Here is another attempt at being an information source instead of a sink :-).
The first time I tried to clean a 2235 CRT shield I used a soft lens cloth like you get with a pair of glasses. I thought this would work well, but instead it left tiny scratches on the plastic. I was surprised.
Since then I have used this thing called "Fuzzy Fingers" that I got at Walmart for $2. We use them at school for cleaning glass touch screens (except we paid $10 for them) and they are super soft. They do a nice job on plastic as well and leave no scratches.
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Re: Tek 422 HV power supply issues
Resistors looked more or less OK, that was one of the first things I checked. The 2 2.2M in series had drifted down to 4.2M, while the 1M focus was up to 1.2M, so more or less a wash. More measurements, here's the bias range: Intensity: Min Midrange High G1 bias -95 -42 -6 I don't have any experience with this measurment, is this reasonable? Is this pointing to low emision on the CRT? On Wed, Feb 20, 2013 at 09:54:01PM -0500, larrys@... wrote: Hi Paul --
Check the resistors in the series string where the focus & intensity pots
live. Your voltages aren't that far off the mark. Per the schematic,
'normal' should be a bias of around -45 V. If your difference is less
and the intensity is still weak, you may be looking at a crt.
-ls-
Paul Amaranth <paul@...> wrote:
So I'm looking at this 422 and the trace doesn't get visible until the
intensity control is around 3 o'clock. Blanking is adjusted, so
that's not the problem -- Paul Amaranth, GCIH | Rochester MI, USA Aurora Group, Inc. | Security, Systems & Software paul@... | Unix & Windows
|
Re: What use for a 640 Ohm 1x Probe?
This probe (it says Fairchild Scientific Instruments 106 on the cable) is a good 1x probe. I bit the bullet and tested it on a scope compensation signal and it has a slight overshoot but a very flat top on the trace. I'll use it for checking ripple and the like. It appears to be very well made and has cushy handle so I rather like it.
Phil...
*
toggle quoted message
Show quoted text
--- In TekScopes@..., "Philip" <ndpmcintosh@...> wrote:
I should have been more specific. Actually I get about 9.3 MOhms on the 10x probe I checked. I am learning a lot though by thinking about this probe, reading everyone's comments and reading the various probe manuals available. Thanks for everyone's input.
I also ohmed out an old 1x Tek probe and got 300 Ohms. The center conductor on the cable is a tiny single strand of wire.
Phil...
--- In TekScopes@..., David <davidwhess@> wrote:
On Wed, 20 Feb 2013 00:24:09 -0000, "Philip" <ndpmcintosh@>
wrote:
The publication on scope probes mentioned earlier is good and I am working my way through it. I already had it in my document collection and it was on my reading list.
If I ohm out a 10x 10Mohm probe in the same way, I get about 10 MOhms. I'll keep reading though... I get almost exactly 9.00 MOhms on each of several different x10
probes within reach.
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On 02/21/2013 02:44 AM, Craig Sawyers wrote: John
I can't remember the precise gauges, but this is what I put together ages
ago when I was making my own extender. Surveyed from a Tek unit.
Note that the wires that take high current are significantly thicker than
the signal wires. Thanks Craig, Craig was referring to his spreadsheet with tallies of types of wire used, (but not their wire gauge). Since an original Tek extender uses 58 thin wires, and only 4 thick wires and 6 coax, it would speed assembly of flex extenders to use 28 gauge ribbon cables with crimp connectors plus 4 separate wires that are thicker -- probably 24 gauge. Can anyone confirm the wire gauge of the thin wires in a Tek original 7K flex extender?
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Re: TroubleShooting Some TM500 gear.
I'm with Tom.? I ordered the arcade
cards first, then got two sets each of the TM500 and 7000
extenders from John.? Much, much better IMO.
Mark
On 2/20/2013 10:23 PM, Tom Miller wrote:
toggle quoted message
Show quoted text
I might add that your cards are much higher quality than the
ones from the arcade guys.
?
Regards,
Tom
?
----- Original Message -----
Sent: Wednesday, February
20, 2013 10:15 PM
Subject: Re: [TekScopes]
Re: TroubleShooting Some TM500 gear.
?
On 02/20/2013 02:44 PM, Tom Miller wrote:
> That is exactly how I test them I made a plug from one
of the extender cards available from the video game service
people. I
> brought out all six leads for the outboard power
transistors so I can test them on the curve tracer.
