Fantastic work. Causes me some dispare as I am 64 years old and totally lost on all the software aspect. Would not know where to start to learn it. Was an electronic technical offer since the late 70s and kept up with everything until 20 years ago. An analogue and RF expert. Frustrating how dated ones knowledge becomes and how one falls behind. But very enjoyable to see these new projects.
I know what you mean, not far behind you and software writing has always been my weakness when it comes to modern test equipment. However I did learn some Quick Basic better known as QBasic, it wasn't to hard to learn and I was able to do a few things with with. Best Wishes & Blessings. Keith Noneya
Looking forward to the follow up... The printer option will be nice. My 141T is still working fine but the ability to instruct a tracking generator OR to simply provide step by step "sweep instructions" to a regular generator through your display unit will be really nice. Thanks for sharing your work.
I just re-watched the video in hopes I could just figure out how to replace the screen by itself with no options, except may the graph and scale, but even those could be printed on clear plastic and laid on the screen for us code illiterate folks. In addition I was hoping you'd do a quick follow up video on how to use the board and load the software on it, at least we could reproduce the project and go from there. I think this project has many Industrial/Hobby applications in converting old CRT XY outputs into larger LCD screens. I think the software could be used to monitor the ADC inputs/peaks and determine the frequencies and amplitudes based on those alone and then display the results on the screen. This is such a great project to build on, not only for the 141T but, for all CRT based screens where measurements are manually done. With this project those measurement could now be done by the software and displayed. Thanks again for such a great video. Makes me want to learn programing to work on those ideas I just mentioned. Best Wishes & Blessings. Keith Noneya
Hello Seb. Had the classic HP141T years ago ... it was a magical piece of test equipment. Excellent video ... thanks for sharing. Hope to have a QSO some day. Take care ... Mike VE3XLF
I was wondering it you were going to work more on this project? Thanks for the great video I thoroughly enjoyed it. Best Wishes & Blessings. Keith Noneya
Excellent video and explanation. Especially nice work on the waterfall display and interfacing it with the tracking generator. One correction: 141T was actually being made as early as 1969, and some of the other 140-series mainframes are even older! I suspect yours is a 1970's model, as the later ones from the 1980's that I've seen all use a slightly different CRT. I can explain how to easily date HP serial numbers if you are curious what year yours is. With regards to the code for reading the instrument settings, even if you interface to the D-sub on the back, I suspect you will still have a real challenge in estimating the start/stop frequencies precisely, as the LO sweep is controlled by an analog ramp rather than a phase-locked synthesizer. This is going to become especially problematic at narrow sweep bandwidths, as the first LO in the 8555A drifts around noticeably. In a sense, the 141T doesn't really "know" what its exact LO frequency is at any given time. If you need a clean way to connect to the rear D-subs, there is info online on what kinds of mixed-contact D-subs are used (known as a 17W5 IIRC, but you can use backshells for 37-position D-subs for the back portion). I did a partial write-up a while back when I made a replacement cable for my 8445B preselector: www.electro-tech-online.com/threads/making-a-replacement-cable-for-a-hp-8445b-spectrum-analyzer-preselector.150208/
Interesting, I pulled the dates out of the manual I have, but there is a chance that it doesn't match my unit. I am actually very curious how old it is - the serial number is: 1502A 10994. If a year can be deduced from that I would like to know! I think I kinda know what you're talking about, I have seen photos of other 141T units with much darker CRTs. You're definitely right about the issues at narrow sweep bandwidths. Still, I plan to give it a shot and see how it goes. I figure for at least some settings like scan width and scan time, even though there is no real 'output' on the instrument for the settings it shouldn't be too hard to quantize the rough ramp timings and figure the exact setting out (because there are finite possible settings). But, the center frequency will still be an issue at low scan widths as you say. Great! what a fantastic write-up, thanks for the link. I was actually thinking of making a PCB with the cups and connectors mounted to it at the correct positions but I didn't realise you could still buy some parts of the connector. That will be really helpful. Cheers!
Okay, so when reading HP part numbers, the first four numbers in the serial number are the year (added to 1960) and the week of manufacture. so 15 would be 15 years after 1960 (1960+15=1975), and 02 would be the second week, so January of 1975. The letter after the date code is the country of manufacture, so "A" would mean that it was manufactured in the United States. This method works for all HP test equipment, not just 141Ts, made up until about 1996. Is that the serial number from your manual or from the back of the unit? You might even pull out the plugins and check the separate serial numbers on those. Many of these units have been out in hobbyist hands long enough to have had the plugins swapped around between mainframes, so not all of them are matching units these days.
Awesome, thanks for the tips on dating the units. The number I gave you was from the back of the 141T mainframe. Yep, your hunch was dead right. The oldest serial I have seems to be on my 8555A (18GHz RF section). It says '1043A 00184'. 1970! Still going strong... I should have been saying almost 50 years old, not almost 40!
