Keyboard Shortcuts
ctrl + shift + ? :
Show all keyboard shortcuts
ctrl + g :
Navigate to a group
ctrl + shift + f :
Find
ctrl + / :
Quick actions
esc to dismiss
Likes
- TekScopes
- Messages
Search
|
7603 lights, and more about transient protection
wshawlee2
No, the plug in lights to NOT light in a 7603 frame, this was
intentional, but I don't know the orignal thinking that led to it. 7A26 and similar format vertical plug ins don't need it, and the 7B53A (the intended sweep plug in) has white indicator rings around the pushbuttons, and NO internal lights. so, if yours doesn't light, that's just what it's supposed to do, but the rationale is now lost to history. Miroslav's comments about neon lamps in the older supplies as transient protection are not correct, they were warning indicators for lethal voltage, nothing more. This is even explained in the service manuals. Older unit have no AC transient protection. Tek really should have incorporated transient protection with it's switchers, as many were designed before rugged high voltage FETs existed, and they are easily damaged by transients. I was not suggesting you buy a crappy $4.95 trasient protector, as I use some very high end ones here, but it's up to you. Tek (after many field failures) added this protection to later 2200 series units, and it seemed to help significantly, they were just single ordinary GE varistors. If you are really in love with your gear, by an autocorrecting Liebert UPS, the ultimate in line conditioning. Leaving it on vs. turning it off. well, this argument has raged for decades, but I think you need to consider some simple math: the 7K series runs VERY hot, and it has some definite MTBF limits associated with capacitor and semiconductor failures caused by this, not to mention consuming the CRT. if you leave it on, you are wasting 2/3 of that MTBF at night, and when no one is around. I get the thermal shock argument, but my own long standing experience is that this is an order of magnitude less of a problem than burning the equipment for endless hours. It makes no difference to me what other people do, but to me, the wasting of so much equipment life is silly, and serves no purpose whatsoever. When the tube is gone, you can't exactly whittle one from a block of wood, so think it over carefully. I have often thought of putting a small NTC or other surge limiter in series with the filament to reduce thermal shock, but interestingly, the overwhelming failure mode I have seen from Tek CRTs is going weak or gassy, NOT filament failure. What do you suppose that means? Not good statistical support for leaving it on, that's for sure. all the best, walter |
|
Re: On screen display and other CRT items....
Stan or Patricia Griffiths
The only two Tek scopes that I can remember having more than one power switch
are the 507 and 517 and I don't really recall what the real story was on those. I think they were separate switches for filament and DC power. I don't recall anything like a "standby switch". One other reason you might not want to keep your scope turned on all of the time is that tubes in distributed amplifiers develop cathode interface over long hours of on time. The only answer to cathode interface is to retube the amplifier. In order the "save the CRT" it has also been suggested to simply turn down the intensity to cut off the CRT beam current. In the case of some of the 560 series, I understand that even if there is no visible display on screen, the CRT cathode may be emitting anyway. This is because some scopes used a scheme of driving the beam off screen during retrace time so it was not visible, rather than actually shutting down the CRT gun. I can't be more specific about model numbers because this is all from my weak, 63 year old, memory . . . I also recall, vaguely, something about some adjustments in some 7K mainframes to minimize things like readout jitter due to thermal heating of the vertical position stages when the vertical has to make large and rapid changes in beam position due to going from displaying readouts on screen to switching way off screen to a trace way above or way below the screen. This is another "weak" memory of mine. Maybe Dean has more on this . . . Stan w7ni@... |
|
Re: Question about 7603
Michael
Is the 7603 supposed to light up the buttons on the plug-ins? Some of mybut no light emerges....I remember reading somewhere that the 7000 plugins were designed to be lit, but the poor reliability of the bulbs and the difficulty in changing them caused Tek a rethink and the idea was scrapped. Dunno if this is correct. (mine don't light either). :-( Michael |
|
Re: Question about 7603
Is the 7603 supposed to light up the buttons on the plug-ins? Some of myThere is a listing in the catalog for the 040-0686-01 "lights power supply for 76XX mainframes", but I haven't been able to find out anything about it. I wonder if this existed because the 76XX +5V supply doesn't have enough reserve to run the lights with some combination of plugins, or if it provided the intensity switch that most mainframes have. (I always run mine on the lower intensity setting because I hate changing the *&*$#@ lamps.) Does anyone have any details on this kit? |