> I also brought out the supplies to some load resistors
so I can check voltage and ripple on each slot.
> Regards,
> Tom
I have plenty of TM500 cards for sale as kits, but I will
also sell a card set, no connector,
to make a plug with, no wires, shipped in a flat envelope
for $13.
John
|
Re: DC504 counter display
Other possibles listed by DoD WEBFLIS include MAN10 (Monsanto, probably hard-to-find) and TIL302 (Texas Instruments) - try Lite-on for a cross reference. Mouser carries Lite-on, so their drill-down paramteric search may help too. Your display characters are .300" or .270", not sure, but you could always replace all 5 to ensure a good match with the replacement. Displays are about a dollar-fifty each.
TIL302's are on eBay - buyer beware, of course.
Taylor
toggle quoted message
Show quoted text
--- In TekScopes@..., HankC <hankc918@...> wrote:
Tnx to the group for the suggestions on my DC504 display.
I swapped one display digit with another & the problem followed the swap.
So, the consensus of the group that it was a display problem was
correct.
The pn of the originals is DATA-LIT10A, which I believe was made by Siemens.
Tek pn is 150-1018-00 but it is not listed in Tek's 1982 Parts Catalog.
I cannot find a source for these so I can't be sure of its configuration (common cathode ?? Pinout, etc)
The chips are soldered into the display PCB. the leads come out the back of the package, along the 2 long edges. The leads are round wires, about 1/8 inch long. Package is about 1/8 inch thick.
Pin spacing is the same as a socket but there is no room to install sockets because the main PCB is right up against the back of the display PCB.
Sockets would make the whole assembly too thick to fit. I had to grease it to get it out :<)
Not all pin positions are populated; One edge has 4 pins, then a gap, then 2 more pins. The other edge is opposite; the pins are grouped 2 pins, gap, 4 pins.
The individual digits butt right up against each other; there is no space between them.
Someone suggested using FND357's as a replacement but there is a lot of variation among parts with this number so there is no telling what I would get.
(leads along the short edges, common anode, decimal point location, socketed, gap in pin spacing, etc).
The display board which holds these chips has a number on it which looks like a truncated Tek pn (3659-01)
If anyone has a parts donor DC504 & is willing to sell the display board, pls let me know.
HankC, Boston
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Re: PYRAMID CALIBRATOR AND TESTER FOR TEKTRONIX OSCILLOSCOPES
Thanks for the links Dave Daniel.
|
--- On Thu, 2/21/13, Glenn Ford wrote:
From: Glenn Ford
Subject: Re: [TekScopes] PYRAMID CALIBRATOR AND TESTER FOR TEKTRONIX OSCILLOSCOPES
To: TekScopes@...
Date: Thursday, February 21, 2013, 2:47 AM
?
I will take one of those pyramid calibrator.
lmk,
Glenn R. Ford
--- On Wed, 2/20/13, Bob Albert wrote:
From: Bob Albert
Subject: Re: [TekScopes] PYRAMID CALIBRATOR AND TESTER FOR TEKTRONIX OSCILLOSCOPES
To: TekScopes@...
Date: Wednesday, February 20, 2013, 2:45 PM
?
Well it seems that $25 plus $5 for shipping is the price.
If you want one, let me know.
Bob
--- On Mon, 2/11/13, Richard Solomon wrote:
From: Richard Solomon
Subject: Re: [TekScopes] PYRAMID CALIBRATOR AND TESTER FOR TEKTRONIX OSCILLOSCOPES
To: TekScopes@...
Date: Monday, February 11, 2013, 4:12 PM
?
$1 each and you ship !!!!
Seriously though, put a price on them and let folks decide if it's OK or too much.
73, Dick, W1KSZ
On Mon, Feb 11, 2013 at 4:35 PM, Bob Albert <bob91343@...> wrote:
?
I have several of those Tek evaluation boards.? Put in a 9V battery and you are set to go.? Manual available on line.? Make offer.
Bob
--- On Mon, 2/11/13, Dave Daniel <kc0wjn@...> wrote:
From: Dave Daniel <kc0wjn@...>
Subject: Re: [TekScopes] PYRAMID CALIBRATOR AND TESTER FOR TEKTRONIX OSCILLOSCOPES
To: TekScopes@...
Date: Monday, February 11, 2013, 3:24 PM
?
