Date   

Re: Very Inexpensive 7623A, but Problems

Tom Lee
 

The answer depends critically on whether in the northern or southern hemisphere.

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

On 2/13/2021 14:46, Jeff Dutky wrote:
Tom,

So do I need to replace my bench stool with a cot, or can I just turn the scope 90 degrees?

Also, which side, left or right?

-- Jeff Dutky




Re: Very Inexpensive 7623A, but Problems

Tom Lee
 

The answer depends criticaly on whether in the northern or southern hemisphere.

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

On 2/13/2021 14:46, Jeff Dutky wrote:
Tom,

So do I need to replace my bench stool with a cot, or can I just turn the scope 90 degrees?

Also, which side, left or right?

-- Jeff Dutky




Re: Checking sampling diodes

Tom Lee
 

The HSMS-2812 is a dual Schottky that can replace that pair 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 2/13/2021 14:45, Charles wrote:
Sorry, I skipped a couple steps in my train of thought. There are also lots of GaAs diodes (not tunnel diodes) from Russia, for mixing and microwave applications. I figured on using a pair of those to make sure I'd meet the 350 ps spec.

Anyway I'll read some Schottky diode spec sheets and pick one, unless you have a p/n to suggest?

Meanwhile... I did check with a power supply set to 1 volt, and a 1K series resistor. Sure enough, one of the diodes was open. So I carefully removed the holder per the manual without incident... but while manipulating it with a hemostat and test probes, I not only managed to break the aged and brittle plastic holder in two,. but also pull the lead off one of the incredibly tiny diodes. I think it's the good one, too. Oh well, they are supposed to travel in pairs anyway.

It looks like I can either fabricate a mount to span the gap in the PC board where the holder slid in, or perhaps carefully solder the diodes (with very short leads) directly across the gap. As we've noted, 350 ps is not quite as critical as the faster heads are.




Re: Checking sampling diodes

 

On Sat, Feb 13, 2021 at 11:44 AM, snapdiode wrote:


You said " Russian GaAs diodes", I assume you refer to the mountains of
Russian tunnel diodes, since Schottky diodes aren't GaAs.
Some are.
https://www.mouser.com/datasheet/2/249/MA4E20xx_Series-938308.pdf


Re: Tektronix 7904 Repier

Jean-Paul
 

Bonsoir Bravo for the repair

You dont attach photos to messages on this forum, you must use the photos section, creating a new album, name and descriptions then choose the photos to upload

Cumbersome process but the only option in groups.io forums.

Kind Regards


Jon


Re: Very Inexpensive 7623A, but Problems

 

Tom,

So do I need to replace my bench stool with a cot, or can I just turn the scope 90 degrees?

Also, which side, left or right?

-- Jeff Dutky


Re: Checking sampling diodes

 

Sorry, I skipped a couple steps in my train of thought. There are also lots of GaAs diodes (not tunnel diodes) from Russia, for mixing and microwave applications. I figured on using a pair of those to make sure I'd meet the 350 ps spec.

Anyway I'll read some Schottky diode spec sheets and pick one, unless you have a p/n to suggest?

Meanwhile... I did check with a power supply set to 1 volt, and a 1K series resistor. Sure enough, one of the diodes was open. So I carefully removed the holder per the manual without incident... but while manipulating it with a hemostat and test probes, I not only managed to break the aged and brittle plastic holder in two,. but also pull the lead off one of the incredibly tiny diodes. I think it's the good one, too. Oh well, they are supposed to travel in pairs anyway.

It looks like I can either fabricate a mount to span the gap in the PC board where the holder slid in, or perhaps carefully solder the diodes (with very short leads) directly across the gap. As we've noted, 350 ps is not quite as critical as the faster heads are.


Re: Very Inexpensive 7623A, but Problems

Tom Lee
 

You're supposed to use the scope while lying on your side.

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

On 2/13/2021 14:08, Jeff Dutky wrote:
I'm reading through the service manual before I start testing the power rails. I am amused that they mounted the vertical amp board vertically and the horizontal amp board horizontally. It's a shame that they could not find space to mount the Z-axis board perpendicular to them both.

-- Jeff Dutky




Re: Very Inexpensive 7623A, but Problems

 

I'm reading through the service manual before I start testing the power rails. I am amused that they mounted the vertical amp board vertically and the horizontal amp board horizontally. It's a shame that they could not find space to mount the Z-axis board perpendicular to them both.

-- Jeff Dutky


Re: Stan Griffiths estate sale

Greg Muir
 

I still suggest contacting him on his FB page. There are even more people talking to him about it there.

In addition, he seems to be helping people find parts for their equipment there.

Greg


Re: EIP 101B Spectrum Analyzer Plug-In on E-bay

Alain Mionnet
 

Dan,

I have asked about you because in the topic it wasn't clear that finaly you have the unit except that you wrote about the EIP 101B as a plug-in for Tek scope 500 serie in the tek wiki.
I will see if I may find 1 detector ok for this application...
Note that the detector amplifier circuit isn't detailed in the SM of the 101A.
It is as an EIP parts.
I will powered tomorrow the unit I think...
Stupid, I bring back it but not a N cable...I may test @ 1 GHz. For higher Frequency range it will depends if a Gigatronics 1026 here with the transformer to be replaced will be ok (is OFF since 2006 ....so may be an other failure now (was ok))

Alain

France


Re: EIP 101B Spectrum Analyzer Plug-In on E-bay

Alain Mionnet
 

Chris,

The album is free acces. I don't think that is a trouble for the storage size of the group.
I wait better quality photos for my device taken today by a friend.