|
Re: Question about 7603
Hi Craig,
toggle quoted message
Show quoted text
my 7603 doesn't do it either. The backplane has two empty pins, where you could connect some 5V source. I thought about connecting that to the stabilized +5V and to ground. Finally i didn't do it, because i didn't know whether the power supply has enough power on that line to drive all the lamps. Regards Dieter Craig Sawyers wrote: Hi folks |
|
Re: Price of Tubes
Phil (VA3UX)
Don't feel bad about that one Craig. $132 for a pair of 12AU6 - matched
toggle quoted message
Show quoted text
Tektronix or not - is foolishness. That's got to be the audio guys again. Phil At 07:28 AM 1/21/2002 +0000, you wrote:
I'm astonished! |
|
Re: Price of Tubes
Craig,
toggle quoted message
Show quoted text
You can call that 'e-bay syndrome'. I have seen 7000 series plug ins reaching $150 while there were similar ones with $10 opening bids without bidders. Regards Miroslav Pokorni ----- Original Message -----
From: "Craig Sawyers" <c.sawyers@...> To: <TekScopes@...> Sent: Sunday, January 20, 2002 11:28 PM Subject: [TekScopes] Price of Tubes I'm astonished!I thought that given the price of NOS RCA 12AU6's here in the UK is around???4 each that I'd be happy to pay around $15 for a pair of Tek ones.$132.50!!!
_________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at |
|
Price of Tubes
Craig Sawyers
I'm astonished!
I was bidding on a NOS pair of Tek 12AU6 tubes on eBay - a matched pair. Nice for my Type L plug in (didn't really need them, but good insurance). I thought that given the price of NOS RCA 12AU6's here in the UK is around ???4 each that I'd be happy to pay around $15 for a pair of Tek ones. I was rapidly disabused of that notion - they went eventually for $132.50!!! Craig |
|
Re: Digitizer on eBay
I believe that those digitizers were used to measure all sorts of parameters
toggle quoted message
Show quoted text
during test, so a number of them was consumed for a single test. My understanding was that they were lowered down the hole, but somehow digitizers lived until data was transmitted to a safe location. I remember talking with Tektronix salesman in Orange County who was covering company that I worked for and, must have been, EGG also. Much later in time, I found out that EGG was a major contractor for Nevada site and frequently a front company for ordering long lead time supplies. In that conversation I was lamenting about problems of failures in field and Tek guy laughed and said how he never gets service calls, just another order. He never said who was his customer, I guessed that after reading about testing. There also seems to have been test parameters recorded photographically from screens of 7903, blue phosphor and reduced deflection options. I bought one of those to cheaply get hold of 7A19s; guy was selling those scopes for less money than asking price for a single 7A19, at the time, and would not hear of selling just plug ins. I had to take the whole thing; something like Stan's venture in government auctions. The camera mount adapter was hard bolted to scope frame. I have never seen something like that before: the screws that hold CRT in place were replaced with longer ones so that camera mount adapter was grabbed, too. I guess, camera falling of the scope was not considered an acceptable event. Guy who was selling those 7903s would bring two or three at the time to swap-and-meet at the TRW. He was probably hoping that tea-spooning would hold up price, but he did not have many takers. I saw him asking $450 for a scope, two pieces of 7A19 and 7B80 and after several months at the other swap-and-meet asking price was down to $250. I am pretty inept at bargaining, but I got a unit for $200. The 7A19 were option WF, something not shown in a Tek catalog; comparing physical unit with description in catalog makes WF a recessed control mod. In the case of 7A19 it was trace position that was recessed; there was no trace ID, either, but that must have been incidental to recessed control. The mainframe (7903) was also WF option and that was intensity control that was recessed. Time base was kind of a standard unit, though serial number indicated Guernsey (numerals only). Regards Miroslav Pokorni ----- Original Message -----
From: "Stan or Patricia Griffiths" <w7ni@...> To: <TekScopes@...> Sent: Tuesday, January 15, 2002 10:42 PM Subject: Re: [TekScopes] Digitizer on eBay Lynn,. . when you need to catch the EMP on your screen.like a Tek part number on it? Is it a rackmounted item with a hinged door onthe front?need actuallyto go with it to make it useful? onbought it for the box ($5 + S&H) shippingthe list a few days ago. There is one listed on eBay, item 1690813203 costs to the UK would be astronomical. |
|
I found a nice 7CT1N :-)!
