Date   

Re: Grey, blue or clear? filter colors

Richard Knoppow
 

I remember a dark trace CRT but don't remember how it worked.
   There  were a couple of methods of decreasing the surface reflection of the CRT screen and increasing contrast. Kodak had a patent on a non-reflective screen it used on a slide viewer. It used a combination of a black mask and glass beads. It was used for rear projection and concentrated the transmitted light toward the viewer. A Fresnel lens accomplishes somewhat the same purpose but the beaded screen is different and could be combined with a Fresnel field lens. I don't know if either was used for CRTs. Also, many CRTs were aluminized. That is, a coating of aluminum was deposited on the inside between the phosphor and electron beam. The purpose was to reflect light from the phosphor toward the viewer and prevent light from the inside of the phosphor from  causing a flare. This arrangement was adopted for TV picture tubes and probably many other CRTs. Various arrangements were used for "daylight" television screens, i.e. screens that could be used in strong incident light. A filter on the outside of the CRT can reduce the amount of light reflected by the surface of the screen but does nothing for light or electrons reflected from the insides of the tube back to the screen. It seems to me there were also  methods of coating the phosphor to reduce the spreading of light laterally in the coating in order to sharpen the trace.

On 3/18/2020 6:45 PM, Harvey White wrote:
IIRC, the blue (P11, I think) was rich in blue and ultraviolet. Orthochromatic films, at that time (and still) are blue sensitive and not red sensitive.  Panchromatic films were sensitive to blue, green, yellow, and red.  A portrait taken with orthochromatic film would not look normal because the red component would not be picked up.  For accurate gray scales you needed Panchromatic film.

Kodak fine grain positive release film was an ortho, blue sensitive film that was used for making B&W transparencies of negatives.  Kodalith was an orthochromatic film that could be developed to an intense black and was used for PCB master negatives.

Blue phosphors were used because the film they recorded on was very sensitive, (high ASA rating, and it was ASA then, not ISO) and could be developed under red light (which the film couldn't see).  Panchromatic film had to be developed in total darkness, or at the best, under a very faint green light.  The film was still sensitive to green light, but the human eye is most sensitive to that, so that's the right color for the dimmest possible light.

Most black and white films were panchromatic, except for some special purpose films mentioned above.

The P1 phosphor was green, but not necessarily efficient and could burn in.  Once developed, the P31 phosphor was highly efficient and had good resistance to burnin.  Hence, lots of scope tubes. P12 was orange, there was an odd (P10?) phosphor that darkened with an electron beam and had to be erased with heat, it was somewhat of a one shot.)  P4 was the standard white phosphor, and P22 was the tricolor dot phosphor.  P7 was an odd one, a two layer phosphor with a long persistence phosphor closest to the screen (yellow), and a blue/UV phosphor that excited the yellow phosphor.  It gave a blue trace with a yellow fadeaway, and was used for radar.

Harvey


On 3/18/2020 3:36 PM, Clark Foley wrote:
As I recall after some 40 years or so, the 7603 shipped with the grey filter/implosion shield 337-1700-00 installed and the other two filters came along for the ride as standard accessories.  As these served as implosion shields, one of them should always be installed.  The was another shield as part of the EMI gasket option that had a conductive surface.  I don't recall if that one had a metal mesh or not.  We referred to the grey as neutral density and it gave the best overall viewing contrast.  We recommended the clear for maximum writing rate. I don't remember if there was any technical advantage for the blue. Check the 7603 manual and you will find standard accessories, the blue and clear filters along with the calibrator adapter cable, listed near the end of the book.



--
Richard Knoppow
dickburk@...
WB6KBL


Re: Tek 5441 Scope

lists@...
 

I recently fixed up a 5440 power supply, so here's what I've learned.

First, be sure there aren't any shorted Tantalums on the output side. you might also need to lift the wire to the load to be sure there is not a short on another board.

Second, R911 and similar resistors in the other supplies are parallel to the pass resistor, sharing some of the load current. This is a really nasty idea when it comes to troubleshooting. With insufficient load the output voltage will rise to the raw input voltage even though the pass transistor is cut off. I put a load resistor on the supply to prevent that. When it's finally fixed, plug in the modules before setting the regulation voltage. The good news is that apparently the load circuits can tolerate the greater voltage without damage.

For the transistor, pull it from the circuit and check its gain and bias voltage. Mine had one that part of the Darlington pair worked and the other part didn't, giving a seemingly working transistor but with low gain and a single junction instead of two in series. I used MJE800, still common and available from Digikey.