Alain

France


Re: Very Inexpensive 7623A, but Problems

 

Jean-Paul,

I was not thinking of this as a "daily driver" but more for special purpose work. I have a full stable of portables that I would prefer as my daily use scope, but I understand that a storage scope has specific use cases, and it just be nice to be able to pull this out when/if I need it. I'll be using it pretty lightly, after I've fixed it up and played around with it a bit (what good are toys that you don't play with?).

If this ends up being a good experience I would like to get a second 7000-series, non-storage, with a larger screen. That was why I got the ill-fated 5103N (have I mentioned that it arrived packed in dog food?), and I'm still interested in that. I'll worry about that when I've cleared my backlog of projects (which might not be for another year, at this rate).

I was thinking that a good use for the storage scope would be as a curve tracer, either with an external curve tracer or a 7CT1N. That's a low utilization task that would benefit from the storage and doesn't need a high bandwidth scope. I'm still a little intimidated by the spectrum analyzer plugins: I'm not used to doing my electronics using nothing but physical geometry (also, I've got a tinySA, and I'm still wrapping my brain around how to use it and what for, so I'm far from ready to take the training wheels off and jump in the deep end, to mix a metaphor).

Tom,

Also, the display is unaffected by tilting or tapping on the case, and there are no ominous rattling sounds, which (I think) tells me that there aren't things flopping around loose in the CRT. Still, I worry.

The CRT in the dog food packed 5103N might be displaying double peaking, so I ordered a very cheap parts mule that arrived atrociously packed with the CRT shattered. That was quite a disappointment, and it took a few weeks to get a refund and return shipping. I sent it back properly packed; I wonder if the seller noticed.

-- Jeff Dutky


Re: Very Inexpensive 7623A, but Problems

Jean-Paul
 

Jeff,

the 7000 are classics and include a wide variety of mainframes and plug-ins, storage and the 7104 microchannel plate 1 ghz used by AEC in nuclear weapons testing.

At ham radio Fleas they went for $50-200 usually with plugins.

Shipping scopes is always a risk. Few epay sellers know how to do the packing.

I have used my non store 7904 as an everyday bench scope, a reliable workhorse.

My 7803 is used with 7L5 and 7L12.

The storage CRTs have limited life and subject to flaws and burnin. Not reccomended for everyday use.

Your scope would most useful with a spectrum analyzer plugin that needs the storage.

if you are interested in some spares parts or plug-ins in need of repair, I might have some.

Bonsoir,

Jon


Re: Very Inexpensive 7623A, but Problems

Tom Lee
 

The display is bright, the readout works. That tells you a lot right there.

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

On 2/13/2021 12:12, Eric wrote:
The good news is you check pre trippler not post so you only need to measure -4Kv. If you have any image it is safe to assume the trippler is working.

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Jeff Dutky
Sent: Saturday, February 13, 2021 2:22 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Very Inexpensive 7623A, but Problems

Eric,

Wow! It's a good thing I got myself a brand new HV probe for Christmas (rated to 40KV)! And here I was jumpy about the 2.5KV on the 475! Good times.

-- Jeff Dutky











Re: Very Inexpensive 7623A, but Problems

 

Bert,

I'm glad to hear that. This is my first toe dipped into the 7000-series, and I was hoping for a good experience.

I've got a 5000-series scope that has been a tale of woe, and nearly put me off the mainframes for good.

I also have a small stable of 400 and 2200-series scope that have been absolute joys, as well as a 2465 that was another surprising bargain. While this scope is only the slow end for me (the vertical plug-ins limit it to only 75 MHz) I was really interested in having an analog storage scope.

-- Jeff Dutky


Re: Shipped They Are

Ed Pavlovic
 

Larry,
Just to let you know my set of boards showed up here north of Chicago this morning. Thanks again for taking on the task of arranging the group order and all of the shipping!!!!

I did a quick inspection of the boards and was impressed with the quality of the boards.

Now I need to strip out one of my plug in frames and start assembling things!!!

Ed Pavlovic
KC9MMM


Re: Very Inexpensive 7623A, but Problems

Bert Haskins
 

On 2/13/2021 2:55 PM, Jeff Dutky wrote:
Other minutia:

The serial number is B183764.

The date codes on the ICs range between 77 and 78, so this scope looks like it's about 42 years old.
Hi Jeff.

I have two 7623As each in two different work areas.

They have been rock solid for over two decades.

Well worth your effort to restore.

 Bert



Re: Tektronix 7904 Repier

Kaveh
 

Hello everybody,
I wanted to let you know that I have now repaired the device. The fault was in the amplifier on the horizontal board. Three transistors were defective. I was not able to install the original parts from Tektronix, but I have installed comparison types that show quite a lot of values. I put the device into operation today and I'll be calibrating it soon. At this point I would like to thank you all for your advice and help. Have a nice evening to all of you and watch out for Covid 19. Thank you
Kaveh
PS: I took a few photos of the device, but I cannot attach them to this message. I'll try, maybe it'll work.


Re: Very Inexpensive 7623A, but Problems

Eric
 

The good news is you check pre trippler not post so you only need to measure -4Kv. If you have any image it is safe to assume the trippler is working.

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Jeff Dutky
Sent: Saturday, February 13, 2021 2:22 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Very Inexpensive 7623A, but Problems

Eric,

Wow! It's a good thing I got myself a brand new HV probe for Christmas (rated to 40KV)! And here I was jumpy about the 2.5KV on the 475! Good times.

-- Jeff Dutky

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