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Just in case people are not viewing the FS/WTB Group, I still have 468/465/465B for sale (in the UK only) on that group and am open to offers.

Check that Group site for full info.

Regards

Nigel

Hi Siggi,

Thanks, I've been able to run through the CAL01 (X) and CAL02 (Y), however I'm still lost at step 'jj'. I connect up a second scope as it says, with CH1 from the marker generator (in my case the Siglent) and CH2 coming from the Gate output of the 2465B, and set triggering to CH2.

Then for cal step 17 set the Siglent pulse gen to 500mV p/p (is that supposed to be 0 to +500mV, or -250mV to +250mV? I used the latter), 1uS period, 100nS pulse width. Then I see that waveform as expected on the second scope.

But next, the manual says:

"adjust the Delta control for roughly the listed number of markers over the center 8 divisions, then superimpose markers on bench scope screen"

- I've got the markers i.e. the pulse gen output visible on the bench scope, and the gate waveform, what does 'superimpose' mean? Have the two traces on top of each other?

It then says "Manually set SEC/DIV setting of bench scope to keep a usable time mark as listed in Table 5-3"

- I presum if just means keeping the pulse train on CH1 and the gate waveform on CH2 visible?

Then it says "Use IUT DELAY POS to bring markers on screen".

- Err, which screen? Is that the 'Delta REF / DELAY POS' control? Where are they if they are not 'on screen'?

Next, "When markers are superimposed"

- Again, on what screen?

I just skipped thru steps 17-34 as it was not clear how to do these steps. I do wish Tek had added some images of what you're supposed to be doing on the Table 5-3 steps. The waveforms after cal seem to have the correct amplitude and time with the A timebase, but probably the delayed timebase is not right as you mention.

- Keith

Hi all,

I have a very unstable 7A15A Plugin ... for example, signal varies in amplitude on some Volts/Div settings, but not others, incorrect Readout (incorrect numbers, missing symbols), signal changes when touching the Volts/Div knob.

As the Plugin is quite dirty inside, I am in the process of removing the Readout/Attenuator pcb's and Cam switch as a Unit to clean the switches properly. I have removed everything except the BNC. I am unable to get a decent grip of the BNC nut without damaging other components ... C100 and the Attenuator shield mount are blocking sockets or tube spanners. What do you recommend as the best approach???

This is my first attempt at pulling apart one of these Plugins. Advice appreciated.

--
Cheers,
Ian,
Melbourne, Australia

I recently acquired a second TDS-380 that was "working" - meaning with an signal at the output it displayed a trace on the screen. But the 'scope displays an offset with no input signal. With no input to either channel, Channel 1 measures a mean voltage of about -1.95 volts on the 2 volt scale, and Channel 2 a mean voltage of about -2.55 volts on the 2 volt scale. These measurements vary with the vertical scale setting.

I ran through the calibration procedure, and then measured the 5 volt calibration signal. For sweep rates of 25 uSec per division and slower (not fit to screen mode) the amplitude measures about 5 volts. When I increase the sweep speed to 10 uSec per division the displayed waveform and measured amplitude almost doubles.

I have replaced U402, the acquisition RAM, as that has been found a problem elsewhere, including my other TDS-380 which had similar problems that were corrected by replacing that RAM. No change for this 'scope.

I have the manual with schematics and layouts, but there is no circuit description in the manual. Is there a circuit description available somewhere? This would certainly be helpful in trying to isolate the problem to a block. on the Root Sheet - block diagram.

I don't believe there are any surface mount electrolytics on the mainboard. On the other hand, I have software to communicate with the 'scope over the RS232 port, and discovered eleven open traces on that board that required jumpers before the computer would communicate with the 'scope.

Any assistance will be appreciated.

Gary Appel

I got this piece new-in-the-box a last year and I've finally powered it up & checking it out. Even the battery seems ok. It must be time for me to start digging through the history of the group and this scope. First need to see if it can talk to my computer.
Ron

On Tue, Jan 21, 2025 at 02:35 PM, vk2bea wrote:

but I don't see where to actually set the pattern that is matched.