Finally, I agree with the post about checking the small resistors. Mine drove me crazy and I almost said the heck with it and threw in a 3-terminal chip regulator. I finally found one resistor of the precision pair that sets the reference voltage had gone open, after lifting one end of most of the small components in that circuit.

Good Luck.


Re: Beware of cheap "crock-a-gator" clips

n4buq
 

Thank you for posting this. I decided to test my set and the very first one was very intermittent. I removed the plastic boots and, sure enough, one end was not soldered to the clip. I plan to check all of them.

Fortunatly, the wire in mine appear to be a bit better than you describe - maybe 22-ga stranded so resoldering is all I plan to do.

I wonder how many times things didn't work right and I never thought to check for that as being the problem.

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "ArtekManuals" <manuals@...>
To: TekScopes@groups.io
Sent: Tuesday, March 17, 2020 4:08:27 PM
Subject: [TekScopes] Beware of cheap "crock-a-gator" clips

I was recently troubleshooting a piece of equipment. Like many of you I
often use "crock-a-gator" clips (piece of wire with a alligator clip on
either end) to access and hold a measurement point on a component on a
PCb while I take measurements, power the assembly outside of its mother
ship, etc.

Recently at one of the local ham/tailgate swap meets, I picked up a
bundle of these clips with their multi color wires and clips covers at a
bargain price as my old set was getting a bit ragged. Today I was taking
some measurements and the readings were quite erratic, this in a circuit
that didn't have any� erratic behavior before. Further checking I found
that this 1ft wire with clips on either end i was using� had a
resistance (jumping) around between 1 and 2 K ohms ! Upon closer
inspection I found that wire had simply been folded back under the
insulation and the whole assembly crimped, NO SOLDER!. I started
checking and even the "good" ones measured between 2 and 4 ohms . I
thought oh well I 'll just solder them and everything will be fine. The
resistance on the soldered cables now down around 1.5 ohms still not
great if used to jumper any current carrying circuit. Further inspection
revealed that the wire was 7 strands of #35 wire !! or the equivalent of
about #28 . ...

Conclusions

1) Yet another instance of� a "gift" from China
2) Please until you have gone and checked your own clips dont trust them
to take readings with.
3) If you want good c-g-clip jumpers ...make them yourself out of at
least #18 wire

Just a heads up , Go measure your C-G-Clips to determine what you have
before making measurements and getting bad data

PLEASE DO NOT TO TURN THIS INTO� ANOTHER NEVER ENDING THREAD WITH WAR
STORIES OF SIMILAR EXPERIENCE..This thread should be enough

Regards
Dave
manuals@...


--
Dave
Manuals@...
www.ArtekManuals.com


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https://www.avast.com/antivirus





Re: Grey, blue or clear? filter colors

Harvey White
 

IIRC, the blue (P11, I think) was rich in blue and ultraviolet. Orthochromatic films, at that time (and still) are blue sensitive and not red sensitive.  Panchromatic films were sensitive to blue, green, yellow, and red.  A portrait taken with orthochromatic film would not look normal because the red component would not be picked up.  For accurate gray scales you needed Panchromatic film.

Kodak fine grain positive release film was an ortho, blue sensitive film that was used for making B&W transparencies of negatives.  Kodalith was an orthochromatic film that could be developed to an intense black and was used for PCB master negatives.

Blue phosphors were used because the film they recorded on was very sensitive, (high ASA rating, and it was ASA then, not ISO) and could be developed under red light (which the film couldn't see).  Panchromatic film had to be developed in total darkness, or at the best, under a very faint green light.  The film was still sensitive to green light, but the human eye is most sensitive to that, so that's the right color for the dimmest possible light.

Most black and white films were panchromatic, except for some special purpose films mentioned above.

The P1 phosphor was green, but not necessarily efficient and could burn in.  Once developed, the P31 phosphor was highly efficient and had good resistance to burnin.  Hence, lots of scope tubes.  P12 was orange, there was an odd (P10?) phosphor that darkened with an electron beam and had to be erased with heat, it was somewhat of a one shot.)  P4 was the standard white phosphor, and P22 was the tricolor dot phosphor.  P7 was an odd one, a two layer phosphor with a long persistence phosphor closest to the screen (yellow), and a blue/UV phosphor that excited the yellow phosphor.  It gave a blue trace with a yellow fadeaway, and was used for radar.

