Date   

Re: CRT book by Keller

Tom Lee
 

Your question baffles me, Roy. If someone were to hand you a non-Coke bottle crt, would you ask, "Yeah, but what does it do?"

It's a crt. Made out of a Coke bottle, yes, but a crt nonetheless.

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 1/14/2021 12:09, Roy Thistle wrote:
On Wed, Jan 13, 2021 at 05:49 PM, Glydeck wrote:

check it out
There is a bad photo of Peter's artifact... and as Peter claims... '... results in an operable CRT..." [pg. 24]
But given that it was "operable," what did it do?
Peter doesn't say?




Re: CRT book by Keller

Roy Thistle
 

On Wed, Jan 13, 2021 at 05:49 PM, Glydeck wrote:


check it out
There is a bad photo of Peter's artifact... and as Peter claims... '... results in an operable CRT..." [pg. 24]
But given that it was "operable," what did it do?
Peter doesn't say?


Re: Tektronix 492BP

Tom Lee
 

I've had the same experience as John, and not only with Tek's instruments. HP gear of that period also seems to suffer from the same affliction. That likely implies that you'd find this in the products of other manufacturers as well.

-- 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 1/14/2021 11:27, John Miles wrote:
It's not a question of them being set incorrectly, it's a question of whether their contacts actually match their settings.

The DIP switches used by Tek in this era are extremely failure-prone due to aging. But normally they are OK until they're toggled on or off for the first time in 20+ years. You can rule out the switches by checking them with an ohmmeter to see if the ones that are in the 'OPEN' position are actually open (i.e., med/high resistance across the contacts.) Likewise for the others, with ~0 ohms expected across the contacts for the switches that are closed.

-- john, KE5FX


-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
Mike Yepes
Sent: Thursday, January 14, 2021 8:54 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Tektronix 492BP

The only boards with dip switches are the memory board and the vertical
digital storage board. I have no idea which ones supposed to be on or off.






Re: Tektronix 492BP

John Miles
 

It's not a question of them being set incorrectly, it's a question of whether their contacts actually match their settings.

The DIP switches used by Tek in this era are extremely failure-prone due to aging. But normally they are OK until they're toggled on or off for the first time in 20+ years. You can rule out the switches by checking them with an ohmmeter to see if the ones that are in the 'OPEN' position are actually open (i.e., med/high resistance across the contacts.) Likewise for the others, with ~0 ohms expected across the contacts for the switches that are closed.

-- john, KE5FX

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
Mike Yepes
Sent: Thursday, January 14, 2021 8:54 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Tektronix 492BP

The only boards with dip switches are the memory board and the vertical
digital storage board. I have no idea which ones supposed to be on or off.



2465B trace and readout focus at different positions of focus knob

Mark Hatch
 

Hi,

Have a late model 2465B. Noticed today that the focus point for the readout is at one point on the focus knob. But it I also want to get an optimal focus for the trace, I need to turn the knob to a different position.

I guessing that I should first perform the 2465B CRT Adjustments (Grid Bias, High Drive Focus, and Edge Focus). Is this the right path here?

Focus knob is more or less in the center position when Readout is in focus and only a little off center with trace in focus.

Thanks

Mark


Re: Tektronix 492BP

Thomas S. Knutsen
 

That is the same as my 492BP.
If I remember it, I will take the cover off and note the switch settings. By flipping the switches you can get any model no. And any version. Often the switches fails after years and need replacement.

Thomas.

Sendt fra min iPhone

14. jan. 2021 kl. 19:05 skrev Mike Yepes <theamberco@hotmail.com>:

9.1 and 1.1 panel ver.





Re: Tektronix 492BP

 


Re: Tektronix 492BP

 

9.1 and 1.1 panel ver.


Re: 2247A Is this normal?

Alex
 

When that happens to me, I usually increase the screen intensity and then I can see that there was either some pulses or noise on the signal that go beyond the signal and are what actually are defining the position of the cursors, and where invisible under normal intensity conditions. Other than that I find the voltmeter function very accurate and useful.


Re: Tektronix 492BP

Thomas S. Knutsen
 

Start by giving what version no. Your SA gives when starting up. The dip
switches changes between the software versions.

If there is sockets on the front, and the correct cabling inside your SA
has external mixers. There was a different front panel for those without
it, and there is no pushbutton hole nor hole for IF in.
The only strange version is the 75ohm version that has some of the coaxes
inside re-routed and an 75ohm:50ohm transformer with BNC that goes into the
hole where IF input should have been.

BR.
Thomas.


tor. 14. jan. 2021 kl. 17:54 skrev Mike Yepes <theamberco@hotmail.com>:

The only boards with dip switches are the memory board and the vertical
digital storage board. I have no idea which ones supposed to be on or off.





--
With Best regards, Thomas S. Knutsen.

Please avoid sending me Word or PowerPoint attachments.


Re: Tektronix 492BP

 

The only boards with dip switches are the memory board and the vertical digital storage board. I have no idea which ones supposed to be on or off.


Re: Tektronix 492BP

 

Check the DIP switches in the CPU section for continuity, as well as the ones
on the Z-axis board. Sounds like one or more of them may have failed, and the
instrument thinks it doesn't have the external mixer jack.
I only have the operators manual. Let me see if I can find the schematics in pdf format somewhere.
I will revise that , thanks a lot.
So all units with the external mixer jacks must provide extended range? Becasue I was told there is an option that eliminted the extended range and this unit had erased the tag for the options so not sure if it may had that option.