OK, I did overlook the paragraph...

a. Turn the Δ REF OR DLY POS control to the clock mode character, the qualifier bit, or a digit of the word.
b. Turn the Δ control to define the underlined character. Digits of the word can be set to 0, 1 , or X with BIN radix, 0 to 7 or X with OCT, and 0 to F or X with HEX . Note that the clocking edge can be redefined here.

I've looked over the 2465B manual but I can't for the life of me find where it describes setting the word recognizer pattern.

I can set the trigger to trigger on the word recognizer match and I can change the radix but I don't see where to actually set the pattern that is matched.
If anyone knows ... please let me know!

On Tue, Jan 21, 2025 at 12:15?PM Keith via groups.io <keith=
[email protected]> wrote:

The initial step of probing TP800 and twiddling the delta ref knob seemed
straightforward, but I'd love to know what this is for, the manual does not
say.

...

I believe I was able to get up to step 16 correct, but the next steps
(starting from 17) baffled me. The manual says connect the time marker to
both the 2465B and a second scope's CH1, and the Gate Out of the 2465B to
the second scope's CH2 and trigger off that channel. But then the next
paragraph (jj in the manual) completely confused me. What is it all about?
What's the purpose of the second scope, what is a 'usable time mark' ? It's
as clear as mud.

Hey Keith,

I remember wondering the same things when I calibrated my 2467, though at
the time I didn't understand enough of how these scopes work to do more
than follow the instructions.
There is some mention of calibration and calibration constants in the
Theory of Operation section, maybe that'll help?

The principle involved is that you first calibrate the CRT and the cursors,
and then everything else is adjusting gains & offsets to a given time
reference to align sweep times, and delay offsets (I believe) to the
calibrated CRT (and cursors), as well as calibrating the the two sweeps (A
and B) with respect to each other. Note that sweeps on these scopes are
calibrated even with the horizontal VAR control out of detent, which is not
the case for earlier scopes (I believe).
The sweeps need their delays calibrated as you can e.g. measure time delays
with dual delay display and e.g. overlaying edges or waveforms. The A sweep
delays can be calibrated by displaying the B-trace after a delay (or dual
delays), but the B-sweep delays are calibrated by looking at the B sweep
gate, I believe.
If you look at the sweep schematics, you'll see that the delay gate of the
B-sweep hybrid is routed to the sweep gate output, which I believe is only
useful for calibration, and hence I believe the steps using the B-delay
gate are calibrating the B-sweep delay.
It's been a while since I dug into this. I'm fairly sure I never sussed out
the purpose of each of the steps, and my reasoning might have been off to
begin with, but maybe you'll figure this out?

... time passes ...

Now that I think about it, I can see how the A sweep delay(s) are used to
highlight the A sweep, as well as to implement B delay sweeps and dual
delay sweeps. I'm struggling to figure out what the B sweep delay reference
is actually used for. After reading the ToO section, I believe the B-sweep
may be used for options to measure stuff, maybe e.g. pulse timings, meaning
it'd need calibrated delays?

Siggi

John,

Look for pots R2918 and R2931 on the A5 board. These are the centering and gain. Usually the centering pot is centered and the gain is adjusted. Resistors R710 and R910 on the A1 board could be too high. The latter is for the horizontal section. These I replaced with a pair of 20meg 1% in series in my B version. The original 39 meg 1/4W carbons were almost 60 meg in mine.

Mark

Hi All. On my 2465A the scale factors are readable and seem to be accurate but they are nearly off the bottom of the screen. I have to look at an angle to read them. Is there an adjustment that is necessary to bring them back into view? Or do I just need to learn to stand on my tip toes!

Everything else seems to fine with the scope... but this is pretty annoying.

Thanks in advance for any advice.

John w.
N7ZMG

So I started to go through the cal steps - the power supplies, DAC ref and CRT (cal08) steps seem reasonably straightforward. Then I tried cal01, the horizontal cal step.

The initial step of probing TP800 and twiddling the delta ref knob seemed straightforward, but I'd love to know what this is for, the manual does not say.

