Date   

Re: Cheap cables from China

Mark Goldberg
 

I've tended to use double or triple shielded cable or hardline for
interconnects. I happened on some really good ones. I suppose you
could transmit into a dummy load and see what leaks out the cable, but
it depends on the leakage in the dummy load and transmitter also. I've
definitely seen differences in cable leakage but have not taken
qualitative measurements.

Regards,

Mark

On Sun, Mar 14, 2021 at 8:07 AM Charles <charlesmorris800@centurytel.net> wrote:

Thanks for the info. I'd forgotten about the shield coverage! Can anyone help me devise a simple test that doesn't require switching 200 amps? :) I can generate 500 watts or more of RF at 50 ohms with my ham gear, but only up to 30 MHz.

These cables actually do look reasonably well made, but of course I would not expect them to hold up to daily continuous use like Tek or GR cables. For 99 cents each, they'll probably be fine for occasional tinkering.





Re: 308 Data Analyzer

stevenhorii
 

I know that HP (sorry!) uses signature analysis for troubleshooting some of
their computing counters. Does Tek specify signature analysis for
troubleshooting of their scopes with digital processing and control?

Steve Horii

On Sun, Mar 14, 2021 at 12:44 Dick <w1ksz@outlook.com> wrote:

In my 5 year purge of deep storage I came across a Model 308
Data Analyzer. It seems to have all the cables and manual and
does turn on.

Is this of any use in todays world or should I just recycle it ?

Thanks, Dick, W1KSZ






Re: 308 Data Analyzer

Dick
 

OK, you talked me into keeping it. Back on the shelf it goes.

Thanks for replying,

Dick, W1KSZ
________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Paul Amaranth <paul@auroragrp.com>
Sent: Sunday, March 14, 2021 9:58 AM
To: TekScopes@groups.io <TekScopes@groups.io>
Subject: Re: [TekScopes] 308 Data Analyzer

Do NOT recycle it!

It's a useful 8 bit logic analyzer along with a signature analyzer.

With all the cables you should be able to get $75-100 for it, give
or take.

Signature analyzers have been going up in price in the last
couple years.

Somebody's going to want it.

Paul

On Sun, Mar 14, 2021 at 04:44:19PM +0000, Dick wrote:
In my 5 year purge of deep storage I came across a Model 308
Data Analyzer. It seems to have all the cables and manual and
does turn on.

Is this of any use in todays world or should I just recycle it ?

Thanks, Dick, W1KSZ







!DSPAM:604e3d77221071127818502!
--
Paul Amaranth, GCIH | Manchester MI, USA
Aurora Group of Michigan, LLC | Security, Systems & Software
paul@AuroraGrp.Com | Unix/Linux - We don't do windows


Re: 308 Data Analyzer

Paul Amaranth
 

Do NOT recycle it!

It's a useful 8 bit logic analyzer along with a signature analyzer.

With all the cables you should be able to get $75-100 for it, give
or take.

Signature analyzers have been going up in price in the last
couple years.

Somebody's going to want it.

Paul

On Sun, Mar 14, 2021 at 04:44:19PM +0000, Dick wrote:
In my 5 year purge of deep storage I came across a Model 308
Data Analyzer. It seems to have all the cables and manual and
does turn on.

Is this of any use in todays world or should I just recycle it ?

Thanks, Dick, W1KSZ







!DSPAM:604e3d77221071127818502!
--
Paul Amaranth, GCIH | Manchester MI, USA
Aurora Group of Michigan, LLC | Security, Systems & Software
paul@AuroraGrp.Com | Unix/Linux - We don't do windows


Re: 308 Data Analyzer

 

I still use mine from time to time to do signature analysis debugging

David

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Dick
Sent: 14 March 2021 16:44
To: TekScopes@groups.io
Subject: [TekScopes] 308 Data Analyzer

In my 5 year purge of deep storage I came across a Model 308
Data Analyzer. It seems to have all the cables and manual and
does turn on.

Is this of any use in todays world or should I just recycle it ?

Thanks, Dick, W1KSZ


308 Data Analyzer

Dick
 

In my 5 year purge of deep storage I came across a Model 308
Data Analyzer. It seems to have all the cables and manual and
does turn on.

