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Re: Tips on repairing the stick attenuator in the HP86603A
开云体育Perhaps a picture would be useful too.Daun Daun E. Yeagley II, N8ASB
On 11/21/2018 12:19 PM, Glenn Little
wrote:
I guess a part number for the attenuator in question would help. |
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Re: 50 ohm thermocouples was RE: [HP-Agilent-Keysight-equipment] Issue with homemade diode power sensor for HP meters
Ham Radio magazine (Dec. '77) had an article on building a "bolo-meter" type rf power meter ...Used small light bulbs in the sensor . I found a few pilot lights from old cb's that had the right resistance curve ...
Also in April '86 an article using a "zero bias hot carrier diode"? chopper stabilized (with relays) Jim
On Wednesday, November 21, 2018, 7:18:10 AM PST, Roy Morgan <k1lky68@...> wrote:
Chuck and others, No doubt you are right about the small light bulb been used:? Here is my memory from EE school: In ancient times, the 1960’s (if I remember right) a bolometer system was implemented with a common low current fuse.? It was arranged in a bridge circuit of sorts: It’s resistance was adjusted with DC current by a “zero setting” arrangement to get zero indication on a meter.? Then when RF power was applied, the bridge/feedback circuit automatically rebalanced the thing back to the resistance set earlier - the reduction in (dc?) power drove the indicator to show the RF power that was being applied. One advantage of this scheme is that the unavoidable non-linearities in the bolometer fuse did not affect the measurement, since the bolometer was returned to its initial resistance/dissipation condition.? This basic scheme of “first set null balance, and then return the bridge to null when the unknown is introduced” was used throughout General Radio bridges of all sorts.? I would expect the GR instruments to include a bloomer-based power indicator, though I am not familiar with it/them. One (or more) of the MIT Radiation Lab series of books covers this topic, and quite thoroughly.? I have a small group of those books “in storage” here and can look among them before the temperature goes too far below freezing.? But see below for an online example of Volume 11. Likely one of these covers the topic: 8. Principles of microwave circuits - Montgomery, C. G.; Purcell, E. M. and Dicke, R. H. (1948) 11. Technique of microwave measurements - Montgomery, C. G. (1947) (It appears that my list of the RadLab books came from: This link no longer works but: Does and I did get volume 11 from there. At MIT, I find a page about the series, but not the texts of the volumes: ) In the second above, page 81 mention is made of “bolometers”, being implemented with thermistors and bolometer, these having negative and positive temperature coefficients.? It goes on to describe bridge circuits and the characteristics of the measurement elements. Roy > On Nov 20, 2018, at 10:20 AM, Chuck Harris <cfharris@...> wrote: > > A bolometer is not a thermocouple sensor.? What it is is a > small lightbulb filament in a vacuum that is exposed to the > RF power. ... > If I recall correctly, Bolometers were used in a bridge circuit, > where you applied AC power, and the bridge measured the resistance > of the filament.? Next, you applied DC power, increasing the > level until the resistance measured by the bridge matched that of > the unknown RF power source.? At that point, the DC power was equal > to the unknown RF power source's power. > > -Chuck Harris Roy Morgan K1LKY since 1958 |
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Re: Readings from 436A power meter using 82357B USB-GPIB?
