Date   

Re: Extracting a buggered knob grubscrew

-
 

I ordered this set when I had to remove some damaged 1/8 inch o.d. set
screws in some door hinges. <
https://www.amazon.com/gp/product/B01H9FGQVK/ref=ppx_yo_dt_b_asin_title_o08_s00?ie=UTF8&psc=1>
They worked like a charm for that use but you'll probably need smaller ones
for the set screws in the Tektronix knobs. If Amazon doesn't have them then
try an industrial supplier like MSC or Grainger.

If you can't find any then use the shank of an old small drill bit or
a piece of drill rod and grind it into the shape of a spade bit and then
reharden it. It doesn't need to be an effective drill, you just want
something that will dig in and twist the set screw in a counter clockwise
direction.

On Tue, Feb 2, 2021 at 8:29 AM David Slipper <softfoot@hotmail.com> wrote:

Where did you get your set of left-handed drills ???

On 02/02/2021 12:31, - wrote:
I have a set of them and I keep them in their own protective box and
they're
used only to remove stubborn set screws and broken bolts. For me left
hand
bits work *much* better than Easy Outs for removing broken bolts and
buggered set screws.

On Mon, Feb 1, 2021 at 8:43 PM Bob Albert via groups.io <bob91343=
yahoo.com@groups.io> wrote:





Re: User Experience of Sampling Scopes

Jeff Kruth
 

I have been a professional microwave engineer for over 40 years. I have "heard" this said. However, the quality stainless steel type SMA's (like OSM, Narda or Weinschel) I have used have been mated MANY MANY more times that that and, if you clean them, and keep them clean, and do not overtorque them, perform very well, almost as good as new. 

I think the 100 cycle thing is either for gold plated brass, or from the connector vendors that want to sell new connectors.Jeff Kruth In a message dated 2/2/2021 7:09:12 PM Eastern Standard Time, jeff.dutky@gmail.com writes: Jim Ford wrote:


SMA is only rated for something like 100 mating cycles, maybe less, while the 3.5 mm is rated for 2000 cycles.


Re: User Experience of Sampling Scopes

Tom Lee
 

It is true, but for hobbyist use, it may not be as great an issue. What happens is that the SWR degrades with each cycle, but the criterion for failure is pretty strict in these ratings. Unless you’re doing lots of work at X-band and above, the useful lifetime of an SMA is far greater. Those of us with nanoVNAs and tiny SAs don’t have as much to worry about because those instruments are limited in their frequency range, and are thus more tolerant of connector imperfections. But if you wish to extend lifetime, you can always buy some connector savers and let them bear the brunt.

Tom

Sent from my iThing, so please forgive typos and brevity.

On Feb 2, 2021, at 4:09 PM, Jeff Dutky <jeff.dutky@gmail.com> wrote:

Jim Ford wrote:

SMA is only rated for something like 100 mating cycles, maybe less, while the 3.5 mm is rated for 2000 cycles.
Is this true?

I just got a tinySA and I'm going to have to get some adapters for the SMA connectors, pronto, if I have to worry about them wearing out in only 100 matings.

The Amphenol web site says minimum of 500 mating cycles (https://www.amphenolrf.com/connectors/sma-connectors.html) which is still seems pretty low, but if you look at other types of connectors that seems to be the most they will commit to (e.g. BNC also says minimum 500 mating cycles).

-- Jeff Dutky





Re: 2467 U800 heatsink

Jim Ford
 

I believe it about the thermal design, Chuck. A few years ago I was working with an RF power amplifier that dissipated almost 2 Watts. The package was 4 mm square, IIRC, so we thought it was a lot of heat in a small area and bought several types of heatsinks. Well, I had laid out the PCB such that it had a bunch, maybe 25, of thermal and RF ground vias directly under the package, and I had the fab shop plate the copper to shut the vias. Well, there was so much heat wicked out of the PA by the copper in the board that the difference in temperature at the package on the top side was essentially the same with or without a heatsink on the bottom side. I was surprised how well the PCB operated without any heatsink. Copper is your friend!