Is this of any use in todays world or should I just recycle it ?

Thanks, Dick, W1KSZ


Re: Cheap cables from China

 

Thanks for the info. I'd forgotten about the shield coverage! Can anyone help me devise a simple test that doesn't require switching 200 amps? :) I can generate 500 watts or more of RF at 50 ohms with my ham gear, but only up to 30 MHz.

These cables actually do look reasonably well made, but of course I would not expect them to hold up to daily continuous use like Tek or GR cables. For 99 cents each, they'll probably be fine for occasional tinkering.


Re: Tek 2465 (1st gen) - help with A5 board troubleshooting?

Chuck Harris <cfharris@...>
 

Contrary to how a modern person might think they are
done, the 2465 (orig) does not use digitizer pots to
handle the variable controls on the front panel. They
use actual pots. The cursors use a very strange two
element, two wiper pot without any rotation stop.

When one wiper is about to run off the end of one pot's
element, the other wiper is just starting on its element.

The CPU figures it all out when the pot's position is
digitized.

Your cursor problem is painfully common, and is caused
by noisy pot elements. It can easily be fixed by taking
the pot apart and putting a drop of Caig's FaderLube on
the element.

I have never seen a failed EAROM on a 2465 (orig).

-Chuck Harris

AngiesHusband via groups.io wrote:

Ok, I will check that out! The Lead Electronics link seems to be a pretty good price - thanks for the link!

How about thoughts the issues with the display:
*When the trace markings are on (knob CW), there are little “single pixel” specks that flash now and then in the upper and lower margins of the scope.
*When the delta-T/delta-V markers are on - same thing happens, little specks randomly seen on the scope
*The biggest issue: when the "delta ref" or "delta" knob is turned, the marker stutters as it moves. Sometimes even moves randomly in the opposite direction it is being turned.

I can't see that being an EAROM issue... feels more like something with the logic/timing/etc...?

Paul






Re: SMB Adaptor (again)

Joseph Strickland
 

My experience when I worked at Collins Radio in Richardson was that there were two types of BNC connectors. In the 50 ohm case there was a white nylon or Delrin plastic protection sleeve around the female center contact of the connector. The 50 ohm male pin that interfaces with the female contact is physically a little larger than the male pin in the 75 ohm mating BNC connectors. The 75 ohm BNC connectors with the female contacts have exposed contacts not surrounded by the white plastic seen in the 50 ohm connectors. That makes them more subject to damage from mating connectors pushed on to them at a slight angle. That is why you often see 50 ohm BNC connectors used on 75 ohm cables and their mating connectors on test equipment. In true 75 ohm connectors both the female and male contacts are exposed in the center of the connector and somewhat thinner than their 50 ohm family equivalents. When 50 ohm connectors are used in 75 ohm applications the main difference seen is that there is a slight reduction in return loss when compared to true 75 ohm connectors. Typical BNC connectors cause about 1/2 dB of signal loss whether 50 ohm or 75 ohm.

When it came to coaxial cables, the best quality ones specified in Collins/Rockwell telecommunication equipment used double shielded 1% 30dB or better return loss specified cables made by Times Cable Co. I don't know if it was a standard practice of Times Cable for their 75 ohm coaxial cable of the 1% return loss type or not, but they usually came with a violet stripe along the length of the coaxial cable. The high return loss (30dB or higher) had to be checked against 50 ohm or 75 ohm high accuracy loads in order to verify the true quality of the coaxial cable. Times Cables always were consistently best in that measure. 50 versus 75 ohm impedance connectors become more important the higher the signal frequencies are that are being handled by the equipment being tested or verified.

Collins often used variable trimmer capacitors on both baseband and RF circuits that required best impedance match to the highest expected frequency to be handled. They were adjusted with unit under test equipment having its normal cables within the equipment already connected while using a swept input signal covering the full range of signal frequencies to be handled by the equipment. The trimmer capacitors were adjusted for the best return loss over the full range of the signals being handled. Typically Selective Volt Meters of high accuracy by HP, Tektronix or Wandel & Goltermann were used for those checks and adjustment verification. Test equipment had to be verified against industry calibration standards on a regular schedule. Most of the analog equipment had to have good return loss at baseband frequencies from near DC to at least 30mHz. All the systems and unit test technicians I worked with insisted upon the very best performance that could be obtained with state of the art products.

