Re: 7T11 horizontal memory
Say, since I have the 7S12 and 7S11, is there any reason to obtain a 7T11 or 7T11A?? Aside from the fact that it's another cool piece of Tek gear to own, I mean.? IOW, do I have a justification before the finance committee (my wife ;) )?
TIA.
Jim F
Sent from my Verizon, Samsung Galaxy smartphone
toggle quoted message
Show quoted text
-------- Original message --------From: Albert Otten <aodiversen@...> Date: 12/6/18 2:56 AM (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] 7T11 horizontal memory On Wed, Dec? 5, 2018 at 10:19 PM, cmjones01 wrote:
- in real time mode, it's hard to get a trace that makes sense. presumably the
50kHz-ish clock from the real time multivibrator limits the display to about
one sample every 20us, so some of the faster sweep speeds don't show a lot.
Even on the slower sweeps, the edges of my test squarewave exhibit terrible
risetime (about half a division) which is puzzling, and very different to the
behaviour in equivalent time. Maybe it's something to do with the recovery
time of the sampling head, or there's something amiss with the 7S11. I tried
adjusting the 'dot response' control and making sure smoothing was switched
off, but it didn't improve much.
Just to be sure that the fault is in the 7S11, you might check that the terrible rise time is also present when you use the 7S11 in combination with an ordinary timebase unit in stead of the 7T11. You probably did not verify that you could adjust the dot response for loop gain one, it only "improved not much". I would check this first of all. The sampling head has an internal GAIN adjustment that could be too far off to correct with the 7S11 dot response adjustment. You can probably tell that I'm new to the
7000-series sampling world. I regularly use my CSA803A/SD24 sampling setup,
but that makes it all so easy...
I followed the normal(?) route. I started with sampling units for the 564, then for the 7000 series and now I also have a CSA803A? with SD-20 and SD-26. Still waiting for a good opportunity to buy an SD-24. Albert
|
Re: TDS3032 does not boot. LCD backl-ight and fan working.
" @Dave, when you have had the bad NVRAM installed, how did the no-boot situation look? I.e., was it also a white screen, no beeps and no relay clicks, or did it at least show the DPO splash screen? " Gosh, I'm afraid I am of no help then. I looked through old message threads I had on here from the last month and found my message concerning the fake NVRAM from China: ""After re-assembly, it will not boot past the "Digital Phoshor Oscilloscope" splash screen. During bootup, you do hear the hear the relays click, the splash screen flickers a bit and the floppy drive seeks. The splash screen never goes away. "" My TDS3032 did get to the splash screen and locked up with the fake Chinese i.c.. Sorry. The NVRAM is probably about the only thing you can fix on that main board. It cost about $38.00. You have to decide if it's worth a shot. I wonder if you removed it (lot of careful de-soldering - use a powered de-soldering pump (i.e. Hakko 808). Maybe if you removed it it would boot to the splash screen, then you know. If it is still totally dead, I doubt there is much you can fix. Look for a XTAL near the microprocessor and make sure it is good and not broken (if scope was dropped). I will be getting mine back with calibration seals, so I will not be able to open it to help do comparisons with you. Dave On Thu, Dec 6, 2018 at 5:42 AM benj3867 via Groups.Io <benj3867= [email protected]> wrote: @Dave, when you have had the bad NVRAM installed, how did the no-boot
situation look? I.e., was it also a white screen, no beeps and no relay
clicks, or did it at least show the DPO splash screen?
Thanks,
Benjamin
|
Re: 7T11 horizontal memory
On Wed, Dec 5, 2018 at 10:19 PM, cmjones01 wrote:
- in real time mode, it's hard to get a trace that makes sense. presumably the
50kHz-ish clock from the real time multivibrator limits the display to about
one sample every 20us, so some of the faster sweep speeds don't show a lot.