Harvey

On 3/18/2020 3:36 PM, Clark Foley wrote:
As I recall after some 40 years or so, the 7603 shipped with the grey filter/implosion shield 337-1700-00 installed and the other two filters came along for the ride as standard accessories. As these served as implosion shields, one of them should always be installed. The was another shield as part of the EMI gasket option that had a conductive surface. I don't recall if that one had a metal mesh or not. We referred to the grey as neutral density and it gave the best overall viewing contrast. We recommended the clear for maximum writing rate. I don't remember if there was any technical advantage for the blue. Check the 7603 manual and you will find standard accessories, the blue and clear filters along with the calibrator adapter cable, listed near the end of the book.



492AP Memory Battery

Doug Wilson <calmissile@...>
 

Has someone investigated the replacement of the memory backup battery located on the memory board? Mine measures 2.8V and the schematic lists it as a 3V battery. What are the consequences to the operation of the analyzer when the battery drops too low?

The battery has a sticker on it that identifies it as Catalyst Research Corp 2736. An internet search does not list any for sale. Is there a direct replacement someone has found or is it necessary to make a kludge from some other replacement?


Re: Grey, blue or clear? filter colors

Edward Prest
 

I took some pictures of the filters in front of the 466 scope and posted them here (Tek 466 P2 phosphor ...). This is kitchen table stuff but in daylight and fairly bright. The tube phosphor itself is a very light cream color so it does not help the contrast. If chemists could have made a black phosphor that glowed...

The images are all shot at the same exposure but the truth is they are a little less contrast-y that the naked eye. Here they are detailed from a to j...
Image a is bare CRT
b is the Tektronix clear plastic - does nothing optically
c is the neutral grey. Contrast is a better than shown here. Reflections don't help.
d is the Tek blue filter.

Of these 4 its a close toss up - neutral grey slightly edging out blue. Note the plastic has a lot of reflection. A dulling coat should be helpful.

I tried green theatrical gels...
e is one layer green gel.
f is two layers, two is better than one as the contrast is good and grid is still visible.
g is two green gels topped by the Tek neutral grey-makes a very contrast-y image but grid is mostly gone.

I have Tek metal CRT filters from another smaller scope I just put in front of this CRT.
h is metal on left and bare CRT on right.
j is metal on left and Tek neutral grey on right.

My conclusions are that because the metal screen type is non reflective - effectively a dark hole - it easily beats the neutral grey but grid is not usable.

The double green is quite good. Why didn't Tek make a green filter? Marketing?

The graticule lights can't do much against the sun - they are for lab work only.


Re: 184 Time mark Gen. Needs filter caps

Harvey White
 

First thing when looking at ripple in a linear supply is to look at the ripple in the primary supply.  While the regulator *can* reduce ripple and should, it can only do so much.

Secondly, the regulator is a bit of an amplifier, and is connected so that it tries to remove ripple (and anything due to load and line voltage changes) from the output.

If, with the ripple within spec, the output ripple is not within spec, then you look at the regulator.

I had a case where the output of the regulator effectively was at about 25% of the expected value.  Don't remember the ripple at the output, though.  Turned out that the main filter capacitor was gone, and the regulator was doing the best it could.  Replace main filter capacitor and it all worked.

Harvey

On 3/18/2020 5:07 PM, david via Groups.Io wrote:
Voltage's are good but ripple is real bad. Is 200mV, specification says 15mV. You guys have any suggestions where to look? Still haven't replaced cap 512 on 125 volt supply, Could that affect all three supply voltage's? Picture's of PCB and Marker output are in folder "184 Time mark Gen. Needs filter caps"
David



Re: 184 Time mark Gen. Needs filter caps

david
 

Scope says amplitude is varying 160mV. Amplitude is 1.18V to 1.34V. has to be power supply ripple that is problem now.
David


Re: 184 Time mark Gen. Needs filter caps

david
 

I think the ripple is probably the problem with the 50mS to 5S range, because the amplitude of the time marks in other ranges is not stable. It is oscillating about 100mV.
David


Re: 184 Time mark Gen. Needs filter caps

david
 

Voltage's are good but ripple is real bad. Is 200mV, specification says 15mV. You guys have any suggestions where to look? Still haven't replaced cap 512 on 125 volt supply, Could that affect all three supply voltage's? Picture's of PCB and Marker output are in folder "184 Time mark Gen. Needs filter caps"
David


Re: Grey, blue or clear? filter colors

Richard Knoppow
 

The main sources of lighting filters are Rosco and Lee. Both are readily available. A google search will find color charts showing what is available. Standard color filters for use on stage and motion picture lights come in regular and heavy duty varieties. The heavy duty ones are thicker and more resistant to heat and UV. This is probably of no relevance for a scope filter but the heavy duty ones probably stay flatter. Both companies provide transmission charts so one can choose the best for a given phosphor. I have not checked to see if they have polarizing filters but have had them in the past. I think, however, they are probably linear rather than circular. Anyway a Google search will soon show what is available.
   None of these is expensive.

