|
Re: Extracting a knob grubscrew
They are typically 1/20" or 0.050" keys. Sometimes it's Bristol drive but if someone forced a hex key in there it's probably not a Bristol drive anymore. Unfortunately I have found no way to extract a stuck set screw of that size. You might try a 1.3mm key, sometimes they really are 1.3 and not 1.27 so you get a bit more grip. I don't know, seems random. |
|
Extracting a knob grubscrew
Need to remove the horizontal control knob on my 576 so I can remove the board to get at the display selector board. One of the grubscrews undoes easily enough, but the other appears to have its hex slot stripped. A 1/16th allen key just rotates in the slot.
Any tips on how this could be removed? I don't have a screw extractor small enough (I presume the grubscrew is 1/8th ?). |
|
Re: Bandwidth vs rise time of digital 'scopes: Behavior of the TDS3054
Hello all just checked the Yokogawa DL7440, with Leo B 40 ps BNC pulser, get 570 pS RT, OS ~ 14.5%
Using HP RG gen 8640B , Gen Rad RG/6U cable and 20 db atten, getting 3 db at 607 MHz. 0.35/Tr gives 614 MHz so very close. Will post screenshots in photos soon, under DL7440 album Bon journ¨¦e, Jon |
|
Re: Sloppy front panel BNC connector - 475
Carbon comps with metal end caps have bulges, too, so you can't always tell by sight. Crack yours open to be sure (but I'm pretty sure it's a CC).
toggle quoted message
Show quoted text
Cheers Tom Sent from an iThing, so please forgive the typos and brevity On Feb 1, 2021, at 4:37, "Torch" <tekscopes@...> wrote:
Colin,- |
|
Re: NEW TOPIC: Outstanding Rockland Instruments 7000 Plugin; WAS: Slightly OT- Wavetek 7530B?
On Mon, Feb 1, 2021 at 01:11 AM, santa0123456 wrote:
Yes. That is a good recommendation. However, I don't know how to follow it. If one parses effects into: "short term" exor "long term" OR "acute" exor "chronic"...(to suggest some combination of them)... and then assume the effects santa0123456 observed were short term and chronic... Then, I don't know how much of the stuff we get (from before the year 2000) came from mountain tops, close proximity to nuclear reactors, prolonged high altitude flights and so forth. For long term and chronic... say... the U.S. DNA (now renamed) was for many years looking into ways to reduce these kinds of failures... and I'm assuming what they learned was passed on to fabs. I'm also assuming that very expensive equipment from Tektronix meant to support military avionics et. al. ... got a lot of these parts. Most of us have got bricked stuff, or have bricked stuff... but I don't know how much of "rom rot" (or "recap") is relevant or just YouTube-istic flummox. (I'm not saying it is... I'm not saying it is not: I'm saying, I don't know.) |
|
Re: Sloppy front panel BNC connector - 475
Colin,-
Ooooh! Thanks for the part number. I have a pair of used ones on the way from Q-service now. Lord knows how long that will take with the current state of our post office... <sigh> I agree, it looks like a cast-iron SOB to change. Maybe I am completely wrong about the resistor. "cmpsn" sure looks like it could mean "composition". The one I removed is tan, has 4 bands and a bulge on either end characteristic of a film resistor. The one on channel 2 is identical in appearance. I have always understood that carbon composition resistors are straight (ie: do not have a can on either end) and are usually a deep brown colour. I'm not sure how to insert a photo with this group, but here is a photo of the damaged resistor: On Mon, Feb 1, 2021 at 02:28 AM, Colin Herbert wrote: <snip>
|
|
Re: Sloppy front panel BNC connector - 475
I think you might be able to get one of these 3-conductor BNC sockets from Qservice or Sphere. It is described in the Service Manual as "connector, Rcpt,: BNC, Male, 3-contact", the Tek p/n is 131-0679-02 and it was originally made by Specialty Connector Co., of Indianapolis. Good luck with replacing it, though, I wanted to replace one where the factor-switching connector had come adrift . I gave up eventually, as it seemed that you need to remove more stuff than seemed sane to just to get at it. I tried making a thin-wall socket to loosen the nut and that failed, too. I eventually drilled a small hole through the sensing-ring, poked a bit if tinned-copper wire insulated with sleeving and soldered it to the sensing-ring. It worked.