Got it. I found the thread. See the TekScopes thread entitled "Scope Tester on Ebay" (around 12/22). Reed Dickinson sent an email owning up to being the designer and seller of these.
Cheers,
Dave
On 2/11/2013 2:36 PM, Pa4tim wrote:
?
Nice build cabinet, could be a handy tool. But strange he uses 75 Ohm bnc connectors for a 50 Ohm output. ?Also rather expensive
For that price you can make a very nice one yourself.?
Just a uProcessor to generate some squares, or maybe a Xtal and something like a 4060, for higher frequency and trigger test you add the cute little Jim williams pulser. Williams also has a schematic of a very simple timemark generator ( i do not the app note from the top of my head)
a TL431 or LT1027, a good opamp and some 1% resistors and a switch to make some accurate voltages ( a scope is 2 to 3% so this will be close enough)?
It does not matter if frequency is not in all exact steps. For a test its OK to see if the ranges still work. I think for real calibrations this is will not be enough , it only goes up to 1uS/div and for buy-checks it can do more than needed.?
If I needed one I would use this as a base :? the Tek evaluation board we reverse engineered around 2 or 3 years ago here on the group.
And add this :? if you want use a switch and resistors to make fixed frequencies. 500 ps Tr and 16-160 MHz in 3 ranges so if you use 5 resistors and two switches you have 15 frequencys.
Total cost maybe 10 dollar in parts, 10 bucks for a nice cabinet so you can spend 130 dollar for another scope ;-)
Fred PA4TIM
Op 11 feb. 2013 om 21:54 heeft Dave Daniel <> het volgende geschreven:
?
This instrument was specifically discussed a while back. I'm trying to locate the emails I have; I can't recall whether it was in open forum or a series of private exchanges. The person who is selling these wanted something that he could carry around to Hamfests and other places and use to quickly evaluate 'scopes before he bought them. It looks like a very nice instrument to have, IMO.
Dave
On 2/11/2013 1:47 PM, ukchastuck wrote:
?
Anyone ever tried one of these: to test and calibrate Tek oscilloscopes? The ebay description of the Pyramid Generator implies it can be used to reliabily set vertical amplitude calibration, horizontal time calibration and triggering capabilities. Seems you get a lot for your money if it works.
Regards, Charles
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|
|
|
Re: OT: was Re: Re: replacing 475 psu electrolytics
Austin 10 1936, 3 landrovers (serie 2a from 1970, defender 90 V8 50th annyversary from 1998, a 90 Td5 from 1999) a Triumph speedtwin (1954) and a EML bermuda trike ( based on a 1998 Honda GL1500 anniversary model)? Had to sell my 1976 Landrover 101FC a few months because of health problems, the others probably have to go one day too :-( i used to work on some cars ( most landrovers) and a lot of motorbikes since i was 17,( I'm now 49) i have had over 30 motorobikes over those years.
Fred PA4TIM
Op 21 feb. 2013 om 00:35 heeft Don Black < donald_black@...> het volgende geschreven:
?
I'm guessing your spitfires didn't have wings????
Don Black.
On 21-Feb-13 10:24 AM, Jim wrote:
?
Don't feel bad -- I had three Spitfires, a GT6,
three Alfas, and mechanicking privileges on a Saab 98.
Now
I only do water-cooled Porsches, and stuff with Ford
460s. ?Anybody got a straight Spitfire 1500 body and
frame to sell? ?No drivetrain needed, I have a spare
460 to put in it. ?I can trade vintage test gear :)
Seems
like an awful lot of folks who play with vintage test
and radio gear also play with specialty-interest
vintage motorcars. ?I don't think it's a coincidence.
73
Jim
N6OTQ
From: Rob
To:
TekScopes@...
Sent:
Wednesday, February 20, 2013 5:08 PM
Subject:
RE: [TekScopes] Re: replacing 475 psu
electrolytics
Strangely,
I know quite a number
of Brits over here. I'm also a fan of old
Brit cars; I have
a Triumph Stag and a 90 Jag XJS. They're
pretty even if they
don't move much :-) ?
|
Re: DC504 counter display
You could look to see which other instruments Tektronix used part number 150-1018-00 in to widen your selection of parts mules. Also, you can reverse engineer the pinout from either the schematic (they are common anode and the decimal point is pin 6) or by just pulling one and using your multimeter diode test function to check each pin versus each other pin. It does not take long to do. There is some weirdness with the common anode connection since it appears that the displays internally are made of three units with 3 separate anodes (pins 3, 9, and 14) but maybe the anodes are connected together internally. I guess even low profile collet socket pins would not be low profile enough to use as sockets. That is too bad. On Wed, 20 Feb 2013 22:48:28 -0800 (PST), HankC <hankc918@...> wrote: Tnx to the group for the suggestions on my DC504 display.
