Date   

Re: FG502 problem?

EJP
 

I would also check all the resistors around the loop leading from pin 6 of U664 back to pin 2, and R670 from pin 3 to ground, and R666, and the two-diode string from pin 7 to ground, and all the transistors.

EJP


Re: Tek 2230, almost fixed but with a problem out of my competences

Pitpat
 

I've noticed something new yet prbly uncorrelated, BW limit switch seems not to have any affect on the trace and correlated to that R226 and R227 on schem n. 3 gets really toasty (enough to darken the other side of the PCB)
Should i investigate?
Also i just got in mail the new resistor network (compulsively ordered) should i replace them?


Re: Tunnel diode pulses for calibration fixture

Gerald
 

Hi Everyone,

Thank you for the links and feedback. Such an interesting exotic device.

My quest started with the necessity to create a set of time marker pulses to correct errors during horizontal alignment on my 2465B.

The NASA paper is very good, combined with other feedback and W140.com site which completely slipped my mind, I have some good heads up info now.

Given this is the Tek scopes group, FYI.

I am still having alignment issues with my 2465B after my 7-8th attempt cycle I think, to align down to 5 and even 2ns. I picked up a TG501 and alignment from 10 5, 2 and 1ns isn't working well. I am experimenting with 74LVC1G, but still keen to look at using 2 good as new 1N3716 TD.

I need to get my 2465b right to experiment with TD, last evening for the 10th time going through cal 01 steps 7-34 and using the combination of the Tektronix and US army alignment papers for the 2465-7, I was able to get all horizontal settings within spec, actually better than spec with the exception of 5 and 2ns. The TG501 has poor output with excessive jitter.

I now feel a need to write a 24xx cal 01 doc with photos to help others guide their way through alignment for a unit s/n B052 and up, especially after A5 re-work.

Again thanks for the assistance with TD.

Regards

Gerald
VK3GJM


FS: Original Tek Op/Serv for DM501A and Serv for R7603 Manuals

Liam Perkins
 

Original Tek Op/Serv for DM501A and Service only for R7603.

The DM501A Op/Serv is PN 070-2749-00; 1st printing Jun 1979, Revised
Nov 1982. Perfect condition $US35.00 + Canada Post shipping from Calgary
AB, Canada.

The R7903 Service only is PN070-1464-00, Rev. C, Mar. 1978. Like brand
new, $US50.00 + Canada Post shipping from Calgary AB, Canada.

e-Mail me off -list at sales – at – pearl-hifi – dot – com

Liam


Re: Problems with t935a HV supply

 

I will document the Vf on the 10KV 10 ma replacement diodes when they arrive in the mail.

Also, I will do a summary of this thread once (if?) I get the HV supply going. The ring test procedure for this type of HV transformer is non conclusive.

--
Regards,
Bernie Murphy


Re: FG502 problem?

Mark Vincent
 

Chris,

Check the series pass for the -20V supply. That could be shorted. It appears that a connector, by looking only at the schematic, to the pins are on a plug that can be removed. See if there is about -21V at 11A (base of the series pass) and about -21,5 to -22V at the base of Q662 if the series pass is good.

Check R672. Replace if bad. Also check the voltage at pin 7 of U664. It should be 1,2-1,4V.

Mark


Re: FG502 problem?

Tom Lee
 

The schematic shows that the -20V supply is derived from inverting the +20V output. So, if the latter is good, then the problem is with the inversion. Check U664 and associated components.

--Cheers,
Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 6/10/2021 17:25, Chris van Lint wrote:
Hi

I recently tried to fire up my FG502.  The unit was not working and the green power lamp was not illuminated. I discovered that one of the 741 opamps in the power supply was faulty.  I replaced the 741 and the unit now appears to be working OK.  However although the +20V supply is within specs, the -20V is way out at -30V. The +20V supply is easily adjusted with R625, but I cannot find any adjustment pot for the -20V supply. _The +17V and -17V supplies are also within specs._

- Does this mean that I should not be concerned about the -20V being too high?

- Am I correct in assuming that R672 on pin4 of U664 is out of range?

Any advice would be appreciated

Chris





FG502 problem?

