Date   

Re: Tek 575 tube adapter

magnustoelle
 

Hi Julian,

I am glad to see you are making good (further use) of your 575.

We just had that topic some months ago. I'd say give the search function a try and it shall come up with this:

http://glydeck.blogspot.de/2012/02/testing-miniature-pentodes-with-tek-575.html
and George's postings on subject such as
http://tech.groups.yahoo.com/group/TekScopes/message/84878
He did some quite marvelous things...

Cheers,

Magnus


Re: TEK 453 Vert Amp - not 453A

Mark Wendt <mark.wendt@...>
 

On 05/20/2013 12:46 PM, David wrote:
The 453A manual uses a thick light blue line for the demarcation,
solid circles for soldered connections, and arrows for mechanical
connections.

Based on the legend in the 453 manual which immediately follows the
schematic, the thin demarcation line was originally blue, solid
circuits are soldered connections, and open circles are mechanical
connections.

Maybe the 453 manual from ArtekManuals is a more faithful reproduction
then the various free ones floating around.
Okay, mea culpa. In my defense, I did say I was a bit dense. I just realized what I thought were circuit traces were the board edges... Doh!

Mark


Re: FIXED: TDS544A error "acqdataconf"

 

Hi Andy,

Nice job. For future reference, I don't think the memory controllers and SRAM chips are laid out in order 4, 3, 2, 1 from left to right of the ACQ board (with the scope upside down and the BNCs facing you) like one would think lining up with the input channels. I believe that in this orientation it is 3, 4, 1, 2. I will check later on when I get home - I have an old parts board that I marked up. I'm not even sure that the memory map I posted earlier has the channel references correct; I may have done that before I realized that the channels were not in order. In fact it could also be 4, 2, 3, 1.

Jay

--- In TekScopes@yahoogroups.com, "baltimora86" <acuffe@...> wrote:

It was U217, one of the SRAMs for channel 3. I found the problem by replacing one SRAM, and then reinstalling the one I just replaced in the next location, and repeating until the error went away. I hit it on the third try, and only needed one replacement chip.

Andy

--- In TekScopes@yahoogroups.com, "baltimora86" <acuffe@> wrote:

Can anyone give me any hints about what the following error on a TDS544A means?

acqdataconf.** addr = 0x738000e exp data = 0x8000 actual = 0x8002

The scope was recapped several years ago. They did a very good job, and there isn't a trace of corrosion, or leftover electrolyte on the boards. Someone also replaced U300 (one of the ADG219C memory controllers). I would guess it's the one for channel 2 based on its location.

At the moment, it powers up, but fails the acquisition, and acq/proc interface tests. I can't find any obvious functional problems with any channel, even at fast sweep rates and long record lengths. I've confirmed that the acquisition board is at fault by temporarily swapping in a known good acquisition board.

I've read that address 0x738000 corresponds to channel 3. Could the error indicate a bad SRAM chip?

Thanks in advance,

Andy


Re: 434 Storage Scope triggering problem

fiftythreebuick <ae5i@...>
 

It was indeed. I have an early one and a late one and they are both very nice scopes. The later one has a much more elaborate power supply control system than the early one. Both work quite well though....

Tom

--- In TekScopes@yahoogroups.com, larrys@... wrote:

text removed<< Properly adjusted, the 434 was a
very nice bistable storage scope.
-ls-


TDS 784D CRT Adjustment Questions

W1WF <hwashcraft@...>
 

I am working on a TDS 784D, Serial # B010510

I have removed and installed a new CRT/LCD Shutter assembly and now need to adjust the display. The manual I have tells me to set the dip switches closed except 3, 6 & 7 that should be open, start the scope, and then enter the utility menu and display the composite test screen. (So far, so good). I am then supposed to adjust the trace rotation using R401 (described as second adjustment from the fan), brightness using R403 and contrast using R404. The problem is that the main board doesn't have R401, R403 and R404. I have looked all over the unit and can't find any adjustable resistors where the manual says they should be.

So...where are they? Or do they not apply to this serial number? And if so, how do you make the adjustments?

Thanks, Howard


Re: 434 Storage Scope triggering problem

Michael A. Terrell
 

VR635 Zener, fed through R636 from the +15 volt supply. The Zener is shown as 5.1 V on the schematic. (Trigger Pickoff and Generator) P 181
of the manual at w140.com/tektronix_434_service.pdf near the top and towards the right side of the page.

