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Re: CORRECTION TO HP #
John Miles
Is that a standard 10811 or 10544 module? They are fairly common on eBay,
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if so. -- john KE5FX -----Original Message----- |
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Re: 8552B problem
Dave Haupt
Dave,
Interesting that you have that problem. I have an 8552B that exhibits the same symptoms! Or at least I think it does. My display (in log mode - linear mode is not often useful in a spectrum analyzer) shows about 20dB down from the intended calibrated level. You are to be congratulated on narrowing it down to the final amplifier - that's good troubleshooting. Remember that if an amplifier fails, it does not block all signals. Instead, a single-stage amplifier may change from a 15dB gain block (if that's what it was intended to be) to a 15dB LOSS block - in my case, that would explain the 30dB down symptom. In a solid state amplifier, the first suspect is the amplifying device itself - the transistor. If the amplifier is common-emitter, it may have a resistor from emitter to ground, bypassed by a capacitor. If that capacitor fails open circuit, then the amplifier's gain will be seriously degraded. Particularly suspect would be any electrolytic capacitors, at the age of these instruments. How were you able to operate the IF section outside of the mainframe? Or did you plug the module into a mainframe without an RF section and able to troubleshoot from the little bit of topside access that would get you? As far as the vertical positioning question, remember that a spectrum analyzer is not intended to be zero-centered like a scope. Instead, the bottom line or the top line of the graticule is the reference. In linear mode, that means zero volts at the bottom of the screen. The analyzer uses a diode detector in linear mode, so there's never negative voltage - just RF envelope voltage. In log mode, the top line is the reference. If you set the gain controls so that zero dBm (one milliwatt into 50 ohms) is at the top of the screen, then each division down from that is 2dB or 10dB depending on the setting of the log/lin switch. With an oscilloscope, we move the vertical position control around to get the signal on screen, and take note of where zero landed. The signal goes up and down from zero. On a spectrum analyzer, the absolute position of the signal on screen is a part of the measurement, so the zero volt line is at the bottom, always, and the dB reference line is at the top, always. Good troubleshooting! Dave Date: Tue, 3 Aug 2004 15:06:34 -0700 From: "Dave Faria" <dave_faria@...> Subject: HP 8552b Problem Good afternoon list. I have an HP141T with the Hp 8553b and Hp 8552b plug ins. I am new to solid state test equipment and need some help. I have down loaded all the manuals from the BAMA list. The situation of my unit is it appears to work in all aspects except it does not have sufficient vertical gain. It will show its calibration signal in all modes 2db log, 10db log, and linear but, the display will not show the peaks at the levels that it should(7.1mv, -30db). The signals are abt 2/3 of what they should be on the .1uv and -60db scale. I have done the test indicated in the 8552b manual to test the final amp. I injected a 3mhz signal at pin 14 of card XA4 with that card pulled. The test indicated the amp was not working. Where do I go from here?? The down loaded Hp manual is not that easy to use or read. Another thing that I don't understand is why would all functions continue to work with a failed amp. One thing that may help someone who understands this unit is when I change the gain(db or mv) the entire trace will shift either up or down on the screen, sometimes out of the range of the vertical position control. This problem would be corrected by a balance control adjustment on an old tube type scope. Thanks for any help or comments Dave Faria WA5TEZ __________________________________ Do you Yahoo!? Yahoo! Mail - 50x more storage than other providers! |
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Re: HP 8552b Problem
开云体育Hi Dave,
Unfortunately, we are only resellers and we don't
know anything about the unit.? I am very sorry I can't help you.?
Maybe you should contact HP/Agilent Company.? Sometimes they are willing to
help; it depends of the employee you are dealing with.
Good Luck,
Annie
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HP 8552b Problem
Dave Faria
开云体育Good afternoon list.? I have an HP141T with
the Hp 8553b and Hp 8552b plug ins.? I am new to solid state test equipment
and need some help.? I have down loaded all the manuals from the BAMA
list.? The situation of my unit is it appears to work in all aspects except
it does not have sufficient vertical gain.? It will show its calibration
signal in all modes 2db log, 10db log, and linear but, the display will
not show the peaks at the levels that it should(7.1mv,
-30db).? The signals are abt 2/3 of what they should be on the
1uv and -60db scale.? I have done the test indicated in the 8552b manual
to test the final amp.? I injected a 3mhz signal at pin 14 of card XA4 with
that card pulled.? The test indicated the amp was not working.? Where
do I go from here??? The down loaded Hp manual is not that easy to use or
read.? Another thing that I don't understand is why would all functions
continue to work with a failed amp.? One thing that may help someone who
understands this unit is when I change the gain(db or mv) the entire trace will
shift either up or down on the screen, sometimes out of the range of the
vertical position control.? This problem would be corrected by a balance
control adjustment on an old tube type scope.
?
