Вставка
- Опубліковано 31 сер 2018
- In this episode Shahriar analyzes the failure of two Agilent 8449B Preamplifiers. These units should provide up to 30dBm of gain from 1.0GHz to 26.5GHz intended for use as a preamplifier. Both amplifiers test positive for power supply voltages and operation. After removing the interface cables from the amplifier module to the front panel, it becomes clear that mechanical shock has caused damage to the front panel connectors. Replacement cables and connectors are used to correct the problem.
The Signal Path
www.TheSignalPath.com
/ thesignalpath
www.Patreon.com/TheSignalPath - Наука та технологія
Based on the feedback from all of you, it seems everyone wants the unit to remain intact. I will therefore not break it. I am sure there will be lots of microwave components to take apart in the future.
xray it
No engineer (or hobbyist) would break it. Only a researcher would :)
Great video, per the usual.
Dont break that rf amplifier!
_we're not worthy, we're not worthy_
Thank you again for selflessly sharing your wisdom.
You are a god amongst men
Thanks for your kind words.
I’m happy that you chose not to risk damaging the working unit. These pieces of test gear are a fairly precious resource to people who don’t have corporate budgets to fund their obsessions :)
Please don't destroy it!!! I'd feel guilty if you did! Very cool none the less.
Hope you can do a video on leveling. As an approximation I guess that could be achieved by the output of the detector (the 3.6Ghz amp you dismantled) being used to adjust the bias of the final stage amplifiers?
For goodness sake don't break it!!! Another great video, thanks!
Great troubleshooting. Yes no need to break that apart. We get it. Thanks for sharing.
“1 volt off shouldn’t break it” - I hit my head against the wall a few times when I used a cheap meter(the good one was in storage at the time) to try and fix an HP 5316A, when I finally noticed that the voltage spec in the service manual was 5v +/- 0.01v. Talk about a tight spec! A slight tweak with a more precise meter and it instantly started working.
Thanks for another amazing video!
I like your videos because you take advantage of the things that others have taken for damaged. (It is like what is said that the trash of some is the treasure of others) and I do the same here in Venezuela repairing and recycling electronics and multimeters for my own mini instrumentation laboratory
This is not the EEV blog: Turn it on, don't take it apart.
lol.
Such beautiful technology
Nice video as usual Shahriar,...
It never ceases to amaze me the advances in electronics some companies like HP have made since the 40's.
Early forties tech may have included scopes but they didn't have trigger inputs or a scaled output to measure accurately.
Tektronix introduced gigantic leaps forwards in scope design and they still do. HP or Agilent or Keysight, which ever flavour you prefer have in the most part introduced other measuring equipment that have broken frequency boundaries. The maths involved to create substraights like the Amplifier you show here are incredible and I imagine needed years of RnD to perfect. They look deceptively simple but look at your substraight with the Diode on the right, the extended track, I think you said was to null out the diode parasitics... yes an inductor at those frequenciea and maybe capacitance through the substraight to make a filter but clever and needed to be calculated precisely.
These companies may demand high prices but if you can afford their equipment, you can't go wrong.... GEC in the eighties where I worked were full of HP equipment (Mostly) or 4.5 digit Fluke meters, so much money spent in getting the best.
Absolutely, The biggest leap towards miniaturisation ever.
DON'T BREAK IT! Maybe you can sell the other amplifier and use the proceeds for more instruments to repair? It's so often that the reason an instrument is discarded is some simple failure that is relatively easy to fix. Your troubleshooting and analysis is excellent. I would like to learn more about coaxial cables for microwave use. I'm not familiar with the characteristics of cables beyond 500 MHZ.
Useful video
I have one of those power supplies and another one which is +/-12V. They both came out of an external drive enclosure from the early 1980s. Clones of these power supplies are being made nowadays by a handful of US manufacturers.
WoW. Quality!
Wooooouuuu...!!!! Excelente...!!! Saludos desde Mexico...!!!
Great video, I learn something new from every video you upload thanks!
(I'm just wondering how many pieces of lab RF-equipment do you have in total?)
More than me, definitely.
An excellent video demonstrating the often overlooked importance of input and output connections. I assume that the solder used in the manufacture of those rigid cables is most likely a lead-free type, which in my opinion most likely was the weak point in the connection. In my experience with lead-free solder alloys most tend to be fragile when subjected to repeated tiny mechanical stresses. I have seen rigid connections in field test equipment that were manufactured long before the introduction of lead-free solder that showed no such signs of cracking even on connectors with much less strain support at the mounting points. Communications test gear that had 20+ years of daily field usage, transported in less than ideal conditions, used in outdoor environments with no such problems with solder joints on rigid connectors. An example of why a connection that was most likely designed to be assembled with a lead-based solder should not have been assembled with a lead-free solder alloy. Just my assumption and opinion based on observations of the usage of both types of solder in many different types of connections that are subjected to any type of mechanical stress from flexing to even very slight vibration.
Thanks for the useful information!
While I would love to see one, I'd prefer you keep it intact - it would be just too much of a waste. Thanks for another great video.
On the last unit you showed, the output coupler looks to me like it would measure reflected power, not forward power, based on the location of the load resistor and the output to the detector.