Even on the slower sweeps, the edges of my test squarewave exhibit terrible
risetime (about half a division) which is puzzling, and very different to the
behaviour in equivalent time. Maybe it's something to do with the recovery
time of the sampling head, or there's something amiss with the 7S11. I tried
adjusting the 'dot response' control and making sure smoothing was switched
off, but it didn't improve much.
Just to be sure that the fault is in the 7S11, you might check that the terrible rise time is also present when you use the 7S11 in combination with an ordinary timebase unit in stead of the 7T11. You probably did not verify that you could adjust the dot response for loop gain one, it only "improved not much". I would check this first of all. The sampling head has an internal GAIN adjustment that could be too far off to correct with the 7S11 dot response adjustment. You can probably tell that I'm new to the
7000-series sampling world. I regularly use my CSA803A/SD24 sampling setup,
but that makes it all so easy...
I followed the normal(?) route. I started with sampling units for the 564, then for the 7000 series and now I also have a CSA803A with SD-20 and SD-26. Still waiting for a good opportunity to buy an SD-24. Albert
|
Re: TDS3032 does not boot. LCD backl-ight and fan working.
@Dave, when you have had the bad NVRAM installed, how did the no-boot situation look? I.e., was it also a white screen, no beeps and no relay clicks, or did it at least show the DPO splash screen?
Thanks,
Benjamin
|
Re: Tube test adaptor for Tektroinx 575 was: Re: [TekScopes] FS: miscellaneous Tektronix manuals
Another thing to consider (if you are feeding tube filaments via AC
power) and want to minimize hum is to use twisted pair wiring to
distribute AC power to the tube filament socket connections (rather than
individual single conductor wires which are haphazardly separated from
each other). Twisted pair tends to minimize inductive (magnetic)
radiation within the equipment/chassis that could otherwise occur with
separated wires supplying AC to the tube socket filament pins; the
magnetic field (at 60 hz) can lead to audio hum. Of course, it's also
OK to use single conductor wires which are twisted together in "paired"
wiring for the filament power distriubtion.
Mike Dinolfo N4MWP
toggle quoted message
Show quoted text
On 12/5/18 10:06 PM, Jim Ford wrote: Yep, a colleague several decades ago told me if you ever work with audio tubes, try D.C. for the heater instead of A.C., you'll like it.? I never forgot that, although I have not worked with tubes much.
Jim F
Sent from my Verizon, Samsung Galaxy smartphone
-------- Original message --------From: Harvey White <madyn@...> Date: 12/5/18 5:23 PM (GMT-08:00) To: [email protected] Subject: Re: Tube test adaptor for Tektroinx 575 was: Re: [TekScopes] FS: miscellaneous Tektronix manuals
On Wed, 5 Dec 2018 22:11:12 +0000 (UTC), you wrote:
Brad,
Thank you!
My main interest is audio tubes. I have >1000 different tubes, mostly audio output and small signal/preamp tubes. I also own a Hickok 580A tube tester and a Tektronix 575 Curve Tracer. Thus my interest in using a Tek 575 to match tubes for use in DIY preamps and amps I am planning to make.
I was a electronics tech in the military a long time ago, in the time when tubes were going away and being replaced with solid state, but before the internet and PCs. I don't write code, although I did take a course in Fortran back in the early 1980s.
This group has been a tremendous resource. I truly appreciate the responses that I have humbly received from you and others in the group. I say humbly received because I'm just a audio hobbyist and ME who is humbled because I realize that I know so little about audio electronics who is trying to learn.
For example, I didn't know until recently that tubes usually use AC voltage for the heater. I'm also learning the different terms, such as the anode is usually called the plate. It's humbling that this old technology was invented well before I was born and is still useful today.
Again, thanks to all who responded with the lessons and great information.
Dan Here's another one, and you may want to think of this in a high end
application.
The original heaters (called filaments) were the same as light bulbs,
simply tungsten wires that were heated to boil off electrons.
These were the first heaters, and needed 'A' batteries to run them.