-----Original Message-----
From: cybertheque_museum <msg.together@gmail.com>
Sent: May 20, 2013 9:40 PM
To: TekScopes@yahoogroups.com
Subject: [TekScopes] 434 Storage Scope triggering problem

2. Where is the source of +5 VDC? (manual does not say and I looked carefully over each schematic but failed to find it).

Michael A. Terrell


Re: Tek 7000 Series deflection plate precision?

Don Black <donald_black@...>
 

I'm no expert on electron microscopes but you should be aware of two types, TEM (Transmission Electron Microscopes) and SEM (Scanning Electron Microscopes). A TEM shines a beam of electrons through the specimen as if though a photographic slide and then expands the beam onto a fluorescent screen to obtain the image (often viewed with an optical microscope to see small details). A SEM scans the target with a raster of s fine electron beam. The beam in a SEM is relatively large since it's like an illuminating light source but the SEM needs a very fine beam, smaller in diameter than the smallest detail you are trying to see. I believe the high school microscope is a TEM and so doesn't need as fine a beam as a SEM.
Others who really know what they are talking about please jump in and correct any mistakes I've made here please.

Don Black.

On 21-May-13 2:36 PM, iglesia_cristiana_arpas_eternas wrote:
 

Hi Damian,Here my two cent about:
You need to put an extra objective lens "magnetical prefereble" in order to obtain a very small dot at least half what minimum size yo like to see.and ..or.. increase the tube length, for the same reason.

Most people use a Cristal plate with phosphor where the second emission electron emitted from the target impact and release a photon ,which in turn will be detected by the photomultiplier itself, I believe that such optical conversion is not necessary , just remove the cap on photomultiplier and allow the electron hit the dinodes directly ,If this approach work, surely will be give you a enormous gain and increase in S/N ratio, which in turn allow to use less beam intensity with all benefits.obviously all in high vacuum, inside the chamber.
End of my two cent.
Gabriel.

--- In TekScopes@..., "cheater00 ." wrote:
>
> Hi guys,
> could someone chime in on how precise the deflection in a Tek 7000 can be?
>
> I'm very new to vacuum tubes and the idea of electrostatic deflection,
> so please bear with any stupid questions...
>
> My main consideration is: with modifications, would it be suitable to
> jury rig an SEM (Scanning Electron Microscope)?
>
> I am trying to do something inspired by Ben Krasnow's SEM design. If
> you don't know it, he has some info here on how he made an SEM
> himself:
>
> http://benkrasnow.blogspot.de/2011/03/diy-scanning-electron-microscope.html
> http://benkrasnow.blogspot.de/2011/03/diy-scanning-electron-microscope_26.html
>
> He made the raster generator and deflection assembly and amplifiers
> himself. It was my idea to use a broken 7000 series tube and hook it
> up to a working 7000 scope configured with two time bases in a raster
> generator setup. Of course I'd need a Tungsten filament, the one in
> the 7000 CRT would be broken by having been exposed to air.
>
> What happens in an SEM is that the electron beam *scans* a rectangular
> area on the thing you're zooming in on. It moves in a raster image,
> just like on a TV, or an oscilloscope in raster config. This rectangle
> has to be very small, let's say 2mm across. You'd start out with a
> fairly big rectangle, say 2x2 cm, to see the overall shape of the
> object, then you zoom in a bit so that the rectangle is 1x1cm and pan
> a little, then zoom and pan again, and so on. Think CSI: Miami
> ("enhance"). You might end up with a square of 2mm or even smaller.
>
>
> Here's my question: the deflection needs to be precise, so e.g. if
> you're horizontally 5% of the way, it still needs to be this far
> across, and not erratically in some other place.
>
> It would be bad if it e.g. jumped from 0% to 10% to 20% and so on to
> 100% while skipping the intermediates.
>
> It would also be bad if it e.g. centered around that 5%, but noise and
> interference meant the beam would randomly err between 1% and 9% with
> 5% at its center.
>
> The rectangle as a whole needs to be moved at least in this area of
> 1cm or 2cm as well. It would be fairly bad if the rectangle as a whole
> drifted or if the position were shaky.
>
> How would one modify the deflection circuitry and assembly in a Tek
> 7000 to achieve such a small scan area? Is the circuitry going to be
> low-noise and/or linear enough so that deflection precision is
> retained?
>
> How *wide* across can the electron beam be?
>
> Thanks,
> Damian
>



Re: Tek 7000 Series deflection plate precision?

iglesia_cristiana_arpas_eternas
 

Hi Damian,Here my two cent about:
You need to put an extra objective lens "magnetical prefereble" in order to obtain a very small dot at least half what minimum size yo like to see.and ..or.. increase the tube length, for the same reason.

