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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: |
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Re: Imitation Tek
I have seen something similar in early 70s. That was in a lab of a
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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.
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Re: Using a 7A16P in a 7904 mainframe
Hello Jose,
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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?
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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' } |
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Re: On screen display and other CRT items....
Oh, Walter,
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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 |
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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 |
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Re: Info: 564B found FS in Wollongong, Australia
Phil (VA3UX)
564B's typically sell for around $50 on eBay.
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Phil At 01:08 PM 1/20/2002 -0800, you wrote:
Right, this bargain of $80US will turn into $280US when you include |
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Re: WTB: Tektronix 7D01 w/DF1(or DF2)
Hello Ashton,
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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. |
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Re: WTD: 7704A Power Supply
Hello Lyn,
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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 |
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Re: Info: 564B found FS in Wollongong, Australia
Right, this bargain of $80US will turn into $280US when you include
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shipping. Regards Miroslav Pokorni ----- Original Message -----
From: "Craig Sawyers" <c.sawyers@...> To: <TekScopes@...> Sent: Friday, January 18, 2002 1:25 AM Subject: RE: [TekScopes] Info: 564B found FS in Wollongong, Australia itsale in the "Cash-Mart" second-hand shop in Wollongong a coupleEr - OK, Wollongong is in Australia, right? So $165 is Aussie dollars? up. If I wasn't on the other side of the planet, that is :-) |
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Imitation Tek
Michael
Hi all,
I was talking to a friend yesterday, who is originally from Vietnam. He recounted the story of how he was drafted to work for the communists in some research project or other in the 60's. Among the equipment he was given to work with was a russian copy of a Tek 5-series scope. He said it had the Tek "style" and the layout was the same, only the colours were a little different and the labels were all in russian. Also, he remembered the knobs were larger and more roughly-made than a Tek. Anyone else heard of this? Regards, Michael |
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File - Posting Rules
Please edit any posts/replies to the list to
minimize quoted material. Please do not send personal replies to the list. List replies go to the list by default. To reply only to a message's sender, either cut and paste their name, reply to all and delete "TekScopes", or use a reply-to-sender function if your email client has it. Those congesting the list with with either of the above will have posting rights revoked or moderated. Only by following these simple rules will we have a "clean" archive. They also reduce inbox clutter and make digests much nicer to read. If you do not wish to belong to TekScopes, you may unsubscribe by sending an email to TekScopes-unsubscribe@... You may also visit the Yahoo web site to modify your subscriptions: Check out the files, bookmarks, and photos sections, and remember, you can search the group's archives from its home page, or when reading messages. The group's home is at: Regards, Michael Dunn Moderator, TekScopes |
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Re: WTD: 7704A Power Supply
Lynn Lewis
I'm glad you said that before I started trying to "fix" the focus on my
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7704A. I really was thinking about it. I did, by the way, find a backplane that is being shipped to me so that I can attempt to repair the plugin connectors. -----Original Message-----
From: Stan or Patricia Griffiths [mailto:w7ni@...] Sent: Saturday, January 19, 2002 5:36 PM To: TekScopes@... Subject: Re: [TekScopes] WTD: 7704A Power Supply This is also partly due to poor focus in 7K CRT's in general since they use the mesh screen technology . . . The typical "spot size" of a 7K CRT is several times larger than that of a 453, 547, or 585A for example. Stan w7ni@... donlcramer@... wrote: > "....It is a long time since I used a 4-bay Tek scope, but I recall that the > readout vibrated up and down a little too (it was either a 7704 or a 7904 - I > forget which now)...." > > Craig > --------------- > It seems the on screen readout, while a brilliant feature, is never quite > perfect. For instance, the character focus and/or astig never seems to be > quite sharp, and it varies depending on screen location in some models. Part > of the wonderful character of the scopes I suppose. > > Don > > > > > To unsubscribe from this group, send an email to: > TekScopes-unsubscribe@... > > > > Your use of Yahoo! Groups is subject to Yahoo! Groups Sponsor ADVERTISEMENT To unsubscribe from this group, send an email to: TekScopes-unsubscribe@... Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. |
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Re: WTD: 7704A Power Supply
Lynn Lewis
I'll keep you in mind. It may yet come to that.
