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- HP-Agilent-Keysight-Equipment
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rotary encoders for instruments (54542)
David
Hi,
The key panel data entry encoder on my HP54542C scope has worn out. Anyone know of a source for replacements? Numbers on the encoder are: 9436, and 1-2-36. The part is listed as replaceable by entire board assembly with part number 54542-66506, though it's pretty easy to just change the encoder. I tried to repair it but the plating on the encoder PCB is about done for. It works again but who knows for how long. Thanks. |
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Re: HP 8556A plugin required for an HP141T
Hi MK whereaboutsare you in the UK? I will have to check but I may have a spare frame, though Iam not sure what state its in.
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Alan G3NYK ----- Original Message -----
From: "m1k3k1" <m1k3k1@...> To: <hp_agilent_equipment@...> Sent: Wednesday, December 26, 2012 8:45 PM Subject: [hp_agilent_equipment] HP 8556A plugin required for an HP141T As title, I an in the UK, so would prefer to get one from the UK or europe as postage and vat would make it expensive otherwise |
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HP 8556A plugin required for an HP141T
As title, I an in the UK, so would prefer to get one from the UK or europe as postage and vat would make it expensive otherwise
Aslo would like to get hold of a non-working HP141T chassis, dont mind if the tube is gone, but also best to source from UK as they are quite heavy. would want to use the dead one for spares to keep the other one going. Regards, M K |
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Re: HP Oldies.
We moved from there when I was five years old. I never knew that there
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was as many electronics companies in the area as you list. Dave On 12/24/2012 4:16 PM, petepdx1955 wrote:
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Motorola MSPS7279 and MSPS7278 Transistors
I am looking for any data, substitute, or availability on these transistors. The 7279 is an NPN and the 7278 is a PNP silicon as best I can tell. They are both TO-220 type cases with an 'EBC' pin out.
The application uses 4 of these, with a 36.5 ohm resistor in series with the emitter, all in parallel, to make up a TO-66 type package transistor substitute for each of tne PNP and NPN application. Thanks in advance. Joe |
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Re: 608 output attenuator. and more
On 12/26/2012 12:53 AM, Patrick Wong wrote:
The situation that Patrick envisions is somewhat unknown. I would guess that if the attenuator resistors were blown, then adding a 50 ohm load across the 608 output would probably cause the signal level to drop MORE than 50%, but it would depend on what's the actual impedance of the unterminated attenuator. So we may both be wrong! I suggested the measurement with another source of RF since the poster did not have an antenna analyzer, which of course, is another source of RF. (The antenna analyzer would have actually been my first attempt, because I do own one. But I also own another RF generator or two-- a Measurements Model 80 and two sweep generators that cover 10MHz.) doug, WA2SAY |
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Re: 608 output attenuator. more
On 12/26/2012 12:01 AM, Max Robinson wrote:
Perhaps I misunderstood the measurement, since this thread has been running for a while. If all you are doing is adding and removing a 50 ohm resistor across the 608 output, and measuring the output with a scope, then the test would seem to be kosher, IF you use a high-impedance 10:1 scope probe. (Otherwise the input capacitance of the scope will degrade the results.) --doug, WA2SAY |
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Re: 608 output attenuator.
On 12/26/2012 12:01 AM, Max Robinson wrote:
It would be better if nobody top-posts. That having been said; As you place and remove the 50 Ohm load, you are mismatching THE GENERATOR, such that the signal may vary by 2:1. If you want the test to make sense, you need to connect the generator output thru a fairly large series resistor--say 470 ohms--to the 608 input port. Connect your scope thru a 10:1 probe to that same input port. Now, with that connected, add a 51 ohm resistor in parallel with the 608 input. If the scope reading drops by about 50%, then the 608 has a 50 ohm impedance at the port. If it drops by quite a bit more than 50%, then the 608 has a higher impedance than 50 Ohms, and there would appear to be a problem with the attenuator circuit. BTW, if you don't have a scope, a high-impedance VTVM that will read at 10 MHz (it doesn't have to be accurate) will work similarly. Doug, WA2SAY |
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Re: 608 output attenuator.
I don't have any antenna or RF impedance bridge that I trust. So the 50 ohm termination and "infinite" impedance test is all I have.
