And a lot lower loss at higher frequencies. Loss can be
a little hard to gauge with the usual TDR.
The whole point behind the fancy tek cable is that the
amplitude accuracy of the SG503 requires the cable to be
lossless.... it isn't, but the lower, the better the
amplitude accuracy.
The SG504 reaches a range where the cable will lose a
db or two, so they put its level sensing circuitry right
at the DUT front panel connector.
-Chuck Harris
Craig Sawyers wrote:
toggle quoted message
Show quoted text
Hi Ancel, If everyone can be patient for a few hours more I will test both of those Tektronix cables on a 7S12
TDR along with a couple of commercial cables (Pomona for instance) so we can see what the
differences are in qualitative terms.
Dennis Tillman W7PF Having got one of the fancy Tek cables we've been discussing, I tried precisely that a couple of years
ago with my 7S12. I could find absolutely no difference at all between that and bog standard cables.
No distributed reflections, no connector reflection difference into a precision, wideband 50-ohm load
(the one that comes with a 1502 TDR).
The only thing that that the super-expensive Tek cable has going for it is that you can be sure that
it is going to work perfectly, and is ruggedly built.
Craig
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Transfer option cards from TDS 320 to TDS 350?
Hello from Dublin, Ireland. I have a question some of you knowledgeable folks might be able to advise me on. I have two apparently similar scopes, a TDS 320 (100 MHz, 500 M samples/sec) and a TDS 350 (200 MHz, 1G samples/sec). I will only keep one. However the slower scope is fully loaded with interface cards including parallel, RS 232, GPIB and an VGA output for an external monitor. Is it feasible to transfer the option cards to the faster scope or would there be significant software config required to make them operate? Any advice appreciated. Thanks!
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I am not missing the ABC's of probes and in fact have
previously read it a few times. Rather than look for my paper copy, I just downloaded it and skimmed
it again Raymond
The other things to download and read cover to cover are the Concepts series books "Oscilloscope Probe Circuits", "Probe Measurements" and "Sampling Oscilloscope Circuits" Craig
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You may want to look for an old-fashioned Lo-Z probe like a P6056 (500 Ohm) or P6057 (5000 Ohm).
Even with their standard BNC connection, they work well with your more modern digital 'scope and
can be bought for little money.
Raymond I'd second that. Also the ABC of Probes was published at intervals, and the content changed as time went by. Craig
|
Hi Ancel, If everyone can be patient for a few hours more I will test both of those Tektronix cables on a 7S12
TDR along with a couple of commercial cables (Pomona for instance) so we can see what the
differences are in qualitative terms.
Dennis Tillman W7PF Having got one of the fancy Tek cables we've been discussing, I tried precisely that a couple of years ago with my 7S12. I could find absolutely no difference at all between that and bog standard cables. No distributed reflections, no connector reflection difference into a precision, wideband 50-ohm load (the one that comes with a 1502 TDR). The only thing that that the super-expensive Tek cable has going for it is that you can be sure that it is going to work perfectly, and is ruggedly built. Craig
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On Sat, Apr 27, 2019 at 05:59 AM, Raymond Domp Frank wrote:
If you want to do measurements on high-frequency signals or signals with
high-frequency content, always consider using Lo-Z probes like 1:1 50 Ohm,
1:10 500 Ohm or even 1:100 5 kOhm probes. These have relatively constant
impedance and many can be made at home. Search for that on the Internet.
You may want to look for an old-fashioned Lo-Z probe like a P6056 (500 Ohm) or P6057 (5000 Ohm). Even with their standard BNC connection, they work well with your more modern digital 'scope and can be bought for little money. Raymond
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Hi Jack,
I would recommend thoroughly reading the downloaded document again. Just having a quick look at it just now revealed relevant content at least on page 10 ("Usually, the loading of greatest concern..."), 13 ("keep ground leads short"), 16-17, 29 ("Signal Source Impedance"), 29-30 ("Input Resistance and Capacitance"), 32, 33, 34, 35, 37 ("Bandwidth to the probe tip"), 40, 43.