I swapped one display digit with another & the problem followed the swap.
So, the consensus of the group that it was a display problem was
correct.
The pn of the originals is DATA-LIT10A, which I believe was made by Siemens.
Tek pn is 150-1018-00 but it is not listed in Tek's 1982 Parts Catalog.
I cannot find a source for these so I can't be sure of its configuration (common cathode ?? Pinout, etc)
The chips are soldered into the display PCB. the leads come out the back of the package, along the 2 long edges. The leads are round wires, about 1/8 inch long. Package is about 1/8 inch thick.
Pin spacing is the same as a socket but there is no room to install sockets because the main PCB is right up against the back of the display PCB.
Sockets would make the whole assembly too thick to fit. I had to grease it to get it out :<)
Not all pin positions are populated; One edge has 4 pins, then a gap, then 2 more pins. The other edge is opposite; the pins are grouped 2 pins, gap, 4 pins.
The individual digits butt right up against each other; there is no space between them.
Someone suggested using FND357's as a replacement but there is a lot of variation among parts with this number so there is no telling what I would get.
(leads along the short edges, common anode, decimal point location, socketed, gap in pin spacing, etc).
The display board which holds these chips has a number on it which looks like a truncated Tek pn (3659-01)
If anyone has a parts donor DC504 & is willing to sell the display board, pls let me know.
HankC, Boston
|
Re: DC504 counter display
Tnx to the group for the suggestions on my DC504 display. I swapped one display digit with another & the problem followed the swap.
So, the consensus of the group that it was a display problem was
correct. The pn of the originals is DATA-LIT10A, which I believe was made by Siemens. Tek pn is 150-1018-00 but it is not listed in Tek's 1982 Parts Catalog. I cannot find a source for these so I can't be sure of its configuration (common cathode ?? Pinout, etc) The chips are soldered into the display PCB. the leads come out the back of the package, along the 2 long edges. The leads are round wires, about 1/8 inch long. Package is about 1/8 inch thick. Pin spacing is the same as a socket but there is no room to install sockets because the main PCB is right up against the back of the display PCB. Sockets would make the whole assembly too thick to fit. I had to grease it to get it out :<) Not all pin positions are populated; One edge has 4 pins, then a gap, then 2 more pins. The other edge is opposite; the pins are grouped 2 pins, gap, 4 pins. The individual digits butt right up against each other; there is no space
between them. Someone suggested using FND357's as a replacement but there is a lot of variation among parts with this number so there is no telling what I would get. (leads along the short edges, common anode, decimal point location, socketed, gap in pin spacing, etc). The display board which holds these chips has a number on it which looks like a truncated Tek pn (3659-01) If anyone has a parts donor DC504 & is willing to sell the display board, pls let me know. HankC, Boston
|
Photos would be nice. -Kurt
toggle quoted message
Show quoted text
--- In TekScopes@..., "Dennis Tillman" <dennis@...> wrote:
I picked up the M01 scope and took it over to the VintageTEK museum for a
closer look. It turns out that before the 7000 series got its name Tek
developed two products called the L01 and the M01. The M01 was a 4 slot
scope like the later 7704. The L01 was a 3 slot scope like the later 7603.
These were a nightmare to build. Almost everything was hand wired. The
harmonica connectors had been developed but they were hand wired rather than
using ribbon cable. The wires ended at hand soldered pins mounted in the
chassis walls.
This particular M01 scope is serial A11 which means it is an A-phase
prototype. After A-phase comes B phase, and then production. It came with an
engineering prototype of what would ultimately become the 7B71 Delaying Time
base in it. This was unusual because it used round pushbuttons for the
triggering selection and not the square ones that finally made it into
production.
Dennis
-----Original Message-----
From: Steve, Sent: Wednesday, February 13, 2013 2:52 PM
Probably an engineering "hack" that needed most of a scope to test something
else, or a production test fixture. The front panel looks like it was
actually anodized with the lettering, so it might have been a production
test fixture that they needed more than one of.