On 3/18/2020 1:31 PM, walter shawlee wrote:
I bought two rolls of circular polarized filter sheet from Polaroid maybe 15 years ago. it's no longer available, but works great. I have neutral gray and green, both work very well on scopes, and can be shipped in a padded envelope cheaply. the neutral gray is very similar to the Tek filter. sorry, no blue, it didn't exist as a choice. I should say that blue remains my favorite as the best trade-off between light loss and contrast, it was a very good choice by Tektronix, and not at all the obvious one. Early filters were green, to match the phosphor on the CRT.

I can cut strips of various sizes in either color, up to about 24" wide. if you need some for your scope, let me know, it is quite thin, and fits where the Tek filter would have been. I bought it when I was designing avionics displays, and was studying contrast issues. it is pretty amazing what good contrast can do for a display of any kind, it turns out to be more important than brightness.

all the best,
walter (walter2 -at- sphere.bc.ca)
sphere research corp.
--
Richard Knoppow
dickburk@...
WB6KBL


Re: Grey, blue or clear? filter colors

 

I bought two rolls of circular polarized filter sheet from Polaroid maybe 15 years ago. it's no longer available, but works great. I have neutral gray and green, both work very well on scopes, and can be shipped in a padded envelope cheaply. the neutral gray is very similar to the Tek filter. sorry, no blue, it didn't exist as a choice. I should say that blue remains my favorite as the best trade-off between light loss and contrast, it was a very good choice by Tektronix, and not at all the obvious one. Early filters were green, to match the phosphor on the CRT.

I can cut strips of various sizes in either color, up to about 24" wide. if you need some for your scope, let me know, it is quite thin, and fits where the Tek filter would have been. I bought it when I was designing avionics displays, and was studying contrast issues. it is pretty amazing what good contrast can do for a display of any kind, it turns out to be more important than brightness.

all the best,
walter (walter2 -at- sphere.bc.ca)
sphere research corp.

--
Walter Shawlee 2
Sphere Research Corp. 3394 Sunnyside Rd.
West Kelowna, BC, V1Z 2V4 CANADA
Phone: +1 (250-769-1834 -:- http://www.sphere.bc.ca
+We're all in one boat, no matter how it looks to you. (WS2)
+All you need is love. (John Lennon)
+But, that doesn't mean other things don't come in handy. (WS2)
+Nature is trying very hard to make us succeed, but nature does not depend on us.
We are not the only experiment. (R. Buckminster Fuller)


Re: recommended ESR meters these days

Dwayne Reid
 

Good day to all.

I just ran across this thread - I'm working my way through all the messages. But I thought I'd mention the little ESR meter I purchased a *very* long time ago. I just checked and it is still available.

<<https://www.flippers.com/BlueEsr.html>https://www.flippers.com/BlueEsr.html>

If I recall correctly, I purchased mine from John's Jukes in Vancouver, BC, Canada. But they are readily available.

Mine came as a kit - I had one of my junior engineers assemble it (he needed the practice). It works extremely well to this day.

One hint: touch both probes to one of the corner screws that hold the lid on before pressing the button to Zero the meter. The Phillips head socket holds the probe tips securely and provides a nice zero Ohm short for the probes.

dwayne

At 03:57 PM 3/12/2020, ArtekManuals wrote:
Took out my (apparently not so) trusty ESR meter the other day and it eyes had rolled back in its head and no amount of CPR would revive it.. Anyone bought one _*RECENTLY *_that they can recommend or warn me away from?

Dave
manuals@...

--
Dave
Manuals@...
www.ArtekManuals.com
--
Dwayne Reid <dwayner@...>
Trinity Electronics Systems Ltd Edmonton, AB, CANADA
780-489-3199 voice 780-487-6397 fax 888-489-3199 Toll Free
www.trinity-electronics.com
Custom Electronics Design and Manufacturing


Re: Beware of cheap "crock-a-gator" clips

 

Chiming in,
For wire, I recommend silicone insulated wire from aliexpress.com, such as the wire at https://www.aliexpress.com/item/33015228200.html?spm=a2g0o.detail.1000023.17.6c87590esfsR5Y. I've used a fair amount of it and can vouch for its quality. The copper core is many strands of quite fine wire, which, coupled with the silicone jacket, makes it VERY flexible, and very suitable for meter test leads. You can order it in small to large gauges, depending on your needs. Other vendors sell similar wire; just search for 'silicone wire'.
Use it with whatever clips that you find worthy.
The wire that I bought was from aliexpress, although eBay probably has it as well.

