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Re: Tektronix 7S14 - URGENT!
Stan or Patricia Griffiths
In most sampling instruments I have encountered, signals start distorting when they
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exceed about 2 volts in amplitude. Damage to the sampling diodes occurs around 5 volts and you never want to apply DC to the input of a sampler. There are a couple of exceptions to this . . . Stan w7ni@... Don Black wrote: Hi, |
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Re: Tektronix 7S14 - URGENT!
Don Black
Hi,
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I haven't had any experience with sampling CROs but believe the plugins can be damaged with input signals greater than 5 to 10 volts (depending on model). Be careful to limit input signals as they're very difficult to obtain parts or service. Perhaps others have some comments on this. Good Luck, Don Black. Stan or Patricia Griffiths wrote: My opinion is that a working and calibrated 7S14 that meets all of its |
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Re: Tektronix 7S14 - URGENT!
Mark Kahrs
And don't forget those batteries in the sampling diode bias.
I personally think that the S14 is a washout. You can only go to 1 GHz with it and with a 79xx you can already get to 500 MHz. So, why go to sampling for the extra 500 Meg? Why not just go for the gusto and get a 7S11/7T11 pair? As I remind everyone, you get what you pay for (and that includes advice) (Most of the time) Mark. |
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Re: Tek 465B: Display Problem (Shrinked to 3 divisions)
Stan or Patricia Griffiths
Hi Shiran,
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No, the trace traveling from right to left is not normal. The first suggestion that I have is for you to take off the cabinet and take a look at the CRT neck pins, about halfway from the front to the rear of the scope. The two coming out of the right side of the CRT shield are supposed to go to the horizontal amplifier. One of them may be disconnected and/or the connectors may be connected to the WRONG pins. It may say right on the CRT shield which color of wire should go to which pin. If those wires seem to be connected properly, then I suspect a problem in the horizontal amplifier, but . . . you always need to start by checking the power supplies first. You will need a service manual to check the power supplies since it will tell you where the test points are and what readings to expect there.. Do you have one? If not, get one . . . then we can go from there. Stan w7ni@... shiran@... wrote: Hi, I am a student and I got my Tek 465B from an eBay auction. I know |
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Tek 465B: Display Problem (Shrinked to 3 divisions)
Hi, I am a student and I got my Tek 465B from an eBay auction. I know
how to use the oscilloscopes, but have no experience in idendifying and fixing problems in oscilloscopes. The problem is that, the trace or a signal width is limited to maximum 3 divisions on the time scale (i.e. when the Horizontal Position knob is fully turned to left). Turning the Horizontal Position knob to right will reduce the width to 1 division on the time scale. I cannot get this to occupy the full with (10 divisions) on the screen. Is there a screwdriver adjustment knob somewhere to fix this or is this an internal problem? (Also I notice the trace travels from right to left, Is this normal?). Apprciate if someone can help me to identify the problem. Thanks - Shiran. |
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Re: Here's a challenge (Type 517 scope)
Phil (VA3UX)
At 08:12 PM 6/11/2001 -0400, you wrote:
Can anyone find the current rating of the 6.3V winding on transformerSorry I can't help you with that, but if you have access to 517 power Sorry John but I don't have access to this thing. It's owned by someone several hundred miles from here. I think he intends to keep it and restore it. But I've asked him to let me know if he changes his mind. Phil -- Thanks, |
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Re: Here's a challenge (Type 517 scope)
John Rehwinkel
Can anyone find the current rating of the 6.3V winding on transformerSorry I can't help you with that, but if you have access to 517 power supply parts, I think it contains a tube I'm looking for as well -- the Sorensen 2AS-15 "special diode". I also have use for one of the time-delay relays may of the Tek supplies used, if anyone out there cares to sell me one. -- Thanks, John Rehwinkel KG4L spam@... |
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Re: Here's a challenge (Type 517 scope)
Phil (VA3UX)
At 11:32 PM 6/11/2001 +0000, morriso2002@... wrote:
--- In TekScopes@y..., "Phil (VA3UX)" <phil@v...> wrote:I would if I knew what the thing fed. I've asked the person who asked me for the same info (ie where is the transformer and what does it supply). I believe there is a separate fil transformer in the mainframe itself, along with at least one more stand-alone jobbie in the power supply itself. But I don't know which one he's asked about. I should find out soon.Can anyone find the current rating of the 6.3V winding ontransformer T402(#120027) from a type 517 power supply ? T402 may actually be adedicated6.3V filament transformer since there were something like 106 sixvolttubes in the 517.If all else fails, why don't you just add up the heater currents of Morris |
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Re: Here's a challenge (Type 517 scope)
--- In TekScopes@y..., "Phil (VA3UX)" <phil@v...> wrote:
Can anyone find the current rating of the 6.3V winding ontransformer T402 (#120027) from a type 517 power supply ? T402 may actually be adedicated 6.3V filament transformer since there were something like 106 sixvolt tubes in the 517.If all else fails, why don't you just add up the heater currents of all the tubes fed by it? Morris l |
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Re: Tektronix 7S14 - URGENT!
