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Re: 2754P Frequency Loops Cal
arthurok
if the heater is shot in the filter you might be able to carefully unsolder the can seam
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and fix it. maybe deane kidd has replacement filters. that unit probably has a heated yig too the 7l12 dosent use a heated yig but the 7l13/14 do are you allowing plenty of time for the unit to warm up before calibration?? "1/2 hour" a ham friend of mine was using an ifr communications monitor at work and even though it has a tcxo the unit had to be warmed up for high accuracy. ----- Original Message -----
From: Eric Brownell To: TekScopes@... Sent: Monday, January 01, 2007 4:52 PM Subject: Re: [TekScopes] Re: 2754P Frequency Loops Cal Hi John, - What, specifically, suggests an unlocked first LO? Are you getting specific error messages during self-calibration, or is it just hanging in a loop? <Eric> The offset displayed during all of the CF & LO Driver board alignment steps shows an un-adjustable 107.xxx,xxx GHz - Is the unit thoroughly warmed up prior to calibration? <Eric> Yes - When the calibration routine tells you to adjust various trimmers and controls to bring the values within range, are you able to follow the steps for all of the adjustments up until it starts telling you to adjust the phase-lock assembly? (You'd normally hit SHIFT to end the adjustment procedure at that point, unless you've been working on that particular module.) <Eric> See above - Does the analyzer seem to work properly in both wide and narrow spans? If so, how does its phase noise/sideband performance compare with the 494P? The LO noise profiles should look identical, or at least very similar to each other. <Eric> Yes it seems to work at all Frequencies & Spans - Does it complete its front-panel-based self-calibration routine (CAL button) successfully? <Eric> The 2754 doesn't have such a routine (that I've discovered) One very-common problem I have seen on these is failure of the crystal oven in the 30 Hz/100 Hz IF filter mounted atop the CRT shield. The series pass transistor inside the sealed filter overheats and opens up, making the self-calibration routine either hang up or fail with an error message during its final, narrowband sweeps. Even if you have a separate LO problem, that is something you'll want to check. After running for 20-30 minutes, the filter housing should be very warm to the touch. <Eric> The 2754 doesn't have this filter as its minimums Span/Div is 200 Hz. This is one of the few differences between the 494 & 2754 And the YIG interface board with the electrolytic caps, I'd assume? <Eric> Yes Are the power supply voltages OK and within their ripple specs? <Eric> Yes, in fact the 494 works with the 2754's power supply Which modules, exactly, did you try to exchange between the two? (Don't forget the harmonic mixer, phase gate, counter, and auxiliary synthesizer modules. <Eric> CF Control, 1st LO Driver, Span Attenuator, Auxiliary Synthesizer, Counter, Phase Lock Synthesizer (both), Harmonic Mixer, Phase Gate, Video Processor & Preselector Driver (last two in desperation) Check the power connectors on the harmonic mixer and phase gate, if you haven't already.) <Eric> Done Thanks a bunch, Eric |
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Re: 2754P Frequency Loops Cal
Hi John,
- What, specifically, suggests an unlocked first LO? Are you getting specific error messages during self-calibration, or is it just hanging in a loop? <Eric> The offset displayed during all of the CF & LO Driver board alignment steps shows an un-adjustable 107.xxx,xxx GHz - Is the unit thoroughly warmed up prior to calibration? <Eric> Yes - When the calibration routine tells you to adjust various trimmers and controls to bring the values within range, are you able to follow the steps for all of the adjustments up until it starts telling you to adjust the phase-lock assembly? (You'd normally hit SHIFT to end the adjustment procedure at that point, unless you've been working on that particular module.) <Eric> See above - Does the analyzer seem to work properly in both wide and narrow spans? If so, how does its phase noise/sideband performance compare with the 494P? The LO noise profiles should look identical, or at least very similar to each other. <Eric> Yes it seems to work at all Frequencies & Spans - Does it complete its front-panel-based