The capacitance of *all* Hi-Z probes has a large influence at high frequencies, because the decreasing input impedance becomes an ever increasing short on the resistance. FET probes with their relatively small input capacitance present a higher high frequency impedance than most passive High-Z probes but their input resistance (as observed at DC and low frequencies) will still drown (be shorted) in the capacitive reactance at higher frequencies, just at a lower rate than higher-capacitive (passive) probes.
Low-Z (50 Ohm) probes have the advantage of a constant impedance from a relatively low frequency until their highest useful frequencies, albeit that that impedance is rather low.
Active (FET) probes isolate their output from their input, making a constant 50 Ohm output across their bandwidth impedance possible.
The bandwidth of probes is specified assuming a source impedance of 25 Ohm, see "Bandwidth to the Probe Tip" on page 47.
All this is a matter of physics, not a matter of choosing the right probe to completely get rid of the problem. You can only optimize by making the right choices. You cannot get 10 Mohm or even 1 Mohm input impedance at high frequencies with any regular (FET) probe. Also, transmission line effects (signal reflection, standing waves) would destroy the "improvement".
If you want to do measurements on high-frequency signals or signals with high-frequency content, always consider using Lo-Z probes like 1:1 50 Ohm, 1:10 500 Ohm or even 1:100 5 kOhm probes. These have relatively constant impedance and many can be made at home. Search for that on the Internet.
Among High-Z probes, FET probes with their relatively small input capacitance have the relative advantage of making the setup less sensitive to ground lead inductance, resulting in less "ringing". You can read about that in the ABC as well.
Raymond
|
On Fri, 26 Apr 2019 21:17:09 -0400, you wrote: Hi Raymond,
Thanks for your ever so prompt response.?? I am not missing the ABC's of
probes and in fact have previously read it a few times. Rather than look
for my paper copy, I just downloaded it and skimmed it again and I am
afraid that I am still at a loss as to the usefulness of either of the 1
ghz probes I mentioned at a 1ghz frequency under test.? If you could
describe what I am looking for in the primer, I will certainly go take
another look.? I also understand the convenience and utility of using 50
ohm cable and loads at higher frequencies.? that depends on the circuit. Lots of RF circuits are 50 ohms, some 75. However, high speed TTL, ECL, and the like circuits fake being RF (and quite well, since the boards often have to be designed like RF circuits). So the scope loads the circuit, as all things do. Have I happened on a couple
of "dogs" for the probes I have investigated and mentioned?? The 6243
active probe has only 1 pf of capacitance at the tip and looks like a 50
ohm input to the scope.? what it looks like to the scope is meant to match the scope. What does it look like to the circuit? The P6201 probes look like few pf to the circuit, 100k ohms, but present the plugin with it's required 50 ohm input. Are virtually all 1 ghz circuits of such? low
impedance that throwing say 500 ohms capacitive across them in parallel
doesn't perturb them?? for 50 ohms, that's about 10%. At 1 GHz, what's the reactance of 20 pf of a standard high bandwidth probe? Is there a mysterious phase angle thing here that
I don't fathom?? Should I be looking at other probes?? Tektronix was or
is selling these things as 1 ghz capable probes.? Of what use are they? how would you connect a scope to a circuit that is running at 500 Mhz to 1 Ghz, or has equivalent bandwidth? take the best bandwidth 10x probe you have, put it on a relatively high impedance high frequency circuit (not a signal generator with a low output impedance), then throw a 1x probe across that and see what happens. Harvey
On 4/26/2019 7:57 PM, Raymond Domp Frank wrote:
Hi Jack,
The only thing you're missing is a recent edition of Tektronix' obligatory document "ABC of Probes", downloadable from e..g. <>.
Yes, a probe presents quite a load at high frequencies and it depends on the signal source whether that is a problem.
Where source impedance can be controlled, a low-Z probe (usually 50 Ohm impedance) is preferable.
