#58 Teardown: HP/ Agilent precision step attenuator for HP/Agilent Signal Generator 8648 series
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- Опубліковано 15 вер 2024
- How a precision step attenuator works and how you can check the function of a programmable step attenuator.
HP8648 Signal Generator; 33322-60011HP Step Attenuator
Thank you very much for this awesome video. I'm repairing an Agilent 33321-60051 step attenuator from my Agilent E4402B spectrum analyzer as I'm writing this comment. So far my attenuator is a twin of the one that you've shown. Though the partnumber and attenuation coefficient are different. Anyway, I'm double checking everything just to make sure I don't run into an accidental difference between these parts and don't blow anything. At least the power pins are the same. The part that you've identified as a transistor (the one that feeds the linear stab) is actually a 7.6V zener diode. If you look carefully, you'll notice that one of the pins of the sot-23 package isn't connected anywhere, but the device still maintains 7.6 volts across its outputs. I tested the unconnected pin with a DMM and it reads open. Interestingly enough, the 8L05A can deal with up to 30V volts of input voltage, so I think the zener is just there to lower power dissipation of 8L05A.
Hello Peter! I know this video is now 5 years old, but for me it is new and very helpful. Thank you for this excellent and informative video.
Real good analysis and deduction of function, excellent description and explanation. Signal generator function is so important and a MUST have instrument in the lab ! Great video as usual. Thumbs up.
Satellite_Guy Hi, Thanks for feed-back. Yes a precise working generator is a must!
Wow a really lucky boy! Well done
When Marie and myself go for a walk, she says I walk too fast! I think I need a step attenuator :^) Great video Peter!
Mr Carlson's Lab HaHA yeah I see your problem hi hi. I only can recommend not to buy your step attenuator on ebay. Far too expensive especially for your purposes :-) Thanks Paul for your comment! Your latest video is really excellent as all the other! 73 to you and Marie!
Thanks Peter!
Interesting as always. Thanks Peter.
***** Hello John my friend. Good to see you here. Thanks for the comment.
Another interesting video as usual thanks.Looking forward to seeing some more radio reviews.
technos123 Hi, Thanks you!
Hi Peter. I have a Schlumberger Stabilock 4039 whose attenuator is stuck. Hopefully I will be able to test and repair it using the info in this video. I really hope the attenuators are OK and it's a switching transistor. Thanks for the good info!
A fantastic demonstration of reverse engineering. Would also make a great standalone bench attenuator with a few tactile control switches or a simple micro routine.. Karl
Karl Fell Hi Karl, yes would be a nice bench attenuator as well. Now where we know how it is designed it is easy to build a circuit around. Thanks for feed-back!
Excellent video, very interesting, tnx for sharing..
Bud...
budleyca1 Hi Bud, thanks for comment, glad that you like it!
Hello, great video. When you say "negative input" do you mean negative voltage like -5V or simply grounding the pin temporarily??? Thanks
Nice
I had a feeling that it would be switched by grounding the inputs. That's what makes the most sense here.
Good afternoon, your video is excellent, I have an agilent N9310 a. I carelessly put rf in the input and it lost power, it only comes out -30 dbm. I'm looking for the service manual, do you know any link to get it or any suggestions
Thanks Peter, very interesting. That would be a very expensive unit to replace, so it was a good buy and it is in perfect order. Interesting how they have decided to control it, I wonder why they did it that way instead of straight logic signals?
Alan Cordwell Hi Alan, thanks for feed-back. Yes that is really an expensive component I couldn't believe the price I found on ebay..Well, why do they have decided to control unit as they did. My guess is as good as yours. In the past the very early attenuators without any electronic inside the attenuators were also controlled by switching the ground. So may be traditional or a question of compatibility ?? The second idea I remember that in the mid 70th's when logic chips came out everything was triggered with the trailing edge. As far as I remember it was due to the early available TTL chips...
Hello, thx for the clear explanation. I wonder If anybody has reverse eng. that little pcb into a schematics. I have a step att. from an HP8566b that suffered a polarity inversion (My fault) and I would like to fix it but I cant find schematics of the pcb on internet. Any good hint? thanks...
Nice job, thanks.
Robert Calk Jr. Hi Robert, thanks for feed-back
If you where making a t pad attenuator which type of resistor would you use cfr or mfr
Have you ever repaired the 1khz modulation for the HP 8648a/b/c/d?
Nice video! Thanks!
Thanks for watching Roumen.. 73
Very good video. Thanks.. Not sure if you have a Tek 465 or 475 but these are great scopes, especially, for HF work. I have 4 of these in my lab, 2) 465B's and 2) 475B's. This allows me to move from bench to bench without disturbing the test gear.
I really want the scope to just be a scope. I have counters and meters of various types to get other info. However, The TeK DSO's are also very nice and at some point I may get one. Al, W2AEW uses his often on his youtube videos and I can see the value of such an instrument.
Anyway, Thanks again and I look forward to more of your videos.
I am not sure if you are familiar with the HP 8640B sig gen but it is an amazing instrument and built like the space shuttle. Hi.. I hope someone, perhaps Carlson, Al or you will do a tear down of this instrument.
vy 73, Glenn WA4AOS DSM Labs (dotcom)
wa4aos hi Glenn, my is a 475 and it is still a valuable scope. Gut I have to admit that a DSO is a Great invention. I'm using my DSO now much more then my 475. okay thanks for comment mate 73
Thanks for sharing. Might be nice to have a tour of your lab, and an explanation of all your equipment on your bench. Are you a very knowledgeable hobbyist, or is this your job?
+PelDaddy Hi, electronic engineering is my profession. Thanks for watching 73
+TRXBench No wonder your videos are so informative. Thanks again.
Hi Peter... at 50.40 min you have not 80 dB but 70 dB att (10+20+40). Regards.
Pasquale IW0HEX Yes off course you are right. You see I just can't even count hi hi :-)
Thanks Peter !!! 73s
Pasquale IW0HEX Thanks Pasquale! Did you enjoy Friedrichshafen?? Did you have a stand on the flee market? 73 Peter
Hi Peter. I enjoy so much. I have bought a Rhode & Schwarz Communication Test CMT52, good price, 800 Euro with some option. Works fine !!! :-) About PD55003E, please take a look here : www.ab4oj.com/icom/ic7800/7800txdev.html and here : www.st.com/web/en/resource/technical/document/datasheet/CD00103337.pdf
Thanks.
Pasquale IW0HEX
Pasquale IW0HEX That is a great price! Lucky you are :-)
Well concerning the PD55003E, it is as I thought. You can only manage it with hot-air. If you nevr worked with hot air before, be very careful with air stream. If it is to much you will blow all components from the board!!
Good video Peter...what is the price difference between ebay purchase and factor purchase? Enjoyed the video.
Jack
+Jack neff Hi Jack, thanks for feed-back! Well price difference.. I know there was an offer on ebay for 295$ recently. For the factory price for a refurbished unit I do not really know but I have heard that it is above 1000$ but again not sure on that..All the best...
+TRXBench Wow that's pretty expensive considering what you showed us the inside was made of!!!
Regards...Jack
+Jack neff Hi Jack, yes okay but you can't count the components. You must consider this unit as high precision part which guarantees highest accuracy in development labs. Therefore you can't use my unit for those purposes. If you look into a price list for a new Agilent generator you see what I mean...---very expensive :-) best regards
I think ULN2003s are Darlington BJT, rather than mosfets, but the same idea. Nice reverse engineering.
+PelDaddy Well may be I don't remember....
prisoner number 82030... :-)
+I am the NRA. LOL yes just released