(the "B" batteries provided plate voltages, and the "C" batteries
provided bias voltages, which were difficult to do without a negative
supply since the filament was both the cathode and the electron
supply.? You simply couldn't have the cathodes at any different
potential since they were supplied by the same battery)
Now another problem was that because the heaters had relatively small
thermal inertia (they heated up and cooled down quickly), the use of
AC for the heaters induced hum on the signal ... think of it, your
electron supply was increasing and decreasing with the AC supply
voltage.
So the solution was to put the heater inside a tube, but electrically
isolated from it.? So the heater could run off AC, and the thermal
inertia of the tube (called the cathode), kept the electron flow more
even.
You could even self bias the tubes by elevating the cathode above
ground.
Lead to a lot of nice designs.
Now, there's still a bit of hum induced by the heater in the cathode
sleve.? (cathode sleve has materials on it that release electrons when
heated). In your amplifier/preamp/whatever, you *may* get a reduction
in hum by running the heater from DC.
Just a thought, you may want to look it up.
Harvey
??? On Wednesday, December 5, 2018, 1:28:41 PM PST, Brad Thompson <brad.thompson@...> wrote:
On 12/4/2018 4:52 PM, Dan Cordova via Groups.Io wrote:
? Hi Brad,
Do you have or know anyone selling an adapter/fixture to match tubes on a Tektronix 575?
Or, do you know if there is a schematic I can buy?
Glydeck has a blog about this, but there is no schematic or info to contact him. Hello, Dan and the group--
Thank you for your inquiry. Here's a column I wrote for Test &
Measurement World
magazine (subsequently absorbed by EDN) which describes my version of
a tube-test adaptor for the Tek 575:
You can view a schematic and photos here...
I used an external tube socket, small PC board and some two-piece
surplus connectors to build an adaptor, which suffices for small tubes
that don't need plate voltages in excess of what the 575 can deliver.
Heater or filament and screen voltages get supplied by "wall warts" or
other power supplies
In the schematic, J1 and J2 form a "crossover network" to match a
particular tube's pinout. This approach requires wiring or rewiring
the J1-J2 adaptor to test each tube type and thus is best suited to
testing a batch of identically-pinned tubes at once.
Newcomers to tube technology may be surprised to learn that many tubes
with different part numbers can share a common pinout. For example,
JEDEC base code 8BD
defines an octal (8-pin) base which applies to the 6SN7-GT, the 6SL7-GT
and their
heater-voltage cognates along with 25 or so other tube-part numbers.
Providing 12 pins
accommodates "modern" Compactron tubes.
While I noted no spurious oscillations while testing a batch of 6SN7s, you
may need to slip ferrite beads onto plate and grid leads if needed for
parasitic-oscillation suppression.
One point: use care in selecting the grid/base voltage you apply to the
tube under test. If the tube manual states "maximum positive grid
voltage = 0 volts", believe it! Running the grid voltage positive causes
large amounts of grid current to flow can melt the grid.
Questions welcomed-- I don't have any spare adaptor boards left over
but would investigate making more if there's interest.
73--
Brad? aA1IP
|
Re: Tube test adaptor for Tektroinx 575 was: Re: [TekScopes] FS: miscellaneous Tektronix manuals
Yep, a colleague several decades ago told me if you ever work with audio tubes, try D.C. for the heater instead of A.C., you'll like it.? I never forgot that, although I have not worked with tubes much.
Jim F
Sent from my Verizon, Samsung Galaxy smartphone
toggle quoted message
Show quoted text
-------- Original message --------From: Harvey White <madyn@...> Date: 12/5/18 5:23 PM (GMT-08:00) To: [email protected] Subject: Re: Tube test adaptor for Tektroinx 575 was: Re: [TekScopes] FS: miscellaneous Tektronix manuals On Wed, 5 Dec 2018 22:11:12 +0000 (UTC), you wrote: Brad,
Thank you!