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Regards. Max. K 4 O DS. Email: max@... Transistor site Vacuum tube site: Woodworking site Music site: To subscribe to the fun with transistors group send an email to. funwithtransistors-subscribe@... To subscribe to the fun with tubes group send an email to, funwithtubes-subscribe@... To subscribe to the fun with wood group send a blank email to funwithwood-subscribe@... ----- Original Message -----
From: "Patrick Wong" <patwong3@...> To: <hp_agilent_equipment@...> Sent: Tuesday, December 25, 2012 9:16 PM Subject: [hp_agilent_equipment] Re: 608 output attenuator. Hi Max, |
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Re: 608 output attenuator.
Bob Albert
Ah you were luckier than I. My Marconi TF1066/4 not only had a broken attenuator rack (from removing from cabinet without first turning it inward) but also a burned out 47 Ohm resistor at the probe.
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It required complete removal of the probe assembly, including some gear work and springs and so on. A lot of work but now the generator output is accurate and the attenuator works smoothly. The resistor is 1/4 Watt so it doesn't take much to burn it out. Maybe 5 Volts of rf for most of a minute. A 100 Watt transmitter delivers 71 Volts; that should do it in a second or less. Bob --- On Tue, 12/25/12, Max Robinson <max@...> wrote:
From: Max Robinson <max@...> |
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Re: 3586A encoder question
The 3586, 8568, 8566, 8340 series units All used the RPG encoders with a lamp HP 2140-0016 (653 lamp ??). These RPG's were round flattened cylinders. if the lamps were old/darkened by age/misaligned you could get " works in one direction but not the other". The solution is to remove the RPG, pop the end cover-2 opposite tabs, use needle nose to pull the bulb from the side, check bulb for clarity, resistance-90 ohms, reinsert/replace with base of bulb flush with case of RPG, AND parallel to the optical grating inside - parallel to the PC brd. The detector diodes need to be illuminated equally.
Don B. |
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608 output attenuator.
You may remember that I was concerned about the integrity of the output attenuator in my 608D. Today I checked it again the way I had calibrated it with a short cable and a pass through 50 ohm termination at the scope end. I set the frequency to 10 MHz and the attenuator to 100 mV to be sure there would be no proximity effect between the pickup coil and the output tuned circuit. With the scope reading 100 mV within accuracy spects I then removed the termination and measured 200 mV within accuracy spects. From this I conclude that my output attenuator has not been damaged by someone transmitting into it.
Regards. Max. K 4 O DS. Email: max@... Transistor site Vacuum tube site: Woodworking site Music site: To subscribe to the fun with transistors group send an email to. funwithtransistors-subscribe@... To subscribe to the fun with tubes group send an email to, funwithtubes-subscribe@... To subscribe to the fun with wood group send a blank email to funwithwood-subscribe@... |
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Drifting 608.
I wanted to comment on this but it slipped my so called mind. For the gentleman who was having trouble with a 608 that was drifting and FM-ing I have some suggestions before getting into the RF cage. Check the two power supplies to be sure they are on voltage and free of ripple and other noise. A check with a scope is a must. Be sure the VR reference tube, V15 5651, is igniting. Also check the output from the modulator to be sure it is free of noise. That can most easily be found on the longest filter that comes out from the back near the top of the RF cage.