It's all in ABC of Probes.
Raymond
|
On Fri, 26 Apr 2019 16:36:38 -0700, you wrote: As a result of my recent purchase of a Tek scope with 1 ghz. bandwidth, I have begun looking for probes. I have looked at the specs for a P6243 and a TPP 1000, both rated at 1 ghz bw. Both instruction manuals show a chart of impedance vs frequency. In either case the impedance decreases with frequency (makes sense because of capacitance) to a few hundred ohms at 1 ghz. Am I missing something here? Doesn't that load down the observed ckt in the DUT to the point where the probe (and attached scope) are essentially useless at their rated high end? Thanks in advance for taking the time. I have found a similar problem, not with probes, but with circuits. The higher the impedance, the more that the circuit capacitance limits the bandwidth. Most of the 200 Mhz or higher circuits look like a low impedance driver, I've put a 10:1 50 ohm probe on a TTL circuit, and the probe worked well enough (driving 500 ohms). Naturally, an active probe has less capacitance and lower loading at the expense of more limited voltage range and more fragile electronics. Harvey Jack Reynolds
|
Re: Tek485 - a quick question on disabling/bypassing power supply protection
Hi All. Thanks for linking for the album - I'll work out how to do that for next time. I've added an annotated photo showing my interpretation of the -5V traces on start-up ( /g/TekScopes/album?id=89902 - damned if I can get this 'link' to actually link regardless of how I copy/paste it! Perhaps something in my browser setup?). All the action's in the 1st 20ms or so. For Roger - looks like you're right that the scale in the split screen is per small div, as the BAL node is definitely rising to about 700mV before shutdown and the LIM comes up to several volts +ve from memory. Ch 3 isn't inverted - hopefully my annotations clarify it. For Dan - I did as you suggested an checked rail proportionality (a good while ago now) - all came up to about the same % of final before shutdown, except the -5V rail. All the larger tantalums were replaced ages ago and I went over them all. There are some tiny tants on the horizontal amp board not replaced or checked - but current draw doesn't suggest shorts, I have several marked up schematics from the manual showing voltages, capacitances, and resistances measured in circuit. I'll try and update these and post them as they will help show some of what I've done. I should say that when this scope failed the HV went out (no trace), but at the same time there was an intermittent problem with the -5V supply ('fixed' at the time by reseating transistors on the horizontal amp board). The measurements on my schematics date back to that time when the -5V was working - hence the need to update before posting. At that time I replaced a faulty HV diode and dodgy cap on the HV transformer board and also replaced the HV multiplier (just in case). But by the time that was done the -5V supply had become permanently faulty and my work on it stalled. So I wouldn't exclude the possibility that the problems are linked - but the LV supplies won't now come up with HV disabled (U3 out), so there's an LV problem of some sort to fix first before worrying about HV. With U3 out the LV side should fire up fine. Hence my focus on getting the LV side working with HV disabled and only after that seeing if my repairs have also fixed the HV side. I will try Roger's suggestion of retesting HV TP signal with U3 out - I have been suspicious of the Q1614/Q1618 circuit but they check OK on my Octopus tester. However, I got a couple of spares from Sphere and not sure now whether I've substituted them or not. I'm not an electronics wizard by any means so when I get into detail of how transistor sub-circuits should be operating I easily get out of my depth. Will report back after doing this test.
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Hi Raymond,
Thanks for your ever so prompt response.?? I am not missing the ABC's of probes and in fact have previously read it a few times. Rather than look for my paper copy, I just downloaded it and skimmed it again and I am afraid that I am still at a loss as to the usefulness of either of the 1 ghz probes I mentioned at a 1ghz frequency under test.? If you could describe what I am looking for in the primer, I will certainly go take another look.? I also understand the convenience and utility of using 50 ohm cable and loads at higher frequencies.? Have I happened on a couple of "dogs" for the probes I have investigated and mentioned?? The 6243 active probe has only 1 pf of capacitance at the tip and looks like a 50 ohm input to the scope.? Are virtually all 1 ghz circuits of such? low impedance that throwing say 500 ohms capacitive across them in parallel doesn't perturb them?? Is there a mysterious phase angle thing here that I don't fathom?? Should I be looking at other probes?? Tektronix was or is selling these things as 1 ghz capable probes.? Of what use are they?