My main interest is audio tubes. I have >1000 different tubes, mostly audio output and small signal/preamp tubes. I also own a Hickok 580A tube tester and a Tektronix 575 Curve Tracer. Thus my interest in using a Tek 575 to match tubes for use in DIY preamps and amps I am planning to make.?
I was a electronics tech in the military a long time ago, in the time when tubes were going away and being replaced with solid state, but before the internet and PCs. I don't write code, although I did take a course in Fortran back in the early 1980s.?
This group has been a tremendous resource. I truly appreciate the responses that I have humbly received from you and others in the group. I say humbly received because I'm just a audio hobbyist and ME who is humbled because I realize that I know so little about audio electronics who is trying to learn.
For example, I didn't know until recently that tubes usually use AC voltage for the heater. I'm also learning the different terms, such as the anode is usually called the plate. It's humbling that this old technology was invented well before I was born and is still useful today.?
Again, thanks to all who responded with the lessons and great information.
Dan? Here's another one, and you may want to think of this in a high end application. The original heaters (called filaments) were the same as light bulbs, simply tungsten wires that were heated to boil off electrons. These were the first heaters, and needed 'A' batteries to run them. (the "B" batteries provided plate voltages, and the "C" batteries provided bias voltages, which were difficult to do without a negative supply since the filament was both the cathode and the electron supply.? You simply couldn't have the cathodes at any different potential since they were supplied by the same battery) Now another problem was that because the heaters had relatively small thermal inertia (they heated up and cooled down quickly), the use of AC for the heaters induced hum on the signal ... think of it, your electron supply was increasing and decreasing with the AC supply voltage. So the solution was to put the heater inside a tube, but electrically isolated from it.? So the heater could run off AC, and the thermal inertia of the tube (called the cathode), kept the electron flow more even. You could even self bias the tubes by elevating the cathode above ground. Lead to a lot of nice designs. Now, there's still a bit of hum induced by the heater in the cathode sleve.? (cathode sleve has materials on it that release electrons when heated). In your amplifier/preamp/whatever, you *may* get a reduction in hum by running the heater from DC. Just a thought, you may want to look it up. Harvey
??? On Wednesday, December 5, 2018, 1:28:41 PM PST, Brad Thompson <brad.thompson@...> wrote:
On 12/4/2018 4:52 PM, Dan Cordova via Groups.Io wrote:
? Hi Brad,
Do you have or know anyone selling an adapter/fixture to match tubes on a Tektronix 575?
Or, do you know if there is a schematic I can buy?
Glydeck has a blog about this, but there is no schematic or info to contact him. Hello, Dan and the group--
Thank you for your inquiry. Here's a column I wrote for Test &
Measurement World
magazine (subsequently absorbed by EDN) which describes my version of
a tube-test adaptor for the Tek 575:
You can view a schematic and photos here...
I used an external tube socket, small PC board and some two-piece
surplus connectors to build an adaptor, which suffices for small tubes
that don't need plate voltages in excess of what the 575 can deliver.
Heater or filament and screen voltages get supplied by "wall warts" or
other power supplies
In the schematic, J1 and J2 form a "crossover network" to match a
particular tube's pinout. This approach requires wiring or rewiring
the J1-J2 adaptor to test each tube type and thus is best suited to
testing a batch of identically-pinned tubes at once.
Newcomers to tube technology may be surprised to learn that many tubes
with different part numbers can share a common pinout. For example,
JEDEC base code 8BD
defines an octal (8-pin) base which applies to the 6SN7-GT, the 6SL7-GT
and their
heater-voltage cognates along with 25 or so other tube-part numbers.
Providing 12 pins
accommodates "modern" Compactron tubes.
While I noted no spurious oscillations while testing a batch of 6SN7s, you
may need to slip ferrite beads onto plate and grid leads if needed for
parasitic-oscillation suppression.
One point: use care in selecting the grid/base voltage you apply to the
tube under test. If the tube manual states "maximum positive grid
voltage = 0 volts", believe it! Running the grid voltage positive causes
large amounts of grid current to flow can melt the grid.
