Date   

Re: WTB: Tek 576 and P6015A

Paul Amaranth
 

-----Mensaje original-----
De: TekScopes@groups.io [mailto:TekScopes@groups.io] En nombre de Chuck Harris
Enviado el: sábado, 27 de febrero de 2021 18:07
Para: TekScopes@groups.io
Asunto: Re: [TekScopes] WTB: Tek 576 and P6015A


If I didn't already have some of the freon (stored in my freezer), I would certainly try using butane... but let it boil and eliminate all of the air from the probe.

It is very difficult to create a mix of butane and air that will explode.

-Chuck Harris
I had a small, sealed bottle for my probe stored in my freezer. When I went to fill the
probe, it had all evaporated leaving me with an empty, sealed, bottle.

This had been repackaged by a list member some years ago when he had acquired a small
amount.

Butane sounds like a good alternative to me. From what I can see from a limited search, it
cuts the voltage rating in half compared to R114. At least the probe is usable at that point.

Paul

--
Paul Amaranth, GCIH | Manchester MI, USA
Aurora Group of Michigan, LLC | Security, Systems & Software
paul@... | Unix/Linux - We don't do windows


Re: P6021 Noise Problem?

Ozan
 

2. I attached a 10ft loop of wire to my scope. I did not have a microwave
diode but I think the wire alone is providing a clue. The wire picked up a
93Mhz signal with varying amplitudes from 4 to 6mVpp!
This reminds me a time when I was chasing a ~ 88MHz coupling. Finally I connected a wire antenna to spectrum analyzer and turned on FM demod, it turned out to be a local station (KQED 88.5MHz). Antenna is not very close, over 40 miles away. If you have a spectrum analyzer with FM demod you can try it on the signal.
Ozan


Re: Looking to ID a diode in a 1S1 sampling plug-in

Ed Breya
 

Sean, I don't know about the other diodes discussed earlier, but I have seen those tiny glob ones with the dot (in the picture) before, in Tek and other gear. They could be just a different version (stripline) package for regular TDs, or they could be "back-diodes," which are a close relative. As I recall, back-diodes are even more heavily doped than regular TDs, so they are already in forward bias at zero volts, and the interesting part of their behavior exists around the zero-crossing, and includes that small region that seems kind of like a crappy TD. Your mention of the weird curve reminded me. So, don't assume they're bad TDs just yet, until you study it some more. Somewhere in the circuit description or schematics it may become more clear. I don't recall what the usual TD part designations are, but somewhere in tekwiki, there's a nice listing and summary of many TD numbers from the old days. Look for that - it may explain what TD253 is supposed to be. Also, you can look up back-diodes, and see if the description matches the curve you saw.

You are right that this unit is a prototype. If the same phase development stages were used back then, as in more modern times, then "B11" should be very close to what went into production. The poor solder joints you mentioned, around those tiny diodes, may result from a couple of considerations. First, those things are very delicate, so anyone soldering them in or out would know they have to work fast - very fast - to get that iron tip out of there ASAP, even if the joint looks crappy, as long as it worked. Second, being a prototype, these diodes may have been swapped out or had type changes many times during development, and the same soldering issues apply. This could also mean that those diodes are not necessarily the same part number that was ultimately used in production. But, you'd think they would be close at least. Good luck in figuring it out.

Ed


Re: P6021 Noise Problem?

Jim Ford
 

Nearby FM radio station, maybe?                   Jim Ford Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: Chappy <sb.chadwick@...> Date: 2/27/21 8:07 AM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] P6021 Noise Problem? I finally had a chance to get back to this yesterday. Thanks again to all who provided suggestions, and especially Dennis with his detailed reply.  I have been a longtime lurker on this site and I have learned a lot about Tek equipment and troubleshooting in the process. Tests performed:1. I attached a normal Tek 100Mhz probe to two separate power supplies that were powered OFF. On a 2mv/div scale I was able to see a few cycles of a decaying signal that appeared to be approx 100Mhz.  Visible on both my Tek and Keysight scopes.2. I attached a 10ft loop of wire to my scope. I did not have a microwave diode but I think the wire alone is providing a clue. The wire picked up a 93Mhz signal with varying amplitudes from 4 to 6mVpp!3.  I hooked up the 6201 probe to my Keysight 1102G scope, injected a 1Mhz 5mVpp square wave.  The square wave had both noise and an additional signal riding on the square wave.  Using the single shot capture I was able to break out a 93Mhz signal riding on the square wave from the noise.4. I tested my 6201 probe following the procedure that Dennis suggested by shorting the tip to the ground sleeve and then shorting that to the scope. I am still able to see the 93Mhz signal under the noise.  Both the noise and the signal had an amplitude of less than 1mVpp. I suspect that the 93Mhz signal is getting into the circuitry of the 6201 probe either through the the power cable, or the probe cable. For now I am going to leave the probe as is. Most of the hobby work that I do right now is below 1Mhz, and if I need to use the probe, I will run it through my 7A13 plugin with the 5Mhz BW limit enabled. I will check this issue again when I move to a new location. Reference the 93Mhz signal, could this be a sub harmonic of a surveillance radar working in the GHz range?  Could it also be a sub harmonic of wireless routers that can be as low as 900Mhz?  I turned off all of the other potential noise sources in my house while performing these tests, to include fluorescent lights, and all SMPS wallwarts.Sincerely,Steve