toggle quoted message
Show quoted text
On 4/26/2019 7:57 PM, Raymond Domp Frank wrote: Hi Jack,
The only thing you're missing is a recent edition of Tektronix' obligatory document "ABC of Probes", downloadable from e..g. <>.
Yes, a probe presents quite a load at high frequencies and it depends on the signal source whether that is a problem.
Where source impedance can be controlled, a low-Z probe (usually 50 Ohm impedance) is preferable.
It's all in ABC of Probes.
Raymond
|
Hi Jack,
The only thing you're missing is a recent edition of Tektronix' obligatory document "ABC of Probes", downloadable from e..g. <>.
Yes, a probe presents quite a load at high frequencies and it depends on the signal source whether that is a problem.
Where source impedance can be controlled, a low-Z probe (usually 50 Ohm impedance) is preferable.
It's all in ABC of Probes.
Raymond
|
As a result of my recent purchase of a Tek scope with 1 ghz. bandwidth, I have begun looking for probes. I have looked at the specs for a P6243 and a TPP 1000, both rated at 1 ghz bw. Both instruction manuals show a chart of impedance vs frequency. In either case the impedance decreases with frequency (makes sense because of capacitance) to a few hundred ohms at 1 ghz. Am I missing something here? Doesn't that load down the observed ckt in the DUT to the point where the probe (and attached scope) are essentially useless at their rated high end? Thanks in advance for taking the time.
Jack Reynolds
|
Exterior bits and pieces for TDS 500,600 or 700
I just purchased a TDS 600 series scope which had apparently been rack mounted. Consequently, it is missing the rear cover, handle, bottom feet and kickstand. If someone has rack mounted or has a parts mule TDS 500, 600 or 700 family unit and has any or all of these pieces available for sale, I would relish the opportunity to purchase some or all of them. Please feel free to contact me at jackandladyreynolds@....
Thanks,
Jack Reynolds
|
Hi Ancel,
That is not the same cable as a 012-0482-00 at all.
If everyone can be patient for a few hours more I will test both of those Tektronix cables on a 7S12 TDR along with a couple of commercial cables (Pomona for instance) so we can see what the differences are in qualitative terms.
Dennis Tillman W7PF
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-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of
Ancel
Sent: Friday, April 26, 2019 1:06 PM
To: [email protected]
Subject: [TekScopes] SG504 or 503 cable
The cable I have for the instruments is a Tektronix 012-0057-01, Z0 =
50 ¦¸, coax cable assy, with connector boots.
The engraving on the BNC metal is 'KINGS KC-59-123'
-- Dennis Tillman W7PF TekScopes Moderator
|
Re: SG503 amplitude precision
Hi Tony,
WE ARE THE RIGHT GROUP. The members of this group, as a whole, share a common interest in ANY and ALL TEKTRONIX instruments even though Individual members may only own one Tektronix instrument.
You just needed to change the subject of your email, as I suggested, so our members understand what Tektronix instrument you need help with.
No need to apologize. STOP RESPONDING to the emails whose subject is "SG503 amplitude precision".
You can read their contents but DON'T REPLY TO ANY MORE OF posts whose subject is "SG503 amplitude precision".
Instead start a new thread with the subject that says: "I need help troubleshooting my 2465".
Dennis Tillman W7PF
toggle quoted message
Show quoted text
-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Tony
Fleming
Sent: Friday, April 26, 2019 9:37 AM
To: [email protected]
Subject: Re: [TekScopes] SG503 amplitude precision
I'm very sorry that I emailed the wrong group!
I'm little desperate and it shows!