self-calibration routine (CAL button) successfully? <Eric> The 2754 doesn't have such a routine (that I've discovered) One very-common problem I have seen on these is failure of the crystal oven in the 30 Hz/100 Hz IF filter mounted atop the CRT shield. The series pass transistor inside the sealed filter overheats and opens up, making the self-calibration routine either hang up or fail with an error message during its final, narrowband sweeps. Even if you have a separate LO problem, that is something you'll want to check. After running for 20-30 minutes, the filter housing should be very warm to the touch. <Eric> The 2754 doesn't have this filter as its minimums Span/Div is 200 Hz. This is one of the few differences between the 494 & 2754 And the YIG interface board with the electrolytic caps, I'd assume? <Eric> Yes Are the power supply voltages OK and within their ripple specs? <Eric> Yes, in fact the 494 works with the 2754's power supply Which modules, exactly, did you try to exchange between the two? (Don't forget the harmonic mixer, phase gate, counter, and auxiliary synthesizer modules. <Eric> CF Control, 1st LO Driver, Span Attenuator, Auxiliary Synthesizer, Counter, Phase Lock Synthesizer (both), Harmonic Mixer, Phase Gate, Video Processor & Preselector Driver (last two in desperation) Check the power connectors on the harmonic mixer and phase gate, if you haven't already.) <Eric> Done Thanks a bunch, Eric |
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492BP chassis heat.
Gerald Molenkamp
Happy new year to you all.
After quite a number of positive replies to the issue of 492BP chassis heat, I am satisfied that it is fine. John, thanks. I did see the thermal switch today, it is also 103 Degrees C down here. My new years resolution is to take John's advice, ( Quit messing with it and have fun using it. :-) Thanks for the assistance. Cheers Gerald |
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Re: Tektronix 492BP chassis heat.
gleamfollower
--- In TekScopes@..., "arthurok" <arthurok@...> wrote:
protection internally "thermostat" Yes, there's a thermal cutout in series with the line. It calls a halt to the festivities at 103 degrees C. -- john, KE5FX |
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Re: WANTED: 492 Front Cover
John Miles
Agreed, the older ones do feel more robust. The problem is really the
weight of the SA itself. If the whole thing isn't secured inside its shipping box, then almost any off-center force can pop the latches out of their shallow detents. Not a big deal if properly packed, but a liability otherwise (speaking from experience buying them on eBay with covers attached). Putting the cover on and stowing it in the back of a truck or under a plane seat would be fine, but tossing it in a used Dell box full of peanuts and handing it off to UPS Ground is asking for trouble. It was probably less risky when the latches were brand new, but I don't trust them now. -- john, KE5FX Hi John: I would like to take issue with you about the covers for the 49x analyzers. The original cover has two toggle actuated fingers that fit into the front flange of the instrument and hold the cover very tightly in place. The newer cover fits on with a friction fit and can come loose when banged around. Both covers are made from rather hard plastic material and will withstand very heavy impacts without breaking. If the instruments is packaged in a heavy box with firm plastic chusions, I can't believe that either cover could come loose and cause damage. With the cover installed, I can throw my 494AP in the back of the car or van and feel that the instrument is safe. Now, to the original question, I have all ready posted an answer that I do not have either cover and I do not know of a source. Deane |
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Re: WANTED: 492 Front Cover
arthurok
unless the front cover is captive like on a 2336 scope
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they often become "lost" if one really wanted to make a replacement maybe it could be done with some hardwood plywood and gasketing material. or maybe some lexan sheeting glued together ----- Original Message -----