Wanted 152-0634-00 HV Multiplier for SC50x Scope

DaveH52
 

This is probably a futile request, but I'm looking for an HV multiplier for an SC502 that I'm attempting to bring back to life. The original Tek part 152-0634-00 would be preferred, but probably unobtanium, so anything small enough to fit will also be considered. I'm trying to avoid having to roll my own.
Dave


Re: WTB: Tek 576 and P6015A

Miguel Work
 

Mine leaks in two years. I use some silicone grease to seal o-rings.
I think that there are two o-ring, one in tip and other in cap.

Which is the o-ring sizes?


-----Mensaje original-----
De: TekScopes@groups.io [mailto:TekScopes@groups.io] En nombre de Chuck Harris
Enviado el: sábado, 27 de febrero de 2021 18:07
Para: TekScopes@groups.io
Asunto: Re: [TekScopes] WTB: Tek 576 and P6015A

Boil off is an essential part of filling the probe... it is how the heavier than air freon eliminates the air in the probe.

The probe is *NOT* filled completely with liquid freon. It is only necessary that there be some liquid in the probe, and that the probe be entirely full of freon vapor.

The probes are generally very well sealed. I filled my 6015 about 20 years ago, and it still has the proper amount of liquid in it.

One way the seal gets compromised is if you get too brutal while removing the BNC cable, and loosen the BNC connector, making its o-ring leak. As I recall, the o-rings and gaskets are all teflon.

If I didn't already have some of the freon (stored in my freezer), I would certainly try using butane... but let it boil and eliminate all of the air from the probe.

It is very difficult to create a mix of butane and air that will explode.

-Chuck Harris



Sean Turner wrote:

I wouldn't recommend it. There's a seller on ebay who has flourocarbon 114 in small vials...enough for 2 or even 3 fills if you are careful and chill the probe body and the 114 down in the freezer for a while before filling. You won't get any boil off if you have everything colder than 20 F.

Sean

On Fri, Feb 26, 2021 at 04:06 PM, Chris Wilkson wrote:


I've heard about the butane trick before. I think I read about it
here. I haven't tried it myself.





Re: WTB: Tek 576 and P6015A

Chuck Harris <cfharris@...>
 

Boil off is an essential part of filling the probe... it is
how the heavier than air freon eliminates the air in the probe.

The probe is *NOT* filled completely with liquid freon. It is
only necessary that there be some liquid in the probe, and that
the probe be entirely full of freon vapor.

The probes are generally very well sealed. I filled my 6015
about 20 years ago, and it still has the proper amount of liquid
in it.

One way the seal gets compromised is if you get too brutal while
removing the BNC cable, and loosen the BNC connector, making its
o-ring leak. As I recall, the o-rings and gaskets are all teflon.

If I didn't already have some of the freon (stored in my freezer),
I would certainly try using butane... but let it boil and eliminate
all of the air from the probe.

It is very difficult to create a mix of butane and air that will
explode.

-Chuck Harris



Sean Turner wrote:

I wouldn't recommend it. There's a seller on ebay who has flourocarbon 114 in small vials...enough for 2 or even 3 fills if you are careful and chill the probe body and the 114 down in the freezer for a while before filling. You won't get any boil off if you have everything colder than 20 F.

Sean

On Fri, Feb 26, 2021 at 04:06 PM, Chris Wilkson wrote:


I've heard about the butane trick before. I think I read about it here. I
haven't tried it myself.





Re: P6021 Noise Problem?

Chappy
 

I finally had a chance to get back to this yesterday. Thanks again to all who provided suggestions, and especially Dennis with his detailed reply. I have been a longtime lurker on this site and I have learned a lot about Tek equipment and troubleshooting in the process.

Tests performed:

1. I attached a normal Tek 100Mhz probe to two separate power supplies that were powered OFF. On a 2mv/div scale I was able to see a few cycles of a decaying signal that appeared to be approx 100Mhz. Visible on both my Tek and Keysight scopes.