Questions welcomed-- I don't have any spare adaptor boards left over
but would investigate making more if there's interest.
73--
Brad? aA1IP
|
Re: Tube test adaptor for Tektroinx 575 was: Re: [TekScopes] FS: miscellaneous Tektronix manuals
On Wed, 5 Dec 2018 22:11:12 +0000 (UTC), you wrote: Brad,
Thank you!
My main interest is audio tubes. I have >1000 different tubes, mostly audio output and small signal/preamp tubes. I also own a Hickok 580A tube tester and a Tektronix 575 Curve Tracer. Thus my interest in using a Tek 575 to match tubes for use in DIY preamps and amps I am planning to make.?
I was a electronics tech in the military a long time ago, in the time when tubes were going away and being replaced with solid state, but before the internet and PCs. I don't write code, although I did take a course in Fortran back in the early 1980s.?
This group has been a tremendous resource. I truly appreciate the responses that I have humbly received from you and others in the group. I say humbly received because I'm just a audio hobbyist and ME who is humbled because I realize that I know so little about audio electronics who is trying to learn.
For example, I didn't know until recently that tubes usually use AC voltage for the heater. I'm also learning the different terms, such as the anode is usually called the plate. It's humbling that this old technology was invented well before I was born and is still useful today.?
Again, thanks to all who responded with the lessons and great information.
Dan? Here's another one, and you may want to think of this in a high end application. The original heaters (called filaments) were the same as light bulbs, simply tungsten wires that were heated to boil off electrons. These were the first heaters, and needed 'A' batteries to run them. (the "B" batteries provided plate voltages, and the "C" batteries provided bias voltages, which were difficult to do without a negative supply since the filament was both the cathode and the electron supply. You simply couldn't have the cathodes at any different potential since they were supplied by the same battery) Now another problem was that because the heaters had relatively small thermal inertia (they heated up and cooled down quickly), the use of AC for the heaters induced hum on the signal ... think of it, your electron supply was increasing and decreasing with the AC supply voltage. So the solution was to put the heater inside a tube, but electrically isolated from it. So the heater could run off AC, and the thermal inertia of the tube (called the cathode), kept the electron flow more even. You could even self bias the tubes by elevating the cathode above ground. Lead to a lot of nice designs. Now, there's still a bit of hum induced by the heater in the cathode sleve. (cathode sleve has materials on it that release electrons when heated). In your amplifier/preamp/whatever, you *may* get a reduction in hum by running the heater from DC. Just a thought, you may want to look it up. Harvey
On Wednesday, December 5, 2018, 1:28:41 PM PST, Brad Thompson <brad.thompson@...> wrote:
On 12/4/2018 4:52 PM, Dan Cordova via Groups.Io wrote:
? Hi Brad,
Do you have or know anyone selling an adapter/fixture to match tubes on a Tektronix 575?
Or, do you know if there is a schematic I can buy?
Glydeck has a blog about this, but there is no schematic or info to contact him. Hello, Dan and the group--
Thank you for your inquiry. Here's a column I wrote for Test &
Measurement World
magazine (subsequently absorbed by EDN) which describes my version of
a tube-test adaptor for the Tek 575:
You can view a schematic and photos here...
I used an external tube socket, small PC board and some two-piece
surplus connectors to build an adaptor, which suffices for small tubes
that don't need plate voltages in excess of what the 575 can deliver.
Heater or filament and screen voltages get supplied by "wall warts" or
other power supplies
In the schematic, J1 and J2 form a "crossover network" to match a
particular tube's pinout. This approach requires wiring or rewiring
the J1-J2 adaptor to test each tube type and thus is best suited to
testing a batch of identically-pinned tubes at once.
Newcomers to tube technology may be surprised to learn that many tubes
with different part numbers can share a common pinout. For example,
JEDEC base code 8BD
defines an octal (8-pin) base which applies to the 6SN7-GT, the 6SL7-GT
and their
heater-voltage cognates along with 25 or so other tube-part numbers.
