Date   

Re: Type 284 TD Bias issues

Eric
 

I am reviving a long dead thread to say thanks for the help on this repair. I was able to get the 284 back to working 100%. The TD was good and this was a biasing issue with the resisters. If any one else has this issue 1206 surface mount resisters will fit inside the 54 Ohm back terminator and can easily be used you will need to form a lead on one sided to get the leg to terminate at the back of the air line but this actually helps a little as lead inductance is reduced. I cannot say how much of an effect this has cause my gear doesn’t go that fast.

Eric

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Eric via groups.io
Sent: Sunday, February 28, 2021 1:59 PM
To: TekScopes@groups.io
Subject: [TekScopes] Type 284 TD Bias issues

I have a type 284 that I am working on again to see if I can’t get the td pulse side working again. Where I am at now is the last time I was in the pulser I was able to confirm that D180 is good on a curve tracer. My issue seems to be in R184 B&C. R180 seems to be good as well as R184A R184 B&C is a 2 carbon comp series resistance that should be 660 Ohms mine measure 724 Ohms if my understanding of the circuit is correct the 2 resister combination was done due to size constraints along with parasite capacitance reduction. They are carbon 1/8 Watt resisters. The challenging part is they need to be inside R184 so space is extremely critical. I can get resisters from NTE that look like they might fit. Is there any reason that I can not play with the resistance values as long as the sum total is 660 Ohms? Also given that there are IN the tunnel diode air line is resister material an important consideration given the 70 Ps rise time of the TD. In circuit this is the negative bias driver for the TD. On the positive side of things R180 is reading 749.82 Ohms so that does not need to be changed.

Thanks,
Eric


Re: 7603 horizontal performance

 

Hi Eric,

I have 7B53A also. I just got some extra plugins with one 7603.
Wanted to see how faster sweeps behave using 7B87; not so well.

BR,
Jouko


Re: 7603 horizontal performance

Eric
 

One other thing to note is the 7B87 is a special time base for the 7854 mainframe it puts out some additional signals that are needed for single shot digitize in that mainframe only. The delayed time base would be the 7B85. The 7B53A is the best match for a 7603 since it is only a 3 bay it gives the best feature set in the limited space. Good news is they are cheap. And it wont over drive the frame.

Eric

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Raymond Domp Frank
Sent: Tuesday, March 9, 2021 10:01 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] 7603 horizontal performance

On Tue, Mar 9, 2021 at 03:42 PM, Brian wrote:


Hi Raymond Would I be anywhere near right if I suggested the P6230 --
is that the one providing DC offset . If I am wrong then I would gp
for the P6056/6057
You are completely right, Brian! P6230 first, then P6056.
I hardly ever use a 7S14.
I mostly use a 7904(A) or a 7854. If necessary, I use a 7T11A/7S11 with S-4 or the like. I hardly ever play with my 7104 because it's in absolutely mint/NOS condition, including the painted edges and I like to keep it that way. It has spent almost all its life in a dark closet and that's where I'm keeping it as well.

Raymond


Re: TEK370A >> 370B ?

73_Fred
 

Hi Bob, thanks for the information.
The only reason for a upgrade was:
"Allows saving screen images to the floppy in .bmp format.........shift/hardcopy
Allows saving curve files to the floppy in .csv format.............local/hardcopy".
But in the meantime i have a tool to convert the curve.cxx files in a bitmap curve.cxx.png or .bmp and also in a csv file.
Also using the plotter emulator software from KE5FX succesful.


Re: 7603 horizontal performance

 

On Tue, Mar 9, 2021 at 03:42 PM, Brian wrote:


Hi Raymond Would I be anywhere near right if I suggested the P6230 -- is that
the one providing DC offset . If I am wrong then I would gp for the P6056/6057
You are completely right, Brian! P6230 first, then P6056.
I hardly ever use a 7S14.
I mostly use a 7904(A) or a 7854. If necessary, I use a 7T11A/7S11 with S-4 or the like. I hardly ever play with my 7104 because it's in absolutely mint/NOS condition, including the painted edges and I like to keep it that way. It has spent almost all its life in a dark closet and that's where I'm keeping it as well.

Raymond


Re: Provenance of your vintage gear

John Griessen
 

On 3/8/21 10:53 PM, Charles Plunk wrote:
Made me ponder how it made it down to the hills of West Tennessee.
A 475 with Hughes Aircraft tag might have been something to do with Oak Ridge Labs,
since Hughes was a govt contractor with capital C.


Re: To Beeswax or not to Beeswax: that is the question.

Li Gangyi
 

I've always thought it was called Glyptal? I'm still using it for some
instances where I'd have to lock a potentiometer in place after tweaking
it, in a high vibe environment.