Jim Ford

------ Original Message ------
From: "Chuck Harris" <cfharris@erols.com>
To: TekScopes@groups.io
Sent: 2/2/2021 1:37:47 PM
Subject: Re: [TekScopes] 2467 U800 heatsink

U800 is a strange and unique thing in the 2465 scopes.

It is fairly likely that early in the design, when the
IC packages were selected, so the main board could be
laid out, U800's designer wasn't very far along in his
design, and estimated U800 would dissipate a lot more
power than it ultimately did.

The U800 package is made to mount over a centrally
located heat sink that is sandwiched between the IC
and the circuit board. The IC's leads either passed
along side of the heat sink, or passed through holes
in the heat sink. The IC was made to be clamped to
the heat sink using mounting studs, or screws on either
end of the package.

In preproduction testing, they must have found out that the
finalized chip drew less power than expected by quite a lot,
and they decided to leave the heat sink off for the full
production life of the 2465 family. It was never added in
any form for any of the models, at any time.

Because the heat sink tab is the -5V power connection for the
IC, they had to do something to make the electrical connection.
If they had included the under chip heat sink, it would provide
the electrical path, but they didn't. Instead, they punted,
and just stacked a pair of star lock washers over the mounting
studs to lift the package up, clear the extra long leads, and
make the connection.

If the nuts that mount the package are over tightened,
or the star lock washers are omitted, the slightly longer
than usual DIP package leads will force the IC's lead frame
to crack the epoxy package, and allow moisture infiltration..
which is never a good thing. This is probably the cause of
the so called unreliability problems with U800.

The 2465 family is designed to operate at ambient temperatures
as high as 50C. U800 is designed to operate as it is applied
at that temperature as well. The fan must work, the scope
must be clean, and have room around it for air circulation, but
that was the design temperature. There are even holes in the
scope's case bottom right there to feed fresh air to U800.

I can see no reason to put a heat sink on U800, and I have
seen quite a lot of damage caused by poorly applied heat
sinks, like are shown in your picture. They break free,
and rattle around in the scope shorting this, and that.

I suspect that the installer of the heat sink on your scope
read some of the damage reports, and decided to mitigate the
problem on your scope... probably after the fact.

If it was necessary, tektronix would have made an ECO and a
kit available to install one.

-Chuck Harris


Ondrej Pavelka wrote:
Heatsink is glued to the U800, the wire on the top is a secondary safety
measure. It doesn't really touch anything but the question is how much can
extra heatsink help.
I am also hoping for people like Chuck to give me the answer because there
seam to be many contradicting advices.

On Tue, 2 Feb 2021, 21:10 Jean-Paul, <jonpaul@ix.netcom.com> wrote:

Hallo, where are you located?

The fine photos reveal the U800 is precarious as the bolts carrying the
wire lash up are at 87V and the heatsink is apt to fall out or move.

Suggest that you removed the HS carefully, see if the U800 is Tek original
or Maxim and followed other threads on U800. Very deep issues re heat,
heatsinks and failures.

I am sure that Chuck Harris or Dennison can give you better advice

Kind Regards


Jon













Re: Extracting a buggered knob grubscrew

Ken, WA2LBI
 

I have a small collection of triangular screwdrivers. I first ran across
them in a Lionel model train controller I had to repair. I volunteer at a
number of Repair Cafes and have come across a number of household items
that use them. So far I am the only Repair Coach who has had them at the
Cafes.

I have all of the following: 2mm, 2.3mm, 2.5mm, 2.7mm, 3mm, 3.5mm, and 4mm
i a couple different shaft lengths. When I encounter a new size I buy one.
So far all of them have been purchase through Amazon.

Ken
WA2LBI

On Tue, Feb 2, 2021 at 18:56 Jim Ford <james.ford@cox.net> wrote:

Well, Charles, I've had a few screws come out with the SpeedOuts my wife
got me for Christmas one year. But probably not better than 50%, which
is disappointing. Going to try HF left-handed drill bits. I'm sure
there's something else useful when I get over there. There always is!