The seller is from Portland, so either they worked at Tek, or bought it from
the company surplus store. These sort of test fixtures and engineering
hacks showed up in the store often 20 years ago.
- Steve
--- In TekScopes@..., Jim Reese wrote:
Close to a 7504 or 7704. Early prototype?
Jim
-----Original Message-----
From: davidnickdaniel, Sent: Tuesday, February 12, 2013 2:30 PM
Anyone know what a Tek type M01 'scope is? Ebay item #350714574978.
Thanks,
Dave
|
Re: Frequency response flatness in conventional sampling (say 7S11/S
Sorry for taking a while to get back to you on this. It seems it is time for me to add an S-6 manual to my binder of sampling stuff. Here is why I do not believe the blow-by matters in this application: When you are looking at the aberrations from a clean pulse measured by a sampling head, instead of the impulse response which correlates with the frequency and phase response of a linear network, you see charge coupled through the sampling bridge from the fast edge and level shift. When measuring an AC signal, there are no fast edges and no DC level shift to couple through the sampling bridge. In addition, the memory gate is too slow to see any AC leakage. There is a simulation showing the S-6 AC feedthrough here: I like discussing this subject because it yields ideas for correcting the annoying blow-by response in my S-4 sampling heads. Unfortunately if it was easy to correct, I suspect Tektronix would have done so. Do you actually need triggering to see just the peak to peak values? I think you could add probe a different part of the generator circuit to find a trigger so the leveled output could go only to the sampling head. On Mon, 18 Feb 2013 17:02:21 -0000, "Albert" <aodiversen@...> wrote: Hi David,
So far I didn't find effect of S-6 blow-by adjustment on sine wave amplitudes. I probably did something wrong, since the effect on square waves (tilt) is considerable. A change of C20 in the S-6 only causes a vertical shift of the sine wave. I tested some frequencies from 100 kHz to 1 GHz.
It's very annoying that the SG503 and my GR-type oscillators don't have a trigger output. Since the S-6 doesn't have a trigger output either I'm forced to use a CT-3 trigger pick-off and external triggering. With the S-2 I can compare internal triggering (CT-3 omitted) with such external triggering. The CT-3 has considerable effect on frequency response, about 6% to 8% downward trend when frequency is increased to 900 MHz.
Albert
--- In TekScopes@..., David <davidwhess@...> wrote:
The blow-by effect on frequency response could be tested. Grossly
misadjust it deliberately and see if the frequency response changes. I
found it to be the easiest thing to calibrate on my S-4 sampling heads
so I would not worry about temporarily misadjusting it.
I would also compare two different types of sampling heads like an S-2
and S-4 which have significantly different transient response
characteristics in the 10ns range do to design and see if they agree.
I may try the above with an S-1 and S-4 and my SG503 just to see what
kind of results I get.
|
Re: What use for a 640 Ohm 1x Probe?
I should have been more specific. Actually I get about 9.3 MOhms on the 10x probe I checked. I am learning a lot though by thinking about this probe, reading everyone's comments and reading the various probe manuals available. Thanks for everyone's input.
I also ohmed out an old 1x Tek probe and got 300 Ohms. The center conductor on the cable is a tiny single strand of wire.
Phil...
toggle quoted message
Show quoted text
--- In TekScopes@..., David <davidwhess@...> wrote:
On Wed, 20 Feb 2013 00:24:09 -0000, "Philip" <ndpmcintosh@...>
wrote:
The publication on scope probes mentioned earlier is good and I am working my way through it. I already had it in my document collection and it was on my reading list.
If I ohm out a 10x 10Mohm probe in the same way, I get about 10 MOhms. I'll keep reading though... I get almost exactly 9.00 MOhms on each of several different x10
probes within reach.
|
I picked up the M01 scope and took it over to the VintageTEK museum for a
closer look. It turns out that before the 7000 series got its name Tek
developed two products called the L01 and the M01. The M01 was a 4 slot
scope like the later 7704. The L01 was a 3 slot scope like the later 7603.
These were a nightmare to build. Almost everything was hand wired. The
harmonica connectors had been developed but they were hand wired rather than
using ribbon cable. The wires ended at hand soldered pins mounted in the
chassis walls.
This particular M01 scope is serial A11 which means it is an A-phase
prototype. After A-phase comes B phase, and then production. It came with an
engineering prototype of what would ultimately become the 7B71 Delaying Time
base in it. This was unusual because it used round pushbuttons for the
triggering selection and not the square ones that finally made it into
production.
