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Ray, Bonjour

No idea about the divider, the output must drive a 50 ohm load, at leas 1 V

Easier with discrete parts. No freq divider needed.

Usually a 1-10 MHz rate.

many fast pulser designs on EEVBLOG, see " show me your fast square wave ", as well as Jim Williams as mentioned.

See old Tek pulser adapters, with TD and avalanche transistors.

Amicalement

Jon

Hi all,
As I am incompetent in this field you will take this with indulgence please but as Raymond above asks for "Any comments welcomed.
" I add my 2€ cents...
To generate a square signal at any frequency with a fast rise time I was thinking of using an Analog Devices HMC363S8G/GE SMT GaAs HBT MMIC DIVIDE-BY-8, DC - 12 GHz.
Output transition time claimed is 100 pS. GE is around 25€ with Mouser.
Output level is -6 to -9 dBm so with a good attenuator following to ascertain the 50 ohm the level would not be large but would that be silly?
Best
Renaud

On Sat, 18 Jan 2025 at 04:29, Michael - AF7U via groups.io
<michael.rosanbalm@...> wrote:

...I found C1743, a tiny 1.0pF cap had a weak/broken leg...

At any rate, I just wanted to update the thread for the unlikely chance

anyone was following it.

Thanks; some of us are following it.

Interesting to find a different type of capacitor fault, one that might
conceivable be diagnosed by holding your finger in exactly the right spot :)

I currently have
- one 485 that is definitely a parts mule,
- one that was working until I came back from a coffee break (and I haven't
looked at yet)
- one that almost works and I ought to sell after getting the second to
work.

The most frequent fix I've had to do is C911 (!) and other 15V tants on the
"hidden" 13V rail.

The most interesting fix was to repair a fault inside U660 which drives the
vertical deflection plates. The internal resistor had gone open circuit,
but since both ends were exposed to pins, I was able to add an external SMD
resistor. Successful, except that the risetime was extended from 1ns to
1.25ns.

Hi
Look here.

Hardy

-----Oprindelig meddelelse-----
Fra: [email protected] <[email protected]> P? vegne af daniel.ungureanu via groups.io
Sendt: 17. januar 2025 14:40
Til: [email protected]
Emne: [TekScopes] FlukeView for Fluke 105B Scopmeter Series II

Hi! I have an old Fluke 105B Scopmeter Series II. I have its serial cable, but I have the chance to access its floppy disk with the FlukeView app. Is there anybody who can help me with the app or a compatible one?

Thank you!

I think the term for the cap using enameled wire is called a "gimmick".

Sam Reaves
ARS W3OHM
Owner / Moderator of:
LeCroy Owners Group on Groups.io
Sencore Owners Group on Groups.io
Sprint Layout Group on Groups.io
Pulsonix EDA Group on Groups.io
LPKF Owners Group on Groups.io
Electronics and Mechanical Hardware Design Engineering Manager
Staff Scientist Andritz Rolls Global Research Center (RETIRED)

That's called a 'gimmick' -- a very useful thing indeed!

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
420 Via Palou Mall
Stanford University
Stanford, CA 94305-4070

Michael,


Make sure to tick the 'in stock' box. These are the radial types. The lead spacing of the leads will match the original 100meg resistor. I do not remember the exact hole spacing.

Mark

On Fri, Jan 17, 2025 at 03:41 PM, Mark Vincent wrote:

Great information .. just the guidance I was looking for. Thanks, I'll make the changes!

Resistors: R1853, R1854, R1871, R1872 and R1880 are stressed. It is advised to
make them 1W 1%. when these go bad, the focus will be off or not at all. R1991
is advised to replace with a 1% type. Mouser has these. For R1991, there is a
radial blue body style that will have its leads drop in the holes. A 1/2W
axial is available in Vishay VR37 series. The original 1/4W carbon will be way
out of tolerance. R710 and R910 are likely out of tolerance. A pair of 20 meg
resistors in series will work as replacements for each resistor.