2. I attached a 10ft loop of wire to my scope. I did not have a microwave diode but I think the wire alone is providing a clue. The wire picked up a 93Mhz signal with varying amplitudes from 4 to 6mVpp!

3. I hooked up the 6201 probe to my Keysight 1102G scope, injected a 1Mhz 5mVpp square wave. The square wave had both noise and an additional signal riding on the square wave. Using the single shot capture I was able to break out a 93Mhz signal riding on the square wave from the noise.

4. I tested my 6201 probe following the procedure that Dennis suggested by shorting the tip to the ground sleeve and then shorting that to the scope. I am still able to see the 93Mhz signal under the noise. Both the noise and the signal had an amplitude of less than 1mVpp.

I suspect that the 93Mhz signal is getting into the circuitry of the 6201 probe either through the the power cable, or the probe cable.

For now I am going to leave the probe as is. Most of the hobby work that I do right now is below 1Mhz, and if I need to use the probe, I will run it through my 7A13 plugin with the 5Mhz BW limit enabled. I will check this issue again when I move to a new location. Reference the 93Mhz signal, could this be a sub harmonic of a surveillance radar working in the GHz range? Could it also be a sub harmonic of wireless routers that can be as low as 900Mhz? I turned off all of the other potential noise sources in my house while performing these tests, to include fluorescent lights, and all SMPS wallwarts.

Sincerely,
Steve


Re: WTB: Tek 576 and P6015A

Sean Turner
 

I wouldn't recommend it. There's a seller on ebay who has flourocarbon 114 in small vials...enough for 2 or even 3 fills if you are careful and chill the probe body and the 114 down in the freezer for a while before filling. You won't get any boil off if you have everything colder than 20 F.

Sean

On Fri, Feb 26, 2021 at 04:06 PM, Chris Wilkson wrote:


I've heard about the butane trick before. I think I read about it here. I
haven't tried it myself.


Re: Which probe is better suited for 2465B?

Giuseppe Marullo
 

Would this P6500 be a suitable substitute while looking for a cheap P6137?

https://www.ebay.it/itm/P6500-500Mhz-High-Precision-Oscilloscope-Passive-Probe-Clip-for-Tektronix-HP/133508177735

Would it work for an 485 too?

It not clear to me the relation between the capacitor compensation range and the input C capacitance. Could you confirm that is related to the charging added to the circuit under test?
Looking at these specs, the P6137 loads the target with 10MOhm/10.8pF and provides 12 to 18pF range to the scope.
https://www.tek.com/datasheet/p6131-p6137-p6138a-passive-voltage-probes

Since the cheap P6500 has a adjustable range of 9 to 28pF(https://www.ebay.it/itm/P6300-P6400-P6500-passive-probes-voltage-Oscilloscope-10-1-with-high-frequency/123420509064?hash=item1cbc6f8388:g:tmUAAOSw9~5bvwll)
Albeit with a 13pF input C capacitance, would they be "compatible" with 2465b input?

Sorry for the naïve questions but last time I used extensively a scope I had a Hunk Chang 60MHz...many years ago.

Giuseppe Marullo
IW2JWW - JN45RQ

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Tom Gardner
Sent: Thursday, February 25, 2021 12:36 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Which probe is better suited for 2465B?

On 24/02/21 23:23, Giuseppe Marullo wrote:
Hi Jon,
Trusting and returning is very risky and inconvenient especially if the seller and buyer are not in the same country!
There is no risk, they are listed as not working. You only risk to get your money back if the item does not show. Any other case, you are screwed. Simply as that.

Thanks but "Ebay" Item condition is very important. 199USD+shipping+customs+handling fees and no guarantee(not working/parts only) is a no-no.

I will try some local resellers, or should anybody willing to part with a couple of good P6137, write me off list.

485 is arrived, seems in pretty good shape. Same apply, any good recommendation of probes for it?
I use hp10020a - but they are a little difficult to come by :)

Try any Z0 resistive divider probe, or make some yourself.


Re: Looking for P6042 current probe transformer/hall-sensor replacement instructions

 

On Wed, Feb 24, 2021 at 04:26 PM, benj3867 wrote:


I am desperately looking for the instructions that Tek. used to attach to the
P6042 probe transformer/hall assembly T1 replacement kit (050-0439-00/01).
Find it here: www.hakanh.com/dl/docs/kitinstructions/050-0439-01.pdf

/Håkan


Re: Looking to ID a diode in a 1S1 sampling plug-in

Sean Turner
 

I uploaded a small album of this plug-in: https://groups.io/g/TekScopes/album?id=261202

On the third picture, another curiousity is the tunnel diodes (circled in red). These do not look like any Tek tunnel diodes I've seen, and they show signs of soldering that is decidedly not up to the standards of factory Tek soldering. Whether this is a symptom of being a prototype (serial number 11 after all) or later work, no idea. D430 (the uppermost one circled) also has a weird curve with only a very tiny negative resistance region (though it is 10 mA), and the manual calls for a TD253 which is a metal package IIRC.