Most people use a Cristal plate with phosphor where the second emission electron emitted from the target impact and release a photon ,which in turn will be detected by the photomultiplier itself, I believe that such optical conversion is not necessary , just remove the cap on photomultiplier and allow the electron hit the dinodes directly ,If this approach work, surely will be give you a enormous gain and increase in S/N ratio, which in turn allow to use less beam intensity with all benefits.obviously all in high vacuum, inside the chamber.
End of my two cent.
Gabriel.

--- In TekScopes@yahoogroups.com, "cheater00 ." <cheater00@...> wrote:

Hi guys,
could someone chime in on how precise the deflection in a Tek 7000 can be?

I'm very new to vacuum tubes and the idea of electrostatic deflection,
so please bear with any stupid questions...

My main consideration is: with modifications, would it be suitable to
jury rig an SEM (Scanning Electron Microscope)?

I am trying to do something inspired by Ben Krasnow's SEM design. If
you don't know it, he has some info here on how he made an SEM
himself:

http://benkrasnow.blogspot.de/2011/03/diy-scanning-electron-microscope.html
http://benkrasnow.blogspot.de/2011/03/diy-scanning-electron-microscope_26.html

He made the raster generator and deflection assembly and amplifiers
himself. It was my idea to use a broken 7000 series tube and hook it
up to a working 7000 scope configured with two time bases in a raster
generator setup. Of course I'd need a Tungsten filament, the one in
the 7000 CRT would be broken by having been exposed to air.

What happens in an SEM is that the electron beam *scans* a rectangular
area on the thing you're zooming in on. It moves in a raster image,
just like on a TV, or an oscilloscope in raster config. This rectangle
has to be very small, let's say 2mm across. You'd start out with a
fairly big rectangle, say 2x2 cm, to see the overall shape of the
object, then you zoom in a bit so that the rectangle is 1x1cm and pan
a little, then zoom and pan again, and so on. Think CSI: Miami
("enhance"). You might end up with a square of 2mm or even smaller.


Here's my question: the deflection needs to be precise, so e.g. if
you're horizontally 5% of the way, it still needs to be this far
across, and not erratically in some other place.

It would be bad if it e.g. jumped from 0% to 10% to 20% and so on to
100% while skipping the intermediates.

It would also be bad if it e.g. centered around that 5%, but noise and
interference meant the beam would randomly err between 1% and 9% with
5% at its center.

The rectangle as a whole needs to be moved at least in this area of
1cm or 2cm as well. It would be fairly bad if the rectangle as a whole
drifted or if the position were shaky.

How would one modify the deflection circuitry and assembly in a Tek
7000 to achieve such a small scan area? Is the circuitry going to be
low-noise and/or linear enough so that deflection precision is
retained?

How *wide* across can the electron beam be?

Thanks,
Damian


Re: Tek 7000 Series deflection plate precision?

Don Black <donald_black@...>
 

Maybe an image orthicon rather than a vidicon? They have an electron multiplier as part of the tube. I think you might find one to try but I hope there aren't too many IOs destroyed for the project.

Don Black.

On 21-May-13 12:13 AM, cleyson@... wrote:
 

I think one of the biggest problems you're going to have is
focusing the beam down small enogh to make it usable. If you're
going to use a CRT electron gun you would be better off using
magnetic focus and possibly deflection.

It might be worth trying an old one inch diameter Vidicon
camera tube if you can find one. Better still try to get
hold of a complete camera, that way you get the deflection
coil drive electronics as well. In addition, it might be easier
taking the faceplate of the front of a camera tube rather than
taking a gun assembly out of a CRT.

BTW it was Brad's idea of a custom design CRT that made me
think of the Vidicon.