Status update on the 485; as I mentioned in the earlier post, ALL the voltage rails were very close. I¡¯ll list them this time as I was asked if I checked them. Here they are; +- 15v, +-5v, +-5.5v, +50v, +9v, +25v, +120v, +180v, and + 59.4v. There are others but these are the main rails. They all checked within allowable tolerance. While I was checking voltages, I checked for ripple. I used a Fluke 289 in ACmV range for reference and the ripple on all rails was also very close. I backed up my tests with a scope. I have to admit, this was after quite a few caps had already been swapped out.

After R&R a number of Electrolytics in the PS, another Tantalum reared its ugly head, C1748 was shorted. As I mentioned earlier, it had more resistance to ground than most failed Tantalum capacitors I¡¯ve run across. I usually see somewhere around 0.03 to 0.06 ohms, however, C1748 was different, it was 0.28 ohms. I thought it might be through Silicon, but actually, it was via L1748, a small choke. After pulling the bad cap and replacing it, that¡¯s when things went South.

Here¡¯s what I found, after seeing all sorts of odd behavior on the screen I found C1743, a tiny 1.0pF cap had a weak/broken leg. For the life of me, I could not find a 1pF cap in my stash, I remembered some old-timer in the Radio/TV repair business back in the 60s needed a tiny value cap, not having one also, he fashioned one out of a short piece of insulated wire. I remember him calling it a ¡°Tickler¡± cap, whatever it was for escapes me now. However, I remembered what he did so I twisted a couple of pieces of small wire tightly together, maybe 4 inches. I trimmed the two legs and slowly trimmed the wire till I saw 1.5pF on my analyzer. I think it was about ? inch of 22 gauge insulated wire, I soldered it in place of C1743 and everything began working again, with no issues. I put the real deal in place sometime later.

So, there it is¡­ whether or not I broke the lead while replacing C1748, or it was weak/broke after 40+ years of service (I¡¯ve owned this machine since the early 80s), who knows? The important thing is, it¡¯s working again. I took several thermal images of all sides for future reference and filed them away in the manual. While in the manual, I noticed our store stamp, in made me smile, I ID stamped all our manuals, whether it was for bench equipment, or HiFi equipment, everything got stamped. I smiled remembering the day I unboxed the 485, along with a 475 and a couple of 466DM units. That was an exciting day in the shop¡­ many years ago. <smile> At any rate, I just wanted to update the thread for the unlikely chance anyone was following it.

First look up the 570/575 manuals and catalog info and see if P11 was ever even an option for these. I think all the curve tracers used low speed CRTs, so it's possible there was never such a thing in P11 (usually for high writing rate photography) for these. There still could be a match if you thoroughly investigate the various Tek CRT history, families, and uses. Start at tekwiki and see if you can find what CRT part numbers were used, and from there you can sometimes see what other models could have had the same basic tube, maybe including a P11. Also search by the original "T" (like T4XXX) numbers which are the most basic forms of the CRTs - a lot of 154- part numbers have evolved from relatively few T CRTs. After you look around enough and cross reference things, you get used to it. At first it is very confusing. Good luck.

For example, I found long ago and recently confirmed that the 577 (non-storage) model CT uses the same exact CRT as some 5000 series scopes - the 5110 AKA 5103N in this case, because I had a junker one. The carcass ran sufficiently to check the CRT which was in great shape, so it is now a spare for the 577. I have others of these too, but none so thoroughly tested for condition.

Ed

Raymond no replys seen in your last msg.

Forgot that latest Leo Bodnar site update no longer lists the BNC pulser version,

Their new pulsers are SMA connectors, with SMA to BNC adapter

Jon

Hi Jon,
Please find my responses interleaved.

Try Reference material - TekWiki

| | |
Reference material - TekWiki
|


Especially note:?
A couple of other docs also look promising
GL

Hello again Raymond,

A few notes on the CAL and fast rise pulses.

1/ Tek service manual CAL procedure is vague in a few places, see the notes from Chuck Harris on tekscopes2.

2/ since 1980s, we designed and researched low jitter digital transmission and transformers.

