Date   

Re: “High Bandwidth Transient Capture,” Tektronix Publication 1991

Roy Thistle
 

High Bandwidth Transient Capture, Technical Brief No: 45W-8088, Tektronics circa (1991?)


Re: Broken Tektronix scopes free

Michael W. Lynch
 

I would like to hear more about the 465's

--
Michael Lynch
Dardanelle, AR


Re: Broken Tektronix scopes free

john dear
 

Hi Peter,
Where are you located?
Best wishes,
Emil

On 19-Nov-20 16:13, Peter Margolis via groups.io wrote:
I have two broken Tektronix 465s and one 2336 that I want to give away for the cost of shipping. Anyone interest in one or both?

Pete




Re: Broken Tektronix scopes free

 

Interested in the 2336
Chris n9llo@aol.com

On Nov 19, 2020, at 9:13 AM, Peter Margolis via groups.io <pmargolis=mac.com@groups.io> wrote:

I have two broken Tektronix 465s and one 2336 that I want to give away for the cost of shipping. Anyone interest in one or both?

Pete





Broken Tektronix scopes free

Peter Margolis
 

I have two broken Tektronix 465s and one 2336 that I want to give away for the cost of shipping. Anyone interest in one or both?

Pete


Re: Peter Keller Book Order INTERIM UPDATE

 

On Wed, Nov 18, 2020 at 02:30 PM, Raymond Domp Frank wrote:


Dennis,
Uithoorn and Amsterdam may be combined in one shipment to Uithoorn. The places
are close together and I (in Uithoorn) will take care of it, once I know the
name and address of the person in Amsterdam. BTW, my lab is in Uithoorn but I
live in Amsterdam...
Hi Dennis,
The person living in Amsterdam has contacted me, I've met him before. We have agreed that you may send both his (Amsterdam) and my (Uithoorn) book to me.
Payment arrangements will be made separately.

Raymond


TDS 784A / 754A WARNING-ERROR MESSAGE

Gif Sim
 

good morning to the whole group

I have a tds754a upgraded to tds784a by configuring the resistors and removing the capacitors in the acquisition card

the acquisition card is 671-3953-00
the microp board is 679-3488-00
the serial is b010976
the memory board is 1M

all electrolytic capacitors have been replaced and the oscilloscope works perfectly
the ds1486 was replaced with a working battery
It was originally mounted a DS1650y that has been replaced with a DS1250y-100 with a working battery

when I connect the tek FAS software with gpib and start the first calibration phases
in the error log I get some truncated warning messages:

"WARNING: 600 remote nv memory a ...."

the calibration then proceeds smoothly (but I haven't finished it yet)
what does this warning message mean and what can be the cause?
thanks to everyone who can be of help

A greeting

Simon


Re: Tektronix 7D13 and 7A42 wanted

 

Hi Ed and Dan,
I'll toss the battery and remove the jumper in mine also.
Dennis

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Ed Breya via groups.io
Sent: Wednesday, November 18, 2020 7:14 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Tektronix 7D13 and 7A42 wanted

Hi Dennis,

I didn't realize earlier your question "What did you use for a battery?" was to me. There is no battery. For something like this, it's simple enough to set up as needed, for occasional use. Having it remember is a nice convenience, but not worth the trouble and leakage risk. All I did was check it out after enough burn-in, and I removed the BE jumper as Dan suggested. It's running right now for one last time before mothballing.

Ed







--
Dennis Tillman W7pF
TekScopes Moderator


Re: Tektronix 7D13 and 7A42 wanted

Ed Breya
 

Hi Dennis,

I didn't realize earlier your question "What did you use for a battery?" was to me. There is no battery. For something like this, it's simple enough to set up as needed, for occasional use. Having it remember is a nice convenience, but not worth the trouble and leakage risk. All I did was check it out after enough burn-in, and I removed the BE jumper as Dan suggested. It's running right now for one last time before mothballing.

Ed


Re: Q122/222 Jfet J300 subs for 2215A scope ?

Ed Breya
 

Oops - I meant to say Vds here, not Vgs:

The Vds should be fairly constant since the required output excursion is only about +/-100 mV.

Ed


Re: Q122/222 Jfet J300 subs for 2215A scope ?

