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Re: Tek TDS694C advice pls

 

Wrong, when calculating the impedance of a parallel R +C the 90 degree phase shift should be taken into account.
The input impedance is actually closer to 550 ohms.

Bruce

On 09 September 2020 at 07:56 Raymond Domp Frank <hewpatek@...> wrote:


On Tue, Sep 8, 2020 at 09:21 PM, Ray wrote:


On second read I checked the specs of the P6249.??So it is active (Fet) and
has higher input resistance (20 kohm) then the P6158 (1 kohm)So the P6249 will
do less loading of the measured circuit.
At higher frequencies the P6249 is a lighter load than the P6158, not because of its 20 kOhm parallel resistance vs. the P6158's 1 kOhm, but because its input capacity is significantly lower (< 1 pF) vs. the P6158's (1.5 pF).
Because of the much lower input capacitance of the P6249, its impedance decreases much slower than that of the P6058 with increasing frequency.
Be aware that at 160 MHz, the input Z of the P6249's input capacitance (if 1 pF) is around 1 kOhm, the same as the P6158's input-R. Input-R is unimportant at higher frequencies, as always with parallel capacitances. The input-Z of the P6158 at 160 MHz is about 670 Ohm, parallelled with 1 kOhm, so 400 Ohm.

Raymond
Re: Tek TDS694C advice pls

 

Thank you Raymond, learned something new today.RaySent from my T-Mobile 4G LTE device------ Original message------From: Raymond Domp FrankDate: Tue, Sep 8, 2020 14:56To: [email protected];Cc: Subject:Re: [TekScopes] Tek TDS694C advice plsOn Tue, Sep 8, 2020 at 09:21 PM, Ray wrote:


On second read I checked the specs of the P6249.??So it is active (Fet) and
has higher input resistance (20 kohm) then the P6158 (1 kohm)So the P6249 will
do less loading of the measured circuit.
At higher frequencies the P6249 is a lighter load than the P6158, not because of its 20 kOhm parallel resistance vs. the P6158's 1 kOhm, but because its input capacity is significantly lower (< 1 pF) vs. the P6158's (1.5 pF).
Because of the much lower input capacitance of the P6249, its impedance decreases much slower than that of the P6058 with increasing frequency.
Be aware that at 160 MHz, the input Z of the P6249's input capacitance (if 1 pF) is around 1 kOhm, the same as the P6158's input-R. Input-R is unimportant at higher frequencies, as always with parallel capacitances. The input-Z of the P6158 at 160 MHz is about 670 Ohm, parallelled with 1 kOhm, so 400 Ohm.

Raymond
Re: Tek TDS694C advice pls

 

On Tue, Sep 8, 2020 at 09:21 PM, Ray wrote:


On second read I checked the specs of the P6249.??So it is active (Fet) and
has higher input resistance (20 kohm) then the P6158 (1 kohm)So the P6249 will
do less loading of the measured circuit.
At higher frequencies the P6249 is a lighter load than the P6158, not because of its 20 kOhm parallel resistance vs. the P6158's 1 kOhm, but because its input capacity is significantly lower (< 1 pF) vs. the P6158's (1.5 pF).
Because of the much lower input capacitance of the P6249, its impedance decreases much slower than that of the P6058 with increasing frequency.
Be aware that at 160 MHz, the input Z of the P6249's input capacitance (if 1 pF) is around 1 kOhm, the same as the P6158's input-R. Input-R is unimportant at higher frequencies, as always with parallel capacitances. The input-Z of the P6158 at 160 MHz is about 670 Ohm, parallelled with 1 kOhm, so 400 Ohm.

Raymond
Re: Tek TDS694C advice pls

 

On second read I checked the specs of the P6249.??So it is active (Fet) and has higher input resistance (20 kohm) then the P6158 (1 kohm)So the P6249 will do less loading of the measured circuit.RaySent from my T-Mobile 4G LTE device------ Original message------From: fauffing via groups.ioDate: Tue, Sep 8, 2020 07:19To: [email protected];Cc: Subject:Re: [TekScopes] Tek TDS694C advice plsHave you used the P6158 probes with this scope, and if you have, what are the drawbacks of the P6158 compared to the P6249?