Providing 12 pins
accommodates "modern" Compactron tubes.
While I noted no spurious oscillations while testing a batch of 6SN7s, you
may need to slip ferrite beads onto plate and grid leads if needed for
parasitic-oscillation suppression.
One point: use care in selecting the grid/base voltage you apply to the
tube under test. If the tube manual states "maximum positive grid
voltage = 0 volts", believe it! Running the grid voltage positive causes
large amounts of grid current to flow can melt the grid.
Questions welcomed-- I don't have any spare adaptor boards left over
but would investigate making more if there's interest.
73--
Brad? aA1IP
|
Does anyone have any dead TM500 plugins they want to sell (cheaply)?
I'm looking for a couple of carcasses to build some custom
modules with.
thanks
Paul
--
Paul Amaranth, GCIH | Rochester MI, USA
Aurora Group, Inc. | Security, Systems & Software
paul@... | Unix & Windows
|
Re: 7T11 horizontal memory
Chris, I'm envious that you have a CSA803 and SD24!? I had that setup about 25 years ago at my employer the time.? Nice!
Have to make do with 7904, 7S12, 7S11, and two S-4's in my garage lab for now.? I use an S-53 or S-51 for triggering.? Works for what I need it to do.? Someday I'll have a CSA803 again.? And an S-6 for TDR, etc., etc.
Jim F
Sent from my Verizon, Samsung Galaxy smartphone
toggle quoted message
Show quoted text
-------- Original message --------From: cmjones01 <chris@...> Date: 12/5/18 1:19 PM (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] 7T11 horizontal memory On Wed, Dec? 5, 2018 at 08:17 AM, Albert Otten wrote: I might have good news for you.
The real time multivibrator doesn't work when you don't have a 7S11 adjacent
to (or otherwise connected to) the 7T11. So then the memory gate is always
blocked and you have no sweep output at the front panel. Aha! Your news is indeed good :-) I put the 7T11 in to a slot next to my 7S11 and I now have a horizontal sweep in the rea ltime ranges. You mean U512 I suppose. It was U512 when I killed it, but I swapped it with U572 to check that it was actually faulty. My 741 kludge seems to work but I'm not convinced it's perfect. The Tek chip seems specified quite fast (80MHz gain-bandwidth product!) and I think the rather pedestrian 741 may be running out of speed (or slew rate) in the faster real-time ranges. In real time ranges the horizontal amplifier now has
one continuous ramp as input during the whole sweep of the 7T11. It depends on
the time/div setting which outputs of U512 are really used in the amplifier
chain. Not used outputs can be overdriven within short time without any
consequence, and stay at some very high maximum level during the rest of the
sweep .? It's what I see happening. Yes, I've observed that in the U512A/B/C/D chain too. The ramp only really makes sense properly after the last stage. The good news is that, coupled with my 7S11, I now have something resembling a working sampling system. I have three rather tired-looking sampling heads in unknown condition (an S-1 and two S-2s, one labelled 50ps risetime and the other labelled 75ps). I have only tried the S-1 but it does actually work. Observations so far: - equivalent time mode works a lot better than real time mode. At least, the waveform I see on the screen in equivalent-time mode looks like what I'd expect. I haven't tried a really fast edge in to the sampling head yet to see how the performance is at the really short time'div settings. - in real time mode, it's hard to get a trace that makes sense. presumably the 50kHz-ish clock from the real time multivibrator limits the display to about one sample every 20us, so some of the faster sweep speeds don't show a lot. Even on the slower sweeps, the edges of my test squarewave exhibit terrible risetime (about half a division) which is puzzling, and very different to the behaviour in equivalent time. Maybe it's something to do with the recovery time of the sampling head, or there's something amiss with the 7S11. I tried adjusting the 'dot response' control and making sure smoothing was switched off, but it didn't improve much. Thank you for your help so far. You can probably tell that I'm new to the 7000-series sampling world. I regularly use my CSA803A/SD24 sampling setup, but that makes it all so easy... Chris
|
How electrically similar is the 3L10 to the 1L10? Components are numbered similarly. But clearly the circuits are different, at least at the output, since 560-series plug-ins must directly drive the CRT deflection plates (20 V/div).
|
Re: Tube test adaptor for Tektroinx 575 was: Re: [TekScopes] FS: miscellaneous Tektronix manuals
Brad,
Thank you!
