB4EQA &g
Re: [time-nuts] LPRO101 Lamp Exciter Frequency
> Date: Sun, 25 Oct 2009 10:24:38 +1300 > From: Bruce Griffiths > Subject: Re: [time-nuts] LPRO101 Lamp Exciter Frequency > To: Discussion of precise time and frequency measurement > <> > Message-ID: <4ae37096.5030...@xtra.co.nz> > Content-Type: text/plain; charset="iso-8859-1" > > Roberto Barrios wrote: > > Date: Sat, 24 Oct 2009 09:35:03 +1300 > > From: Bruce Griffiths > > Subject: Re: [time-nuts] LPRO101 Lamp Exciter Frequency > > To: Discussion of precise time and frequency measurement > > > > Message-ID: <4ae21377.7070...@xtra.co.nz> > > Content-Type: text/plain; charset=ISO-8859-1 > > > > Roberto Barrios wrote: > > > >> > >> > >> Hi all, > >> > >> > >> > >> I've got an LPRO101 that refuses to lock and you sure will be of great > >> help. These devices are quite cheap but I'm trying to learn in the repair > >> process. > >> > >> > >> > >> I've followed PE1FBO's repair guide and everything noted there seems ok. I > >> could not find a single suspect component. These are some notes I've taken > >> on the unit after a 20 minutes warmup: > >> > >> > >> > >> - Power input current during warmup is 1.2A and 0.4A after it. > >> > >> - 10Mhz out swings between 10.000191 and 9.999875, taking 40s to go up and > >> 60s to go down in freq. > >> > >> - Lamp voltage is a steady 6.7V. > >> > >> - The lamp glows a few seconds after powering the unit. > >> > >> > >> > >> Placing a pickup look over the PCB, the analyzer shows peaks all over the > >> place up to 2.5Ghz (it's limit), so the thing is alive. > >> > >> > >> > >> There is one unexpected thing I found... The frequency of the RF power > >> going into the lamp is 157.3Mhz, very stable. From the repair guide, it > >> should be 70Mhz. I checked it with everything on hand (scope, counter, > >> spec. analyzer) and there is no doubt about it. A clean sine of about 16V > >> peak to peak, at 157.3Mhz can be found at the output (source) of the BF160 > >> MOSFET. > >> > >> > >> > >> Could this unexpectedly high exciter frequency cause the inability to lock > >> or should I look somewhere else? > >> > >> > >> > >> The deviation from the expected 70Mhz seems too big to me, but should I > >> tweak the oscillator tuning capacitor (C901) to try to lower the frequency? > >> > >> > >> > >> > > The oscillator is a Clapp oscillator and the (0.6-4.5pF) series tuning > > cap has a large influence on the frequency. > > Unless the coil has shorted turns or another component has gone open > > circuit its seems likely that the oscillator has been mistuned. > > > >> Thank you all, > >> > >> Roberto EB4EQA > >> > >> > >> > > Bruce > > > > > > Hi Bruce, > > > > > > > > Thank you for taking the time to look at this and answer my message. Thank > > you for pointing to the oscillator type, thanks to that, I've made some > > calculations. I've measured the inductace of the coil and it turns out to > > be 460nH. Given the capacitor values, doing the math, the oscillator is > > tunable from about 129Mhz to 310Mhz by adjusting capacitor C901. I've found > > that there is about 157pF where the 82pF capacitor is, but that has very > > little effect on tuning range. I've tried adjusting C901 and the lower I > > can get is 125Mhz, as expected. > > > > > > > > Could the correct frequency be in that range, and not 70Mhz If you > > confirm it should be 70Mhz, I'll add some capacitance to 901 to get the > > oscillator down again to 70Mhz. About 90pF should do. > > > > > > > > Could this actually be the problem in the unit (the lamp glows...) > > > > > > > > Thank you & best regards, > > > > Roberto, EB4EQA > > > > > > Roberto > > Your lamp exciter differs from the one attached. > Unless a fixed capacitor is faulty you shouldn't need to change it. > > In principle it doesn't matter too much what the lamp excitation > frequency is as long as the coupling coil is suitably proportioned. > If the oscillator operates at a frequency other than the design value > the coupling to the lamp may be redu
Re: [time-nuts] LPRO101 Lamp Exciter Frequency