Oh yes, I wanted to look for triangular screwdrivers; one of the
Christmas light strings crapped out, and the control box has these silly
triangular screws. Only place I've seen them before was holding a
NASCAR HotWheels-sized car to the base. An appropriately sized hex key
fit in there and allowed me to remove it; I got lucky that time.
Unfortunately the Xmas light box is between 1.5 and 2 mm and between
1/16 inch and the next one up (5/64" maybe?).

Jim Ford

------ Original Message ------
From: "Charles" <charlesmorris800@centurytel.net>
To: TekScopes@groups.io
Sent: 2/2/2021 12:36:56 PM
Subject: Re: [TekScopes] Extracting a buggered knob grubscrew

The best hint for easy-outs (two lies in one) is not to use them at all.

I have never found a screw or bolt that was stuck hard enough to break
off, that also wouldn't break the easy-out when steady torque applied. And
now you have an undrillable hard tip stuck in the middle of your screw,
which is still stuck in the part!

Second the motion to use LH drill bits.
--

Ken
WA2LBI

Sent from one of my mobile devices


Re: User Experience of Sampling Scopes

 

Jim Ford wrote:

SMA is only rated for something like 100 mating cycles, maybe less, while the 3.5 mm is rated for 2000 cycles.
Is this true?

I just got a tinySA and I'm going to have to get some adapters for the SMA connectors, pronto, if I have to worry about them wearing out in only 100 matings.

The Amphenol web site says minimum of 500 mating cycles (https://www.amphenolrf.com/connectors/sma-connectors.html) which is still seems pretty low, but if you look at other types of connectors that seems to be the most they will commit to (e.g. BNC also says minimum 500 mating cycles).

-- Jeff Dutky


Re: The reason for Tek delay lines

Tom Lee
 

Early scopes had to use lumped delay lines because the speed of light (even diminished by the dielectric) is much too fast for a practical length of coax to give you sufficient delay.

Coax — if defined loosely enough to include not-really-coaxial — was used in most scopes after the lumped delay line era, once scopes got fast enough that large delays were unnecessary. To keep volume small, the coax was thin and thus lossy. The need for equalization to undo the frequency-dependent loss and dispersion made for some fun. The special helical lines used in, e.g., the 485 allowed for much shorter cables, at the expense of requiring more heroic equalization. Rather than traveling along the helix, very high frequency signals would surf from turn to turn, causing the step response to wiggle before the main edge makes it through. Compensating for this “pre-shoot” requires more L’s and C’s.

Tom

Sent from my iThing, so please forgive typos and brevity.

On Feb 2, 2021, at 3:33 PM, John Williams <books4you4@mail.com> wrote:

As far as I know coax was never used in any delay lines inside Tektronix scopes. When the technology developed specialized delay cable was constructed as solid state drivers with higher impedance were developed. The 519 delay line may have been made from existing coax, but take a look at the size. This is my understanding anyway. The technology was developing by Tektronix engineers as they went, and Howard had to agree with everything. What the hell, it certainly worked.





Re: Extracting a buggered knob grubscrew

Michael A. Terrell
 

Chuck Harris wrote:
Grainger is a B-to-B only store. They won't sell to you,
from their stores, unless you have a business, and an account.

They are easier to deal with over the internet.
I've never had a problem in Ocala. They listed me as the member of a local co-op. After one of the hurricanes, they opened sales to the general public, to supply cords and adapters for portable generators. Zoro tools on Ebay is part of Grainger. The reason that I mentioned Grainger is that they sell individual left had bits. Fasten also has local stores that sell to the public: <https://www.fastenal.com/product/cutting-tools-and-metalworking/general-purpose-holemaking/jobber-drills/609709?categoryId=609709&level=3&query=left%2Bhand%2Bdrill&isExpanded=true&exactSkuMatchLevel=useData&view=LIST_ONLY&sort=2>


Re: 535 near Detroit $75 (not mine)

Bruce Atwood
 

Good catch. I now note that the 535 which is offered is Grey, not blue, and has square corners. The lower left corner of the photo in question shows blue and a rounded corner case. Sure glad I did not drive to Detroit.