Dennis
toggle quoted message
Show quoted text
-----Original Message----- From: Steve, Sent: Wednesday, February 13, 2013 2:52 PM Probably an engineering "hack" that needed most of a scope to test something else, or a production test fixture. The front panel looks like it was actually anodized with the lettering, so it might have been a production test fixture that they needed more than one of. The seller is from Portland, so either they worked at Tek, or bought it from the company surplus store. These sort of test fixtures and engineering hacks showed up in the store often 20 years ago. - Steve --- In TekScopes@..., Jim Reese wrote: Close to a 7504 or 7704. Early prototype?
Jim
-----Original Message----- From: davidnickdaniel, Sent: Tuesday, February 12, 2013 2:30 PM Anyone know what a Tek type M01 'scope is? Ebay item #350714574978. Thanks, Dave
|
Re: TroubleShooting Some TM500 gear.
I might add that your cards are much higher quality than the ones from the
arcade guys.
?
Regards,
Tom
?
toggle quoted message
Show quoted text
----- Original Message -----
Sent: Wednesday, February 20, 2013 10:15
PM
Subject: Re: [TekScopes] Re:
TroubleShooting Some TM500 gear.
?
On 02/20/2013 02:44 PM, Tom Miller wrote:
> That is exactly how I
test them I made a plug from one of the extender cards available from the
video game service people. I
> brought out all six leads for the
outboard power transistors so I can test them on the curve tracer.
> I
also brought out the supplies to some load resistors so I can check voltage
and ripple on each slot.
> Regards,
> Tom
I have plenty of
TM500 cards for sale as kits, but I will also sell a card set, no
connector,
to make a plug with, no wires, shipped in a flat envelope for
$13.
John
|
Re: TroubleShooting Some TM500 gear.
On 02/20/2013 02:44 PM, Tom Miller wrote: That is exactly how I test them I made a plug from one of the extender cards available from the video game service people. I
brought out all six leads for the outboard power transistors so I can test them on the curve tracer.
I also brought out the supplies to some load resistors so I can check voltage and ripple on each slot.
Regards,
Tom I have plenty of TM500 cards for sale as kits, but I will also sell a card set, no connector, to make a plug with, no wires, shipped in a flat envelope for $13. John
|
Re: Tek 422 HV power supply issues
Hi Paul -- Check the resistors in the series string where the focus & intensity pots live. Your voltages aren't that far off the mark. Per the schematic, 'normal' should be a bias of around -45 V. If your difference is less and the intensity is still weak, you may be looking at a crt. -ls- Paul Amaranth <paul@...> wrote:
So I'm looking at this 422 and the trace doesn't get visible until the
intensity control is around 3 o'clock. Blanking is adjusted, so
that's not the problem
This doesn't seem right, so I dug out the HV probe and took some
measurements.
The Accelerating potential is spot on at +4900.
But all of the negative voltages are just a tad off. The high voltage test point
at G1 on the schematic (labeled -1420 or -1400 depending on which side of the
line you're looking at) never gets below -1396. (At midrange it's -1390)
With the intensity at midrange, the cathode is -1360, not -1375 as spec'd on
the schematic.
Right now at the end of the intensity control, I get a range from -1375 to -1390,
so it looks like 10 or 15V can make a difference.
I hate working on HV supplies, but there's not a lot of parts in this one.
Anyone have any experience with this one? I'd appreciate some pointers.
Paul
--
Paul Amaranth, GCIH | Rochester MI, USA
Aurora Group, Inc. | Security, Systems & Software
paul@... | Unix & Windows
------------------------------------
Yahoo! Groups Links
|
Tek 422 HV power supply issues
So I'm looking at this 422 and the trace doesn't get visible until the
intensity control is around 3 o'clock. Blanking is adjusted, so
that's not the problem
This doesn't seem right, so I dug out the HV probe and took some
measurements.
The Accelerating potential is spot on at +4900.
But all of the negative voltages are just a tad off. The high voltage test point
at G1 on the schematic (labeled -1420 or -1400 depending on which side of the
line you're looking at) never gets below -1396. (At midrange it's -1390)
With the intensity at midrange, the cathode is -1360, not -1375 as spec'd on
the schematic.
Right now at the end of the intensity control, I get a range from -1375 to -1390,
so it looks like 10 or 15V can make a difference.
I hate working on HV supplies, but there's not a lot of parts in this one.
