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When I switch between horizontal mode A and B and measures the voltage of pin 7 and pin 10 (of the U305) they switches between 0V and 5V. It’s the same regardless if I have the 7B92A in slot A or slot B.
Does the data in my previous post give you any idea if the U305 work as it should or not?

I'd like to get the Siglent scope, and the HP 8591. Would you ship them to NJ if I pay the shipping and for your trouble?

Thanks H?kan
I might make one myself
Regards
Hardy

-----Oprindelig meddelelse-----
Fra: [email protected] [mailto:[email protected]] P? vegne af zenith5106
Sendt: 27. november 2019 22:54
Til: [email protected]
Emne: Re: [TekScopes] Tektronix TX1---tx2

On Wed, Nov 27, 2019 at 01:16 PM, hardyhansendk wrote:

even a parts nr could help!

Tek P/N for the blue Protective Boot standard accessory is 650-3681-xx.
Since Tek sold the TX series to Fluke who renamed TX1 and TX3
to 183 and 185 you might also find it at Fluke but then it is yellow.

/H?kan

OK Ed, you have piqued my curiosity! What do you want to curve trace at Anode/Collector/Drain voltages of 7.5kV ?

Cheers
David

It's no good again. I discovered a fatal flaw in my test setup. The plate cap lead that I used had a break in the wire inside the insulation, so the tube was not actually hooked up. I was happily going along with experiments and advancing the design, until I found the plate lead folded right over way too easily - a bad sign. When I checked it out and fixed it, the rectification current was there, about the same or worse than with the 1X2. The bottom line is that all these HV rectifiers are no good for general use as vacuum caps. They could work in situations where the plate is negative with respect to the cathode, but not in the forward direction. Oh well, back to the gimmick cap - at least it's very small.

Ed

No, I'm happy to say it's not those horrors!

David

It works just fine with 200 meg - still no sign of rectification. Next is mounting the tube.

Ed

Someone please correct me if I am reading the manual wrong.

I am reading (interpreting) that in using either the A + Gate or B + Gate going into either of the External Trigger Input’s with Ext selected, I should be getting a “positive going pulse” controlled by either the A or B sweep control.

Is this correct?

If so, am I just looking for a small pulse or a type of wave? Also, I do not assume I need to be using any probe for the display I am looking for, please correct if wrong.

Thanks, James

To all TekScopes Members,
For future reference:
When making an offer like this which might result in many people contacting you via TekScopes regarding the details of your offer please provide an email address where they can contact you off line. Also be sure to indicate that they should not reply to your original TekScopes post. This helps to keep the noise level down.

Dennis Tillman W7PF

From: [email protected] <[email protected]> on behalf of johncharlesgord via Groups.Io <johngord@...>
Sent: Wednesday, November 27, 2019 2:49:24 AM
To: [email protected] <[email protected]>
Subject: [TekScopes] Free equipment for pickup noon Saturday, Nov. 30, Los Angeles area

I have the equipment below available for free on this coming Saturday at noon. I live not far too far from the TRW Swap Meet, so you could come here after that.

John Gord
johngord(at)verizon(dot)net
806 Indiana Ave
Venice, CA 90291
(310)392-9339

Everyone present at noon will draw a number at random; late arrivals will be given numbers in sequence. If you cannot be here, but want a single particular item (no larger than a portable SA or oscilloscope), I will draw a number for you and if the item is still available at your turn, set the item aside for you for a maximum of 2 weeks.

Lowest number will select first, then we will cycle through the numbers until items are gone.

(Items were working when stored unless otherwise noted) GR 1602B and accy GR 1602B and accy HP 3577A HP 8566B HP 8591A w/TG HP 8654A HP 8662A R&S SFQ (bad power supply) Siglent SDS1062CM Tek 222 Tek 305 Tek 335 Tek 454A Tek 2335

Many probes
Many BNC and SMA cables
Many N adapters
Many BNC attenuators
Many N attenuators
Several directional couplers, N conn
Many Banana-Banana cables
Many Banana-hook clip cables
Several DVMs
Several Analog VOMs
Junk found around the lab




--
Dennis Tillman W7PF
TekScopes Moderator

You might find some lead tape at a golf shop. It's used to change the swing weight of a golf club

Both 1K3As work great, with no discernible rectification action. I now have two nice ~1.6 pF vacuum caps proofed to about 16 kV, with no X-ray issue. Now I'll have to see about squeezing one in there. I expect it will ultimately fit OK, with the right arrangement of the HV section.

Next will be raising the resistance to around 200-300 megs, to reduce loading and accommodate the higher output range. The higher attenuator impedance will be more sensitive to any rectification in the tube that was not apparent, but I'm pretty sure it will be OK.

Ed

You didn't mention whether those units come with S-parameter test sets or tracking generators.
I am enthused by my nanoVNA.
Bob

2336ya is correct.

Thanks for catching that

Richard W4MCD

Thanks for pointing this out!? I'd not heard of this specific problem before, so now I'll keep a watch for closed frame sockets.
-Dave

On Wed, Nov 27, 2019 at 01:01 PM, David C. Partridge wrote:

Removed display board and reseated U2520 (Row Data Switch) and U2530 (Column
Data Switch) - yes that fixed it!