From: Deane E. Kidd To: TekScopes@... ; gleamfollower Sent: Monday, January 01, 2007 12:38 AM Subject: Re: [TekScopes] Re: WANTED: 492 Front Cover Hi John: I would like to take issue with you about the covers for the 49x analyzers. The original cover has two toggle actuated fingers that fit into the front flange of the instrument and hold the cover very tightly in place. The newer cover fits on with a friction fit and can come loose when banged around. Both covers are made from rather hard plastic material and will withstand very heavy impacts without breaking. If the instruments is packaged in a heavy box with firm plastic chusions, I can't believe that either cover could come loose and cause damage. With the cover installed, I can throw my 494AP in the back of the car or van and feel that the instrument is safe. Now, to the original question, I have all ready posted an answer that I do not have either cover and I do not know of a source. Deane ----- Original Message ----- From: gleamfollower To: TekScopes@... Sent: Sunday, December 31, 2006 3:02 AM Subject: [TekScopes] Re: WANTED: 492 Front Cover > First, does there exist a front cover for the 492 Spectrum Analyzer, > and, if it does, where can I get one ? You'll see them on eBay every once in awhile, or for that matter, Deane Kidd may be able to put his hands on one. There is an older- and a newer-style (all plastic) cover; either will fit. The innermost surface of the newer covers have a cool Easter egg (raised thermoplastic signatures of several dozen Tek employees from the spectrum-analyzer product group). The foam-rubber liner will most likely be in better condition in these as well. Other than that, they will both work OK. They are really just dust covers, though. Under no circumstances should you ever ship a 49x-series analyzer with either front cover in place. The older-style covers are likely to come loose and bash the heck out of the front panel. The newer-style covers are lighter, but their flexible plastic latches are prone to breakage if any force is exerted on them during transport. -- john, KE5FX -- I am using the free version of SPAMfighter for private users. It has removed 841 spam emails to date. Paying users do not have this message in their emails. Get the free SPAMfighter here: |
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Re: WANTED: 492 Front Cover
Deane E. Kidd
Hi John:
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I would like to take issue with you about the covers for the 49x analyzers. The original cover has two toggle actuated fingers that fit into the front flange of the instrument and hold the cover very tightly in place. The newer cover fits on with a friction fit and can come loose when banged around. Both covers are made from rather hard plastic material and will withstand very heavy impacts without breaking. If the instruments is packaged in a heavy box with firm plastic chusions, I can't believe that either cover could come loose and cause damage. With the cover installed, I can throw my 494AP in the back of the car or van and feel that the instrument is safe. Now, to the original question, I have all ready posted an answer that I do not have either cover and I do not know of a source. Deane ----- Original Message -----
From: gleamfollower To: TekScopes@... Sent: Sunday, December 31, 2006 3:02 AM Subject: [TekScopes] Re: WANTED: 492 Front Cover > First, does there exist a front cover for the 492 Spectrum Analyzer, > and, if it does, where can I get one ? You'll see them on eBay every once in awhile, or for that matter, Deane Kidd may be able to put his hands on one. There is an older- and a newer-style (all plastic) cover; either will fit. The innermost surface of the newer covers have a cool Easter egg (raised thermoplastic signatures of several dozen Tek employees from the spectrum-analyzer product group). The foam-rubber liner will most likely be in better condition in these as well. Other than that, they will both work OK. They are really just dust covers, though. Under no circumstances should you ever ship a 49x-series analyzer with either front cover in place. The older-style covers are likely to come loose and bash the heck out of the front panel. The newer-style covers are lighter, but their flexible plastic latches are prone to breakage if any force is exerted on them during transport. -- john, KE5FX -- I am using the free version of SPAMfighter for private users. It has removed 841 spam emails to date. Paying users do not have this message in their emails. Get the free SPAMfighter here: |
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Re: Tektronix 492BP chassis heat.