Roberto Barrios wrote: > Date: Sat, 24 Oct 2009 09:35:03 +1300 > From: Bruce Griffiths > Subject: Re: [time-nuts] LPRO101 Lamp Exciter Frequency > To: Discussion of precise time and frequency measurement > > Message-ID: <4ae21377.7070...@xtra.co.nz> > Content-Type: text/plain; charset=ISO-8859-1 > > Roberto Barrios wrote: > >> >> >> Hi all, >> >> >> >> I've got an LPRO101 that refuses to lock and you sure will be of great help. >> These devices are quite cheap but I'm trying to learn in the repair process. >> >> >> >> I've followed PE1FBO's repair guide and everything noted there seems ok. I >> could not find a single suspect component. These are some notes I've taken >> on the unit after a 20 minutes warmup: >> >> >> >> - Power input current during warmup is 1.2A and 0.4A after it. >> >> - 10Mhz out swings between 10.000191 and 9.999875, taking 40s to go up and >> 60s to go down in freq. >> >> - Lamp voltage is a steady 6.7V. >> >> - The lamp glows a few seconds after powering the unit. >> >> >> >> Placing a pickup look over the PCB, the analyzer shows peaks all over the >> place up to 2.5Ghz (it's limit), so the thing is alive. >> >> >> >> There is one unexpected thing I found... The frequency of the RF power going >> into the lamp is 157.3Mhz, very stable. From the repair guide, it should be >> 70Mhz. I checked it with everything on hand (scope, counter, spec. analyzer) >> and there is no doubt about it. A clean sine of about 16V peak to peak, at >> 157.3Mhz can be found at the output (source) of the BF160 MOSFET. >> >> >> >> Could this unexpectedly high exciter frequency cause the inability to lock >> or should I look somewhere else? >> >> >> >> The deviation from the expected 70Mhz seems too big to me, but should I >> tweak the oscillator tuning capacitor (C901) to try to lower the frequency? >> >> >> >> > The oscillator is a Clapp oscillator and the (0.6-4.5pF) series tuning > cap has a large influence on the frequency. > Unless the coil has shorted turns or another component has gone open > circuit its seems likely that the oscillator has been mistuned. > >> Thank you all, >> >> Roberto EB4EQA >> >> >> > Bruce > > > Hi Bruce, > > > > Thank you for taking the time to look at this and answer my message. Thank > you for pointing to the oscillator type, thanks to that, I've made some > calculations. I've measured the inductace of the coil and it turns out to be > 460nH. Given the capacitor values, doing the math, the oscillator is tunable > from about 129Mhz to 310Mhz by adjusting capacitor C901. I've found that > there is about 157pF where the 82pF capacitor is, but that has very little > effect on tuning range. I've tried adjusting C901 and the lower I can get is > 125Mhz, as expected. > > > > Could the correct frequency be in that range, and not 70Mhz If you > confirm it should be 70Mhz, I'll add some capacitance to 901 to get the > oscillator down again to 70Mhz. About 90pF should do. > > > > Could this actually be the problem in the unit (the lamp glows...) > > > > Thank you & best regards, > > Roberto, EB4EQA > > Roberto Your lamp exciter differs from the one attached. Unless a fixed capacitor is faulty you shouldn't need to change it. In principle it doesn't matter too much what the lamp excitation frequency is as long as the coupling coil is suitably proportioned. If the oscillator operates at a frequency other than the design value the coupling to the lamp may be reduced. It would appear that the design frequency differs from that in the repair manual (unless the coil is faulty). The fact that the 10MHz oscillator frequency ramps up and down suggests that there is something wrong with the frequency lock circuit. Try looking at the photocell signal processing chain. Is the microwave signal actually being modulated? Bruce <>___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LPRO101 Lamp Exciter Frequency