My $0.02 USD worth,
Dave M

On Wed, Mar 18, 2020 at 09:59 AM, <tekscopegroup@...> wrote:


There is a lot of cheap chinese crap jumper going around. Some do not even use
copper. I once had to troubleshoot an intermittent in an AC extension cord
bought at the supermarket. The ones with the thick orange cable that you would
guess would at least have a 3x #16 or #14 inside. Turns out the orange rubber
layer was 95% of the diameter, and only two thin maybe #26 wires where running
through it. So they definitively know how to save on copper and potentially
burning down houses.

The best alligator jumpers for me have always been the ones Radio Shack used
to sell, the mid-size 4-color set, with two of each. Decent diameter real
copper wire (altough not even close to handle more than 5 amps without losses)
and quite consistent albeit crimped construction, and the right size alligator
clip for most jobs. I am still using the 2-3 sets all the time that I
purchased a long time ago, and only very occasionally do I have to cut and
resolder one side when the copper conductor breaks at the usual flexing point
near the clip.

Anything else out there I ever tried was very crappy. I recall once ordering a
set from BGMicro or AllElect that looked good in the picture but each wire
measured btw 15-25 ohms!! I There where only like 3-4 very fine stands in each
wire, and it did not even look like copper, probably was recycled tin.
Replaced all the wires and only reused the clips, but typical the wires one
has around are stiffer so they see very little use, and over time the clips
also have become very stiff to open and close even tough there is no visible
deterioration or corrosion.


Re: 184 Time mark Gen. Needs filter caps

david
 

I replaced Capacitor's no. 552 and 532 today, Voltage's are good now, 184 Time mark generator is working now, up to 10mS. 50mS to 5S is not stable, have to troubleshoot that circuit. I had PCB boards made to mount capacitors. Waiting for PCB boards to replace capacitor no. 512, Capacitor number 552 was the bad one, but I am replacing all caps in power supply. Will try and post photos of PCB cap mounting board and screen shot of output.


Re: Grey, blue or clear? filter colors

Clark Foley
 

As I recall after some 40 years or so, the 7603 shipped with the grey filter/implosion shield 337-1700-00 installed and the other two filters came along for the ride as standard accessories. As these served as implosion shields, one of them should always be installed. The was another shield as part of the EMI gasket option that had a conductive surface. I don't recall if that one had a metal mesh or not. We referred to the grey as neutral density and it gave the best overall viewing contrast. We recommended the clear for maximum writing rate. I don't remember if there was any technical advantage for the blue. Check the 7603 manual and you will find standard accessories, the blue and clear filters along with the calibrator adapter cable, listed near the end of the book.


Re: Tek 5441 Scope

Stefan Lindberg
 

Good Evening

I've got a 5440 myself so the power supply is the same.

If Q940 is working and considering that this is a simple regulation job, I would remove Q940 and measure its hfe and take a similar Darlington NPN with some margin in U/I.

The issue might rather be to fit a model that does not have the special casing since the transistor is squeezed in place for cooling as standard. However, since we are talking about regulation only, then why not take a beefier Darlington and connect it with short wires and mount it to the case.


Re: Tek 5441 Scope

Mlynch001
 

According to the TEK Cross Reference pg. 6-21:

151-0496-00 crosses to a D40K2, which is available from MOUSER their p/n 610-D40K2 @ $3.47 each with 348 in stock.

151-0331-00 crosses to a D40C5, which does not show available.

Good Luck!

--
Michael Lynch
Dardanelle, AR


Re: recommended ESR meters these days

Lawrance A. Schneider
 


Re: recommended ESR meters these days

David Kuhn
 

My shipping was $9.60 USPS. I am looking forward to it.

I am also looking for a Leakseeker 89A. No one is making that anymore.
EDS sells the parts for $99 and the PCB is one ebay for $30 and the case
for $35. I am tempted to order all that stuff an build one.

Dave

On Tue, Mar 17, 2020 at 7:39 PM Reginald Beardsley via Groups.Io <pulaskite=
yahoo.com@groups.io> wrote:

Does anyone have experience with the EDS-89 LeakSeeker? It's no longer
sold, but there are PCBs on ebay and kits of parts available from Dave
Miga, the designer. Looks to be around $150 or so with a good case.

In a world where service data is often not available, that and the EDS-88A
look very attractive with the potential to rescue a lot of stuff from an
early grave without a lot of time invested in the repair.

Reg