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-----Original Message-----
From: jcastanton [mailto:jstanton@...] Sent: Saturday, January 19, 2002 3:04 PM To: TekScopes@... Subject: [TekScopes] Re: WTD: 7704A Power Supply Lynn, I have a 7704A in good shape except that it has a weak tube. If you decide to part out your 7704A and it has a good tube, I would be interested. --- In TekScopes@y..., "Lynn Lewis" <mrzuzu@j...> wrote: > Okay, guys. Here's the deal. I have the 7704A working but I need some > advice. Slot 1 is unusable and slot 3 is unreliable. All the switches and > controls have been cleaned and work smoothly. All the panel lights work. > Go here to see the scope: > > > Is there a way to repair the slots? I can either try to repair them or else > I can break the scope down into parts and sell the parts. Dick already wants > a power supply. Does anyone else need any boards? Except for the slots, you > can see that the scope works. The readouts have a slight ripple so there's > probably a weak filter cap somewhere but it's not bad and it doesn't show up > on the trace. I would be happier with a more focused trace but it's not as > bad as > it appears in the photos. > > Fix it? Or, break it down? What do you think? > > > > > > > > -----Original Message----- > From: w1ksz [mailto:w1ksz@t...] > Sent: Wednesday, January 16, 2002 5:23 PM > To: TekScopes@y... > Subject: [TekScopes] WTD: 7704A Power Supply > > > I have a very clean 7704A with a sick Power Supply. Anyone have one > they will part with ? > > Thanks, Dick, W1KSZ > > > Yahoo! Groups Sponsor > ADVERTISEMENT > > > > > To unsubscribe from this group, send an email to: > TekScopes-unsubscribe@y... > > > > Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. > > > > Yahoo! Groups Sponsor ADVERTISEMENT To unsubscribe from this group, send an email to: TekScopes-unsubscribe@... Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. |
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Re: WTD: 7704A Power Supply
Stan or Patricia Griffiths
This is also partly due to poor focus in 7K CRT's in general since they use the
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mesh screen technology . . . The typical "spot size" of a 7K CRT is several times larger than that of a 453, 547, or 585A for example. Stan w7ni@... donlcramer@... wrote: "....It is a long time since I used a 4-bay Tek scope, but I recall that the |
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7000 Series Readout Jitter
Stan or Patricia Griffiths
One of the things that causes readout jitter is one of the
scope traces positioned way off screen up or down. You have to recall that there is only one vertical amplifier in these scopes and it positions everything on screen . . . traces and readouts. Depending on the readout mode you are in, the scope may refresh readout between traces, but more likely, it takes occasional "bites" out of the trace and refreshes readout randomly during the sweep. If one of the traces is WAY off screen, the vertical amp has to move very fast to refresh the readout and then back to the extreme position of an off screen trace. The verticals just can't move that fast without some recovery symptoms, which is usually vertical jitter of the readout. So just try making sure all of the traces that are active are fully within the screen area and your readout jitter may disappear . . . Stan w7ni@... |
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Re: WTD: 7704A Power Supply
jcastanton
Lynn,
I have a 7704A in good shape except that it has a weak tube. If you decide to part out your 7704A and it has a good tube, I would be interested. --- In TekScopes@y..., "Lynn Lewis" <mrzuzu@j...> wrote: Okay, guys. Here's the deal. I have the 7704A working but I needsome advice. Slot 1 is unusable and slot 3 is unreliable. All theswitches and controls have been cleaned and work smoothly. All the panel lightswork. Go here to see the scope:or else I can break the scope down into parts and sell the parts. Dickalready wants a power supply. Does anyone else need any boards? Except for theslots, you can see that the scope works. The readouts have a slight ripple sothere's probably a weak filter cap somewhere but it's not bad and itdoesn't show up on the trace. I would be happier with a more focused trace but it'snot as bad asone they will part with ?Service. |
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Re: WTD: 7704A Power Supply
Craig Sawyers
An obvious thing to try first is one of the DeOxit products.Caig also make a product called Pro-Gold that is specifically formulated for gold plated contacts. Craig |
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