That D suffix indicates Delay line, not Distributed amplifier. (So you could view the edge that triggered the sweep.) Tek's first distributed-amp scope was Type 517.

Dave Wise

On Mon, 16 Sep 2019, Chuck Harris wrote:

Sorry for jumping in but is it somehow possible to share those ROMs?

I do have 11801C sitting on a shelf with difficult access to it and I'm not
sure it has 1T option that would've been nice to have...

My 11801C, with OPTS 1T (Telecom std masks),

has, Exec: 4.05, Disp: 4.00, Timebase/Controller: 4.03, ACQ1: 9.02, ACQ2: 9.02

-Chuck Harris

Reginald Beardsley via Groups.Io wrote:

My scope is an 11801. That should be visible in the screen photo I posted.
Based on the dates on parts it is 1989 production. It is enough different from
the 11801C that it was obvious from the meager information in the service manual
for the 11801C that I needed an actual an 11801 manual. Zenith was kind enough to
furnish a scan of the 11801 service manual, which is now available online, but I
bought a paper copy.

I currently am triggering off a square wave on one channel of the 33622A while
displaying a ramp from the other channel. There is a periodic jitter in the time
base, so even with an external trigger I cannot get a stable sweep. In 1024 point
mode at 1 ps/div it appears that there are 4-5 subsweeps before it repeats. As a
result the trace oscillates back and forth over a span of about 1.3 ps as it
drifts across the screen. In 5120 point mode it seems to have just 2 subsweeps
with ~1 ps dither between them.

When the OXO heater kicks on everything jumps out of sync for a while. It may
well be that the mystery NVRAM calibration constants are intended to correct the
time offset between the sweeps. IIRC my timebase ROMS have a 1991 or 1992 date,
so it is possible that my scope had a FW update and could be corrected if I knew
where and what values to write with a PROM programmer.

If someone has an 11801C or other newer model open I'd appreciate version and date
information on the timebase board ROMS. But if anyone knows *anything* about this
I'm very interested in investigating. I've got another 11801x in CA at my
sister's house which I'm waiting for her to ship to me. I have had more fun with
my 11801 than any other piece of test gear I've bought. Being able to see
reflections from each side of a high grade SMA-F to N-F adapter is quite amazing.

Have Fun!
Reg

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How extensive is the damage? If it's just the thread, a fine triangular needle file will fix that.

If the side has been pushed in so it is no longer round, but not too badly damaged, it's a bit more complex, but still a fairly simple repair if you have access to a small lathe with which to make a plug expander to fit inside the connector.

I made one once to fix a friend's flute foot joint which was worn and allowed the foot to fall off. It took a couple of tries to make one that worked, but I'm not a machinist and had no experience. All I had to go on was the concept of a conical plug being pulled into a conical hole which then forced the outer cylinder to expand.

Would you post a close up photo to the files section?

Have Fun!
Reg

That D suffix indicates Delay line, not Distributed amplifier. (So you could view the edge that triggered the sweep.) Tek's first distributed-amp scope was Type 517.

Dave Wise

My scope is an 11801. That should be visible in the screen photo I posted. Based on the dates on parts it is 1989 production. It is enough different from the 11801C that it was obvious from the meager information in the service manual for the 11801C that I needed an actual an 11801 manual. Zenith was kind enough to furnish a scan of the 11801 service manual, which is now available online, but I bought a paper copy.

I currently am triggering off a square wave on one channel of the 33622A while displaying a ramp from the other channel. There is a periodic jitter in the time base, so even with an external trigger I cannot get a stable sweep. In 1024 point mode at 1 ps/div it appears that there are 4-5 subsweeps before it repeats. As a result the trace oscillates back and forth over a span of about 1.3 ps as it drifts across the screen. In 5120 point mode it seems to have just 2 subsweeps with ~1 ps dither between them.

When the OXO heater kicks on everything jumps out of sync for a while. It may well be that the mystery NVRAM calibration constants are intended to correct the time offset between the sweeps. IIRC my timebase ROMS have a 1991 or 1992 date, so it is possible that my scope had a FW update and could be corrected if I knew where and what values to write with a PROM programmer.

If someone has an 11801C or other newer model open I'd appreciate version and date information on the timebase board ROMS. But if anyone knows *anything* about this I'm very interested in investigating. I've got another 11801x in CA at my sister's house which I'm waiting for her to ship to me. I have had more fun with my 11801 than any other piece of test gear I've bought. Being able to see reflections from each side of a high grade SMA-F to N-F adapter is quite amazing.

Have Fun!
Reg

My scope is an 11801. That should be visible in the screen photo I posted. Based on the dates on parts it is 1989 production. It is enough different from the 11801C that it was obvious from the meager information in the service manual for the 11801C that I needed an actual an 11801 manual. Zenith was kind enough to furnish a scan of the 11801 service manual, which is now available online, but I bought a paper copy.

I currently am triggering off a square wave on one channel of the 33622A while displaying a ramp from the other channel. There is a periodic jitter in the time base, so even with an external trigger I cannot get a stable sweep. In 1024 point mode at 1 ps/div it appears that there are 4-5 subsweeps before it repeats. As a result the trace oscillates back and forth over a span of about 1.3 ps as it drifts across the screen. In 5120 point mode it seems to have just 2 subsweeps with ~1 ps dither between them.

When the OXO heater kicks on everything jumps out of sync for a while. It may well be that the mystery NVRAM calibration constants are intended to correct the time offset between the sweeps. IIRC my timebase ROMS have a 1991 or 1992 date, so it is possible that my scope had a FW update and could be corrected if I knew where and what values to write with a PROM programmer.

If someone has an 11801C or other newer model open I'd appreciate version and date information on the timebase board ROMS. But if anyone knows *anything* about this I'm very interested in investigating. I've got another 11801x in CA at my sister's house which I'm waiting for her to ship to me. I have had more fun with my 11801 than any other piece of test gear I've bought. Being able to see reflections from each side of a high grade SMA-F to N-F adapter is quite amazing.

Have Fun!
Reg

On Sep 15, 2019, at 1:17 PM, David Holland <david.w.holland@gmail.com> wrote:

Anyone recapped a Tektronix 561B, and have some pointers for capacitor
replacement specifications?  (ESR/DF & ripple current ratings
particularly)

Looking up the Tektronix part numbers will lead to NSN numbers, which
will give original manufacturers, (Sprague/Mallory), and purported
original part numbers, that I can not find references to.

There's nothing I'm aware of specifically wrong with the scope at the
moment, other than 47 years on those caps - based on the 1972 date
codes, and a serial # in the B19xxx range.

There is also 2 (of 3) tantalum capacitors that don't seem to be
de-rated particularly well (C11 & C31). - (Yes, they look like
tantalum, the NSN's say they are tant., and their tiny physical size
strongly implies it as well.)

I've a DER DE-5000 and a HV supply (Eico 950B) so I could pull them
and measure DF/ESR/leakage/etc to my hearts content, but if I'm going
to remove them, I'd just as soon put new caps back in circuit.

Suggestions? Comments? Cries of Derision?

Thanks,

David

Hmmm.. I have (and had back in 2014) a working 310.

As cool as an MDO would be, and not that I want a 'scope that I can't repair when
(not if) it breaks, but there have to be hundreds of owners of vintage Tektronix
'scopes out there that own working 'scopes that are older than the 511 cited in the
post, Europe or not.

I don't recall hearing of this "contest". It is weird that it did not come to light
while it was in progress. Does anyone have any information about the the contest itself?

DaveD