Discovered your channel couple of days ago, can't stop watching your videos, extremely helpful. Very detailed and nice mix of theory and practical experiments, fun! Clearly you are very intelligent, gifted and natural at teaching. Thank you for taking your time to create & share these wonderful videos with us! Keep up the great work! I think you, Dave/EEVblog, Afrotechmod and Electroboom should team up and create your own online type of nano EE degree or program or may be partner with Udacity or such :)
do not break it
Very good investigation - but a small critisism - knowing that the front panel was pushed in I would have immediately inspected the connectors and cable path from the panel. The damage you observed to these would mean that it was not strictly necessary to carry out that extensive trouble shooting.
Neh. Leave it working. Useful piece of kit. A bit big, but useful.
Maybe modify one units, and put TWO modules into it? To conserve some bench space. :) Might require upgrading PSU PCB, but maybe the existing can do it.
Greate video.
Hi Shahriar,
Thanks again for yet another great video that teaches total RF dummies like, a lot every time...
You might want to correct the title of this video ? You forgot to add the numbered prefix to it, like " TSP # 131 - " ;-)
Looks like your channel is doing really well : if memory serves me correctly (?) when I subscribed to your channel, no more than 12 months ago IIRC, you had 17K subscribers, and now 54K ?! :-O That's going exponential eh ?
Well deserved of course ! Hoping it will keep sky rocketing :-) Keep up the excellent work, always much appreciated ! :-)
Vincent Trouilliez
Why did they use different type of screws on the bottom of the amplifier module? Two are Phillips and the others are Pozidriv.
Would be awesome to see a video on DROs and more microwave analysis videos like the radar one. Thanks
I did take apart an amplifier for the low end of the little brother of your tracking gen (85644A). I would guess the 8449B amp module looks like that but on a much smaller scale. I'll see if I can pull out 1997 designer cat of comm components again. Because I believe I saw a 1 - 26.5GHz GaAs MMIC while searching for other components recently.
flic.kr/s/aHskHdQfQN here is the die I believe. Its 2-26.5Ghz though. Also will post more to follow on that album later today.
Very cool. I wonder where all those engineers from 1997 are now.
@@vincei4252 Same. 1997 is somewhat recent compared to others so most will still be among us probably elsewhere as well. Retired or running their own thing. I also have a HP 9816 computer (needed to communicate data on these old equipment) and on the side of it is a HP business card with person named "Art Cashin" (I think) full info as a sales rep. This was back in around '82 so I don't think the phone works anymore but I haven't tried though. The 9816 is back in Houston while I'm in Amarillo now so will take time to check. The comp was up for scrap in Cali 2 years ago and I happened to come across it along with its keyboard (both sold separately). It's only problems were bad on system RAM (kept it original by working around that and getting expansion RAM cards and changing addressing switches) and a burned out light the helps detect motion for the cursor wheel on keyboard).
Interesting ;)
Does anyone have a book suggestion on practical microwave design that's light on the math? I'm doing good to find my way around an oscilloscope, and goofing around with Ardy's PIC's and an old intersil ICM7216 to experiment with frequency stuff. I've got a few chips to play with for a front end like the ancient 11c90, MC12095, and SAB6456. I'm curious about layout design, materials and a starting point for rules to follow. I'm also a poor gimp and looking for reading material I can pick up that is an edition or two old for cheap. Any suggestions would be greatly appreciated.
For a practical approach to microwave design, the best place to start is probably amateur radio. The ARRL (US) and RSGB (UK) have a range of books on microwave RF, including antennas and miscellaneous projects. Some of them are available in Kindle format.
Interesting that the gold case had two different sets of screws - two philips and two pozidrive - I wonder why....
Please, dont destroy working equipment. Its just not a good way to go, somobody, maybe even You will need it in future projects.
TNX 4 yet another great video !
Don't suppose you would share how YOU would measure the NF without using NF meter ?
73 N8AUM
break it!
this is the best way to learn the rf voodoo!
I wonder if it is possible to xray it?
👍👍
Any chance you can X-ray the module?
Don’t breach it!
Looks like the second one has a date as well, right next to the transformer: Jun 09 1997
If you do want to take it apart, you might be able to get away with prying the RF absorber off with it turned upside down so any chips wouldn't fall inside. A piece of tape could also help to keep it in one piece. You could glue a new piece of flexible material on the lid as a replacement. Still, I'd rather not destroy a working part if you might be able to get your hands on a broken one.
do not break it, its a waste
Speaking as a ham radio operator, rigid coax is annoying.
Don’t break it
2 philips and 2 pozi ?! strange. @19m52s
I saw that too. I wonder why they would mix screws... I wonder if the other module has it mixed as well.
I noticed that too.
I was searching the comments to see if anyone else had mentioned that before i made my own comment.
most of the HP gear I have has a strange mix of metric and imperial hardware. The units even warn you about this. However, in this case god knows what's going on.
If they didn't work they still would had made good project enclosures.
Please do not break it.
No don't destroy it pls.
one more vote for not breaking the preamp
Do not open! No user serviceable parts inside :D
Breaking functional microwave components is sacrilege to the gods of Mho.
esoteric shit, man.
Please don't break the working amplifier. It would be a crime towards the microwave God's.
@MichaelKingsfordGray I don't know? Are you a genuine card carrying member of the grammar police?