Hello,
Addressing another device using interactive IO doesn't seem to release the 436. What I did find out though was that viRead - wich is what interactive IO actually does - gets 14 characters back, but it expected 1024... I guess I IO doesn't get an end of line from the 436 and decides it never returned enough characters... Reading the 436 manual, it's clearly stated that it returns exactly 14 characters for each read. So, a response is given, but asking in the wrong way gives an error, not due to the instrument, but due to the setup of I IO... I found a couple of nice functions in the VISA? library - there is a way to deassert the REN line for example. I know now that it isn't needed. Nevertheless, this exercise was good for learning a bit more about Keysight (Agilent/HP) Connection Expert, Interactive IO and, most importantly, how to get the communication working the the VISA library! Regards, ? Staffan |
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Re: Tips on repairing the stick attenuator in the HP86603A
开云体育I guess a part number for the attenuator in question would help.Everyone does not have 86603A manuals to check the part number. The o-ring failures are quite common. The attenuators with o-rings are used in a number of instruments. Without the attenuator part number, who would know that your attenuator is of a different design. Glenn On 11/21/2018 10:13 AM, Jeff Kruth via
Groups.Io wrote:
-- ----------------------------------------------------------------------- Glenn Little ARRL Technical Specialist QCWA LM 28417 Amateur Callsign: WB4UIV wb4uiv@... AMSAT LM 2178 QTH: Goose Creek, SC USA (EM92xx) USSVI LM NRA LM SBE ARRL TAPR "It is not the class of license that the Amateur holds but the class of the Amateur that holds the license" |
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Re: 50 ohm thermocouples was RE: [HP-Agilent-Keysight-equipment] Issue with homemade diode power sensor for HP meters
Roy Morgan
Chuck and others,
No doubt you are right about the small light bulb been used: Here is my memory from EE school: In ancient times, the 1960’s (if I remember right) a bolometer system was implemented with a common low current fuse. It was arranged in a bridge circuit of sorts: It’s resistance was adjusted with DC current by a “zero setting” arrangement to get zero indication on a meter. Then when RF power was applied, the bridge/feedback circuit automatically rebalanced the thing back to the resistance set earlier - the reduction in (dc?) power drove the indicator to show the RF power that was being applied. One advantage of this scheme is that the unavoidable non-linearities in the bolometer fuse did not affect the measurement, since the bolometer was returned to its initial resistance/dissipation condition. This basic scheme of “first set null balance, and then return the bridge to null when the unknown is introduced” was used throughout General Radio bridges of all sorts. I would expect the GR instruments to include a bloomer-based power indicator, though I am not familiar with it/them. One (or more) of the MIT Radiation Lab series of books covers this topic, and quite thoroughly. I have a small group of those books “in storage” here and can look among them before the temperature goes too far below freezing. But see below for an online example of Volume 11. Likely one of these covers the topic: 8. Principles of microwave circuits - Montgomery, C. G.; Purcell, E. M. and Dicke, R. H. (1948) 11. Technique of microwave measurements - Montgomery, C. G. (1947) (It appears that my list of the RadLab books came from: This link no longer works but: Does and I did get volume 11 from there. At MIT, I find a page about the series, but not the texts of the volumes: ) In the second above, page 81 mention is made of “bolometers”, being implemented with thermistors and bolometer, these having negative and positive temperature coefficients. It goes on to describe bridge circuits and the characteristics of the measurement elements. Roy On Nov 20, 2018, at 10:20 AM, Chuck Harris <cfharris@...> wrote:Roy Morgan K1LKY since 1958 k1lky68@... |
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Re: Tips on repairing the stick attenuator in the HP86603A
I had asked if anyone was familiar with this type of atten. NOT the 8495 style, but a long stick. I guess no one reads. NO O rings.
Jeff
Here is a video on repairing one of these attenuators: The O-Rings are 2mm od x 1 mm id x 0.5mm thick. Theses are used in watch making. Hope this helps Glenn On 11/20/2018 6:31 PM, g lowrey wrote:
> Hey Jeff. Have you measured one to check the size? I have several > sources that might be able to supply them - > 73, > Bo L. > > On 11/20/18, Jeff Kruth via Groups.Io <kmec=[email protected]> wrote: >> Hi All! >> Dont ask why, but I am resurrecting several HP 8660D generators with the >> HP86603A plugin. The attenuators are "sticky", get stuck in a certain >> position. If you have experience with this exact type of stick attenuator >> (long silver block) with the 3 - 40 dB, 20 dB, & 10 dB sections and can >> advise how to make a reliable repair, I would love to hear about it. Several >> that I cleaned the solenoid shafts on seemed to be working only to stick >> again. I do not know how to search the archives as well, can someone >> advise?Thanks!73Jeff Kruth >> >> >> >> > > > -- ----------------------------------------------------------------------- Glenn Little? ? ? ? ? ? ? ? ARRL Technical Specialist? QCWA? LM 28417 Amateur Callsign:? WB4UIV? ? ? ? ? ? wb4uiv@...? ? AMSAT LM 2178 QTH:? Goose Creek, SC USA (EM92xx)? USSVI LM? NRA LM? SBE ARRL TAPR "It is not the class of license that the Amateur holds but the class of the Amateur that holds the license" |
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Re: Tips on repairing the stick attenuator in the HP86603A
NOT O Rings. Different design than the small flat guys.
On 11/20/2018 1:48 PM, Jeff Kruth via Groups.Io wrote:
Sounds like the universal problem of decaying O-rings Jeff.? They are easier to replace than source. Dan |
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Re: Readings from 436A power meter using 82357B USB-GPIB?