I think you are reading the second harmonic. I would recall that: - the LPRO loses lock if the lamp gets too hot. This is indicated by a color more close to red than to pink (which is normal). This could happen if the temperature control circuit has some fault. I would suggest cheching the voltage at the base of Q703: it should drop to about 5V from the initial 11V after warm-up. If the voltage remains around 11, then R721 61.9K (bottom of PCB) could be interrupted. Onboard it should read 14K if good, 18K if broken. - the lamp could glow even if the lamp assy is cold, and the LPRO doesn't lock. This is easily checked touching the lamp assembly after one minute of power-on, you should burn your finger. If you don't burn your finger, then check the heating circuit, particularily the small 100K resistors on the bottom pcb near the lamp assy. Be aware: once again I would remind that the LPRO doesn't lock if the cover is off and there is some light coming from an incandescent light or any light that has ripples or pulses. Antonio I8IOV > Date: Sat, 24 Oct 2009 09:35:03 +1300 > From: Bruce Griffiths > Subject: Re: [time-nuts] LPRO101 Lamp Exciter Frequency > To: Discussion of precise time and frequency measurement > > Message-ID: <4ae21377.7070...@xtra.co.nz> > Content-Type: text/plain; charset=ISO-8859-1 > > Roberto Barrios wrote: > > > > > > > > > > Hi all, > > > > > > > > I've got an LPRO101 that refuses to lock and you sure will be of great > > help. These devices are quite cheap but I'm trying to learn in the repair > > process. > > > > > > > > I've followed PE1FBO's repair guide and everything noted there seems ok. I > > could not find a single suspect component. These are some notes I've taken > > on the unit after a 20 minutes warmup: > > > > > > > > - Power input current during warmup is 1.2A and 0.4A after it. > > > > - 10Mhz out swings between 10.000191 and 9.999875, taking 40s to go up and > > 60s to go down in freq. > > > > - Lamp voltage is a steady 6.7V. > > > > - The lamp glows a few seconds after powering the unit. > > > > > > > > Placing a pickup look over the PCB, the analyzer shows peaks all over the > > place up to 2.5Ghz (it's limit), so the thing is alive. > > > > > > > > There is one unexpected thing I found... The frequency of the RF power > > going into the lamp is 157.3Mhz, very stable. From the repair guide, it > > should be 70Mhz. I checked it with everything on hand (scope, counter, > > spec. analyzer) and there is no doubt about it. A clean sine of about 16V > > peak to peak, at 157.3Mhz can be found at the output (source) of the BF160 > > MOSFET. > > > > > > > > Could this unexpectedly high exciter frequency cause the inability to lock > > or should I look somewhere else? > > > > > > > > The deviation from the expected 70Mhz seems too big to me, but should I > > tweak the oscillator tuning capacitor (C901) to try to lower the frequency? > > > > > > > The oscillator is a Clapp oscillator and the (0.6-4.5pF) series tuning > cap has a large influence on the frequency. > Unless the coil has shorted turns or another component has gone open > circuit its seems likely that the oscillator has been mistuned. > > Thank you all, > > > > Roberto EB4EQA > > > > > Bruce > > > Hi Bruce, > > > > Thank you for taking the time to look at this and answer my message. Thank > you for pointing to the oscillator type, thanks to that, I've made some > calculations. I've measured the inductace of the coil and it turns out to be > 460nH. Given the capacitor values, doing the math, the oscillator is tunable > from about 129Mhz to 310Mhz by adjusting capacitor C901. I've found that > there is about 157pF where the 82pF capacitor is, but that has very little > effect on tuning range. I've tried adjusting C901 and the lower I can get is > 125Mhz, as expected. > > > > Could the correct frequency be in that range, and not 70Mhz If you > confirm it should be 70Mhz, I'll add some capacitance to 901 to get the > oscillator down again to 70Mhz. About 90pF should do. > > > > Could this actually be the problem in the unit (the lamp glows...) > > > > Thank you & best regards, > > Roberto, EB4EQA > > _ > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LPRO101 Lamp Exciter Frequency