Thanks,
- Frank
Re: Help Troubleshooting 466, No +15VDC

 

There are a number of tricks.? One is to put a current limited supply on the +15.? Adjust the supply to +15 volts and the current limit to roughly between 50 ma to 100 ma.? Look for the lowest voltage across each capacitor.? Suspect the ones with the lowest voltage drop.? Bear in mind that in a parallel string fed from one end, the bad one and all the ones in the string after that would have the same voltage.

Another would be to take a current trace probe (HP made one), feed the line with a pulse train, and then see where all the current is going.

The third method is the LED test.? In a dark room, look to see what capacitor lights up like a dim LED, the dull red glow may be something you could observe.? Ditto if you had an infrared camera.? If there are any filter resistors (Tektronix frequently used a 10 ohm series resistor for isolation), check for damage.

Oh, and disconnecting boards to try to isolate to a particular board isn't a bad idea.

Harvey

On 9/7/2020 3:18 PM, Sparky wrote:
This 466 worked great for years, then suddenly I smelled something burning, and the fan stopped. All low voltages good on interface board, *except* for +15VDC. Reads about 4VDC, (and about 4 ohms to ground with power off....). If I leave power on past about 15 sec, I can smell something burning again, so I only power up long enough the check the voltages.
I'm thinking tantalum cap, but wondering a good way to isolate the offender? Assume the the +15VDC goes all over the scope, to other boards, so would be a bear to lift all tant caps one at a time. Thinking of breaking the trace somewhere near the PS source. Any other tips or likely suspects?

Thanks in advance!
Re: Tek TDS694C advice pls

 

Frank, Ray,

I recently needed to measure some 600 MHz clock signals and the folks I was
working with were not convinced that probe and scope bandwidth was so
important, so I came up with this data. It's not directly related to
Frank's question, but maybe of some value. I don't have a TDS694, instead,
a TDS684B, and somewhat different probes. This info covers most of the
systems I have. Sorry for the crude formatting, I can provide an Excel file
if anyone is interested, contact me off list at pvhengineering at g
mail dot com

Tom Bowers
PVH Engineering

OSCILLOSCOPE SYSTEM BANDWIDTH, SCOPE AND PROBE OPTIONS

SCOPE Scope BW Scope Tr PROBE Probe BW Probe Tr System BW System Tr
Comment
TDS684B 1000 MHz 0.35 nS P6205 750 MHz 0.467 nS 600 MHz 0.583 nS Active
probe, +/- 10V, 1M ,2pF, +/- 40 V Max
TDS684B 1000 MHz 0.35 nS P6156 3500 MHz 0.100 nS 961 MHz 0.364 nS Passive
Probe, 10X, 500 ohm (1x, 20x, 100x) 15V RMS
TDS684B 1000 MHz 0.35 nS P6056 3500 MHz 0.100 nS 961 MHz 0.364 nS Passive
Probe, 10X, 500 ohm, 9V Max
TDS684B 1000 MHz 0.35 nS P6245 1500 MHz 0.233 nS 832 MHz 0.420 nS Active
probe, +/- 8V, 1M <1pF, +/- 8V Max
TDS684B 1000 MHz 0.35 nS P6057 1500 MHz 0.233 nS 832 MHz 0.420 nS Passive
Probe, 100X, 5000 ohm, 21V Max
TDS684B 1000 MHz 0.35 nS P6201 900 MHz 0.388 nS 669 MHz 0.523 nS Active
probe, 10X , 1M <1.5pF, +/- 6V Max
7904/7A19 500 MHz 0.70 nS P6201 900 MHz 0.388 nS 437 MHz 0.800 nS Active
probe, 10X , 1M <1.5pF, +/- 6V Max
TDS684B 1000 MHz 0.35 nS P6137 400 MHz 0.875 nS 371 MHz 0.942 nS Passive
Probe, 10X, 10M, 10.8pF 500V Max
TDS684B 1000 MHz 0.35 nS P6106 250 MHz 1.40 nS 243 MHz 1.433 nS Passive
Probe, 10X, 10M, 11.2pF (2 Meter) 500V Max
7904/7A19 500 MHz 0.70 nS P6106 250 MHz 1.40 nS 223 MHz 1.565 nS Passive
Probe, 10X, 10M, 8.7pF (1 Meter) 500V Max
7904/7A26 200 MHz 1.75 nS P6106 250 MHz 1.40 nS 156 MHz 2.241 nS Passive
Probe, 10X, 10M, 13.2pF (3 Meter) 500V Max
7904/7A26 200 MHz 1.75 nS P6046 100 MHz 3.50 nS 89.4 MHz 3.913 nS Active
Differential, 1x to 1mV/Div, 25 V Max
TDS684B 1000 MHz 0.35 nS P6006 70 MHz 5.0 nS 69.8 MHz 5.012 nS Passive
Probe, 10X, 10M, 8.5pF (6 Foot) 600V Max
Note: Active probes are very fragile!