Stan or Patricia Griffiths
My opinion is that a working and calibrated 7S14 that meets all of its
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original specifications should be worth $150. The problem is that almost nobody has the ability to determine if one is really working properly or not. You have to have a very fast rise and clean pulse generator, an amplitude calibrated 50 ohm voltage source, and a fast time mark generator at a very minimum in order to get any idea if it really works correctly. If it does not work correctly, it may be impossible to find the parts you need to fix it. The most vulnerable parts are the sampling diodes and I suspect they are impossible to find, but I have to admit I have not searched for any. I am sure there are other critical, hard to find parts in the 7S14. Does this unit come with a "money-back guarantee" . . . ? Stan w7ni@... JOSE V. GAVILA (EB5AGV/EC5AAU) wrote: Hello! |
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Re: Here's a challenge (Type 517 scope)
Stan or Patricia Griffiths
Hi Phil,
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Yes, that is a challenge. First, there were several 6.5 volt filament windings on T402. Here is some of the info you need: pins 17 & 18, 6.5 VAC, 12 A pins 21 & 22, 6.5 VAC, 12 A pins 5 & 6, 6.5 VAC, 4 A pins 15 & 16, 6.5 VAC, 2 A pins 19 & 20, 5.2 VAC, 2 A The usual reason that there were so many separate filament windings on Tek transformers that seemed to supply the same voltage is that these filament windings were often elevated to different DC voltages to reduce the heater-to-cathode potential difference in an effort to prevent internal tube arc-overs. One winding may be elevated to +100 V DC and another to +225 V DC. In researching this, I found out that I don't own a 517 or 517A manual. I do have at least two sets of microfiche on the 517/517A but both sets are very nearly unreadable (too small, too dark, and out of focus). But even if you had perfect microfiche or a good manual, you would not find the current ratings in either place since Tek never published transformer current ratings in those places. There was an internal Tek document describing each Tek-made transformer, including the pin-outs and current ratings. You have to know someone who has a set of these very rare documents . . . Maybe this is something we should add to our Tek web page, huh? Stan w7ni@... PS I would be happy to accept a 517/517A manual as the prize ! ! Phil (VA3UX) wrote: Can anyone find the current rating of the 6.3V winding on transformer T402 |
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Re: 475 hor.jitter: Plan for replacing capacitors?
Richard Gagnon
Hi Dean
Sorry I confused you. I thought I read a message about replacing a number of capacitors in a 475 that was posted by you. Sorry for the confusion. Richard --- dhuster@... wrote: Is there any plan for replacing capacitors? I haveseen referenceto this a few times.I'm not sure I'm on the same page here. What kind __________________________________________________ Do You Yahoo!? Get personalized email addresses from Yahoo! Mail - only $35 a year! |
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Re: Tektronix 7S14 - URGENT!
Michael Dunn
> I am in need of some info about the 7S14 plug-in... is it worth $150I have one, though I haven't really used it. It seems to work ok, except for a slight "ghost" signal on one trace. Think mine was closer to U$100! If you get a manual too, I will gladly pay a bit for some photocopies. Keep in mind that these samplers typically have more finicky triggering circuits than a normal module. Also, all the buttons on mine are quite sluggish -- almost binding. I'm sure that'll improve with a bit of maintenance... Michael |
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Re: Tektronix 7S14 - URGENT!
John Rehwinkel
I am in need of some info about the 7S14 plug-in... is it worth $150I used one of these plugins for a couple of years back in the 1980's. It worked just dandy for me (measuring risetimes of pulsed electron guns), under some fairly demanding conditions. I'd happily pay $150 for one in operating condition. -- John Rehwinkel spam@... |
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Tektronix 7S14 - URGENT!
JOSE V. GAVILA (EB5AGV/EC5AAU)
Hello!