Ed Breya
 

Yup, I see it. I finally looked at the schematic for the 2215A. Looks like the quiescent drain current should be around 11 mA, and the source at Vbe.I'm looking at the J310/J309 data sheet here:

https://www.mouser.com/datasheet/2/308/J309-D-109346.pdf

If I'm interpreting Fig. 1 properly, the lower curve set is for the J309, and the Id is about right for Vgs= -Vbe. The upper curves for the J310 are about 3 X higher - too far out there for the nominal circuit conditions, although Q15 could probably pull it hard enough to DC balance (but things would start getting weird). The JFET runs with Vds about 8V, so pretty close to the 10V used in the specs. The Vgs should be fairly constant since the required output excursion is only about +/-100 mV.

This circuit reminds me of the ones in all the other 2200 series, and may be essentially exactly the same. More info may be discerned by looking at those others to see what JFETs were used. The 2N5486 keeps sticking in my brain.

Ed


Re: Tektronix 7D13 and 7A42 wanted

 

What did you use for a battery?

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Ed Breya via groups.io
Sent: Wednesday, November 18, 2020 2:18 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Tektronix 7D13 and 7A42 wanted

The cleaned up 7A42 is still working OK. I'm calling this one fixed and done, ready to go back on the shelf. Hopefully it will still be good whenever I need it.

Ed







--
Dennis Tillman W7pF
TekScopes Moderator


Re: Tektronix 7D13 and 7A42 wanted

Dan G
 

I was lucky that I caught the leaking NiCd battery in my 7A42 back in 2016, when
it was still in the early stages. Surprisingly, the only damage was to the nearby
jumper plugs, many of which had seized and became encrusted with blue crystalline
deposits. This damage was not immediately obvious -- one had to examine contacts
inside the black plastic plug housing.

Amphenol still makes identical jumper plugs today (Mini-Jump p/n 65474).

I should note that I had decided _not_ to replace the battery, as any new NiCd
battery will just cause more of the same damage if allowed to run empty.
(And, depending on the quality of the replacement battery, possibly much
sooner than the original part made by Saft.) This is not suitable for a unit that
only sees occasional use, and where the hope is to preserve it for many years
into the future.

If the battery is not replaced, then it is important to move the BE (Battery
Enable) jumper to the open position, to stop the plug-in from attempting to
initialize the front panel settings from invalid memory contents. With the BE
jumper in the closed position, and no battery, the plug-in can occasionally
lock-up during power-up.


dan


Re: Q122/222 Jfet J300 subs for 2215A scope ?

Tom Lee
 

Yes, a J310’s IDSS range is centered high for this particular circuit. The J309’s IDSS range is actually about right, as the buffer circuit aims to operate the FET at a VGS of -0.6 (to compensate for the VBE of the bipolar follower that the FET drives), so the drain current for a J309/J310 is perhaps 8-10mA lower than IDSS, assuming a typical gm of 15mS.

AFAIK, the J309 and J310 come from the same process recipe.

—Cheers
Tom

Sent from my iThing, so please forgive typos and brevity.

On Nov 18, 2020, at 1:53 PM, Ed Breya via groups.io <edbreya=yahoo.com@groups.io> wrote:

For some reason I've been referring to the original working JFET as a J310, but looking back all the way to the OP, I'm not sure what it is - all kind of parts are floating around this thread. So Charles, can you identify the one official, working JFET that I've been referring to?

The reason I ask is that I looked up the J310, and found it is a very heavy beast - VHF/UHF, with Idss 24-60 mA - way too big and fast for this little scope amplifier, and way too big for Tom's estimated max of 30 mA for circuit operation. The correct part must be something else more "normal," among many possible choices. The J309 may work, but even it seems a bit much.The J300 seems about right, and the J210 or preferably J211 may be a good option. Also, I mentioned the 2N5485 and 2N5486 earlier, which I'm pretty sure were used a lot under various Tek part numbers. I think especially the 2N5486 was used extensively in scope input amplifiers.

Anyway, there are types that it could be, and types it shouldn't be.