Compliments for such an interesting and useful project! Did you make any progress in this project? Is the second part ready to be upload? We are all waiting for this! Regards
Super cool. You can get some easy wins by replacing that LM358 with an OPA277 (but you lose out with 1/f noise), OPA828 (great tempco, 1pA of input bias, and 4 nA per sqrt hz at 1k). Get a more powerful chip and drive a bigger screen, with more resolution so your waterfall doesn't look like an Atari . Considering the time investment you put into this, buying a Zync or SmartFusion2 or one of them SoC's with an FPGA on-board might be the sweet spot. The SoC will easily drive a 1024x768, and the FPGA can pull the ADC data and do all of the frame buffer junk. Also, when you hooked that TG up to your scope, did you just turn your scope into a low dynamic range SA, cos that's what it looked like....if so, 'super cool' turns into 'wat. awesome so awesome.
Hi Seb, what a great project, I going to get a STM32F74g board and follow your progress I have a HP141t here which i am not using.it will now be come useful. 73 Gary vk2kyp
Nice work Seb. Quick question though: Isn't there a GPIB interface on the back that you could take advantage of? I really need to shake the dust off of my Tektronix storage scope and see about doing something similar.
Thanks Chris! Unfortunately not, no HPIB/GPIB buses on this old thing! Only those analog expansion headers on the back for the tracking gen & preselector add-ons.
Hello very interesting video. you are very good at what you do. I have this HP unit and i would like to read out the center frequency. what is the easiest way to do that with some kind of frequency conter . With best regards klas jonsson Sweden. ps i am not near your knowledge but its all about learning.
Cześć,Mam taki analizator i z wielką radością zobaczyłem twoją modernizację ,chciałbym wprowadzić taką zmianę w moim HP141T . proszę o pomocz z softem .Pobrałem soft z GitHub (Compiles with STM32Cube_FW_F7_V1.17.0) próbuję to załadować do STM32F746G i nic z tego.Nie mam wiedzy w jaki sposób mam ten plik załadować do disco .Komputer jest połączony przez usb z disco ,na pulpicie urządzenie DIS_F746 wgrywam lecz na ekranie disco nic się nie dzieje .Proszę o pomoc.
Yeah, all the content on this channel suddenly stopped. I discovered it a few years ago, and got really excited, and then forgot about it because there hasn't been anything new in a long time. I just re-discovered it again with the making and testing filters with copper tape video, which I definitely watched before, and there's nothing new :( Wish he'd make more videos again
73's de F6EZI very good video I'm trying to follow you you are speaking very fast for me but I play your video many times to understand - tank you you give me many ideas
That's not a "waterfall". The term generally means a series of sweeps presented in a 3d-ish manner. Your mode is usually called a spectrogram. Very nice tho :)
Will be interested to see the hardware. I recently breadboarded f1frv.free.fr/main3n_HP141T.html after ordering the mentioned opamps and was getting terrible signal results that I'm pretty sure wasn't due to the unshielded cables. I found that you can bring down the 16V-18V pen lift to around 500mV with a simple BNC Tee adapter and 50 ohm terminator. This puts both signals well within the voltage range of a soundcard input and don't need to build a circuit. You don't get the Y inversion of course and would need to correct for that in software which many of them can do. I opted to purchase www.ebay.com/itm/272787408868 rather than make my own and it looks good even though the cable isn't shielded.
Excellent write up and detail! Thanks for sharing. I've been debating rescuing one of these and go back today for another shelving unit at the estate. Thinking, since I have room and will motivate me to clean up some more space, I may get another shelve unit and a few more pieces of equipment to rescue and restore.
Wound up grabbing one of the HP 141T's with a pair of plugins and another RF unit. Sounds like powers on, though the CRT doesn't display anything. I still need to download what manuals I can find regarding and then try to find more if I need for troubleshooting the repairs. Then for the upgrade. Thanks again for sharing and the motivation to save another made in the USA system.
I'm replicating your build with a 141T 8555A 8552B and its a week away in the mail. I noticed you don't have a schematic up or reference PDF from your circuit. Can you DM or reply on here and upload to your website? It would be a big help! Thank you for the upload!
I guess I'm confused because the scope can go up to 14+Ghz and assumed you would need a FPGA or something to deal with that type of high speed data. however it seems you are using the video out to analog pins in the discovery kit. The video out must have a smaller bitrate? The reason why I care is because I'm more interested in decoding. I want to make it so you can choose the trigger/keying for 1's and 0's, kind of like a RF reverse engineering tool. If anyone can enlightenment me on what his theory behind the data I would appreciate it!
*(**2:27**).... ON THIS HP ..YOU CAN **#SEE** THE "SAME" .!* *JUST TO MAKE IT CLEAR* *AND ..IS NOT BAD "JUST FIND OUT HOW TO" ...* *BUT ... GOOD VIDEO*
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