Joe KC5LY


Re: Broke my TDS3000B

 

I've just put it back together after yet another cleaning session, but with no change ☹

However I do have something to report which may be useful: If I bring up the acquire menu, and select "Fast Trigger" (500 points), then the calibrator wave form is display correctly down to a sweep speed of 20us/div (400us/div in "Normal Resolution" mode). If I go down 10us/div it all breaks up into a mush again.

I'm sure this means something useful to someone who knows more about how this beastie works.

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Martin
Sent: 12 March 2021 13:52
To: TekScopes@groups.io
Subject: Re: [TekScopes] Broke my TDS3000B

I've no idea what I should be looking for and those pins are mighty small
and close together.
Oh yes, thats not easy.

I was thinking about checking if the lines are totally stuck or are looking normal, i.e. change state every now and then.
Or if a line is moving a little when you switch below 400us... things like that, to confirm or not if the ASIC really has a problem.

cheers
Martin


Re: Cheap cables from China

Jean-Paul
 

The work we do involves a sytem of probes, cables, scopes, etc.

The weakest point in the signal chain will determine the BW, risetime, CMRR etc of the observations.

Cables are often assumed to be OK but there are many differences.

We noticed that the BNC cables poorly made in China easily fail, bad connections, improper crimps, poor quality connectors, etc.

I bought a bunch of original Tektronix USA made calibrated BNC><BNC 0.5M cables. 012-0480-00 from an Ex TEK man.

These are the very best. They have served me for decades.

Kind Regards,

Jon


Re: Cheap cables from China

cmjones01
 

I've had similar experiences with cheap RF cables. As far as matching and
signal quality goes, they seem fine at least for my uses though I wouldn't
want to use them for any quantitative measurements higher than a couple of
GHz (for the SMB cables).

What I have noticed is that the cheap "RG58" cables often have terrible
screening. This became apparent when I used some to connect AM503 current
probe amplifiers to a scope in an environment where there were high-current
(>200A)transients from switching a large battery. These transients found
their way in to the cheap cables making proper current measurements
impossible (the scope still triggered even with the AM503s powered down!).
The problem went away when I used old scruffy cables with a heavier screen.
Some of this may have been due to a lower earth loop impedance.

Chris

On Sun, 14 Mar 2021, 03:18 Charles, <charlesmorris800@centurytel.net> wrote:

I got a closeout deal, five 3-foot RG-58 BNC male to male cables for $4.95
(shipped!). The ebay ad did not say where they were made, but the price
should have told me. They have tags with a p/n and "Made in China", of
course.

Anyway I figured they'd be OK up to HF, at least, but not high speed. So I
hooked up my avalanche generator and GR power divider, and put one of the
cables in the path to the faster (S-4) sampling head. Plus a GR-BNC adapter
on one end, and an SMA-BNC on the other end. Figured it should look like
crap.

Well... there are NO differences in the dual traces, once I adjusted the
3S2 (B Delay knob) for the extra 5 ns or cable! There is a slight
difference in transient response but I have not attempted to adjust either
head (and the S-4 has a new hybrid diode assembly). That was a real
surprise to me. Figured there would be reflections, sags, etc. everywhere.
Both at 1 ns/div (photo in Sampling with 3S2 album) and zoomed out (slower
sweep speeds). Nothing but the artifacts from my still-in-development
pulser.

I figured I couldn't get too hurt for $5...
Thoughts?






Re: Tek 2465 (1st gen) - help with A5 board troubleshooting?

 

Paul,

I am far from the best person to be making diagnoses of these display issues, but since I happen to also have a 2465 handy, let me try to reproduce your symptoms. Then we might at least know if they are a common malfunction (even if we can't know if they are or are not an actual malfunction).

I powered up my scope, hooked up a P6131 to channel one, connected to the calibrator signal, turned off all but channel 1 (all off), set the time base to 1 ms, and the V/DIV to 100 mV.

When displaying either the delta V or delta T cursors and moving them actively, I occasionally get a flicker of a pixel in the upper and lower readout areas, more frequently in the lower area than in the upper. The flickering pixels share intensity with the readout. The flickering pixels happen whether or not the readout is active, but only happen with the cursors are active (and they have their own read out that does not turn off when the scale factors are turned off).