toggle quoted message
Show quoted text
I don't know where you got the information that the 43R resistor is described by Tek as carbon film - my 475A Service Manual describes it as "Res., Fxd, cmpsn: 43 Ohm, 5%, 0.25W" which I read as "carbon composition", as is its analogue in the other channel. Colin. -----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Torch Sent: 31 January 2021 20:40 To: [email protected] Subject: Re: [TekScopes] Sloppy front panel BNC connector - 475 Thanks everyone who replied. The 475 connector body (ie: the part that incorporates the outer, probe sense, ring is secured firmly to the front panel with a nut. The nut is not loose and won't move under power of needle nose pliers (it would require some sort of really thin wall socket, I think). Between that outer ring and the next "ring" (ie: the BNC shield proper) is a layer of nylon(?) insulation. It is that layer that is loose, allowing the entire BNC portion of the connector to float within the body. I can look all the way around using a mirror, and don't see any sign of a set screw. Unless it is under the nut, I don't see where one could be. If anyone knows the part number or a source for the style 3-conductor BNC assembly used on the 475 front panel, I'd love to replace it. In the meantime, as a temporary fix, I stood the chassis gently on it's nose so the connector was vertical with access to the back, and drizzled in a few drops of thin cyanoacrylate. I wiggled and jiggled the connector to work the cyano in as deep as I could before letting it sit and set up. That firmed things up mechanically -- for now, anyway. That leaves the resistor. So much debate about a 10? part. Probably every single one of you knows more than I about the subject. I suspect a couple of you have forgotten more than I know about the subject. So when one of you says that a carbon composite is a better choice for this application, I think it's worth listening. That said, after careful consideration, I decided to stick with the original Tek-speced carbon film resistor. I don't use this for any high-energy measurements. I mostly use it for things like transistor curve tracing (my digital scope is great but sucks at XY display) combined with a personal bias towards restoring old equipment as opposed to modifying old equipment. But thankyou again for the input. |
|
Re: Bandwidth vs rise time of digital 'scopes: Behavior of the TDS3054
Ed and Raymnond:
HAve several Yokogawa scopes, with 500 MHz BW will try out and post images. The transient response on analog scopes can be tweaked for best risetime but sime overshoot, and usually several small ripples. Unclear if digital scopes can be adjusted for this. Bon journee, Jon PS: the number bits referred to as "effective number of bits " ENOB " may include a few "marketing bits" (:-:) as per Bruce Jackson, Apogee Electronics |
|
Re: NEW TOPIC: Outstanding Rockland Instruments 7000 Plugin; WAS: Slightly OT- Wavetek 7530B?
Hi Dennis,
This job is indeed very busy and complex. The temperature, ice and wind conditions at 3600m altitude forced me to develop a lot of specific equipment for the task. The problem is not only design, construction and repairs. The need for day-long observations depending on a very unpredictable meteo puts chaos on my agenda and consumes most of the time that would be needed for development. Since 2008, I could implement internet remote measurements that were considered impossible by my predecessor. But covid and the impossibility to reach the lab for repairs put it down since november. I would like here to bring to the group attention the probable cause of this failure. We had two IP KVMs to control a vintage critical computer. So, one KVM was a spare. The two died within three months and my diagnostic is that the two forgot their firmware programmed at around the same time. One has to be aware that at 3600m altitude the cosmic rays are more intense and speed-up memory loss. This to say that I see a lot of people careful enough in the HP and Tek lists to remove (sometimes desolder) the eproms in their nice equipment to save their contents (if possible and safer, reprogram them to refresh their contents). Now, the situation got worse with the embedded EEPROMs in microcontrollers. In that case, the contents are not accessible and the instrument is doomed when the contents