JOSE V. GAVILA (EB5AGV/EC5AAU)
Hello my friends,
As saying says, 'early bird gets the worm'! I start working at 7:00AM... yes, I know it is early in the morning. But it has its advantages: I stop working at 3:05PM (so I have lots of time for other things, including family, hobbies :-), extra works, ...). Also, I am able to look at late at night listed auction items (specially those at eBay Germany and eBay UK) very early. This time, there was a 'Buy It Now!' Tektronix 7CT1N curver tracer. It was not too cheap, I must admit (US$180), but it seems in perfect cosmetic shape and comes with manual. And it is in Germany, so there is no Customs to Spain and shipping is not expensive :-) I have been looking for that curve tracer for a while so I am very happy to have located one. Now I 'just' need to explain it to my wife... but this is another story ;-) I would appreciate any hints about operating that plug-in. Regards, JOSE ---------------------------------------------------------------------- 73 EB5AGV / EC5AAU - JOSE V. GAVILA La Canyada - Valencia (SPAIN) EB5AGV Vintage Radio Site: European Boatanchors List: |
|
Re: Imitation Tek
I have seen something similar in early 70s. That was in a lab of a
toggle quoted message
Show quoted text
reasonably fancy institute, but that lab did not rate real Tektronix, they just had a copy. I was there to install a printer controller and line printer and had my own scope; my scope was a portable Tek, but for life of me I do not remember which one. I am sure it was not 422, because I had trouble with that one before and would not take it to an important job; then, it must have been 453. Anyways, after few days of work there, when I walked into computer room there was that scope on a cart, both painted in a bleached Tek blue. Weird thing was that scope just set there, no probes attached, as if it was brought in for show. There was an outside chance that someone worked on computer after hours or during night, but there was no need for any of that, they were customer, all they wanted to know they just had to ask, so the whole thing was puzzling. Besides, Russians were not famous for working during business, let alone after hours. It looked to me that a reaction was expected from me and I was not to disappoint them. I walked over to the scope, looked it over, said that color was like bleached Tektronix, red knobs were like ones on Tektronix, but dull colored and then I pointed to blank slug where Tektronix would have the serial number and said what was purpose of it. One of them, who seemed to have been in charge of blushing, when embarrassment called for it, did his duty, turned to beet color and haltingly said something to effect how all smart heads think the same way and that is where similarity came from. That was first and last time that I saw that scope. It is 30 years from that time and memory is somewhat hazy, but I think scope disappeared while I was at lunch. In all this time, I do not think that I remembered that scope more than three or four times. Regards Miroslav Pokorni ----- Original Message -----
From: "Michael" <m_d_d@...> To: <TekScopes@...> Sent: Sunday, January 20, 2002 12:18 PM Subject: [TekScopes] Imitation Tek same, only the colours were a little different and the labels were all inrussian. Also, he remembered the knobs were larger and more roughly-made than aTek.
|
|
Re: Using a 7A16P in a 7904 mainframe
Hello Jose,
toggle quoted message
Show quoted text
I believe that 7A16P requires programming through backplane, otherwise it would not work. That is a plug intended for 7612 and 7912. You would need a plain 7A16 (without P). Regards Miroslav Pokorni ----- Original Message -----
From: "JOSE V. GAVILA (EB5AGV/EC5AAU)" <eb5agv@...> To: <TekScopes@...> Sent: Wednesday, January 16, 2002 11:51 PM Subject: [TekScopes] Using a 7A16P in a 7904 mainframe Hello!some trouble with signals over 100MHz (it seems a timebase trouble, as withthink?
|
|
Re: File - Posting Rules
Please do not send personal replies to the list.In most (?) mail clients, reply-to-sender won't work because of the Reply-To: header inserted by the Yahoo software. Those using procmail may want to use a rule like this: : * ^Mailing-List: list TekScopes@... { :0f | sed -e '1,/^$/{;/^Reply-To: /d;}' :0f | sed -e '/^--* Yahoo! Groups Sponsor/,/^-------------------------------------------/d' :0f | sed -e '/^To unsubscribe from this group, send an email to:/,$d' } |
|
Re: On screen display and other CRT items....