开云体育Try addressing another device?? (Even one that doesn’t exist...) Dave B (G0WBX) Re: Readings from 436A power meter using 82357B USB-GPIB? From: Staffan Date: Tue, 20 Nov 2018 10:26:07 PST Hello,
-- Created on and sent from a Unix like PC running and using free and open source software. :: |
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Re: HP8555A attenuator switching characteristics - notes and questions
Hi Ed,
The output pulse is inhibited while the switch is rotating by?the pulse from?contact 4F on S1 (attenuator level) this feeds an RC network R18/C4 and Q2 on A7. If you turn the switch too fast the pulse is not generated. The pulse signal is narrower than the?coil circuit connection time due to differing contact widths.?Its explained in the service manual Robert G8RPI. |
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Re: Readings from 436A power meter using 82357B USB-GPIB?
Hello,
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Indeed a point. Not having a second 436 around, I will try this one and see where it gets me for now, but if anyone would send me a 436 - I’d be happy to test :-) Regards, ?Staffan On Wednesday, November 21, 2018, Kuba Ober <kuba@...> wrote:
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Re: Readings from 436A power meter using 82357B USB-GPIB?
开云体育It’s not impossible that you have a stuck gate somewhere, and the operation you observe is not normal for the instrument. It’d be worth checking that against another 436A. Cheers, Kuba
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HP8555A attenuator switching characteristics - notes and questions
I'm fixing up a magnetic step attenuator salvaged from an 8555A SA plug-in, to use in my TG project. I have some of these nice old attenuators, and the special rotary wafer switches that encode the binary sequences for the 10/20/40 dB step coils, and trigger the drive pulse. After some grief trying to figure out how the coil driver is supposed to work, and modifying the switch, I've got it going nicely. I built a pulse driver to run the coils according to the operational info in the 8555A manual - the coils take 12V, with the polarity selected by the switch, and are pulsed for about 150 mSec.
In the 8555A, the attenuator was only used over a 0-50 dB range, but I want the full 0-70 capability for the TG. This required some simple mods to the switch. First, the CCW stop on the shaft was eliminated, giving eight positions instead of six. 0 dB is at full CW, which is what I wanted. When I took it apart the first time, it looked like the switch was fully set for all the coil states, but when I got the whole thing operational for experimenting, it still only had the 0-50 dB range - the last two added spots were dead. On closer inspection, I found that one tab on one of the 10 dB wafer rotors was not included, but only on one coil side - the other side's rotor has all four tabs, and properly connects, for some reason. After some consideration, I decided the easiest fix was to do some simple switch surgery, to add a couple of contacts on the wafer, to pick up another tab when it went by, so the last two steps would fully encode. These contacts are redundant with some of the others, except in the last two spots, where they do their thing. It worked beautifully. I'm working on optimizing the timing now, so am wondering about how well the original 8555A implementation worked - user interface-wise. Since the coil drive relies on open-loop triggering and pulsing, it's possible to overrun the state control by turning the switch knob too quickly, which doesn't hurt anything, but may result in the attenuator's actual state not matching the switch position. For example, if it's rotated quickly through a few steps, it can misfire. Changing it one more step either way will trip the cycle and restore it to the right condition. Does anyone who has or has used the 8555A (or anything else with a similar setup) remember if this was an issue or minor nuisance? I had some many years ago, but don't recall being able to spin the knob fast enough on the cramped front panel, to misfire. Also, it only had five steps that could be rapidly switched anyway, since the last one had a manual release button to enable the 0 dB setting. On the TG, the knob has lots of room, so it's easy to whip through the steps fast, and I have to remember to take it easy, and be more deliberate in changing the setting. It seems to work fine up to about three or four steps per second. Of course, beyond that, there's less and less time to put out valid coil pulse duration and reset everything. For the coil driver, I made a small board that attaches right to the coil pins on the attenuator. The board space is kind of tight, and it needs to run from the raw +33V supply, and include various protection circuitry. I decided to go old-school, and made the pulse driver with a relay and capacitor, where the cap discharges through the coil resistance for timing. The trigger from the switch fires the relay coil initially through a small cap, then the relay hooks up the main cap, and applies the juice to the attenuator coils through