I hope your group will forgive me and I'll try not to repeat my mistake!
Have a great weekend!
Thank you.
Tony
On Fri, Apr 26, 2019 at 11:34 AM Dennis Tillman W7PF
<dennis@...>
wrote:
Hi Tony,
The subject line of a thread tells our 8,000 members around the world
whether this is a topic that is relevant to them.
In this case the thread is about the SG503 amplitude precision. It
makes it simple for anyone who doesn't own an SG503 to delete this
email without spending any time reading it.
When you used this"SG503 amplitude precision" topic to ask for help
with your 2465 two things happened:
1) You annoyed the members who are having a conversation about the SG503.
It is as if you are butting into a conversation among many people, you
interrupted what they were talking about, and you asked an irrelevant
(to
them) question that has nothing to do with their conversation.
2) No one who owns a 2465 is paying attention to a conversation about
the
SG503 so you will not reach the very people who can help you.
The proper thing to do is to start your own topic with a subject line
that clearly and succinctly states what you want. For example the
subject line might say "I need help troubleshooting my 2465".
So feel free to send a new email to TekScopes with a new subject line
and in the email state as clearly and succinctly as you can what the
problem is with your scope.
Dennis Tillman W7PF
-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of
Tony Fleming
Sent: Thursday, April 25, 2019 8:56 PM
To: [email protected]
Subject: Re: [TekScopes] SG503 amplitude precision
I'm new here and I'm looking for someone to help me with my
Tektronix
2465 DNS (aslo known as 2465 CTS ) I made few videos here:
about my sick scope.
Can anyone tell me where is a special group for my scope?
Thank you all for helping me and each others!
Have a great day!
Tony
On Thu, Apr 25, 2019 at 9:17 PM Rick <rpbale@...> wrote:
I may be a little late to the game but I posted this question to a
Tek expert on Youtube:
This comment/request might be a little out of scope, to calibrate
a Tek
SG503 Tek says a special cable is required, Tek part 012-0482-00.
This is an extremely expensive 3 foot 50 ohm BNC cable, $200+ on ebay.
There's a discussion going on at TekScopes@... about the need
for this cable and thought this was right up your alley for a
video. How do you make a precision application cable in the home
workshop? What is this cable doing that another 3 foot 50 ohm
terminated cable can't do? I'm a m addicted to collecting Tek 500
series plugins for my home lab and have a SG503 and would love to
make one. Thanks and love your videos.
His reply:
w2aew
I looked up the engineering specs for that cable - doesn't look
like anything super special. 012-0482-00 refers to a 36" +/-0.5"
long RG-58C/U cable with BNC connectors and strain reliefs. The
BNC connectors are to be per MIL-C-39012 spec, which basically
applies to most high-quality (reputable manufacturer) connectors,
rated to 4GHz, max insertion loss of 0.2dB at 3GHz, VSWR of 1.3:1
max with TFE insulation. Nothing super special, just a 3' 50ohm
coax made with
quality materials.
--
Dennis Tillman W7PF
TekScopes Moderator
-- Dennis Tillman W7PF TekScopes Moderator
|
Re: Tek485 - a quick question on disabling/bypassing power supply protection
I had a 485 that hiccupped when I got it. The way I determined the bad rail
was to look at the turn-on and turn-off edges while in hiccup mode. One rail
didn't get as (proportionally) high when ON, and it decayed much faster to
zero when OFF. Based on that I supposed that there may be a heavy load on
that rail, and pulled combs to isolate boards, eventually finding a shorted
tantalum behind a filter choke.
I'm sure you're looking the tantalums?
Good luck - that thing is not easy to work on.
Dan
|
If anyone wants to have cables made for them, or buy wire or connectors, consider RF Connection:
Rfconnection.com No ¡°s¡±.
Long in the business of making cables for military, government, and industry. See the website, send an email or call via phone to explore.
Roy sends.