Thanks for any help or comments
Dave Faria WA5TEZ |
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Re: HP 8566A / B differences
John Miles
Interesting. I know the 8566B used a 68000 CPU, but I'm not sure what the
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8566A used. (It wouldn't have been discrete logic, though -- that would have filled a van in itself!) -- john KE5FX When I worked for NIST, we did a lot of 8566A to B |
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Re: HP 8566A / B differences
Dave Haupt
When I worked for NIST, we did a lot of 8566A to B
upgrades (thus making them 8566AB units). To the best of my knowledge, the whole point was for speed. I seem to recall that the "A" version had discrete logic for the controller, and the "B" version had a microprocessor of some sort. The major difference to us was certainly the transfer rate of data across the HP-IB bus. We had racks of 8566x analyzers in a van, which we hauled to whatever location the gov't wanted to make spectral signature measurements on. We needed measurement speed, and the 8566B was the fastest instrument around at the time, by a wide margin. Dave __________________________________ Do you Yahoo!? New and Improved Yahoo! Mail - Send 10MB messages! |
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Re: Hewlett-Packard 141T, 8552B and 8556A
D. Dufresne
Answer to John Miles,
He wrote: 1) NEVER remove or disable a crowbar circuit. It was triggering for a reason! You're very lucky not to have done serious damage to your analyzer and plugins by removing CR10. This is no different from shorting a fuse to find out why it blew. Reply: I had to, because I did not have a memory scope and the full set of test cables. This was temporary. He wrote: 2) Germanium pass transistors become leaky with age. These need to be replaced as a matter of course in any equipment older than the mid-70s. Daniel's 8552B dates from 1975, or at least its revision level does. They can almost always be replaced with modern silicon power transistors with no ill effects. Reply: The pass transistor is silicon, Si, not germanium, the manual says Si and that was confirmed by test on a curve tracer. Leakage would cause the problem to be worse at light load. I had a problem at full load, but all was OK with a light load. Regards Daniel from Ville Saint-Laurent, QC, Canada. |
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Re: Hewlett-Packard 141T, 8552B and 8556A
John Miles
Two lessons here:
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1) NEVER remove or disable a crowbar circuit. It was triggering for a reason! You're very lucky not to have done serious damage to your analyzer and plugins by removing CR10. This is no different from shorting a fuse to find out why it blew. 2) Germanium pass transistors become leaky with age. These need to be replaced as a matter of course in any equipment older than the mid-70s. Daniel's 8552B dates from 1975, or at least its revision level does. They can almost always be replaced with modern silicon power transistors with no ill effects. -- john KE5FX -----Original Message----- |
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Hewlett-Packard 3310A Function Generator and hot carrier diode or Schottky barri
D. Dufresne
Hewlett-Packard 3310A Function Generator, serial number 1151A0XXXX.
Report of repairs. A friend's generator had failed and during his attempts at repairs had broken a diode by accident. The manual specified the test point as being the diode's leads, the oscilloscope probe proved to stressful. Suspecting it was a tunnel diode, he stopped his repair attempts and asked me to locate some tunnel diodes. I had some time so I took the unit and the service manual off his hands. Investigations revealed that the diode, A1CR4, was not a tunnel diode but a hot carrier diode, HP part number 1901-0518. I replaced it with a 1N914 just for now. The original problem was A1Q12, A1Q19 and A1Q20, all three transistors where defective. The service manual troubleshooting aids and maintenance tips section is quite useful, section 5-172. I replaced A1Q12, a 1855-0081 transistor, field effect, 2N5245 made by Texas Instruments with a 2N5486 by Motorola. Replaced A1Q19, 1854-0019, the part bears only 4-019, transistor Si NPN, Motorola SS2188 with a 2SD668 by Hitachi, now Renesas, no heatsink. Replaced A1Q20, 1853-0034, the part bear only 3-034, transistor Si PNP, 2N3634 or Motorola SM3197, with a Renesas 2SB648A, no heatsink, but with the original ferrite bead on the base lead. Redid the Triangle Amplifier Bias Adjustment, section 5-126. The generator now works, but on the two highest frequency ranges, 10 k and 100 k, the waveform is not within specifications. The duty cycle is not close to 50 % for the square wave. I tried a Schottky diode for A1CR4, same results. I tried to locate a Schottky hot carried diode and found 1N5711. It now bears the description Schottky barrier diode but is the same as a hot carrier Schottky diode. It looks as a Schottky diode but with very little zero bias capacitance, about 1 to 2 picofarad. A regular type 1 A Schottky diode has 100 to 1000 times that much more capacitance. My friend bought some 1N5711 diodes and sent them to me. Placed the 1N5711 in the unit. All within specifications, no need to calibrate. Daniel from Ville Saint-Laurent, QC, Canada. |
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Hewlett-Packard 141T, 8552B and 8556A
D. Dufresne
Hewlett-Packard 141T Display Section, serial number 1615A148XX, 8552B