Chris

--- In TekScopes@..., "cheater00 ." wrote:
>
> Brad,
> you need a way to put a photomultiplier in there somewhere. Won't do a
> lot of good otherwise.
>
> Have a look at Ben Krasnow's links, he has a very down to earth
> explanation of what's what.
>
> At his BOM, which is around the $1000 mark, a school can already
> afford one of those if it is so inclined.
>
> Cheers,
> D.
>
> On Mon, May 20, 2013 at 3:14 PM, Brad Thompson wrote:
> > On 5/20/2013 8:32 AM, cheater00 . wrote:
> >> Hi guys,
> >> could someone chime in on how precise the deflection in a Tek 7000 can be?
> >>
> >> I'm very new to vacuum tubes and the idea of electrostatic deflection,
> >> so please bear with any stupid questions...
> >>
> >> My main consideration is: with modifications, would it be suitable to
> >> jury rig an SEM (Scanning Electron Microscope)?
> >>
> >> I am trying to do something inspired by Ben Krasnow's SEM design. If
> >> you don't know it, he has some info here on how he made an SEM
> >> himself:
> >>
> >> http://benkrasnow.blogspot.de/2011/03/diy-scanning-electron-microscope.html
> >> http://benkrasnow.blogspot.de/2011/03/diy-scanning-electron-microscope_26.html
> >
> >
> >
> > Hello--
> >
> > A concept that I've kicked around for a while comprises a scanning
> > electron microscope that would be inexpensive enough to offer
> > high-school science departments. Please understand that I'm
> > not familiar with electron microscope technology and the
> > concept may be technically impractical, financially unsupportable
> > or otherwise hopelessly flawed.
> >
> > Imagine a custom-designed "cathode ray" tube that has a fixed
> > target located in place of the phosphor screen. Make the target
> > "interesting"-- e.g., a well-used coin with a small smear of
> > bacteria on the surface (metallized). The tube would include an
> > oscilloscope-tube-like electron gun and electrostatic-deflection
> > plates and a collection means for electrons deflected by the
> > target.
> >
> > Use an oscilloscope or dedicated interface box to provide
> > controllable beam deflection, amplification of the scattered
> > electrons, and display of the recovered image. Further signal
> > processing by a PC might be needed.
> >
> > My hunch is that the specialized specimen-containing tubes could be
> > mass produced at relatively low cost, since the target is not
> > replaceable and thus eliminates the need for vacuum apparatus.
> >
> > In the lab, students could explore the coin's surface and study
> > the effects of varying deflection voltages, etc.
> >
> > Comments welcomed.
> >
> > 73--
> >
> > Brad AA1IP
> >
> >
> >
> >
> > ------------------------------------
> >
> > Yahoo! Groups Links
> >
> >
> >
>



Re: 434 Storage Scope triggering problem

teamlarryohio
 

"Ed Breya" <edbreya@yahoo.com> wrote:
BTW, I think the 434 is one of the nicest scopes ever made. I don't
have one, nor have I seen or used one since over thirty years ago - it
made a great and lasting first impression on me.
One thing the 432 / 434 brought was an early SMPS predating the
custom Tek-made control IC. Properly adjusted, the 434 was a
very nice bistable storage scope.
-ls-


Re: Tek 7000 Series deflection plate precision?

Carlos
 


Hello--

A concept that I've kicked around for a while comprises a scanning
electron microscope that would be inexpensive enough to offer
high-school science departments. Please understand that I'm
not familiar with electron microscope technology and the
concept may be technically impractical, financially unsupportable
or otherwise hopelessly flawed<g>.



Comments welcomed.

73--

Brad AA1IP
Brad:

I'm not familiar with electron microscopes, but I remembered having read many years ago an article about an electron microscope built by students. It was featured in the 'Amateur Scientist' section of Scientific American magazine (when it was an excellent publication).

I just found the article here:

http://jesseenterprises.net/amsci/1973/09/1973-09-fs.html

Maybe this could be of some interest for you.


(By the way, I found also a source for the book 'The Scientific American book for the Amateur Scientist' by Clair L. Stong, published in 1960. 605 pages of very interesting material, in my opinion:

http://www.sciencemadness.org/library/books/projects_for_the_amateur_scientist.pdf

Just in case someone is interested)


Regards,

Carlos


Re: 434 Storage Scope triggering problem

Ed Breya
 

I'd guess that the guts are OK, but you have a switch or pot (including tweaks) that has contact problems. If you exercise and sufficiently jiggle all of the controls a few dozen times, it may start acting more normal - or not.