Oh, Walter,
toggle quoted message
Show quoted text
I have a bone to pick with you over some things that you said. But before that, let me tell you that it never occurred to me that this wiggling of display was done deliberately to protect phosphor. I always found it annoying and thought it was some mis-adjustment, never guessed a real cause. No argument about keeping beam intensity as low as needed and off when not using scope, but turning scope off and on several times a day is not the very best of ideas. Personally, I would turn off scope only when it was unlikely to be used for several days; there have always been exceptions, like company fire regulations and freaked out bosses, that made mandatory turn off before going home, but given choice, I stuck to my habit. Let's face it, even well designed equipment experiences most stress at turning on/off. For (working) tube scopes (and all CRTs) turning off seems quite logical, considering cathode emissivity degradation over time. However, turn on filament current inrush and thermal shock kill more tubes than old age (loss of emissivity). I understand that tube computers used to have a gradual application of filament voltage, in order to keep tube mortality low, and still the machines were kept on at all times except when maintenance required differently. An attempt to preserve emissivity by turning off plate voltage, led to discovery of 'sleeping sickness', an effect that a seemingly good cathode looses emissivity if it was heated to rated temperature for an extended period of time without current, i.e. plate voltage applied; I believe that 'extended period of time' also means an accumulation of multiple minutes without voltage, not only stretches of hours. In another scheme to extend tube's life, the cathode is heated just to a glow, not to full temperature. In that way turn on shock from cold cathode is greatly reduced and emissivity is for most part preserved, without 'sleeping sickness', plate voltage applied or not. This mode is a kind of a standby that is widely used in TV receivers for CRTs. I thought that there was a standby mode for 551 (2 box, dual beam job), but picture in Stan's book does not show a switch for standby mode. Anyone remembers standby switch on a Tektronix scope and what does it really do? As for 'surge protected power bar', in principle that is very good idea, but you must consider reality of it. All commercially available surge protectors, that I have seen, use MOVs (metal oxide varistor). The UL requires that a certain surge profile (so many volts for so many milliseconds) is applied to DUT (surge protector, office appliance etc.) and the result must not be flying shrapnel or flames. The surge protectors usually available at Ace Hardware and 'Computor Stores' use a quarter (coin) sized MOVs. Such a small MOV can not absorb much energy and its voltage tolerance is rather wide, so they are sized to fire around 375Vac, nominal, where spikes are narrow and do not overstress MOV; the equipment is yours, so that is your problem. Using those 375 Vac MOVs keeps manufacturer of 'protection bar' out of UL hot waters, even without fusing that would not break under load but disconnect before fire becomes steady. The better surge protectors use 1 ???" diameter sized MOVs, free standing or packaged in plastic housing, and always have an adequate fuse or circuit breaker. Besides better energy absorption, those bigger and more expensive MOVs also have narrower firing voltage tolerances. As an example, looking at 1995 Harris data book (nee GE, nowadays I do not know), a 130 V device in quarter sized form (largest LA series) has firing voltage range 184 to 255 Vdc, corresponding to 130 to 180 Vrms, while bigger device from HA series has a range from 184 to 228 Vdc (130 to 160 Vrms); bigger devices cost more so manufacturer can absorb a bigger yield hit. Then, after firing point, as current rises so does voltage across 'crow bar', much steeper across a smaller device than the bigger one. Now, the protection takes an additional hit, on top of the tolerance based one. Using HA series devices does not give you anything to brag about, but small device is dis-proportionally worse. The tolerance spread and low energy absorption found in a small device makes a 130 V rated devices impossible to use, so you are pushed to higher rating, like 375 Vrms, what renders the whole surge protection to a farce. This discussion based on GE devices is valid across the board or it is a better case, since all Japanese and Taiwanese made devices, that I have seen, have same form factor, though the color is different. The presumption is that those are knock offs of GE devices, possibly with wider tolerances. Semiconductor based clamps, pure brute force zeners or integrated zener and SCR, have very much better characteristics, but I have not seen them used in a power strip. Your statement that there was no