Does this sound like what you are seeing?

I will try to get pictures that I can post to the photos section.

I don't see any "stuttering" of the delta REF cursor on my scope. I would suspect a bad or dirty rotary encoder. I have no idea what to do about that (again, other folks here will probably have better advice).

-- Jeff Dutky


Re: Cleaning Scratchy Bourns MOD pots

Jim Adney
 

On Thu, Feb 18, 2021 at 06:01 PM, Dennis Tillman W7pF wrote:

McMaster-Carr sells 2-56 screws up to 1 3/4" long at very reasonable prices
($7 for 25 screws). There are even longer ones but they cost much more.
M-C also sells 2-56 threaded rod, hex nuts, and washers in lots of choices of material. Buy 3' and make your own. You could even solder the hex nuts on and make your own hex head 2-56 bolts in any length you like. The Mod Pots I've worked with might not have enough room for the hex nuts unless you put a couple #2 washers under them.


Re: 454 fireworks

Sean Turner
 

Good call on checking the +75 supply too...it's running at +100!

Sean


Re: Repairing broken pots

 

Hi Rick,

so what I have here is not "Bourns" but "Allen/Bradley", with the blue pot body on the left and the shaft with its actuator, right? The knob on the front is not damaged, but it must have got a hit to make the shaft/actuator break up like that.

I would be happy with a good picture of this shaft/actuator assembly to see how its supposed to look like. When I try to position the shaft on the remains of the actuator it does not fit well because the actuator is bent somehow. Unbending the part looks possible, but I'm afraid of breaking it up alltogether by doing too many try-and-error cycles.

cheers
Martin


Re: Tek 2465 (1st gen) - help with A5 board troubleshooting?

AngiesHusband
 

Ok, I will check that out! The Lead Electronics link seems to be a pretty good price - thanks for the link!

How about thoughts the issues with the display:
*When the trace markings are on (knob CW), there are little “single pixel” specks that flash now and then in the upper and lower margins of the scope.
*When the delta-T/delta-V markers are on - same thing happens, little specks randomly seen on the scope
*The biggest issue: when the "delta ref" or "delta" knob is turned, the marker stutters as it moves. Sometimes even moves randomly in the opposite direction it is being turned.

I can't see that being an EAROM issue... feels more like something with the logic/timing/etc...?

Paul


Re: SMB Adaptor (again)

n4buq
 

I've only seen them in the Collins R390/R390A and Collins aircraft radios. I don't know whether those are 50-ohm or 75-ohm.

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "Tom Lee" <tomlee@ee.stanford.edu>
To: TekScopes@groups.io
Sent: Saturday, March 13, 2021 7:58:48 PM
Subject: Re: [TekScopes] SMB Adaptor (again)

They are pretty cute, but I've not seen 50 ohm versions. Do they exist?
And if they exist, do they mate with their 75 ohm cousins? (That may be
illegal in some states)

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 3/13/2021 17:24, n4buq wrote:
The mini-BNC (MBNC) connectors are cuter.

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "Jeff Dutky" <jeff.dutky@gmail.com>
To: TekScopes@groups.io
Sent: Saturday, March 13, 2021 6:27:08 PM
Subject: Re: [TekScopes] SMB Adaptor (again)

Tom,

Clearly my complete unfamiliarity with RF equipment of any kind betrays
me.

They're awfully cute little connectors. I'm a bit surprised that they
weren't
used more frequently on the various plug-in families: space is quite
limited
on those front panels.

My main exposure to RF connectors is the tiny, right angle coax connectors
used on modern laptops for the WiFi antennas. I expect that they are not
rated for a large number of connect/disconnect cycles.

-- Jeff Dutky













Re: More 1S1 fun...a closer look at tunnel diodes and power supply ripple

Jonathan Pyle
 


Photo Cheap Chinese cable meets fast pulse, 1 ns/div updated #photo-notice

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

The following photos have been updated in the Sampling with 3S2 album of the TekScopes@groups.io group.

By: Charles <charlesmorris800@...>

12801 - 12820 of 192862