Sean


Re: Looking for P6042 current probe transformer/hall-sensor replacement instructions

snapdiode <snapdiode@...>
 

Yes, and there weren't 4 heads in there though.


Re: WTB: Tek 576 and P6015A

Chris Wilkson
 

I've heard about the butane trick before. I think I read about it here. I haven't tried it myself.


Re: Transformation TR503 into TR502

Attilio
 

Hi Ed,
I'll try tomorrow.
Thank you.

--Cheers
Attilio


Re: Transformation TR503 into TR502

Ed Breya
 

The varicap diode is pretty high in capacitance, so 10 pF added is probably about right. Put the cap across the diode - not to ground. Ed


Re: Transformation TR503 into TR502

Attilio
 

Hi Ed,
so I confirm that the C522 capacitor is 0.47 uF (470000 pF).
In the diagrams there are several inaccuracies, but if you look at the drawings of the printed circuits they all show the resistor R522 (1000 ohm).
CR526 diode (MV1404) is called "Hyper-Abrupt Tuning Diode" the nominal capacitance is 120 pF (the range should be from 10 pF to 140 pF).
I put the 10 pF capacitor (NP0) between the crystal terminal (connected to CR526) and the system ground (basically the ground where the 55 MHz crystal container was connected).
I tried several capacitors in parallel to the 12 pF capacitor but without positive results, with 22 pF capacitance the oscillator by adjusting the "Tracking Adjust" stops oscillating, with 10 pF there is not enough adjustment, in any case the track is not stable.
What I try now?

Thanks for your help and patience.

--Cheers
Attilio


Re: Looking for P6042 current probe transformer/hall-sensor replacement instructions

benj3867
 

Thanks, I looked at the picture and I must say it does not look like a Tektronix label on that bag. It definitely looks like some reseller-company repackaged this.


Re: Transformation TR503 into TR502

Ed Breya
 

Hi Attilio,

I'm surprised that adding some C across C524 didn't do it. First, let's make sure we're on the same page - I'm looking at the TR503 manual schematic of the XO section. C524 is the variable trim cap "MODE ADJUST," 9-45 pF, and C526 12 pF is in parallel with it. The node you mentioned where the crystal and varicap CR526 join, is bypassed by C522 0.47 uF (apparently) to the same cold ends of C524 and C526, which is the "ground" for the oscillator. The actual DC level is set by the Vbb reference from U520, so its ECL receivers U520A and U520B will be properly biased. U520 is set up for PECL (positive ECL) operation, so Vbb ends up at +3.6 V, as marked on the schematic.

The first question is what is C522 - 0.47 uF, or 0.47 pF? The label is kind of ambiguous. Other Cs in the area that look like bypass spots, have the same label, "0.47." It would make more sense if C522 is 0.47 pF (although that seems way low for something like this), because then it's clear how the feedack gets to the input. If C522 is indeed 0.47 uF, then it should effectively short out that end of the crystal to "ground" (Vbb), and no obvious feedback would be available at the front. Since ECL has very little gain and isolation from output to input, it could be some scheme where the feedback is internal, but I don't recall ever seeing this kind of topology. I suspect that there may be one or more errors in the schematic, or missing parts.

I just took a quick look at the TR502 manual, and the circuit looks the same, but shows a mod R522, unidentified value, between C522 and the crystal/varicap node. Now that would make more sense - C522 can be big, for bypassing the tune voltage, and R522 would isolate it so some feedback is there to sustain oscillation.

So, I think it would be good to check the possible different versions of manuals for both models, to get a better idea of what's actually in there. Then, double check that your added 10 pF experiments were truly at the right spots, across C524 or C526, and if there's any effect with 10 pF, but not enough, then try more, like 22 pF, and so on. For any shunt capacitors, the ground is the Vbb, not the system ground. You can try various experiments and see how it goes. If reasonable extra C across C524 really doesn't work, then I think the next best spot would be some C across the varicap diode, but it may need to be a lot less than 10 pF. If you can, find the specs for CR526, and see what its capacitance range should be - that will give some idea of how much extra tweaking is needed.

Ed


Photo 20210226_141836.jpg updated #photo-notice

TekScopes@groups.io Notification <noreply@...>
 

The following photos have been updated in the P6042 album of the TekScopes@groups.io group.

By: snapdiode <snapdiode@...>

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