Oh well, onto the next step, connect up a time mark generator. I used the Siglent function generator, it seems to be adequate when using it in Pulse waveform mode, specifying the period e.g. 0.1mS where it says set the time markers. You need to set a suitable pulse width, not too large but not so small that the pulses become difficult to see. But it seems adequate.

I believe I was able to get up to step 16 correct, but the next steps (starting from 17) baffled me. The manual says connect the time marker to both the 2465B and a second scope's CH1, and the Gate Out of the 2465B to the second scope's CH2 and trigger off that channel. But then the next paragraph (jj in the manual) completely confused me. What is it all about? What's the purpose of the second scope, what is a 'usable time mark' ? It's as clear as mud.

- Keith

Thank you David.

I am very curious to see any data on their tunnel and pin diodes.

On Tue, Jan 21, 2025 at 10:20?AM david via groups.io
<davide_us@...> wrote:

I will check for them there. I don't remember where I got them from, will look there.
David

I will check for them there. I don't remember where I got them from, will look there.
David

Did as you suggested, main TB at 5ms/div and delayed at 5us/div, sync in from VSync. Got what I needed from an excellent but faint display. Now to deal with the revealed issue (NOR gate coupled to an SR Latch, to truncate the VSyncso it starts immediately after the end of the last line in the frame is complete).

Thanks for the steer. - much appreciated

--
Christopher Hilton-Johnson
The Stone Barn
Cottisford
Oxfordshire
NN13 5SW

07831 458867

Are they on the TekWiki and KO4BB sites? They would be the best places to
archive them if they are not already there.

DaveD
KC0WJN


On Mon, Jan 20, 2025 at 16:33 david via groups.io <davide_us=
[email protected]> wrote:

I have a PDF File titled - "TEK_XREF_TUNNEL_DIODES", also have a PDF file
- "TEK-MADE INTEGRATED CIRCUIT CATALOG" If you would like them, I will
upload to files directory.
David

I have a PDF File titled - "TEK_XREF_TUNNEL_DIODES", also have a PDF file - "TEK-MADE INTEGRATED CIRCUIT CATALOG" If you would like them, I will upload to files directory.
David

Hi all,

I thought it might be useful to share my updated conclusion. My fix tamed the problem somewhat, but not enough to make it fully usable, so I replaced it with a compatible tube, which was a 154-0731-00 from a 465. This solved the problem: the display is now perfect, pin-sharp, constrasty and, more importantly, it remains so over time.

Besides, I found what seems to be the explanation in a document available on Tekwiki, discussing the Tektronix CRT reject codes:



More specifically, code R324 (page 5) entitled "Spurious mesh emission" is described as causing "a glowing spot or area which persists after the beam is removed" - well, well!. This is caused by "MgO particles not properly covered by aluminum [on the surface of the scan expansion mesh]". And, "It also appears if the aluminum is not conductive because of oxidation", which, I suppose, might explain why some tube develop this problem after several years, as aluminum deteriorates. So in conclusion, the tube is basically dead when it starts glowing, and there is no other cure than replacing it.

I hope this can be useful to those experiencing the same problem.

Raymond ACK on all,

I forgot about " show quoted text" to see interleaved response.

I referenced Jim W avalanche and Tek TD pulsers only as possible alternatives to Leo Bodnar, the gold standard

The PG506 is reasonable on fast but nowhere near as good the Leo B. I never used the avalanche JW.

I tried old Tek TD pulser adapter, but tweaky, high level input required.

Am lucky to have two of the old versions of the Leo Bodnar, handy to compare two plugins or channels.


Jon

The following items have been added to the Files area of the [email protected] group.

* /070-6860-00.Tektronix.2465B-Operators.Manual.pdf ( /g/TekScopes/files/070-6860-00.Tektronix.2465B-Operators.Manual.pdf )

*By:* vk2bea <vk2bea@...>

*Description:*
070-68860-00 2465B / 2455B / 2445B Oscilloscope - Operators manual (high quality scan with navigation links)

Sorry for delay and thanks!