Date   

Re: Extracting a buggered knob grubscrew

 

I once tried to order some items from Grainger and actually HAD a small business incorporated at the time... but I abbreviated the name of the company and they rejected my order, saying they couldn't find my business! So they did check.

I emailed back, gave them the full name and state charter number, and told them where they could shove their "businesses only" attitude and to cancel my account. Haven't bothered with them since. And as someone already pointed out, they tend to be more expensive than many other sources anyway.

-Charles


Re: The reason for Tek delay lines

Roy Thistle
 

On Tue, Feb 2, 2021 at 03:32 PM, John Williams wrote:


coax was never used in any delay lines inside Tektronix scopes.
From the TekWiki entry on Delay Lines
"The first Tektronix scope to contain a delay line was the 513D, which uses an L-C network. Soon after, the 517 appeared, using 51 feet of RG-63U coaxial cable as a 65 nanosecond delay line. 7000-series scopes use special twin-lead delay cables. The delay line in the 519 is a large coil of low-loss air-dielectric semi-rigid coax."


Re: Slightly OT: OK Electronics tinyscope

Greg Muir
 

I remember seeing ads in the trade rags for NLS scopes back in the 70’s. I’m not sure which of the series of manufacturer products introduced during this ears of miniature scopes but do remember that some were made in England and other countries.

Greg


Re: The reason for Tek delay lines

Ed Breya
 

Hi Tom, I wasn't referring to your nice description, but in response to some mentions earlier in the thread. I was composing my post while yours appeared. There's a natural delay in conversations too. One thing I like about these groups is that our posts show up nearly instantly. In some groups, it may take up to hours or even days, making it very hard to follow the pattern. But, the writing lag is always there.

Ed


Re: So while we are all here talking oscilloscopes

Dave Seiter
 

Seems to me that I've seen photos or drawings of them, possibly while looking into 519 history.  I know I've seen references to them, but don't recall if they were Russian or just early attempts by various universities to get to the GHz threshold.
-Dave

On Tuesday, February 2, 2021, 03:18:49 PM PST, snapdiode via groups.io <snapdiode=yahoo.com@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

Miguel Work
 

"The trigger and sweep circuitry need about 60 ns to start so there is no signal display during this time".

https://vintagetek.org/113-delay-line/#:~:text=A%20delay%20line%20is%20used,signal%20display%20during%20this%20time.


Re: Spectrum analyzer Tektronix 7L13 on mainframe Tektronix 7603

Miguel Work
 

Hi Attilio, I calculate that with the7L13 adjusted at 105Mhz center and 5 Mhz span, 1st sweeps from 2175 to 2225 Mhz, and 2st is fixed at 2200Mhz.
If TR502 oscillator is at 2095 Mhz, mixed with 1st IF sweeps from 80 to 130Mhz, and mixed with 2st 105Mhz, fixed

Voltage seems a little high, Is easy to look what is inside the 2095 (2072 in TR503) oscillator? May be it can be adjusted to increase frequency at 2095 with 7V

I have never done this calibration.


Re: What is a Telex 453A?

Michael A. Terrell
 

Robert Simpson via groups.io wrote:
Saw this in Craigslist
https://sfbay.craigslist.org/scz/atq/d/felton-vintage-oscilloscope/7270622648.html

Looks very similar to a Tektronix 453A
It is a Tektronix. I've had one for over 30 years. They were surplussed when Telex left the IBM mainframe compatible terminal business. The face has the 'Property of Telex' silk screened on it. Mine came from their Orlando facility. I paid $400 for it, and I repaired many Commodore computers with it.


Re: The reason for Tek delay lines

Tom Lee
 

Yes, which is why I specifically redefined coax to include non-coax. :) And your supposition is absolutely correct — the helical lines misbehave so badly that they’re only practical below a few hundred MHz. At some point the equalization circuitry becomes so complex that regular old cable starts to look attractive, despite the length/weight.

The variable part of the delay lines used in the 7A19 and 7A29 with that option are a very nice mechanical design. I like the “trombone slider” arrangement used to vary the path length.

Tom

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

On Feb 2, 2021, at 4:49 PM, Ed Breya via groups.io <edbreya=yahoo.com@groups.io> wrote:

It may be good to be a little more specific in order to avoid confusion of terminology between "delay line" and coax and the differential straight or helical delay lines often seen in analog scopes. As I recall, one 500 series scope I had (maybe 585?) had a differential delay line that looked "old-school" in style (braided wire outer shield, I don't know if helical) compared to say the 7000 series ones (flat twin-lead, with gapped copper foil shield). As I recall, the 7K (except 7104 which I don't know) all have these straight twin lines, and are thus quite long for the delay, compared to helical types, which I don't think are capable of good enough fidelity much above the hundred MHz class. The 2200 series 100 MHz scopes managed to go helical, and have very compact lines - a few turns wrapped around the back end of the CRT. Regular coax is used in the 7S14, for instance, since its sequential sampling system needs a delay line (random sampling and DSOs don't). There's a big roll of bare (presumably to save volume) coax squeezed in there for each channel. The 7A19 and probably 7A29 use some semi-rigid coax, to provide for the variable (on one channel) delay option. High grade single coax is still the best delay line for electrical signals, but of course can get very large for long delays.

Ed





Re: Slightly OT: OK Electronics tinyscope

-
 

I never had a Tiny Scope but I did have one of the small NLS scopes. You
couldn't see much detail on the small CRT but it was still a very handy
piece of gear for simple troubleshooting, Mine disappeared one day and I
never found out what happened to it but I wish that I still had it.

On Tue, Feb 2, 2021 at 2:54 PM Greg Muir via groups.io <big_sky_explorer=
yahoo.com@groups.io> wrote:

I know that this a wee bit off-topic but I also know that there are a
bunch of “tinyscope” people out there who deviate from Tek products purely
to experience the Lilliputian world.

Found on ePay:

https://www.ebay.com/itm/OK-Electronics-10MHz-1010-Portable-Battery-Operated-Oscilloscope-w-Charger/174351418853

Greg






Re: Slightly OT: OK Electronics tinyscope

Michael A. Terrell
 

John Williams wrote:
Very interesting topic. Please do not forget the 321 and 321A. These while not tiny are certainly small compared to the other scopes of the times. And they offered not only big scope performance but a variety of power sources including internal batteries. I have a dozen of them now, and have forbidden myself from buying any more!
I have several of both the 323 (5MHz) and 324 (10MHz) Tek scopes.


Re: The reason for Tek delay lines

Ed Breya
 

It may be good to be a little more specific in order to avoid confusion of terminology between "delay line" and coax and the differential straight or helical delay lines often seen in analog scopes. As I recall, one 500 series scope I had (maybe 585?) had a differential delay line that looked "old-school" in style (braided wire outer shield, I don't know if helical) compared to say the 7000 series ones (flat twin-lead, with gapped copper foil shield). As I recall, the 7K (except 7104 which I don't know) all have these straight twin lines, and are thus quite long for the delay, compared to helical types, which I don't think are capable of good enough fidelity much above the hundred MHz class. The 2200 series 100 MHz scopes managed to go helical, and have very compact lines - a few turns wrapped around the back end of the CRT. Regular coax is used in the 7S14, for instance, since its sequential sampling system needs a delay line (random sampling and DSOs don't). There's a big roll of bare (presumably to save volume) coax squeezed in there for each channel. The 7A19 and probably 7A29 use some semi-rigid coax, to provide for the variable (on one channel) delay option. High grade single coax is still the best delay line for electrical signals, but of course can get very large for long delays.

Ed


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>

9401 - 9420 of 186939