vanishes with time. I already have IP cameras in the lab that seem to have been attacked by this modern electronic Alzheimer. For sure, this is a very convenient unavoidable obsolescence for the sellers. Your motherboards will also forget their Bios in soldered EEPROMs btw. Socketed EPROMS are long gone. Back to Fourier Transform SA. When you are in the domain, you get quickly the feeling that you can easily buy more resolution by taking more samples, which takes more memory and time. This is the same feeling as an analog SA that needs a slow sweep at small resolution bandwidth. But with FT SA you need a stable source. Otherwise you just would mix-up added noise on top of runing your line profiles. In our case, the target resolution is the one needed to well resolve the thin absorption lines of the atmospheric gases. This means a resolution between 500000 and 1 million. Hence the reason why we usually manipulate 2 million points samples (Nyquist). If the frequency domain of interest is reduced, applying a bandpass digital filter to this set would allow the equivalent of a heterodyne frequency change and the possibility to undersample a lot to speed-up FFT. Otherwise, with a big FFT you can get a 0 to Fmax spectrum at max resolution. The possibility you mention to slow down the clock of the 7530 is indeed to reduce RBW but at the expense of the maximum input frequency at the instrument input. Because the problem is that you can't increase its maximum resolution which is determined by its memory size. Unless an antialiasing low-pass analog filter was put in front of the S/H, Nyquist would hit you hard and mix-up all your frequencies. ;-) I never had the chance to see a J20/7J20 and I would have been very happy to play with. It for sure was very compact. Much more than my 4 meter long interferometer. I remember now that the Rockland synthesizers were operating at 1.6MHz, not 8. I repaired one of them once. A lot of 74xx chips in them and one had failed. So, group members, save all your Eprom contents when possible and be cautious when buying post-2000 equipment containing soldered or embedded EEPROMs. The time bomb is running... |
|
Re: Bandwidth vs rise time of digital 'scopes: Behavior of the TDS3054
Hi Raymond, I meant to look at effective bits as a general view on all DSOs. I don't know what the detailed differences are among the TDS scopes. I actually find it quite confusing with all the various models, since I'm not very familiar with them. One thing I do know, is that I "upgraded" my TDS754 (I think) a while back, to perform as a TDS784, using some mods I found online. As I recall, some BW limiting caps needed to be deleted from the amplifier circuits, and some jumpers needed to be changed to make the brain think it was the higher-end model. It appeared to work.
Ed |
|
Re: 7104 readout issue
Said switch is on the front panel of the 7104 - turn the readout pot fully clockwise into the detent at the end (PULSED position). To quote page 2-10 of the manual:
The READOUT control determines the operating mode of the Readout System. With the READOUT control set to free run (out of OFF or PULSED detent positions) the Readout System operates continuously, interrupting the crt display at random (for about 20 microseconds) in order to write each character on the crt. With the READOUT control set to the PULSED position, the Readout System operates in a triggered mode; one complete frame (up to eight words) of readout is displayed. The + GATE or EXT switch determines whether readout is displayed at the end of the + GATE or when an external signal is applied to the rear-panel GRATICULE/READOUT SINGLE SHOT input. The+ GATE switch selects whether A gate or B gate triggers the readout. HtH David |
|
Re: Bandwidth vs rise time of digital 'scopes: Behavior of the TDS3054
I have a couple of TDS3054Bs and have had one TDS3064A, and have done rise time and -3dB measurements on them. Just as others have mentioned, I saw around 700pS rise times and 600MHz -3dB points - on both the '54 and '64! Exactly the same! So, my guess is that Tek somewhere along the line decided to sell a 600MHz labelled version of what was essentially the same electronics because somebody said they could do so (legitimately by some measure), but then had second thoughts or maybe the engineers told the marketing folks to back off!