Date: Sat, 24 Oct 2009 09:35:03 +1300 From: Bruce Griffiths Subject: Re: [time-nuts] LPRO101 Lamp Exciter Frequency To: Discussion of precise time and frequency measurement Message-ID: <4ae21377.7070...@xtra.co.nz> Content-Type: text/plain; charset=ISO-8859-1 Roberto Barrios wrote: > > > > > Hi all, > > > > I've got an LPRO101 that refuses to lock and you sure will be of great help. > These devices are quite cheap but I'm trying to learn in the repair process. > > > > I've followed PE1FBO's repair guide and everything noted there seems ok. I > could not find a single suspect component. These are some notes I've taken on > the unit after a 20 minutes warmup: > > > > - Power input current during warmup is 1.2A and 0.4A after it. > > - 10Mhz out swings between 10.000191 and 9.999875, taking 40s to go up and > 60s to go down in freq. > > - Lamp voltage is a steady 6.7V. > > - The lamp glows a few seconds after powering the unit. > > > > Placing a pickup look over the PCB, the analyzer shows peaks all over the > place up to 2.5Ghz (it's limit), so the thing is alive. > > > > There is one unexpected thing I found... The frequency of the RF power going > into the lamp is 157.3Mhz, very stable. From the repair guide, it should be > 70Mhz. I checked it with everything on hand (scope, counter, spec. analyzer) > and there is no doubt about it. A clean sine of about 16V peak to peak, at > 157.3Mhz can be found at the output (source) of the BF160 MOSFET. > > > > Could this unexpectedly high exciter frequency cause the inability to lock or > should I look somewhere else? > > > > The deviation from the expected 70Mhz seems too big to me, but should I tweak > the oscillator tuning capacitor (C901) to try to lower the frequency? > > > The oscillator is a Clapp oscillator and the (0.6-4.5pF) series tuning cap has a large influence on the frequency. Unless the coil has shorted turns or another component has gone open circuit its seems likely that the oscillator has been mistuned. > Thank you all, > > Roberto EB4EQA > > Bruce Hi Bruce, Thank you for taking the time to look at this and answer my message. Thank you for pointing to the oscillator type, thanks to that, I've made some calculations. I've measured the inductace of the coil and it turns out to be 460nH. Given the capacitor values, doing the math, the oscillator is tunable from about 129Mhz to 310Mhz by adjusting capacitor C901. I've found that there is about 157pF where the 82pF capacitor is, but that has very little effect on tuning range. I've tried adjusting C901 and the lower I can get is 125Mhz, as expected. Could the correct frequency be in that range, and not 70Mhz If you confirm it should be 70Mhz, I'll add some capacitance to 901 to get the oscillator down again to 70Mhz. About 90pF should do. Could this actually be the problem in the unit (the lamp glows...) Thank you & best regards, Roberto, EB4EQA _ ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LPRO101 Lamp Exciter Frequency
Roberto Barrios wrote: > > > > > Hi all, > > > > I've got an LPRO101 that refuses to lock and you sure will be of great help. > These devices are quite cheap but I'm trying to learn in the repair process. > > > > I've followed PE1FBO's repair guide and everything noted there seems ok. I > could not find a single suspect component. These are some notes I've taken on > the unit after a 20 minutes warmup: > > > > - Power input current during warmup is 1.2A and 0.4A after it. > > - 10Mhz out swings between 10.000191 and 9.999875, taking 40s to go up and > 60s to go down in freq. > > - Lamp voltage is a steady 6.7V. > > - The lamp glows a few seconds after powering the unit. > > > > Placing a pickup look over the PCB, the analyzer shows peaks all over the > place up to 2.5Ghz (it's limit), so the thing is alive. > > > > There is one unexpected thing I found... The frequency of the RF power going > into the lamp is 157.3Mhz, very stable. From the repair guide, it should be > 70Mhz. I checked it with everything on hand (scope, counter, spec. analyzer) > and there is no doubt about it. A clean sine of about 16V peak to peak, at > 157.3Mhz can be found at the output (source) of the BF160 MOSFET. > > > > Could this unexpectedly high exciter frequency cause the inability to lock or > should I look somewhere else? > > > > The deviation from the expected 70Mhz seems too big to me, but should I tweak > the oscillator tuning capacitor (C901) to try to lower the frequency? > > > The oscillator is a Clapp oscillator and the (0.6-4.5pF) series tuning cap has a large influence on the frequency. Unless the coil has shorted turns or another component has gone open circuit its seems likely that the oscillator has been mistuned. > Thank you all, > > Roberto EB4EQA > > Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