You seem to know what you're doing, so you know you can figure it out if you have the right info - instruction manual, etc, and you can access the points to make the right measurements. I think your results with going around the normal TD bias are key to understanding what's going on. Yes, the TDs and associated passive components can drift out of spec, but I'd look at the electromechanical stuff first.

BTW, I think the 434 is one of the nicest scopes ever made. I don't have one, nor have I seen or used one since over thirty years ago - it made a great and lasting first impression on me.

Ed

--- In TekScopes@yahoogroups.com, "cybertheque_museum" <msg.together@...> wrote:

Advice sought regarding the following failure on a 434 storage scope and also a question about the power supply:

1. Scope would not sweep regardless of trigger source, level, polarity; single sweep inoperative (and lamp would not light) and auto mode also would not produce a trace.

Waveform tracing up to Q645 base was ok (as per manual)

-- tested tunnel diodes CR644 and CR675 on curve tracer(both good)

-- tested Q645 on curve tracer - displayed parasitic oscillations
but IsubC - VsubC curve family was in spec, however base lead
broke off so replaced with a BC557B

-- adjusted +15 volt supply (was +15.11 V)

-- verified that ripple on all supply rails is in spec

-- verified high voltages (above +15) are in spec

At this point, in AUTO or NORM mode could get a single or few sweeps by switching the slope switch back and forth when the level control was adjusted to produce correct waveform on TP640 (as per manual). Verified that AUTO mode monostable was working properly (AUTO mode same as NORM however - no AUTO).

Discovered that by injecting a current of about 730 uA into TP678 a stable display with proper triggering can be obtained (used a 100 ohm resistor to a bench supply) - slope switch works as intended.

-- with kludge, verified all sweep rates work and are linear

-- verified triggering works at 1/3 division (has some instability)

-- single sweep runs continuously (no difference to NORM except lamp
lights or flickers with sweep rates)

-- AUTO mode same as NORM (no auto).

Interior of scope is very clean, no burnt smells or visible discolorations, no brittle insulation, etc.

Injecting current into the TD moves its operating point enough to permit trigger to begin and end the sweep but the auto mode and single sweep depend on a reset current which could be still out of range. There are a number of connections to '+5 V' in these circuits but the voltage measures at +5.14 V (I have been unable to locate the source of +5 V in the diagrams).

How likely is component aging out of specs in this scope (especially resistors)? This scope was working well, including all of the storage controls, until it abruptly had this failure when powered up two years ago. So far I have not found any 'dead' semiconductors. Within the tolerances specified, the measured voltages at test points and marked points on the schematic are in range for the specified operating conditions, as are the waveforms.

2. Where is the source of +5 VDC? (manual does not say and I looked carefully over each schematic but failed to find it).

Thanks,

Michael


434 Storage Scope triggering problem

cybertheque_museum
 

Advice sought regarding the following failure on a 434 storage scope and also a question about the power supply:

1. Scope would not sweep regardless of trigger source, level, polarity; single sweep inoperative (and lamp would not light) and auto mode also would not produce a trace.

Waveform tracing up to Q645 base was ok (as per manual)

-- tested tunnel diodes CR644 and CR675 on curve tracer(both good)

-- tested Q645 on curve tracer - displayed parasitic oscillations
but IsubC - VsubC curve family was in spec, however base lead
broke off so replaced with a BC557B

-- adjusted +15 volt supply (was +15.11 V)

-- verified that ripple on all supply rails is in spec

-- verified high voltages (above +15) are in spec

At this point, in AUTO or NORM mode could get a single or few sweeps by switching the slope switch back and forth when the level control was adjusted to produce correct waveform on TP640 (as per manual). Verified that AUTO mode monostable was working properly (AUTO mode same as NORM however - no AUTO).

Discovered that by injecting a current of about 730 uA into TP678 a stable display with proper triggering can be obtained (used a 100 ohm resistor to a bench supply) - slope switch works as intended.

-- with kludge, verified all sweep rates work and are linear

-- verified triggering works at 1/3 division (has some instability)

-- single sweep runs continuously (no difference to NORM except lamp
lights or flickers with sweep rates)

-- AUTO mode same as NORM (no auto).

Interior of scope is very clean, no burnt smells or visible discolorations, no brittle insulation, etc.

Injecting current into the TD moves its operating point enough to permit trigger to begin and end the sweep but the auto mode and single sweep depend on a reset current which could be still out of range. There are a number of connections to '+5 V' in these circuits but the voltage measures at +5.14 V (I have been unable to locate the source of +5 V in the diagrams).