On Mon, Mar 8, 2021 at 8:03 PM Ed Breya via groups.io <edbreya=
yahoo.com@groups.io> wrote:

I'm pretty sure that at least for non-high voltage transformers, Tek used
a black polyurethane varnish for impregnation. I recall long ago, I picked
up a couple of expired gallon cans at the Country Store. I never used it
for transformers, but it made a great restoring material for rusted steel.
On my "rust-bucket" '68 MGB project, I stripped the interior, and washed it
thoroughly, then coated the whole inside with this stuff. The metal was OK,
except the floorboards were full of pinholes and some up to maybe 1/8 D,
and spongy in some places. The goop was thin enough to soak into the spongy
parts, yet thick enough to just slop on and cover everything nicely, even
bridging the holes, and made it very strong.

Ed






Re: 7603 horizontal performance

Brian
 

Hi Raymond Would I be anywhere near right if I suggested the P6230 -- is that the one providing DC offset . If I am wrong then I would gp for the P6056/6057 
Brian

On Tuesday, 9 March 2021, 14:28:40 GMT, Raymond Domp Frank <hewpatek@gmail.com> wrote:

On Tue, Mar  9, 2021 at 03:11 PM, Jean-Paul wrote:


On 50 Ohm WB plugins we use a direct connection with BNC/coax or a Zo Probe
like P6156.

The FET probes are huge, costly, have DC offset and VERY easy to damage the
input FETs. Seldom of practical use.
I have P6056/6057's and FET probes - and a P6230. Guess which one I use most.

Raymond


Re: 7603 horizontal performance

Brian
 

I like the P6201 also , I'm lucky enough to have 4 complete sets . I have not used them with a 7S14 though only the resistive probes . I have a 7S14 acquired long before the P6201's but the sampler has not been used that much for a while as I have since purchased 2 x 7104's along with some 7A29's and 7A19's . I also like the 7A29 over the 7A19 as its much easier to reset the input protection than keep replacing fuses that are really hard to find .
Brian

On Tuesday, 9 March 2021, 14:23:43 GMT, Raymond Domp Frank <hewpatek@gmail.com> wrote:

On Tue, Mar  9, 2021 at 03:05 PM, Brian wrote:


Hi Raymond I cant afford better than the P6201 and a home made 1101
substitute , if I need better I have a P6056 and P6057 resistive probes but of
course no Hi-Z input
Hi Brian,
I love the P6201 and actually prefer it over the P6202 because of its handling convenience. I have the luxury of several 'scopes with probe power sockets. Still, I have modified two P6202's (the ones with permanently connected power supply) by cutting the power wire somewhere near the middle and inserting a Lemo male/female plug set like Tek used for probe power. That way, I have a stand-alone probe power supply to use with a P6201, should a probe power socket be absent, in the process converting the P6202's to P6202A's (?)...

Raymond


Re: Restoring CRT emission?

Andre de guerin
 

Hey,I found an interesting anecdotal reference to bad emission no longer manufactured RADAR CRTs and certain hard to source specialist vacuum tubes being temporarily repaired using a Blu-ray or 445nm laser.Seems that zapping the vicinity of the exposed heater while highly reverse biased wrt other electrodes, will sometimes knock off enough of the emissive material from the adjacent plates for it to re-deposit onto the heater as it cools.It sounds pretty unlikely but very easy to test on a bad tube at minimal risk if one wears appropriate safety gear.
The reason why I mention it is that a related hack is to use the same laser on a certain tube to accelerate electrons more efficiently allowing it to function at a lower applied voltage for uh, "research" purposes.This was once upon a time classified TS-SCI but it emerged a few years back in a science journal article.
It will work with longer wavelengths but the reason for using blue light is that it is preferentially absorbed and more likely to heat just the surface rather than the entire electrode.



#include "802701.h"

On Tuesday, 9 March 2021, 04:02:52 GMT, Craig via groups.io <craigyard99=yahoo.com@groups.io> wrote:

Speaking of BeO

Tektronix used BeO substrates in some of the power hybrids. Specifically the gold plated TO8 packages with the heat sink post on the bottom. The substrates came pre-scribed in a sheet and the small squares had to be snapped apart before being attached to the header. This operation was done submerged in a water bath to prevent airborne dust.
Craig


Re: 7603 horizontal performance

 

On Tue, Mar 9, 2021 at 03:11 PM, Jean-Paul wrote:


On 50 Ohm WB plugins we use a direct connection with BNC/coax or a Zo Probe
like P6156.

The FET probes are huge, costly, have DC offset and VERY easy to damage the
input FETs. Seldom of practical use.
I have P6056/6057's and FET probes - and a P6230. Guess which one I use most.