Re: Extracting a buggered knob grubscrew

Jim Ford
 

Well, Charles, I've had a few screws come out with the SpeedOuts my wife got me for Christmas one year. But probably not better than 50%, which is disappointing. Going to try HF left-handed drill bits. I'm sure there's something else useful when I get over there. There always is!

Oh yes, I wanted to look for triangular screwdrivers; one of the Christmas light strings crapped out, and the control box has these silly triangular screws. Only place I've seen them before was holding a NASCAR HotWheels-sized car to the base. An appropriately sized hex key fit in there and allowed me to remove it; I got lucky that time.
Unfortunately the Xmas light box is between 1.5 and 2 mm and between 1/16 inch and the next one up (5/64" maybe?).

Jim Ford

------ Original Message ------
From: "Charles" <charlesmorris800@centurytel.net>
To: TekScopes@groups.io
Sent: 2/2/2021 12:36:56 PM
Subject: Re: [TekScopes] Extracting a buggered knob grubscrew

The best hint for easy-outs (two lies in one) is not to use them at all.

I have never found a screw or bolt that was stuck hard enough to break off, that also wouldn't break the easy-out when steady torque applied. And now you have an undrillable hard tip stuck in the middle of your screw, which is still stuck in the part!

Second the motion to use LH drill bits.







Re: The reason for Tek delay lines

Dave Wise
 

?I thought that Type 585 was the first deployment of the new opposed-twin-helix delay line. They hadn't yet put it inside a shield and jacket like coax, it was held together in a clamshell enclosure. Everything before used the lumped L-C ladder we love to tune.


Dave Wise

________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of John Williams via groups.io <books4you4=mail.com@groups.io>
Sent: Tuesday, February 02, 2021 3:32 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] The reason for Tek delay lines

As far as I know coax was never used in any delay lines inside Tektronix scopes. When the technology developed specialized delay cable was constructed as solid state drivers with higher impedance were developed. The 519 delay line may have been made from existing coax, but take a look at the size. This is my understanding anyway. The technology was developing by Tektronix engineers as they went, and Howard had to agree with everything. What the hell, it certainly worked.


Re: So while we are all here talking oscilloscopes

Chuck Harris <cfharris@...>
 

It has been reported that they did.

-Chuck Harris

snapdiode via groups.io wrote:

Does anyone know if Russians ever made a reaaaaaaaally long CRT to direct-view GHz signals?
I have this notion in my mind but I have no idea if it's true or what.






Re: The reason for Tek delay lines

John Williams
 

As far as I know coax was never used in any delay lines inside Tektronix scopes. When the technology developed specialized delay cable was constructed as solid state drivers with higher impedance were developed. The 519 delay line may have been made from existing coax, but take a look at the size. This is my understanding anyway. The technology was developing by Tektronix engineers as they went, and Howard had to agree with everything. What the hell, it certainly worked.


Tm500 Extender on eBay

John Williams
 

I purchased one of the TM500 extenders from an eBay seller for $70. It is still in the mail but looks really good on the listing. Does anybody here know about these? Thanks.


Re: User Experience of Sampling Scopes

Jim Ford
 

Makes sense, Tom. I read somewhere, I think it was an article by somebody working for W.L. Gore, that the 3.5 mm connector was actually designed for test equipment like VNAs where many mating cycles were expected. As opposed to the SMA, which was designed to be cheap and reasonably high performance. SMA is only rated for something like 100 mating cycles, maybe less, while the 3.5 mm is rated for 2000 cycles.
Interesting because you'd think the 3.5 mm ones would be more fragile because of the longer unsupported pins in air dielectric.

I guess the female ones are, and extended male center pins can damage them. Yes, I need to get a connector gauge someday. Not so much need for it in my garage lab these days, though, as the only 3.5 mm connector I have is the male on my HP 5343A 26.5 GHz frequency counter. Most of the time I have an SMA bullet threaded into it anyway for ease of connecting SMA males on test cables.