arthurok
i wonder if the analyzers have some sort of high temp protection internally "thermostat"
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alot of underhood automotive electronics is designed to run hot. "it does decrease its mtbf i dont care what the car makers say" its the semiconductor junction temp that really counts not the heat sink temperature "i believe this" ----- Original Message -----
From: gleamfollower To: TekScopes@... Sent: Sunday, December 31, 2006 11:21 PM Subject: [TekScopes] Re: Tektronix 492BP chassis heat. Hi, Gerald -- > Hi all, > > I felt the rear if my Spectrum Analyser 492BP. I can not touch the > metal strip just above the plastic cover it's that hot. So I got out > my Fluke IR Thermometer and the surface read 56 Degrees C, wow. > > I have discussed this with other people before, however it is now > summer down here and not being able to touch the rear in a hotter > climate is of real concern. I just tried waving an IR thermometer around the back of my 494AP after about two hours of operation, and the peak temperature I saw was 58C. Ambient temperature was approx. 27C in the room at the time. I know you don't believe me, but that temperature level is fine. Quit messing with it and have fun using it. :-) Seriously: it is easy to do more harm than good by rigging up additional fans or using a non-original replacement fan in these analyzers. If you are not 100% confident in what you're doing, I'd recommend leaving the hardware as-is. There is no problem to be solved here. -- john, KE5FX |
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Re: Tektronix 492BP chassis heat.
gleamfollower
Hi, Gerald --
Hi all,I just tried waving an IR thermometer around the back of my 494AP after about two hours of operation, and the peak temperature I saw was 58C. Ambient temperature was approx. 27C in the room at the time. I know you don't believe me, but that temperature level is fine. Quit messing with it and have fun using it. :-) Seriously: it is easy to do more harm than good by rigging up additional fans or using a non-original replacement fan in these analyzers. If you are not 100% confident in what you're doing, I'd recommend leaving the hardware as-is. There is no problem to be solved here. -- john, KE5FX |
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Re: 2754P Frequency Loops Cal
gleamfollower
Hi, Eric --
I have a 2754P spectrum analyzer that seems to function wellA few thoughts off the top of my head: - What, specifically, suggests an unlocked first LO? Are you getting specific error messages during self-calibration, or is it just hanging in a loop? - Is the unit thoroughly warmed up prior to calibration? - When the calibration routine tells you to adjust various trimmers and controls to bring the values within range, are you able to follow the steps for all of the adjustments up until it starts telling you to adjust the phase-lock assembly? (You'd normally hit SHIFT to end the adjustment procedure at that point, unless you've been working on that particular module.) - Does the analyzer seem to work properly in both wide and narrow spans? If so, how does its phase noise/sideband performance compare with the 494P? The LO noise profiles should look identical, or at least very similar to each other. - Does it complete its front-panel-based self-calibration routine (CAL button) successfully? One very-common problem I have seen on these is failure of the crystal oven in the 30 Hz/100 Hz IF filter mounted atop the CRT shield. The series pass transistor inside the sealed filter overheats and opens up, making the self-calibration routine either hang up or fail with an error message during its final, narrowband sweeps. Even if you have a separate LO problem, that is something you'll want to check. After running for 20-30 minutes, the filter housing should be very warm to the touch. I check all the levels and swapped all of the 1st LO &And the YIG interface board with the electrolytic caps, I'd assume? All of the 2794 parts work in the 494 and none of the 494 modules fixAre the power supply voltages OK and within their ripple specs? Which modules, exactly, did you try to exchange between the two? (Don't forget the harmonic mixer, phase gate, counter, and auxiliary synthesizer modules. Check the power connectors on the harmonic mixer and phase gate, if you haven't already.) -- john, KE5FX |
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2754P Frequency Loops Cal
Hello,
I have a 2754P spectrum analyzer that seems to function well and is stable at all frequencies. However, when I try to run its microprocessor's "Frequency Loops Cal" routine, the 1st LO seems to be in a constant unlock state. Press shift to exit the cal mode, and it immediately locks and behaves. I check all the levels and swapped all of the 1st LO & frequency control related modules between it and my 494P (including the 1st LO YIG). All of the 2794 parts work in the 494 and none of the 494 modules fix the 2754 cal routine. Any thoughts or ideas? Has anyone experienced something like this before? Thanks, Eric |
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Re: Bringing up a 555
arthurok
you believe the crest factor is so high that a modern true rms multimeter wouldnt do the job?