Raymond


Re: 7603 horizontal performance

 

On Tue, Mar 9, 2021 at 03:05 PM, Brian wrote:


Hi Raymond I cant afford better than the P6201 and a home made 1101
substitute , if I need better I have a P6056 and P6057 resistive probes but of
course no Hi-Z input
Hi Brian,
I love the P6201 and actually prefer it over the P6202 because of its handling convenience. I have the luxury of several 'scopes with probe power sockets. Still, I have modified two P6202's (the ones with permanently connected power supply) by cutting the power wire somewhere near the middle and inserting a Lemo male/female plug set like Tek used for probe power. That way, I have a stand-alone probe power supply to use with a P6201, should a probe power socket be absent, in the process converting the P6202's to P6202A's (?)...

Raymond


Re: 7603 horizontal performance

 

On Tue, Mar 9, 2021 at 03:01 PM, Raymond Domp Frank wrote:


Absolutely, Brian. For full BW you need (something even faster than) the
P6201. I was thinking about the convenience of having an "integrated" power
supply, as opposed to needing to hunt for an 1101. I should have mentioned
that but thanks for bringing it up.
Further to this, AFAIK the OP wasn't looking for 1 GHz BW as such, but looking for a significantly faster time base and vertical BW. Even the P6201 "only" achieves 900 MHz "on its own".
Talking about convenience: I often prefer using a 7A29 over a 7A19, even at around 500 MHz, because of the former's variable attenuation knob - and resettable overvoltage protection...

Raymond


Re: 7603 horizontal performance

Jean-Paul
 

On 50 Ohm WB plugins we use a direct connection with BNC/coax or a Zo Probe like P6156.

The FET probes are huge, costly, have DC offset and VERY easy to damage the input FETs. Seldom of practical use.

Best Ref is the Tek Circuit Concepts book Oscilloscope Probes

Kind Regards

Jon


Re: 7603 horizontal performance

Brian
 

Hi Raymond I cant afford better than the P6201 and a home made 1101 substitute , if I need better I have a P6056 and P6057 resistive probes but of course no Hi-Z input 
Brian

On Tuesday, 9 March 2021, 14:02:22 GMT, Raymond Domp Frank <hewpatek@gmail.com> wrote:

On Tue, Mar  9, 2021 at 02:55 PM, Brian wrote:


Hi , if my memory serves me correctly the P6202 FET probe is only 500MHz so
you will likely need a P6201 and an 1101 psu for maximum B/W
Brian
Absolutely, Brian. For full BW you need (something even faster than) the P6201. I was thinking about the convenience of having an "integrated" power supply, as opposed to needing to hunt for an 1101. I should have mentioned that but thanks for bringing it up.

Raymond

Raymond


Re: 7603 horizontal performance

 

On Tue, Mar 9, 2021 at 02:55 PM, Brian wrote:


Hi , if my memory serves me correctly the P6202 FET probe is only 500MHz so
you will likely need a P6201 and an 1101 psu for maximum B/W
Brian
Absolutely, Brian. For full BW you need (something even faster than) the P6201. I was thinking about the convenience of having an "integrated" power supply, as opposed to needing to hunt for an 1101. I should have mentioned that but thanks for bringing it up.

Raymond

Raymond


Re: 7603 horizontal performance

Brian
 

Hi , if my memory serves me correctly the P6202 FET probe is only 500MHz so you will likely need a P6201 and an 1101 psu for maximum B/W
Brian

On Tuesday, 9 March 2021, 13:51:28 GMT, Jouko Koskinen <jouko.koskinen@dnainternet.net> wrote:

Hi Raymond,

I already have 7S14. Have to look into FET probes.
Thread "Sampling with 7S14".

BR,
Jouko


Re: 7603 horizontal performance

 

Hi Raymond,

I already have 7S14. Have to look into FET probes.
Thread "Sampling with 7S14".

BR,
Jouko


Re: [Tek 485] No intensity control

SCMenasian
 

Actually, I see 2N3565s for sale on line at several places, including Jameco. However, they may be new "improved"
parts with different specs.

MPS6520 looks like an excellent replacement. Min hfe is better. Many other specs are better. MPS6521 is even better. These should be widely available. Only max emitter-base breakdown looks worse.


Re: 7603 horizontal performance

 

On Tue, Mar 9, 2021 at 09:09 AM, Jouko Koskinen wrote:


What I like in this 7603 is the large screen. Therefore I thought about this
exercise.
The 7603 works well with a 7S14 sampling plugin. 1 GHz BW, two 50 Ohm channels only but a P6202 FET probe can provide Hi-Z input. The non-A (so, plain P6202, not P6202A) has its own power supply.
High BW, low input capacity, easy-to-operate sampling plugin, 350 ps rise time, and all that in a 7603, you can't lose!

Raymond

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