I did get Raytheon to buy a set of Mini-Circuits SMA female to 3.5 mm male adaptors to use as connector savers on the ENA. IIRC, they were about $60 apiece, as opposed to rip-off Pasternack, who wanted $180!
Fortunately our cables seemed to be fine, at least up to 9 GHz where the ENA tops out.

Jim Ford

------ Original Message ------
From: "Tom Lee" <tomlee@ee.stanford.edu>
To: TekScopes@groups.io
Sent: 1/31/2021 2:07:27 PM
Subject: Re: [TekScopes] User Experience of Sampling Scopes

Thanks for being “that guy”. Not being aware of the difference can cause expensive damage, and it’s one of my pet peeves.

The two connectors can mate, but the 3.5mm connector is made to much tighter tolerances. It also has an air dielectric. Mating to a poorly made (or badly abused) SMA can wreck a 3.5mm connector’s ability to maintain low SWR all the way out to its TEM limit. Permanent damage can be done by a single connect-disconnect cycle.

I have sacrificial connector savers on all of my expensive gear, but occasionally a student will remove them — against the rules — to shorten a path or because they think the savers are introducing some artifacts. If they then connect a random SMA cable to the gear, those students have their lab access cards deactivated pretty quickly.

—Cheers
Tom

Sent from my iThing, so please forgive typos and brevity.

On Jan 31, 2021, at 1:42 PM, snapdiode via groups.io <snapdiode=yahoo.com@groups.io> wrote:

Well, not to be "that guy", but the SD-24 uses 3.5mm connectors... Compatible with SMA but not the same.

And I would just like to add that I have a S-52 which makes me *almost* as cool.








Re: 2235 Horizontal Calibration Issue

Stephen
 

On Tue, Feb 2, 2021 at 05:22 AM, Ozan wrote:

Interleaved



Maybe I’ll check those 2 diodes and the 300ohm resistor, but I’m sure
they’ll probably be ok.
The transistors and 300 ohm are inside the chip, you can see schematic of the
chip at:
https://w140.com/tekwiki/images/4/49/Tek_155-0124-00.pdf
That would certainly explain why I couldn’t find them. 😂

If you want to confirm the currents are OK another way is to measure voltage
drop across 47-ohm resistors R780 and R770. Schematic shows 100mV delta-V is
expected on these resistors.
Ozan
Will do that and report back. Thank you.


So while we are all here talking oscilloscopes

snapdiode
 

Does anyone know if Russians ever made a reaaaaaaaally long CRT to direct-view GHz signals? I have this notion in my mind but I have no idea if it's true or what.


Re: The reason for Tek delay lines

snapdiode
 

I always wondered why they used a bunch of discrete LC sections in some scopes. Either early coax was bad, in which case how did scope probes work? Or some engineers with no practical side whatsoever took the L-C model literally and implemented it in reality.


Re: Spectrum analyzer Tektronix 7L13 on mainframe Tektronix 7603

Attilio
 

On Tue, Feb 2, 2021 at 10:20 PM, Miguel Work wrote:


Did the 85 Mhz position moves when you change the vco control voltage? If not
the VCO is not working
Miguel,
with the connection between the 2nd LO of the TR503 and the 2nd LO of the 7L13 by adjusting the voltage I can position the signal at 105 MHz but then by moving the connection to the 1st LO output of the 7L13 the center of the filter response is at 85 MHz and varying the voltage only changes the amplitude.
I add that to center the 105 MHz signal the power supply voltage is about 13.4 Vdc.

I do not understand.

--Cheers
Attilio


Re: The reason for Tek delay lines

John Williams
 

Hi Walter. Yes you missed the secondary reason for the adjustable delay line. That was to drive we technicians who had to adjust them crazy. Later they had mercy and used non adjustable ones. Maybe it just seemed that way. Or maybe not. Keep laughing.

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