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an iron vane voltmeter is true rms responding. a chinese engineer told me the best true tms voltmeter for non super accurate measurements is a scope read by a trained eye. the best rms converter i know of is a thermal converter "thermocouple vacuum junction" ----- Original Message -----
From: Stan and Patricia Griffiths To: 'coresta' Cc: TekScopes Sent: Sunday, December 31, 2006 8:28 PM Subject: RE: [TekScopes] Re: Bringing up a 555 Hello Pierre, If I remember right, the big iron potted case contains a device is called a "saturable reactor" (or something like that) and is used to regulate the AC voltage applied to the vertical amplifier tubes. I think this was an attempt to minimize the effects of cathode interface which looks like a spike on the leading edge of a fast-rise square wave. Actually, it is a DECREASE in low frequency gain of the vertical amplifiers. In a scope without regulated filament voltage, cathode interface is always worse at low line voltages which means lower filament voltage and therefore, lower filament temperature. If you observe a fast-rise square wave while you lower the line voltage on a scope with bad cathode interface, the leading edge spike seems to grow over about one minute of time. If you look very carefully, it is actually the trailing edge, or flat portion of the square wave, that is DECREASING in amplitude over time as the filaments cool down. You can verify this by simply plugging in the scope calibrator and watching the gain of the vertical change as the calibrator signal appears to decrease in amplitude. No spike seems to grow on the leading edge because there are no high frequency components in the scope calibrator signal. There is actually a filament voltage adjustment in the 555 power supply and the list of equipment needed to calibrate a 555 includes an iron vane AC voltmeter to accurately set the AC filament voltage. I think the 517 is the only other scope Tek made that has adjustable filament voltage . . . but I could be wrong about this since it has been years since I looked at my 517's. Stan _____ From: TekScopes@... [mailto:TekScopes@...] On Behalf Of coresta Sent: Saturday, December 30, 2006 11:53 PM To: tekscopes@... Subject: RE: [TekScopes] Re: Bringing up a 555 Hi Stan, As i see this new thread, i always asked myself about the use of Kalotron in the PSU of the 555 ? What's the big iron potted case too ? I broke a pair of those PSUs many years ago and those are somewhere in the basement . I never saw the schematic . I have a 551 working that doesnt contain these parts . Ah, happy new year to all of you ! And long life to our old old tubed scopes ;-) Pierre |
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Re: Bringing up a 555
Stan and Patricia Griffiths
Hello Pierre,
If I remember right, the big iron potted case contains a device is called a "saturable reactor" (or something like that) and is used to regulate the AC voltage applied to the vertical amplifier tubes. I think this was an attempt to minimize the effects of cathode interface which looks like a spike on the leading edge of a fast-rise square wave. Actually, it is a DECREASE in low frequency gain of the vertical amplifiers. In a scope without regulated filament voltage, cathode interface is always worse at low line voltages which means lower filament voltage and therefore, lower filament temperature. If you observe a fast-rise square wave while you lower the line voltage on a scope with bad cathode interface, the leading edge spike seems to grow over about one minute of time. If you look very carefully, it is actually the trailing edge, or flat portion of the square wave, that is DECREASING in amplitude over time as the filaments cool down. You can verify this by simply plugging in the scope calibrator and watching the gain of the vertical change as the calibrator signal appears to decrease in amplitude. No spike seems to grow on the leading edge because there are no high frequency components in the scope calibrator signal. There is actually a filament voltage adjustment in the 555 power supply and the list of equipment needed to calibrate a 555 includes an iron vane AC voltmeter to accurately set the AC filament voltage. I think the 517 is the only other scope Tek made that has adjustable filament voltage . . . but I