I am in need of some info about the 7S14 plug-in... is it worth $150 in operating condition?. How does it performs? Please, any information will be welcomed. Thanks! JOSE ---------------------------------------------------------------------- 73 EB5AGV / EC5AAU - JOSE V. GAVILA La Canyada - Valencia (SPAIN) EB5AGV Vintage Radio Site: European Boatanchors List: |
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Here's a challenge (Type 517 scope)
Phil (VA3UX)
Can anyone find the current rating of the 6.3V winding on transformer T402 (#120027) from a type 517 power supply ? T402 may actually be a dedicated 6.3V filament transformer since there were something like 106 six volt tubes in the 517. I don't have the thing in hand so I'm not sure.
There should be a prize if someone can answer this. Thanks in advance. Phil |
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Re: Tektronix 50 ohm attenuators
I'd be careful of using a Radio Shack resistor in that spot.
Depending on where it's being used, a 1/8-watt CARBON COMPOSITION resistor might be required as the 1/4-watt (or an 1/8-watt) CARBON FILM resistor may have too much inductance for the application. You can still get carbon comp resistors at Mouser Electronics ( ), but they have only the 1/4-watt size, not 1/8-watt. I looked through my parts and did find a 1/4-watt 3.9K carbon comp resistor. Measure the hole spacing in the PCB and see it it'll fit. You'll need about 5/16" (7mm-8mm) between centers. My part (used) has remaining lead length of about 5/16", so check to make sure your holes aren't TOO far apart or you'll have to add a little lead to the part. I checked through the 50-ohm thin film parts that I have (all new) and didn't find what you needed, which surprised me. 7A24 attenuator parts must be different than those for the 7A19. I have 307-1018, 1034, 1035, 1036, 1037, 1038 and 1040-00 plus the mounting studs/pins (they're staked onto the board 214-1797-00) and the hold-down leaf springs (344-0248-00). E-mail me if you need some pieces or the 1/4- watt resistor (I can mail the resistor for $0.34 or you can have a nasty minimum order and shipping charges from Mouser). Dean |
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Tek 475 chopper failure
JOSE V. GAVILA (EB5AGV/EC5AAU)
Hello!
Well, after some time working with radio gear, now I am back to test equipment... Last time I powered my Tek 475, I found that the chopper circuit no longer worked. CH1 and CH2 work fine sepparately and also in ALT mode. But no in CHOP mode. So I guess it could be related with the oscillator in the chopper. Any hint?. I plan to work on it soon. Now I use the 485 or the 7603 to work. It is nice to have backup gear :-)! Regards, JOSE ---------------------------------------------------------------------- 73 EB5AGV / EC5AAU - JOSE V. GAVILA La Canyada - Valencia (SPAIN) EB5AGV Vintage Radio Site: European Boatanchors List: |
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Re: Tektronix 50 ohm attenuators
John Rehwinkel
Hi All,This is simply a 3900 ohm, 1/8 watt, 5% tolerance resistor. I expect a quarter watt unit would do fine. You can find these at Radio Shack. Or I can send you some. I have plenty (I bought out a Radio Shack when it was going out of business). 307-1020-00 ATTENUATOR,FXD:50 OHM,2X You can actually make these -- though for compensated high frequency use, you generally have to parallel the resistors with small capacitors. There are two basic arrangements for resistive matched-impedance attenuators, "tee" style with two series resistors and one shunt, and "pi" style with one series resistor and two shunts. Here is an attempt at ASCII diagrams: tee attenuator: in o--/\/\/\---+---/\/\/\--o out series | series > < shunt > | = (gnd) pi attenuator in o--+---/\/\/\---+--o out | series | > > < shunt < shunt > > | | = (gnd) = (gnd) Note that these are unbalanced (signal referenced to ground) attenuators -- there are also balanced varieties. When I'm building these myself, I tend to use the tee variety, as it seems a little easier to wire up. Here are the resistor values for the listed attenuators (since the input and output impedances are the same (50 ohms), the attenuators are symmetrical, that is both the series resistors in the tee attenuator are the same and both the shunt resistors in the pi attenuator are also the same. tee attenuator: series (2) shunt 2X 8.58 141. 5X 19.1 55.9 10X 26.0 35.1 pi attenuator: shunt (2) series 2X 291. 17.7 5X 131. 44.7 10X 96.2 71.1 Resistor values are in ohms, and I've rounded them to 3 places. Note that most of these aren't standard values, so you'll have to obtain precision resistors (a good idea any to maintain calibration) or build them up out of combinations of standard values (this doesn't work well for high-frequency use). Good luck, John Rehwinkel spam@... (currently repairing a 7844 and a 570) |
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