Ed






Re: Another A5 board repair attemp - help needed

Rogerio O
 

Hi Folks,
The parts arrived from Mouser.
I replaced U2101 (DAC), U2521 (4051) and U2420 (TL084) as well as all the 0.47uF capacitors connected to the U2521 just in case.
I though I read somewhere the the capacitors in this circuit may be the cause of having low +1.36V/-1.25V values, as I was experiencing (is it true??).
Anyway, I have now the error changed to TEST 4 FAIL 2 but voltages' prior to DAC adjustment are +1.4V and - 1.28V !!!
It seems I will be possible to execute the DAC calibration and move on to the other calibration steps.
Unfortunately I have to travel tomorrow and will only br able to work on the scope on next Monday.
Thanks to all of you that have helped me to get to this point.
Roger


Re: Tektronix 7D13 and 7A42 wanted

Dave Daniel
 

Hmmmm...electrolytics?

DaveD

On Nov 18, 2020, at 17:17, Ed Breya via groups.io <edbreya=yahoo.com@groups.io> wrote:

The cleaned up 7A42 is still working OK. I'm calling this one fixed and done, ready to go back on the shelf. Hopefully it will still be good whenever I need it.

Ed





Re: Tektronix 7D13 and 7A42 wanted

Ed Breya
 

The cleaned up 7A42 is still working OK. I'm calling this one fixed and done, ready to go back on the shelf. Hopefully it will still be good whenever I need it.

Ed


Re: 7L5 Res shaft encoder

Dan G
 

On Tue, Nov 17, 2020 at 05:25 PM, Nenad Filipovic wrote:

Today I attempted disassembly of my Resolution/Freq. Span knob and got halfway
there, photos (album name "7L5 Knob Repair Attempt"):
https://groups.io/g/TekScopes/album?id=256833&p=Name,,,20,1,0,0
Hi Nenad,

Your photos encouraged me to attempt to disassemble my own res/freq knob assembly.
I was hoping to be able to tell you whether my L-shaped insert also appears glued, but
interestingly, I could not even get that far. The best I could do was to remove the black
plastic resolution knob/ring.

My 7L5 s/n is >B090000, and therefore has the 263-0064-00 encoder. In this version,
the hollow cylindrical centre of the (die cast?) metal base seems to extend all the way
through the frequency span knob as a single piece, rather than being made up of
two fluted interlocking parts. Hence, the resolution and frequency span sections do
not come apart when the resolution knob/ring is removed.

Peering down the length of this cylindrical opening toward the underside of the
frequency span knob, I believe I see the bottom of a machine screw, but I cannot be
certain.

It would appear that different disassembly procedures are needed for
260-1693-0x and 263-0064-00 encoders. I don't think that I will attempt any further
disassembly, for fear of damaging or marring a perfectly working pristine unit.

Perhaps someone with an older 260-1693-0x assembly (and more courage) will be
able to make further progress.


Good luck,
dan


Re: Q122/222 Jfet J300 subs for 2215A scope ?

Ed Breya
 

For some reason I've been referring to the original working JFET as a J310, but looking back all the way to the OP, I'm not sure what it is - all kind of parts are floating around this thread. So Charles, can you identify the one official, working JFET that I've been referring to?

The reason I ask is that I looked up the J310, and found it is a very heavy beast - VHF/UHF, with Idss 24-60 mA - way too big and fast for this little scope amplifier, and way too big for Tom's estimated max of 30 mA for circuit operation. The correct part must be something else more "normal," among many possible choices. The J309 may work, but even it seems a bit much.The J300 seems about right, and the J210 or preferably J211 may be a good option. Also, I mentioned the 2N5485 and 2N5486 earlier, which I'm pretty sure were used a lot under various Tek part numbers. I think especially the 2N5486 was used extensively in scope input amplifiers.

Anyway, there are types that it could be, and types it shouldn't be.

Ed


Re: Delayed Timebase on a Tek 2215A

 

Raymond and Leo, thanks for the correction, it was ENTIRELY operator error and misunderstanding. I see that the same thing can be achieved on the 475 by selecting the B trigger source as "STARTS AFTER DELAY" even though the 475 does not offer the more pleasing ALT horizontal display mode.

I know that this is shallow, but I just wanted to be able to see the two signals one above the other rather than stitched together vertically with a sliding transition from one timebase to the other. I don't have any real use for the feature, which is part of the reason that I didn't understand how to use it, but as this is just my hobby, being able to play with a cool looking feature is basically the only requirement.

-- Jeff

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