Anyone have any experience with this one? I'd appreciate some pointers.
Paul
--
Paul Amaranth, GCIH | Rochester MI, USA
Aurora Group, Inc. | Security, Systems & Software
paul@... | Unix & Windows
|
Re: [hp_agilent_equipment] Surplus outfits in Philladephia, PA (USA)?
On Sun, Feb 17, 2013 at 10:29 AM, Daniel Koller <kaboomdk@...> wrote: Hi folks,
Just a random question in the event there is an affirmative answer: Does anyone know if there are any good electronics surplus stores in the Philladelphia, PA area (USA) where one might be able to pick up old Tek Scopes or HP test instruments? Just curious, as I might have an opportunity to check it out.
Has e-bay put all of these places out of business? Surely there must be *some* brick-and-mortar warehouses left, no? Sort of relevant to the thread... here's a nice lot of (mostly) Tek scopes in Belmar, New Jersey, not too far from Philadelphia:
|
Re: Now: 50 Ohm attenuator Re: What use for a 640 Ohm 1x Probe?
OK, I think I've decided on building a
unit inside a little box that can be switched between 1x, 10x, and
100x. I assume I'd just put the resistors in an "L" pattern
totaling 50, 500, and 5,000 ohms?
On 02/20/2013 10:12 AM, Ed Breya wrote:
toggle quoted message
Show quoted text
You don't want the scope attenuator to be the dummy load. You can make a simple pick-off tee with the main signal going straight through, with a high resistance tapped off, feeding a termination resistance to make it 50 ohms locally. Then connect that small signal to the scope with coax and termination there too. Of course, the tee structure should be in a transmission line environment, depending on the frequency.
Just set the resistor ratios to give nice numeric relationships so you don't need brain calculations on the fly to interpret what you see. For example, a 100X voltage attenuator would need a 2.475K tap rated for about 2W or more, terminated in 50R locally and 50R at the scope. The extra load would have only a 2 percent effect on the main line impedance. Higher attenuation would need less power rating and have less loading effect - it depends on how much signal you need at the scope, given the application.
Ed
--- In TekScopes@..., Cliff White wrote:
Ok, that's what I thought. What I'm really trying to do is like this:
100W transmitter into a dummy load, with a tee in that line going to the
scope. Would 10x be enough? Or should I aim for 100x?
Respectfully,
Cliff White, W5CNW
w5cnw@...
On 02/19/2013 10:50 PM, Bob Albert wrote:
You don't generally need impedance matching. The 'scope input won't
load a 50 Ohm source much. I use a 50 Ohm termination without
attenuation and the high impedance of the oscilloscope has negligible
effect.
If you are handling substantial power you will need an attenuator; the
books tell you what the parameters should be. For 20 dB attenuation
you need 45 Ohms in series and 5 Ohms across the 'scope input. And of
course the 45 Ohm resistor has to handle the power.
If you are using a 50 Ohm cable, it needs to be in a 50 Ohm circuit,
so the attenuator components should be right at the 'scope.
Bob
--- On *Tue, 2/19/13, Cliff White //* wrote:
From: Cliff White
Subject: Re: [TekScopes] Re: What use for a 640 Ohm 1x Probe?
To: TekScopes@...
Date: Tuesday, February 19, 2013, 8:05 PM
So, I've had the idea of building a 50 ohm fixed 10x attenuator to
use inline with a 50 ohm cable. What kind of impedance matching
should I use for the 1meg ohm on the scope?
On 02/19/2013 07:26 PM, Don Black wrote:
It should be 9 Meg ohms. Then 90% of the signal is dropped across
the probes 9 Meg and 10% across the scope's 1 Meg input
impedance, giving 10:1 ratio.
The compensating capacitors across them are adjusted for the same
division at high frequencies to maintain the flat response,
that's hat you're setting when you adjust for flat square wave
with the trimmer.
Don Black.
On 20-Feb-13 12:18 PM, David wrote:
On Wed, 20 Feb 2013 00:24:09 -0000, "Philip" ndpmcintosh@...
>
wrote:
>The publication on scope probes mentioned earlier is good and I
am working my way through it. I already had it in my document
collection and it was on my reading list.
>
>If I ohm out a 10x 10Mohm probe in the same way, I get about 10
MOhms. I'll keep reading though...
I get almost exactly 9.00 MOhms on each of several different x10
probes within reach.
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