Does it have the infamous TI C95 IC sockets ?
If so this was most likely only a temporary fix and you could expect it to come back
as well as other intermittent problems. Sorry to be such a pessimist but these sockets
are known to be, to say the least, unreliable.
Not too long ago I acquired a 7844 with multiple intermittent faults and it had the C95's.
I replaced every single one and I think it was more than 50 of them.

/H?kan

On Wed, Nov 27, 2019 at 01:16 PM, hardyhansendk wrote:

even a parts nr could help!

Tek P/N for the blue Protective Boot standard accessory is 650-3681-xx.
Since Tek sold the TX series to Fluke who renamed TX1 and TX3
to 183 and 185 you might also find it at Fluke but then it is yellow.

/H?kan

Removed display board and reseated U2520 (Row Data Switch) and U2530 (Column
Data Switch) - yes that fixed it!

Good to know David!
Albert

All is not lost, regarding using a tube as a vacuum cap. I've been looking at my stock of 1B3-style tubes with higher PIV, and much "cleaner" heater structure, which should better suppress field emission. They all have around 1.5 pF A-K. I found a couple of the 1K3A type, which claims to have integral X-ray shielding (probably leaded glass), according to the datasheet. The downside is that they're huge compared to the 1X2, so would be a challenge to fit in the available space. I'll be rigging up some tests to see how they work.

Ed

Clever idea for the vacuum capacitor. I seem to recall that old CRT color
TVs used a 6BK4 30-watt tube as a shunt regulator across the 25 kilovolt
supply, making plenty of X rays. The shielding was just thin sheet metal.
Then again after there was a radiation panic, you would see some tubes
with a few millimeters of lead stuck on the glass.

On Tuesday, November 26, 2019, Ed Breya via Groups.Io <edbreya=
[email protected]> wrote:

I'm designing a low power 60 Hz HV curve tracer gizmo, with ranges up to
around 5 kV RMS AC, or +/- about 7.5 kV peak in DC mode, up to a couple mA
or so maximum short current. The voltage monitor is to be a 1000:1
attenuator around 80-100 megohms in, then either amplified locally, or fed
to a scope input. I can set up a slightly different (feature) arrangement
where the output can be doubled up to about 15 kV peak in DC mode. My
initial plan was to use a 1X2 HV rectifier tube (just cold - no heating)
(9-pin miniature with plate cap) as a stable, approx 1 pF vacuum capacitor
across the big attenuator resistor, for frequency compensation. This would
be no problem at 7.5 kV, but beyond 10 and up to the 15 kV range, it's
getting into the soft to hard X-ray emission region. The tube isn't being
used as a rectifier, and it's a high impedance environment, so the current
is small (few uA peak), and shouldn't be able to produce much emission.
But, to be on the safe side, I figured I could enclose that section in a
thin steel box, if necessary.

I started searching online for shielding info for this soft/hard region
around 15 keV, but so far only found stuff related to the common big
equipment shielding like 40 keV and up, at high power. Does anyone know of
any info pertaining to emission and shielding in this X-ray region, like HV
tube shielding and such, from the old days of tube TV. Also, has anyone
ever seen such a thing as info on unwanted X-ray emission patterns from HV
tubes (not X-ray tubes, where that's what's wanted)?

I found a bit of info from Kilovac, saying that HV vacuum relays can have
an X-ray problem above 15 kV, but no more detail than that.

I could also skip the tube and just make a HV gimmick capacitor from HV
cable, but I'd prefer the stability of a nice little vacuum cap. Right now,
there is no frequency compensation cap in place, but it works well enough
to see what's going on, and actually makes for a pleasant display with
low-pass filtering - all the crap present in an arc on the output comes out
as nice steps on the scope, so you know a lot of HF info is missing. I need
to also first check to make sure the 1X2 acts as a linear capacitor. I set
aside a bunch of these years ago for the same kind of use in a 10 kV
application, but wondered if the internal structure of the pointy heater
and supports may prefer current flow in one direction, and still be kind of
a rectifier even cold. I never did find any info on this, and haven't
advanced this other project to the point of finding out. Now I'll finally
see, and if it is a problem, then bye bye 1X2 (and possible X-ray issues),
and hello gimmick cap.

Ed

Regarding the 2236, I used to really like that scope, until each one went
dead or annoyingly intermittent. First one died from a shorted HV
transformer. Second one developed intermittent vertical deflection, traced
to intermittent little powder blue homemade IC's in the vertical
front-end. I took the ersatz ICs from the first scope and put them in the
second one and thought myself Master of the Tektronicals. Until two weeks
later those ICs went intermittent too.

Anybody else have these failure modes and found some way around them?
Those scopes were just the right size for a small desktop.



On Wednesday, November 27, 2019, Raymond Domp Frank <hewpatek@...>
wrote:

On Tue, Nov 26, 2019 at 04:20 PM, Richard in Edenton NC wrote:

I do have a question about a readout on the inside of the lid.

That's a 2336YA then.

Raymond