Reinhard |
|
Re: bandwidth
Don Bitters
Jim,
I was one of those HP/Agilent field cal guys doing the MTE, never did it for Raytheon, but did it for 100¡¯s of other customers. We verified that every instrument made published specs - no matter what manufacturer HP, TEK, Fluke, etc. we never adjusted any MTE without notifying the customer - he/she had to authorize it and quite often had to provide the adjustment procedure if it was a manual procedure. I did the manual verification procedures on about 100ea. 11032¡¯s, CSA803¡¯s and plugins. One time I was pressured by a high level manager to ¡°pencil whip¡± the test procedure to speed it up. I pointed out to him that I would not/could not do that because of the damage to our reputation, let alone the legal liability if I passed something that actually failed. You know how many pages the manual test performance for the 11032/CSA803 is - about 75, and the SD-24, SD-26 plugins - about 30 pages. Doing the performance procedure on an 11032 with 2ea. SD-26 plugins was most of a day calibration without the additional paperwork. I did not know of any HP/Agilent/Keysight techs, engineers that would ¡°cheat¡± on a calibration, and I knew well over 100 of them personally to talk to. I also doubt that any of the Tektronix, or Fluke, or Dayton calibration people that I knew, and even a large number of the independent cal labs that I dealt with would also ¡°cheat¡± on a cal. On the other hand I did know of a few labs that were notorious for selling the customer the cal stickers and the certificates for a fee. One of our NA customers went looking for a cal lab in Mexico (Agilent-Mexico declined, they had neither the ETE nor the trained people to do the required tasks). They found a guy that had a small shop above a pharmacy in Guadelejara that said he could do the job calibrating production line optical test systems. He had a 100MHz o-scope and a 4-1/2 digit DMM. The NA customer hired Agilent-Midwest to go down to Reynosa, Mexico for 3 weeks to calibrate his calibrating production line optical test systems, for a princely sum, but got it done to NIST traceable, with data. Don Bitters |
|
Re: P6131, T-coils and other probe stuff
Hi Mark,
toggle quoted message
Show quoted text
Very nice to see you here! Your review article on sampling scopes is a true classic. I blame and thank you for the happy hours I've spent trying to chase down and then read, all the references you cite. :) I can't imagine the hours you spent amassing all of that information. Simply amazing. Gabor is a dear friend, one of the last remaining links to that earlier generation, a rarity who knows that "Bartlett bisection" isn't a medical procedure. Cheers Tom Sent from an iThing, so please forgive the typos and brevity On Jan 31, 2021, at 16:29, "Mark Kahrs" <mark.kahrs@...> wrote:
I can't resist commenting about: |
|
Re: Bandwidth vs rise time of digital 'scopes: Behavior of the TDS3054
On Mon, Feb 1, 2021 at 01:02 AM, Ed Breya wrote:
Sure, important and interesting. Is there a special relevance to the point I was trying to make? AFAIK, the architecture and hardware are the same across the whole family, incl. the TDS3064 600 MHz version. Any suggestion re. how to find out? Basic resolution for these 'scopes is 9 bits. Max. RT sample rate is 5 GSa/s. Raymond |
|
Re: P6131, T-coils and other probe stuff
I can't resist commenting about:
"If there is a network theorist left on your faculty (very rare these days)," In fact, it appears that circuit theory classes have nearly vanished. One of the few I know of is taught by none other than Gabor Temes: I find that some of the old classiques, such as Van Valkenburg or Kuo are truly edifying, for example, conversion from one 2-port form to another. Great stuff, highly recommended, , etc. Once you've seen transfer matrices (ABCD), you'll never look at circuit analysis the same way again. I'll stop before I wax even more ecstatically. On Tue, Jan 19, 2021 at 5:19 PM Dennis Tillman W7pF <dennis@...> wrote: When it is safe come and stay with us as our guest. We have a large house |
|
Re: 7104 readout issue
Chuck Harris
Hi Sean,
toggle quoted message
Show quoted text
I remember now. My 7104 spends most of its time, all dressed up, with no place to go... So, it is not one of the scopes that I am most familiar with. If you look on the front panel, you will see an outlined area that has two intensity pots (A and B), a READOUT intensity pot, and two push buttons for the readout. The one button is marked +GATE or OFF, and sets the readout to be on at the end of the GATE signal, or off. The other push button is marked "MAN", which causes the readout to be on always. Something there is probably in the wrong position, or misbehaving. Also, I keep my plugins off of AUTO on my 7104. Because of the MCP's limited life, you do not want to be wasting it with continuous readout display, or baseline display. I keep my readout in "GATE" mode, so it is off if the sweep isn't being triggered. Typically, I also keep the A and B intensity turned off when the scope is off, to avoid intensity flair during turn on. -Chuck Harris [email protected] wrote: Chuck, |
Jean-Paul
David C. Partridge
Raymond Domp Frank