Re: 2247A Is this normal?

Tim / N8TIM
 

You are correct. It was at 110Mhz. I had just had my SG at that Freq for something else when I hook it to the scope and noticed the Peak to Peak reading. I attached a link to the two screen shots at 25Mhz. It looks to be correct. The curser are just off a little. Thanks all for you help.

https://groups.io/g/TekScopes/photo/259345/0?p=Created,,,20,2,0,0


Re: T912 storage oscilloscope - No 2.7 KV high Voltage

Attilio
 

Thanks Roger,
I have the 5 nF 6 KV capacitors.
I will check the condition of R444 (focus resistors).
I will purchase the new 10KV - 10mA diodes.

Regards,

Attilio


Re: First mixer diode on a 7L18 : how to test (and possibly replace) ?

Miguel Work
 

Hi

https://www.rf-microwave.com/en/siemens/bat14-104/schottky-diode/bat14-104/

In this page you can find a lot of RF stuff

https://www.rf-microwave.com/en/schottky-diodes-hot-carrier/429/

Miguel

-----Mensaje original-----
De: TekScopes@groups.io [mailto:TekScopes@groups.io] En nombre de Jose Luu
Enviado el: miércoles, 13 de enero de 2021 23:46
Para: TekScopes@groups.io
Asunto: [TekScopes] First mixer diode on a 7L18 : how to test (and possibly replace) ?

Dear group,

I am fixing a deaf 7L18, it is responsive to a 510MHz signal injected into the second mixer, I still have to test the 510MHz IF, I am anticipating that the first mixer diode has failed (likely from a power overload).

Testing the diode: I suppose I should pay attention to the voltage applied and possibly limit the current, 1V and a few milliamps?
Replacement: the part number I find on the service manual is: 119-0972-02 , googling it does not fetch much, any ideas, is surgery oof the A45 unit possible ?

Thank you for any insight
Jose









Scanned by McAfee and confirmed virus-free.
Find out more here: https://bit.ly/2zCJMrO


Re: Tektronix 492BP

John Miles
 

Check the DIP switches in the CPU section for continuity, as well as the ones on the Z-axis board. Sounds like one or more of them may have failed, and the instrument thinks it doesn't have the external mixer jack.

-- john, KE5FX

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
Mike Yepes
Sent: Wednesday, January 13, 2021 10:19 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Tektronix 492BP

Frequency not in rage ignored. Also I cannot move the band higher than 15-
21GHz. When I press the buttom external mixer it said: UNDEFINED
FUNTION.



Re: T912 storage oscilloscope - No 2.7 KV high Voltage

Roger Evans
 

Attilio,

If you are buying spare parts it would be wise to get some 5nF (0.005uF) high voltage ceramic capacitors. It will probably be easier to find modern parts rated at 5kV rather than 4kV. Also have a close look for any signs of tracking around the high voltage area and the focus resistors R444.

Regards,

Roger


Re: T912 storage oscilloscope - No 2.7 KV high Voltage

Attilio
 

Roger,
thank you very much for the explanation, I had sensed that the feedback could raise the output tensions. On the HV secondaries I have disconnected all the 4 KV capacitors and the connections to the CRT, but with CR463 and / or CR465 connected to the T460 transformer the other voltages (-120 V and - 220 V drop to - 14 V).
I will try to replace the CR463 and CR465 diodes, but at the moment I don't have them in the house, they are 10 KV - 10 mA diodes.


Re: The first International Mail was delivered today

Jared Cabot
 

Japan Post delivered an exciting parcel today. :)

Thanks!


Re: First mixer diode on a 7L18 : how to test (and possibly replace) ?

Tom Lee
 

Hi Jose,

I recommend that you add "check the attenuator" to your to-do list. Attenuators often act as very expensive fuses.

The mixer diode, whatever it is, will be quite delicate. I've never owned a 7L18, so I have no idea whether the mixer diode is replaceable without special tools. If it is, a possible substitute would be something like a BAT14-104 (a Siemens/Infineon part, IIRC). I've used that diode as a Ka-band mixer, and it works well. They are not cheap though, and easy to damage or kill by casual handling (the capacitance is only around 100-150fF, so when charge transfers from your 100pF body, the voltage can multiply upward by orders of magnitude).

If you get a chance, please take pictures and upload them. I'm very curious to see what the internals look like in that unit.

Good luck!

-- 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 1/14/2021 00:58, Miguel Work wrote:
Wow, a 7l18 I want one!

Can you please upload some photos?

I have some experience with single diode mixers, I have two tek491

Regards!

-----Mensaje original-----
De: TekScopes@groups.io [mailto:TekScopes@groups.io] En nombre de Jose Luu
Enviado el: miércoles, 13 de enero de 2021 23:46
Para: TekScopes@groups.io
Asunto: [TekScopes] First mixer diode on a 7L18 : how to test (and possibly replace) ?

Dear group,

I am fixing a deaf 7L18, it is responsive to a 510MHz signal injected into the second mixer, I still have to test the 510MHz IF, I am anticipating that the first mixer diode has failed (likely from a power overload).

Testing the diode: I suppose I should pay attention to the voltage applied and possibly limit the current, 1V and a few milliamps?
Replacement: the part number I find on the service manual is: 119-0972-02 , googling it does not fetch much, any ideas, is surgery oof the A45 unit possible ?

Thank you for any insight
Jose









Scanned by McAfee and confirmed virus-free.
Find out more here: https://bit.ly/2zCJMrO


9961 - 9980 of 186209