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On Apr 26, 2019, at 4:05 PM, Ancel <protofabtt@...> wrote:
The cable I have for the instruments is a Tektronix 012-0057-01, Z0 = 50 ¦¸, coax cable assy, with connector boots.
The engraving on the BNC metal is 'KINGS KC-59-123'
-=-=-=-=-=-=-=-=-=-
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Re: [Test-Equipment] Suggestions for going through Tek2465DVS/DMM?
Good luck,
the RIFA caps are worth replacing, especially if you're in 240V land. Make
sure you replace them with properly specified X or Y class capacitors, as
required. You can find plenty of info about what that means on the
interwebs, but I wouldn't buy those from any but reputable sources.
Those old scopes are a work of art, and the service manuals are an
education - you're in for a treat :).
Good luck,
Siggi
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On Fri, Apr 26, 2019 at 12:34 PM Tony Fleming <czecht@...> wrote: Thank you very much for comprehensive email, that is pointing me to the
right direction!
It seems to me that the Beam Switch is sticking for sure and could cause
most of my problems.
I'll try to update the videos as soon as I make some progress.
Should I also replace some of the square caps that are something like
0.006xx nF? Many people do this ASAP, since these caps are not a good
quality - despite most of the parts are very good quality.
Where should I buy the caps and other parts, if I'll need them?
I'm sure, China and eBay should not be on my list for caps - right?
Anyway, Have a great day and I'll post videos so you can see what I did and
the results that happen.
Have a great day and weekend!
Tony
On Fri, Apr 26, 2019 at 9:05 AM Siggi <siggi@...> wrote:
Hey Tony,
welcome to the group. I watched the videos you posted in another thread
detailing your 2465 CTS troubles <
>.
Here's my advice for how to proceed:
1. Get a service manual for your scope. You can download one from here <
>, or if you're not satisfied with the
scan quality you can buy a very good quality scan from Artek Manuals <
>.
2. Get familiar with the controls of your scope. Alan Wolke has a bunch
of tutorial-like videos on coupling and trigger setup and such, there's
a
list of his YouTube videos here <
>.
3. Read this document <
> on
how to troubleshoot oscilloscopes.
Now looking through your videos, I think you one problem for sure, and
possibly one more.
1. Your beam finder button sticks or glitches.
2. Something else, possibly more than one other problem.
It's very hard to reason about what the CRT is displaying while the beam
finder is bad, but it's easy to fix. You can probably get by with isopropyl
alcohol - just squirt some into the switch and work it several times. If
that doesn't do it, get yourself some kind of contact cleaner (Deoxit D5 is
what I use), and clean the switch with that.
What makes me think that you may have a second problem is the fact that the
readout would sometimes shrink only in the horizontal, but it's possible
that this is simply due to a high-resistance beam finder switch, so fix
that first.
Once the beam finder switch is good, it's possible to move forward to
diagnose whatever else is wrong, if anything. A key question I found myself
asking while watching your videos was whether the intermittent shrinking
affects only the readout, or whether it also affects the traces.
Unfortunately I didn't see the shrinkage occur while traces and readout
were both displayed.
Note that for the traces to be displayed, your triggering controls have to
be set up right. If you set the trigger to AUTO & CH1, then set the CH1
coupling switch to GND coupling, you should be able to display all traces
reliably.
Siggi
On Fri, Apr 26, 2019 at 1:12 AM Tony Fleming <czecht@...> wrote:
I have the same oscilloscope. It is also listed under (at least that is
what I found today) as Tektronix 2465CTS (or 2465 CTS) .
Mine has some problems, sometimes I loose the text on top and bottom of
the display and also the FIND BEAM gets stuck, so I don't know exactly
where to find the solution.
Anyway, I hope your scope is working.
Tony Fleming
|
The cable I have for the instruments is a Tektronix 012-0057-01, Z0 = 50 ¦¸, coax cable assy, with connector boots.
The engraving on the BNC metal is 'KINGS KC-59-123'
|
Peter Mulvey
Raymond Domp Frank
Ancel