Chris van Lint
 

Hi

I recently tried to fire up my FG502.  The unit was not working and the green power lamp was not illuminated. I discovered that one of the 741 opamps in the power supply was faulty.  I replaced the 741 and the unit now appears to be working OK.  However although the +20V supply is within specs, the -20V is way out at -30V. The +20V supply is easily adjusted with R625, but I cannot find any adjustment pot for the -20V supply. _The +17V and -17V supplies are also within specs._

- Does this mean that I should not be concerned about the -20V being too high?

- Am I correct in assuming that R672 on pin4 of U664 is out of range?

Any advice would be appreciated

Chris


Re: GPIB Connection to 2340A - Response garbled #photo-notice

Abdul Nizar
 

Baud rate or other port settings do not matter since there is no underlying physical UART in Prologix GPIB-USB.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Dave Wright
Sent: Thursday, June 10, 2021 9:54 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] GPIB Connection to 2340A - Response garbled #photo-notice

Not sure about how USB version of Prologix driver will interpret a baudrate setting, as that is only significant if the USB endpoint is in fact a UART, which it may or may not be (anybody familiar with Prologix USB internals here..?). So, you might try using higher baudrates in your PyVisa initialization to see if transfers go faster...


Re: Tunnel diode pulses for calibration fixture

Siggi
 

Some links for those who're tempted to look:
https://w140.com/tekwiki/wiki/Tunnel_diodes,
https://w140.com/nasa_paull_tunnel_diode_logic.pdf.

On Thu, Jun 10, 2021 at 2:00 PM Roy Thistle <roy.thistle@mail.utoronto.ca>
wrote:

Forgot... and the paper Garrahan refers to (Garrahan was a co-author) is
... Paull(1966) Low Power Nanosecond Pulse and Logic Circuits Using Tunnel
Diodes (Goddard Space Flight Center)

--
Roy Thistle






Re: Tunnel diode pulses for calibration fixture

Roy Thistle
 

Forgot... and the paper Garrahan refers to (Garrahan was a co-author) is ... Paull(1966) Low Power Nanosecond Pulse and Logic Circuits Using Tunnel Diodes (Goddard Space Flight Center)

--
Roy Thistle


Re: Tunnel diode pulses for calibration fixture

Roy Thistle
 

On Thu, Jun 10, 2021 at 05:41 AM, Michael W. Lynch wrote:


For those who are intrigued by Tunnel Diodes ... [ and by Tek] ...
Garrahan's paper (and the paper he refers to)... and a ton of other stuff about TDs... It's all on TekWiki. (Thank you TekWiki!)

--
Roy Thistle


Re: Problems with t935a HV supply

Ozan
 

On Thu, Jun 10, 2021 at 10:14 AM, Michael W. Lynch wrote:


Not sure what a good 10KV 10ma diode should measure.
I don't know the expected typical Vf for this diode (SEF100?) either but
here
is some brief data for it:
From the TEK SEMICONDUCTOR CATALOG: 152-0639-00 is TEK Part # MAX I Avg. =
10mA / WV = 10kV / MAX I Surge = 2.0A / MAX I Rev = .0005 mA / MAX V Fwd
20V @ .010 A JEDEC # MX100
I saw that one too, the link I gave has more detail. Unfortunately in both cases Max Vf (20V) at 10mA is given, no typical number. Parts list shows SEF100 as the diode.
Ozan


More FETs and Picoampere diodes added to the stuff page

 

I just posted a nice assortment of FETs, including duals, Tek and HP parts, and J-series JFETs to the stuff page. I also added the amazing JPAD picoampere leakage diodes from Siliconix, which are ideal for input protection. Some amazing discrete parts are all here in one place:

https://www.sphere.bc.ca/test/stuffday.html#fets

I will try and add more Tek/HP items up this weekend, they are just sitting here, it's just hard to get all the photo prep, clean up and testing done in a timely manner.