could be wrong about this since it has been years since I looked at my 517's. Stan _____ From: TekScopes@... [mailto:TekScopes@...] On Behalf Of coresta Sent: Saturday, December 30, 2006 11:53 PM To: tekscopes@... Subject: RE: [TekScopes] Re: Bringing up a 555 Hi Stan, As i see this new thread, i always asked myself about the use of Kalotron in the PSU of the 555 ? What's the big iron potted case too ? I broke a pair of those PSUs many years ago and those are somewhere in the basement . I never saw the schematic . I have a 551 working that doesnt contain these parts . Ah, happy new year to all of you ! And long life to our old old tubed scopes ;-) Pierre |
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Re: Bringing up a 555
The 555 power supply uses that big heavy saturable reactor to
regulate the heater voltages. It relies on a little tube that varies its conductivity according to the temperature of its filament and varies the control current in the reactor, which in turn regulates the heater supply transformers primary voltage. And you are correct, the 551 did not have this arrangement. Bonne Noel. Larry Christopher --- In TekScopes@..., "coresta" <coresta@...> wrote: Kalotron in the PSU of the 555 ? What's the big iron potted case too ?in the basement . I never saw the schematic . |
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Re: Bringing up a 555
Richard Aston
Andy,
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Stan's right. I found a 555 on a dump, full of leaves and dirt. I stripped it down, cleaned all the waterproof bits in the bath, dried it with an airline followed by 3 hours at 60C. When I eventually got it all back together and switched it on, guess what? That's right - worked straight away. It's worth the effort; these are lovely bits of engineering. Richard. Stan and Patricia Griffiths wrote: Hi Andy, |
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Re: Blank plates or ejection mechanism for TM
Lars Ahlstr?m
Anyone have any source available for TM system blank plates, or the eject
button only? /Lars -----Ursprungligt meddelande----- Fr?n: TekScopes@... [mailto:TekScopes@...] F?r jones_chap Skickat: den 31 december 2006 13:16 Till: TekScopes@... ?mne: [TekScopes] DP501 Schematic & Parts List Please Looking for DP501 Parts List & Schematics. Anyone have it in pdf, html, or djvu format? If so, please email to me. If larger than maybe 10MB, encoded, then send to mlcgray@bellsouth. <mailto:mlcgray%40bellsouth.net> net. I'd really like to take a look at this plug-in! Thanks. [Non-text portions of this message have been removed] |
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Re: new to me 310 A scope
Lars Ahlstr?m
Found @ BAMA! ;) 4mbyte djvu file. A beautiful scope btw.
-----Ursprungligt meddelande----- Fr?n: TekScopes@... [mailto:TekScopes@...] F?r jeep534 Skickat: den 31 december 2006 12:42 Till: TekScopes@... ?mne: [TekScopes] new to me 310 A scope I have just aquired a 310A scope SN 023989 and I would like to find the manuals for it. it is in unknown condition. I would like to clean it up and use it. Hopefully I can get it to work properly ( with a lot of help from you guys of course) Happy Hunting archie =) =) =) [Non-text portions of this message have been removed] |
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Re: WANTED: 492 Front Cover
gleamfollower
First, does there exist a front cover for the 492 Spectrum Analyzer,You'll see them on eBay every once in awhile, or for that matter, Deane Kidd may be able to put his hands on one. There is an older- and a newer-style (all plastic) cover; either will fit. The innermost surface of the newer covers have a cool Easter egg (raised thermoplastic signatures of several dozen Tek employees from the spectrum-analyzer product group). The foam-rubber liner will most likely be in better condition in these as well. Other than that, they will both work OK. They are really just dust covers, though. Under no circumstances should you ever ship a 49x-series analyzer with either front cover in place. The older-style covers are likely to come loose and bash the heck out of the front panel. The newer-style covers are lighter, but their flexible plastic latches are prone to breakage if any force is exerted on them during transport. -- john, KE5FX |
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