On Tue, Sep 8, 2020 at 6:19 AM fauffing via groups.io <fauffing=
[email protected]> wrote:

Have you used the P6158 probes with this scope, and if you have, what are
the drawbacks of the P6158 compared to the P6249?

Thanks,
- Frank
Re: Tektronix TDS3PRT Printer

 

To reply to my own message again , the TDS3PRT printer I purchased from an overseas seller arrived yesterday, but without instructions or accessories. Upon examination I found the platen knob to be frozen; however, after disassembling the unit for inspection, and gradually rocking the knob back and forth, the platen finally broke free. I think this problem arose from a long period of disuse.

At that point I found the Sony UPP-110S 110 mm wide print roll I had hoped to work was too large in diameter for the printer. But after unwinding about two-thirds of the paper to a separate mandrel, so as to reduce the diameter to about 1-1/8-inches, the roll fit the printer. It should be possible to salvage the balance of the paper by refilling the core when the roll is depleted. The Sony UUP-110S paper I tried is their standard thermal printer paper used for printers in medical equipment such as ultrasound scanners. They offer two glossier versions: UUP-110HD and UUP-110HG. I have a roll of the latter, but have not tried it yet. As far as I can ascertain, the originally intended Tektronix print rolls no longer available from any source.

When installed in my TDS3052B the print driver for the TDS3PRT seemed to be automatically selected, and the printer worked fine, except there seemed to be no obvious way of cutting the paper after images are printed. Yet, I might have missed something. Also, I am wondering if there is a need for periodic maintenance, such as cleaning the print head. If anyone has access to the manual or instructions, perhaps they can clarify these issues.

Bruce, KG6OJI
Re: 1S1 sampling unit; (also 7B53AN & 7A18 plugins)

 

The only non-Tektronix scope that can accept Tektronix letter- and 1-series plugins is the Lavoie clone AFAIK.
Re: Tek TDS694C advice pls

 

Frank,Wow a fellow TDS694C owner at last.I never get anwers when I ask about this scope.Well don't have your probe type .I got these and they work for what I use them for (up to 148 mhz.62456205Both are fet probes.About the 6158The 6158 probe is x 20. Limit is 22 v rms, low input impedance.Alas it goes to 3 ghz.So it all depends on what you intend is.The goid thing is that they where designed for this scope series.RaySent from my T-Mobile 4G LTE device------ Original message------From: fauffing via groups.ioDate: Tue, Sep 8, 2020 07:19To: [email protected];Cc: Subject:Re: [TekScopes] Tek TDS694C advice plsHave you used the P6158 probes with this scope, and if you have, what are the drawbacks of the P6158 compared to the P6249?

Thanks,
- Frank
Re: WTD - P6201 Probe tips (Tek P/N 206-0200-00)

 

On Tue, Sep 8, 2020 at 02:36 PM, Phil Pemberton wrote:


At least one, ideally two.
Hi Phil, I have (found) two of the tiny screw-in probe tips, NOS, that I can part with. How about a (free) NOS witch hat (015-0135-00) for your P6201 or do you have one?


How much are you asking for the probe tips?
When I purchased components from Japan in a previous life, Japanese vendors asked for an "idea price". So, can you give an idea price?
Let's take this off-group.

Raymond
Re: Lot of 10 scopes (400s & 2400s) with 5 scopemobiles

 

I asked the gentleman in question to plug in the 2465B, 2465, and the second 2445 to take a picture and see if there were a visible screen. He said no. I again wrote back to say it would take 5 minutes. Still no.

I'm 400 miles away. The nobs and such are worth something to people in this group but I would be leery of whatever.

Personal opinion, larry
Re: 7D20 with unknown options or mods

Chuck Harris
 

As I recall, there was a variation of the 7D20 that was called
the 7D20T, that fit in its own chassis, and was used in conjunction
with computers to gather data.

A picture is shown on page 338 of the 1984 TEK Products catalog.