All the best,
walter (walter2 -at- sphere.bc.ca)
sphere research corp.
https://www.sphere.bc.ca/test/stuffday.html


Re: Problems with t935a HV supply

Michael W. Lynch
 

On Thu, Jun 10, 2021 at 12:00 PM, Ozan wrote:




The HV diodes are shot for sure. One has a forward voltage drop of 11.2
volts
and the other one is 11.8 volts. New ones on order. Internally, the diode
stack in the one measuring 11.2 volts is bad.

Not sure what a good 10KV 10ma diode should measure.
I don't know the expected typical Vf for this diode (SEF100?) either but here
is some brief data for it:
From the TEK SEMICONDUCTOR CATALOG: 152-0639-00 is TEK Part # MAX I Avg. = 10mA / WV = 10kV / MAX I Surge = 2.0A / MAX I Rev = .0005 mA / MAX V Fwd 20V @ .010 A JEDEC # MX100
--
Michael Lynch
Dardanelle, AR


Re: Problems with t935a HV supply

Ozan
 

On Wed, Jun 9, 2021 at 02:50 PM, Ham Radio wrote:


The HV diodes are shot for sure. One has a forward voltage drop of 11.2 volts
and the other one is 11.8 volts. New ones on order. Internally, the diode
stack in the one measuring 11.2 volts is bad.

Not sure what a good 10KV 10ma diode should measure.
I don't know the expected typical Vf for this diode (SEF100?) either but here is some brief data for it:
https://datasheet.datasheetarchive.com/originals/distributors/Datasheets-X2/DSA870000-167.pdf

Unfortunately it only shows max Vf (min current at Vf).
Ozan


Re: GPIB Connection to 2340A - Response garbled #photo-notice

Dave Wright
 

Not sure about how USB version of Prologix driver will interpret a baudrate setting, as that is only significant if the USB endpoint is in fact a UART, which it may or may not be (anybody familiar with Prologix USB internals here..?). So, you might try using higher baudrates in your PyVisa initialization to see if transfers go faster...


Re: GPIB Connection to 2340A - Response garbled #photo-notice

unclebanjoman
 

I have never used Prologix but looking at the screenshot of Prologix GPIB configurator I noticed that there is the EOT (End of Transmission) configuration. Surely if it is set to CR / LF there is a good chance that the Tek will interpret the extra CR as an unknown character.
I suggest experimenting with the various configuration possibilities until you find the most suitable choice.

For your information I use by years the Agilent/Keysight 82357B USB / GPIB interface with the Agilent I/O Suite libraries. So I can use the VISA programming API. Sometimes I use low-level SICL libraries (Standard Interface Control Library) to create test programs.

I don't use NI-VISA because they are very "huge". They force you to install all the software package and the .NET framework when you only need a driver and a DLL or two...

The Agilent IO Suite is much more efficient and streamlined. I have been using it since 2014, on WIndows XP. I currently use Windows 7 and Windows 10 and I have never found serious problems, neither in installation, nor in the use of drivers / DLLs.
By contrast, the National Instruments libraries are plenty of bugs, aside from the fact that they are an "elephant" in every sense of the word.
I think NI is more oriented and suitable toward virtual instrumentation. (LabView docet).
Agilent/Keysight are more suitable for "real" instruments, hardware instrumentation with "real" GPIB hardware (and not an emulated one).

Maybe also that Agilent/Keysight (formerly the Hewlett-Packard) GPIB software/hardware are happier when they discover they are connected to my vintage instruments, Tektronix, HP or Philips, haha

Max


Re: Tek 545A Scope

Roy Morgan
 

The Right Stuff

On Jun 9, 2021, at 11:58 PM, Jonathan Pyle <jhpyle@gmail.com> wrote:

When I restored my 1963 rackmount 545A (RM45A)
. . .
maybe scratchy pots could cause the trace to go away (another deoxit fix?);
I think not.
De-Oxit is right for metal to metal contact switches. It *may* harm variable resistor controls.
Caig "Fader Lube" IS the right stuff (formerly called MCL-moving contact lubricant).

Accept no substitutes.

Roy


Re: Tunnel diode pulses for calibration fixture

Michael W. Lynch
 

NASA TN D-3558 Give more details. For those who are intrigued by Tunnel Diodes and their uses. Find it on the NASA's STI Repository.

--
Michael Lynch
Dardanelle, AR

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