Spectrum Analyser IF Section, serial number 1505A095XX and 8556A Spectrum Analyser LF Section, serial number 1907A046XX. Report of repairs. This spectrum analyser system failed at turn on, after the unit had been left unused for a few months. Investigation revealed that on the 8552B the two fuses on the back panel, F1 and F2, where blown. I checked to see that there where no short circuit and installed new fuses. The unit ran for 15 to 20 seconds and then blew both fuses again. Looking at the schematic, the only way for both fuses to blow at the same time is if the overvoltage crowbar circuit is activated. To verify this I removed CR10, the crowbar thyristor, from the A5 assembly. Turned on the unit and it worked OK for a minute or so, then some other type of symptoms appeared. The trace is way off at the top, I can see some light but not the beam it self. Checking the power supply I found all the supplies high by about 30 %. The +100 V was 129 V, the -100 V was -128 V, the 248 V was 320 V, -12.6 V was -16.3 V. I turned off the unit after about 20 seconds. I removed the plug-ins and checked the supply, all four where within limits. Put back the plug-ins, the same problem is now back. I disconnected the 100 V going to the plug ins, all the supply voltages where OK. Checked the +100 V regulator, as it is the master and the three others take their reference from it. With 100 V output, the base to emitter voltage is 0.53 V on Q2, the pass transistor. With 129 V output, the pass transistor base to emitter voltage was -2.9 V. So the regulator circuit was sending the right signal to lower the output. This led me to suspect the plugins, maybe a current path from the 248 V supply to the 100 V supply. Further inspection revealed nothing wrong with the plugins. Back to the 141T supply I measured the current into Q2, the pass transistor with 128 V at the emitter and -3 V between the base and emitter, it should be cutoff, not so, the current was 407 mA! Replaced Q2, a 1854-0294, listed as Q, Si, npn Motorola SJ-1318 with a On Semiconductor MJ15003, silicone, TO-3, NPN, 140 V 20 A 250 W, overkill but I had it on hand. Any 140 V 1 A 75 W TO-3 NPN device would do, maybe a MOSFET also. Everything was back to normal. Reinstalled A5CR10 in the 8552B, all OK. System fully functional. I noticed some PWB discolouration under A5R3, a 4.7 k 5 % 2 W resistor, that dissipates about 1.3 W. I changed it to a 5W resistor and spaced it as far away from the PWB, so the increased surface area and longer leads will give a lower PWB temperature and longer unit life. Daniel from Ville Saint-Laurent, QC, Canada. |
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Re: Wanted Manual: HP 3406A
guy royet
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Re: HP-8657A SIGNAL GENERATOR
开云体育Hello?Bruce ,
?
In Europe and the guy will probably ship to?
other continents :
info@...??
(website :
)
?
Good luck,
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Re: Need adaptors for 8405A probes
jocjo_john
Yes, you are correct that the kit has everything needed. Note that
HP also had BNC adaptors 11570A. One undesirable aspect with this kit is the fact that HP said (in App Note 77-3) that the power splitter method is recommended only for frequencies below about 100 mHz. Above that, they recommend using the 778D dual directional coupler. However, if the kit remains available at near the current price, I would be inclined to purchase it and try the Narda coupler I have on hand with it. I'd guess the kit probably originally cost about $400-$500. Regards, John --- In hp_agilent_equipment@..., Rasputin Novgorod <priapulus@y...> wrote: --- jocjo_john <jocjo@m...> wrote:Thanks, Rasputin.That kit has everything needed for making vector |
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Re: HP5100/5110 Synthesiser set
Robert Middleton
开云体育Hello Thomas.
?
Thanks for the tip, and I apologize to you for not
communicating with you sooner. I live here in the USA. Also, drop me an e-mail
from time to time when you and your associates are looking for HP manuals and
also HP gear as I do run accross alot of it.
?
Thanks for your time and have a great
day.
?
Respectfully, Robert
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Wanted Manual: HP 3406A
Hi Gang,
? I'm in need of an HP-3406 "Broadband Sampling Voltmeter" Operator/Service Calibration and Instruction Manual. ?? Anyone out there have one they'd care to sell?? Anyone know of any downloads?? BAMA has nothing on this one that I can find. Thanks, Mike DiGirolamo, W4XN Charlottesville, VA 22901 ------------------------------- |
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Re: Need adaptors for 8405A probes
Rasputin Novgorod
--- jocjo_john <jocjo@...> wrote:
Thanks, Rasputin.That kit has everything needed for making vector measurements (the whole point of having a vector voltmeter..)Such gear always has "N" connectors so to handle the highest frequencies. Cheap adaptors are easily available to change to BNC. Anyone like to hazard a guess of the original cost of that kit? There is a different kit made up of an assortment of probe end adaptors. Sincerely __________________________________ Do you Yahoo!? Read only the mail you want - Yahoo! Mail SpamGuard. |
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Re: Need adaptors for 8405A probes
jocjo_john
Thanks, Rasputin.
The price is right (with the possible exception of shipping costs to the US), but I need adaptors for BNC as I am not currently set up for type N connections. Thanks again for pointing it out. John --- In hp_agilent_equipment@..., Rasputin Novgorod <priapulus@y...> wrote: As for continuing to look for the adaptor, I haveTry: eBay Item number: 3829178511 |
Mike D.
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