The transient rise time is important but especially the aberrations, eg percent overshoot, ringing, etc.

The PG506 fast rise is OK, and older Tek fast pulse adapter (TD, Avalanche) and Jim Williams Lin Tech can be used.

My standard is the Leo Bodnar 40 pS pulser, fortunately have two of the BNC model, USB powered
10 MHz. Highly recommended!

To have best results, use no cables, buffer pulser output with a Mini-Circuits HAT-20 20 db 50 ohm BNC attenuator (to minimize reflections from VSWR of the scope input).

That setup has worked for 2465/7/B and also 1 ghz scopes and plugins like 7104/7A29, to optimize the vertical transient response.

Note that transient response tweaking is in steps of interacting adjustments, affecting different time scales. The procedure should be repeated a few time for optimal results.

Can post some photos if any interest.

Amicalement


Jon

Michael,

Resistors: R1853, R1854, R1871, R1872 and R1880 are stressed. It is advised to make them 1W 1%. when these go bad, the focus will be off or not at all. R1991 is advised to replace with a 1% type. Mouser has these. For R1991, there is a radial blue body style that will have its leads drop in the holes. A 1/2W axial is available in Vishay VR37 series. The original 1/4W carbon will be way out of tolerance. R710 and R910 are likely out of tolerance. A pair of 20 meg resistors in series will work as replacements for each resistor.

Mark

To find the "where used" info, you need to refer to the RPR microfiche.

Ray M writes: I bought a pallet full of stuff. - a small parts cabinet with drawers of components - About half appear to be Tektronix, many in Tek bags, - Anyway to tell what these belong to?

The 15X series of numbers you refer to are the standard prefix numbers belonging to that family. There are literally thousands or part numbers and many hundreds of Tektronix products. Virtually all of them have transistors and diodes in them. Which ones? Depends on the instrument and the desired specifications of the individual application. To cross reference all of the TEK semiconductor part numbers you can look up the individual part numbers using the Tek Common Parts Catalog available here:

That will not tell you where they are used, just what they are.

Best regards,

Ferrous Steinka

On Fri, Jan 17, 2025 at 10:56 PM, vk2bea wrote:

I did the cal 08 procedure and the "High Drive Focus" was out quite a bit.

Congratulations!

I meant High Drive Focus when I wrote (high intensity) focus.

Raymond

When we closed our Electronics shop at the University, I bought a pallet full of stuff. In that, there was a small parts cabinet with drawers of components. About half appear to be Tektronix, many in Tek bags, others that look like Tek part numbers. Anyway to tell what these belong to? Many parts I will never use but could be of value to people here keeping old Tek gear running.

I can generate a list. Just curious if there is any cross reference of part numbers. I find the list of Parts categories, e.g.

151-0000-00 Transistors (1xxx=FETs)
152-0000-00 Diodes
153-0000-00 Selected diodes
153-0500-00 Selected transistors

The 2465B should keep focus when you turn up the intensity (at least you shouldn't need to change focus from low intensity to high intensity).

Quote from the manual:
"Focus tracking for intensity (VZ OUT) level changes is provided by the VQ OUT (quadrapole output voltage) signal at pin 22 of U950. The VQ OUT signal varies the focusing voltages (and thus the focusing strength) of two quadrapole lenses in the crt (diagram 8). The VQ OUT signal is related to the VQ OUT level exponentially and provides the greatest auto-focus control at high intensity levels. Gain of the VQ OUT signal is set by the High-Drive Focus adjustment, R1842. "

I did the cal 08 procedure and the "High Drive Focus" was out quite a bit.
Now it keeps focus throughout the intensity range. The trim pot is now set close to the end of range so I suspect something on the A9 board has drifted.
(although the "High Drive Focus" trimmer is just housed on the high voltage (A9) board ... it just sets a voltage on a pin of U950 IC/hybrid on the main board (A1)).

All the voltages on the low voltage board are spot on. I'll check the high voltage board (after I borrow an HV probe!).


Michael