-Chuck Harris



Richard Steedman wrote:

I have a 7D20 with a couple of modifications or options added. Can anyone provide some information about these?

The first is a board sitting on top of board A11 above the vacant IC sockets U1230, U1330 and U1430. It has a connector P200, connected to J100 on the CCD board A5. It has three ICs - a dual 4-input NOR gate, a quad analog switch/mux and a dual op-amp. One of the 7D20 photos on Barry Johnson's website looks like it has the same mod [()]().

The second is a small board sitting behind the front panel in-between boards A6 and A7. It's connector has flying leads soldered directly to pins of the CCD chips on the underside of board A5.

I have posted photos [here](/g/TekScopes/album?id=253175).

The 7D20 has a serial number in the B085000's and is running firmware F1.03. Any insights gratefully appreciated!
Re: WTD - P6201 Probe tips (Tek P/N 206-0200-00)

 

On 08/09/2020 11:57, Raymond Domp Frank wrote:
Hi Phil,
I'm pretty certain I have a few, NOS. How "many" do you need?
Shipment from the Netherlands to the UK.
Let me know if not found locally.

Raymond
At least one, ideally two. NL->UK shipping is fine, I can't see that
being too expensive!

How much are you asking for the probe tips?

I've found a few ebay listings in the US but either the price or the
shipping tends to be the killer (or both).

Thanks,
--
Phil.
philpem@...
Help Troubleshooting 466, No +15VDC

 

This 466 worked great for years, then suddenly I smelled something burning, and the fan stopped. All low voltages good on interface board, *except* for +15VDC. Reads about 4VDC, (and about 4 ohms to ground with power off....). If I leave power on past about 15 sec, I can smell something burning again, so I only power up long enough the check the voltages.
I'm thinking tantalum cap, but wondering a good way to isolate the offender? Assume the the +15VDC goes all over the scope, to other boards, so would be a bear to lift all tant caps one at a time. Thinking of breaking the trace somewhere near the PS source. Any other tips or likely suspects?

Thanks in advance!
Re: Tek TDS694C advice pls

fauffing
 

Have you used the P6158 probes with this scope, and if you have, what are the drawbacks of the P6158 compared to the P6249?

Thanks,
- Frank
466 Interface Bd 15V-65V short

 

Troubleshooting an issue with my 466, where both traces would get blurry (unfocus) intermittently. The problem appeared to be mechanical in nature, as it responded to taps on the case.
Opened it up and found a chalky, powdery bridge between C1737 (65V) and the 15V test point on the interface board. Cleaned it up, and appears to have cleared the problem. Has anyone seen this before?
7D20 with unknown options or mods

 

I have a 7D20 with a couple of modifications or options added. Can anyone provide some information about these?

The first is a board sitting on top of board A11 above the vacant IC sockets U1230, U1330 and U1430. It has a connector P200, connected to J100 on the CCD board A5. It has three ICs - a dual 4-input NOR gate, a quad analog switch/mux and a dual op-amp. One of the 7D20 photos on Barry Johnson's website looks like it has the same mod .

The second is a small board sitting behind the front panel in-between boards A6 and A7. It's connector has flying leads soldered directly to pins of the CCD chips on the underside of board A5.

I have posted photos here.

The 7D20 has a serial number in the B085000's and is running firmware F1.03. Any insights gratefully appreciated!
Re: P6249 Oscillation

fauffing
 

Does the probe calibrate? I am new to the 694C and have two probes that calibrate and one which does not. All have oscillation similar to what you've described, with the more pronounced oscillation on the probe which will not calibrate (and I cannot effectively set offset according to documentation on this probe either). Does anyone have a screenshot of a 694C on the calibration pins at various scales they'd be willing to share, so I can use for a comparison? I really don't know what to reasonable expect from a working vs. a non-working P6249 probes.
Re: WTD - P6201 Probe tips (Tek P/N 206-0200-00)

 

Hi Phil,
I'm pretty certain I have a few, NOS. How "many" do you need?
Shipment from the Netherlands to the UK.
Let me know if not found locally.

Raymond
WTD - P6201 Probe tips (Tek P/N 206-0200-00)

 

Hi folks,

I've just picked up a P6201 probe kit which is almost complete -- except for the probe tips. Sadly the one on the probe is a bit worn.

Does anyone have any spare P6201 probe tips (Tek P/N 206-0200-00) for sale?

Cheers
Phil.
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