the encoding switch. At the end of the cycle, the relay flips, disconnecting the load, and connecting the timing cap back to the recharging source. The way the 8555A did it, and the way the switch is set up, is that all three coils are fired simultaneously, forcing it to agree with the setting. The coils are about 70 ohms each, so firing them all takes about half an amp at 12V. I didn't want to add extra power supplies or circuits for a lower voltage, so I took advantage of the non-continuous and pulsed nature of the load, and used the resistive drop of a string of PTC thermistors from the raw supply, with a big cap in the middle to give some isolation against the edges of the pulsed load. The PTCs provide intrinsic overload protection, in case something gets stuck, or in case someone like me gets carried away and spins the knob too often and too fast - the PTCs are clumped together, and will gradually all heat up and trip out. It ain't efficient, but it is simple - there's not a transistor or IC in there, just a few diodes and Zeners. The only active component is the relay. Anyway, if anyone is contemplating re-using any of these fine old attenuators, this info may help. I have had to learn a lot about them lately, and have renewed appreciation for how they work. Ed |
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Re: A homemade diode power sensor for HP meters
Beginning at around 47:50, in the following video,
he discusses HP tc and diode power sensors, and shows a strip down of a diode one. There is some focused discussion about the theory of operation (for tc and diode types)… and you can see the tools he uses to examine the blown diode sensor, for possible repair. Roy VE3RFT |
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Re: Tips on repairing the stick attenuator in the HP86603A
开云体育I have never failed to locate a needed o-ring at Mcmaster Carr.? Google their catalog. Sent from my T-Mobile 4G LTE Device |
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Re: Tips on repairing the stick attenuator in the HP86603A
Here is a video on repairing one of these attenuators:
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Show quoted text
The O-Rings are 2mm od x 1 mm id x 0.5mm thick. Theses are used in watch making. Hope this helps Glenn On 11/20/2018 6:31 PM, g lowrey wrote:
Hey Jeff. Have you measured one to check the size? I have several --
----------------------------------------------------------------------- Glenn Little ARRL Technical Specialist QCWA LM 28417 Amateur Callsign: WB4UIV wb4uiv@... AMSAT LM 2178 QTH: Goose Creek, SC USA (EM92xx) USSVI LM NRA LM SBE ARRL TAPR "It is not the class of license that the Amateur holds but the class of the Amateur that holds the license" |
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Re: Tips on repairing the stick attenuator in the HP86603A
Hey Jeff. Have you measured one to check the size? I have several
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sources that might be able to supply them - 73, Bo L. On 11/20/18, Jeff Kruth via Groups.Io <kmec@...> wrote:
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Re: Tips on repairing the stick attenuator in the HP86603A
开云体育On 11/20/2018 1:48 PM, Jeff Kruth via
Groups.Io wrote:
Sounds like the universal problem of decaying O-rings Jeff.? They are easier to replace than source. Dan |
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Re: WANTED: HP 606B Sig Gen RF Output Attenuator Module A10
Hi Jeff,
I would be very grateful to receive it, whether it is for a 606A or 606B. Beggers can't be choosers! I'll await your advice. (Fingers crossed!). Hi Kim, It may also be possible for me to make up a serviceable (if uncalibrated) 606B replacement unit from a combination of your 606B unit and Jeff's unit, if Jeff's is for a 606A. Thanks to you both for your kind offers which are gladly accepted. What a great day!! Graeme |
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Re: Tips on repairing the stick attenuator in the HP86603A
Hi All! Dont ask why, but I am resurrecting several HP 8660D generators with the HP86603A plugin. The attenuators are "sticky", get stuck in a certain position. If you have experience with this exact type of stick attenuator (long silver block) with the 3 - 40 dB, 20 dB, & 10 dB sections and can advise how to make a reliable repair, I would love to hear about it. Several that I cleaned the solenoid shafts on seemed to be working only to stick again. I do not know how to search the archives as well, can someone advise?
Thanks!
73
Jeff Kruth
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Re: HP Oscilloscope 1703A
Hi Ken
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If you google "HP 1703a" the first hit is an operating and service manual. It's actually a 35MHz scope. The HP memory project also has a nice article on the 1700 series. Paul On Tue, Nov 20, 2018 at 06:15:06PM +0000, george edmonds via Groups.Io wrote:
Hi Ken --
Paul Amaranth, GCIH | Manchester MI, USA Aurora Group, Inc. | Security, Systems & Software paul@... | Unix & Windows |
jim
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