surge protection before 2400 series made me go and look in the manual. Yes and No. I want have you bad mouth my 7904, there are gas filled surge absorbers across both legs of rectifier, so your statement is a slander. I could not see the size of tubes, but very small packages can absorb high energy; telephone companies love them for premises entry protection. The manual for serial numbers 260K and up, shows those tubes as DS1208 and DS1213, 230 V rated, listed as Tek supplied, most likely selected for voltage. The fact that leaves me uneasy is that electrolytics after input rectifier are rated 200 V (working, and surge is probably no more than 250 V). Several months ago someone on this forum lamented that Tek used caps rated on the knife edge and I am sorry that I can not disagree with that statement. As an aside, I checked 7603, too. There are no surge suppressors there, but at least electrolytics are rated more generously, e.g. 53 V nominal (58 V at high line) uses 75 V working rating cap. Those are points that I wanted to dispute. Regards Miroslav Pokorni ----- Original Message -----
From: "wshawlee2" <walter2@...> To: <TekScopes@...> Sent: Friday, January 18, 2002 4:26 PM Subject: [TekScopes] On screen display and other CRT items.... The "ripple" in the on screen display function of the Tek 7K frames |
|
Re: Info: 564B found FS in Wollongong, Australia
Phil (VA3UX)
At 01:03 PM 1/21/2002 +1100, you wrote:
You know, you're right. It really is cheap for what it is. I guess it's because there's so much of it here (the largest volumes of it were made and sold here).564B's typically sell for around $50 on eBay.I'm constantly amazed at how cheap this stuff is in the US... No wonder Phil -Michael |
|
Re: Info: 564B found FS in Wollongong, Australia
Phil (VA3UX)
564B's typically sell for around $50 on eBay.
toggle quoted message
Show quoted text
Phil At 01:08 PM 1/20/2002 -0800, you wrote:
Right, this bargain of $80US will turn into $280US when you include |
|
Re: WTB: Tektronix 7D01 w/DF1(or DF2)
Hello Ashton,
toggle quoted message
Show quoted text
My limited experience with bad electrolytics in Tek scopes was that there is no capacitance. I would guess, the problem was discontinuity rather then drying out, because failure has been sudden, every time. In view of that, I wander how much help would be an ESR meter. However, I am looking into building one myself and would be interested to see what method you are using. Let me know, please, and if you have the schematic in a convenient form to e mail, please do so. A rough sketch showing only the principle is good enough, too. Regards Miroslav Pokorni ----- Original Message -----
From: "Ashton Brown" <ashtonb@...> To: <TekScopes@...> Sent: Friday, January 18, 2002 10:34 AM Subject: Re: [TekScopes] WTB: Tektronix 7D01 w/DF1(or DF2) Apropos - I sold one of [the pair] to a person in Spain via eBay, manyfor the whole lot. There are three sets for sale right now on US Ebay. |
|
Re: WTD: 7704A Power Supply
Hello Lyn,
toggle quoted message
Show quoted text
A couple of years ago I bought a 7904 and it turned out that one of those slot connector bodies was completely missing. Fortunately, all (needed) pins were undamaged so I could slide the plug in; of course, the slot did not work. I bought replacement connector body from Tektronix and price was not unreasonable as one would expect, if I remember it correctly, the price was around $5 per piece. The body just slides over pins (a care not to bend pins is very helpful). With new body, pins got proper tension and the same slot worked. You might want to try Tek spare parts. Bear in mind that not all people working there are the same, some of those ladies were going way out of their way to help out, while some others told me very curtly that instrument is no longer supported; in both cases the query was for 7904 parts. What I meant with 'going way out way.' was using listings that were either off line or just plane hard copy listings. I wander if Walter (of Sphere) would be willing to trash a scope backplane to extract connector bodies. That backplane would have to be burned up badly or cracked to make it a viable business. If I remember it right, body slides on easily but that is one way process, removing the body would damage pins. ----- Original Message -----
From: "Lynn Lewis" <mrzuzu@...> To: <TekScopes@...> Sent: Friday, January 18, 2002 4:12 AM Subject: RE: [TekScopes] WTD: 7704A Power Supply Don, that sounds like some very good advice. I'll look for replacementsfor awhile before I disassemble it. By the way, guys, I'm going to sell ita scope to use them on, give me a ring.and myis that these contact tensioning covers are nylon, snap fit into place, andfrom anyone currently selling Tek parts: Sphere Research, Surplus Sales,Deane Kidd, plus the couple guys who keep showing up on ebay with new Tekparts. Ithink andup a |
to navigate to use esc to dismiss