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Getting into the RF cage I would replace the 6AB4 tube first. It is the buffer and is a UHF TV tube. I don't know about its lifetime but its cousin the 6AF4 was notorious for a short life. The output of my 608D was weak and replacing this tube brought it back without needing to replace the pencil triodes. Come to think of it I don't remember which model 608 you have. This may be a bum steer. However you can get the pencil triodes and the 6AB4 if you need it from Tube Depot I have no affiliation with this company except to have bought tubes from them. Regards. Max. K 4 O DS. Email: max@... Transistor site Vacuum tube site: Woodworking site Music site: To subscribe to the fun with transistors group send an email to. funwithtransistors-subscribe@... To subscribe to the fun with tubes group send an email to, funwithtubes-subscribe@... To subscribe to the fun with wood group send a blank email to funwithwood-subscribe@... ----- Original Message -----
From: "Glenn Little WB4UIV" <glennmaillist@...> To: <hp_agilent_equipment@...> Sent: Saturday, December 22, 2012 2:27 PM Subject: Re: [hp_agilent_equipment] Re: HP Oldies. All issues, 1 through 37, of "The Notebook" are archived here: |
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Re: S11 and S22 comparisons on 8753
David Kirkby
On 25 December 2012 14:23, J. Forster <jfor@...> wrote:
Dr. Joel is a great, helpful guy.I agree with you John, in that Joel is very helpful. This help not only extends to someone owning the latest and greatest VNAs, but people like myself who own obsolete HP kit. His suggest to repair the thread, rather than pay a fortune to get the whole coupler replaced, saved me a lot of money. The US dealer I purchased this from offered to get it repaired, but that repair was changing the test port, not the whole coupler. I had concerns about that, as the tollerence in replacing just the test port is very stringent. IIRC, it has to be aligned to 0.0001". I would not trust anyone other than Agilent to do that job. Anyway, the VNA appears to work well now. I've been making measurement with it this morning - one way to spend Christmas day!! Dave. |
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Re: S11 and S22 comparisons on 8753
Am 25.12.2012 um 10:46 schrieb David Kirkby <david.kirkby@...>:
I hope you find such a well paid job. In the unlikely event that you need an assistent I would work for you for a small fraction of it. I am an engineer (rf and communication) and graduated from TH Darmstadt 32 years ago.No, me neither. It will have to wait until I get paid my next monthsI don't have quite $800k to blow this week after buying Christmas Merry Christmas Heinz |
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Re: S11 and S22 comparisons on 8753
J. Forster
Dr. Joel is a great, helpful guy.
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Merry Christmas all, -John ============== On 25 December 2012 03:17, Peter Gottlieb <hpnpilot@...> wrote:And I'm sure the thing is completely unrepairable except by Agilent,I suspect you are probably right about it being unrepairable except by |
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Re: S11 and S22 comparisons on 8753
David Kirkby
On 25 December 2012 03:17, Peter Gottlieb <hpnpilot@...> wrote:
And I'm sure the thing is completely unrepairable except by Agilent, schematicsI suspect you are probably right about it being unrepairable except by Agilent. I've not looked, but I doubt schematics are available now, but perhaps they might be when is 20 years out of support. once it goes out of support that is basically the end of that.Agilent will attempt to repair items that are out of support. I have an HP 8720D VNA that has been out of support for quite some time, but when I contacted Agilent about a repair a few months back, they said they could probably fix it, and could give me an approximate cost. They also offered to look at it free. In my case, the fault was obvious - it was a damaged thread on the 3.5 mm test port. Lucily it was not on the thread used for the RF measurement, but a secondly thread used to provide extra support to the Agilent test port cables with the large NMD conectors. The test port has both an internal and external thread. There's a picture of the damage here: Agilent intended replacing the whole coupler, which was going to cost around ?3000 ($5000) with labour. However, Joel Dunsmore, the Agilent VNA guru, said on that forum that one could try repairing the damaged bit of thread with a Dremmel. In fact my friend repaired it for me using a needle file at a cost to me of buying the needle files from eBay of around ?5 ($8). No, me neither. It will have to wait until I get paid my next monthsI don't have quite $800k to blow this week after buying Christmas salary, which might be a few months as I'm unemployed at the minute! Dave
Agilent sell a VNA for 110 GHz. At $691,437 for a 4-port model, I |
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Re: S11 and S22 comparisons on 8753
Hi Dave:
I stand corrected, you can not measure phase angle with a SNA, but you can make a more accurate |S11| measurement with the SNA. An air line is very different from a sliding load. If a sliding load is used as part of the VNA calibration the resulting measurement will be better than the common OSL type cal. Note, VNA cal standards come with data, but the data is generic to the model number of the set, NOT to the serial number, hence you can call up cal standards in the CAL menu of the VNA. There's a Wiltron (Anritsu) app note "Reflectometer Measurements - Revisited" (11410-00214) on using the air line and mismatched load to determine reflectometer directivity. From the app note: "The effective directivity after a broadband load calibration is essentially equal to the return loss of the load used for calibration. Unless the user is certain that the return loss of the load is at least 15 dB greater than return loss of devices to be measured, significant errors can result. Sliding loads are recommended for calibration and VNA test port specifications are based upon sliding load calibrations." So, if the desired impedance of the DUT is 50.0 +0j then using the airline measurement method with a SNA will give more accurate results. -- Have Fun, Brooke Clarke, N6GCE |
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