How likely is component aging out of specs in this scope (especially resistors)? This scope was working well, including all of the storage controls, until it abruptly had this failure when powered up two years ago. So far I have not found any 'dead' semiconductors. Within the tolerances specified, the measured voltages at test points and marked points on the schematic are in range for the specified operating conditions, as are the waveforms.

2. Where is the source of +5 VDC? (manual does not say and I looked carefully over each schematic but failed to find it).

Thanks,

Michael


Re: 1N3718 tunnel diode testing (475 scope trigger TD)

cybertheque_museum
 

Using a B&K 501 curve tracer instead of a breadboard kludge, I can verify that all four TDs display good characteristic curves and the funky shift of the negative resistance region I had previously observed is absent.

I am taking a break from work on the 475 in order to repair a triggering problem on a 434 since I need a better scope on the bench than the Ballentine 1032A for working the the 475.


Tektronix 502 available in Ottawa

r_corriveau
 

Someone contacted me to see if I was interested in a Tektronix 502. It is located in Ottawa, Canada. If anyone local is interested please contact me and I will foward the message to him.

Robert


7854 parts 'scope on eBay

Dave Daniel
 

I found this while perusing eBay - Looks like a(n) (currently) affordable parts mule.

I know there were several people looking for 7854 parts a while back ...

DaveD


FIXED: TDS544A error "acqdataconf"

Andy
 

It was U217, one of the SRAMs for channel 3. I found the problem by replacing one SRAM, and then reinstalling the one I just replaced in the next location, and repeating until the error went away. I hit it on the third try, and only needed one replacement chip.

Andy

--- In TekScopes@yahoogroups.com, "baltimora86" <acuffe@...> wrote:

Can anyone give me any hints about what the following error on a TDS544A means?

acqdataconf.** addr = 0x738000e exp data = 0x8000 actual = 0x8002

The scope was recapped several years ago. They did a very good job, and there isn't a trace of corrosion, or leftover electrolyte on the boards. Someone also replaced U300 (one of the ADG219C memory controllers). I would guess it's the one for channel 2 based on its location.

At the moment, it powers up, but fails the acquisition, and acq/proc interface tests. I can't find any obvious functional problems with any channel, even at fast sweep rates and long record lengths. I've confirmed that the acquisition board is at fault by temporarily swapping in a known good acquisition board.

I've read that address 0x738000 corresponds to channel 3. Could the error indicate a bad SRAM chip?

Thanks in advance,

Andy


Re: Tek 575 tube adapter

lindberg.adam
 

I usually use a 1kohm resistor connected between the base and emitter connection, doing so converts the current markings to voltage markings in the step generator.

so 1mA = 1V and 0,5mA = 0,5V and so on

this is also handy when measuring mosfets

I built a small rigg with different tube bases and banana jacks to patch the heater and external g2 source if needed then you can just connect the rigg to the curve tracer.


Re: Repair question for Type D High-Gain Differential plug-in

Michael A. Terrell
 

I once had the joy of having to find 16 matched 6146 out of 150 tubes. This was for a video modulator, where they were run in parallel to get the required power and a low output impedance. I managed two almost matched sets, but they aged rapidly in use. Wasn't '50's brute force technology interesting? ;-)

-----Original Message-----
From: "tubesnthings@aol.com" <tubesnthings@aol.com>
Sent: May 20, 2013 3:26 PM
To: TekScopes@yahoogroups.com
Subject: Re: [TekScopes] Repair question for Type D High-Gain Differential plug-in

Dan;
Tube tolerances vary greatly but in a few cases I have seen remarkable consistency.
Strangely, one example is a certain NOS 12AT7WA - 10-out-of-ten (20 triodes!) showed perfectly matched transconductance readings, exactly centered between min/max specs!!

I just picked up a stash of tubes which should contain at least a few 5879s but I haven't gotten around to sorting…

Tek matched tubes for current in test fixtures which resembled the circuit conditions the tube was designated for.
Michael A. Terrell


U400 (155-0236-00) Channel Switch replacement

thomas.lafay
 

Greetings. I have a replacement for the U400 in development, revision B, that is near finished in layout amd am wondering if there's any interest in this project. It would be nice to have others review the schematic before layout is completed. Send me an email at my yahoo address and I'll forward a copy of the schematic to you. Tom

100061 - 100080 of 193026