My main interest is audio tubes. I have >1000 different tubes, mostly audio output and small signal/preamp tubes. I also own a Hickok 580A tube tester and a Tektronix 575 Curve Tracer. Thus my interest in using a Tek 575 to match tubes for use in DIY preamps and amps I am planning to make.?
I was a electronics tech in the military a long time ago, in the time when tubes were going away and being replaced with solid state, but before the internet and PCs. I don't write code, although I did take a course in Fortran back in the early 1980s.?
This group has been a tremendous resource. I truly appreciate the responses that I have humbly received from you and others in the group. I say humbly received because I'm just a audio hobbyist and ME who is humbled because I realize that I know so little about audio electronics who is trying to learn.
For example, I didn't know until recently that tubes usually use AC voltage for the heater. I'm also learning the different terms, such as the anode is usually called the plate. It's humbling that this old technology was invented well before I was born and is still useful today.?
Again, thanks to all who responded with the lessons and great information.
Dan
toggle quoted message
Show quoted text
On Wednesday, December 5, 2018, 1:28:41 PM PST, Brad Thompson <brad.thompson@...> wrote: On 12/4/2018 4:52 PM, Dan Cordova via Groups.Io wrote: ? Hi Brad,
Do you have or know anyone selling an adapter/fixture to match tubes on a Tektronix 575?
Or, do you know if there is a schematic I can buy?
Glydeck has a blog about this, but there is no schematic or info to contact him. Hello, Dan and the group-- Thank you for your inquiry. Here's a column I wrote for Test & Measurement World magazine (subsequently absorbed by EDN) which describes my version of a tube-test adaptor for the Tek 575: You can view a schematic and photos here... I used an external tube socket, small PC board and some two-piece surplus connectors to build an adaptor, which suffices for small tubes that don't need plate voltages in excess of what the 575 can deliver. Heater or filament and screen voltages get supplied by "wall warts" or other power supplies In the schematic, J1 and J2 form a "crossover network" to match a particular tube's pinout. This approach requires wiring or rewiring the J1-J2 adaptor to test each tube type and thus is best suited to testing a batch of identically-pinned tubes at once. Newcomers to tube technology may be surprised to learn that many tubes with different part numbers can share a common pinout. For example, JEDEC base code 8BD defines an octal (8-pin) base which applies to the 6SN7-GT, the 6SL7-GT and their heater-voltage cognates along with 25 or so other tube-part numbers. Providing 12 pins accommodates "modern" Compactron tubes. While I noted no spurious oscillations while testing a batch of 6SN7s, you may need to slip ferrite beads onto plate and grid leads if needed for parasitic-oscillation suppression. One point: use care in selecting the grid/base voltage you apply to the tube under test. If the tube manual states "maximum positive grid voltage = 0 volts", believe it! Running the grid voltage positive causes large amounts of grid current to flow can melt the grid. Questions welcomed-- I don't have any spare adaptor boards left over but would investigate making more if there's interest. 73-- Brad? aA1IP
|
Re: TDS3032 does not boot. LCD backl-ight and fan working.
" Unfortunately, holding the B-trig during power up makes no difference. " My experience: When I replaced by NVRAM with a fake one I bought in China, the scope would light up, but would not boot. I then order a NVRAM from a place in Florida and replaced it again and then it worked fine (Have to hold the B-TRIG in as powering up to reset the new NVRAM. It worked great then. Its out to Spectrum now for re-certification (Calibration tables were NOT lost). Dave On Tue, Dec 4, 2018 at 5:01 AM benj3867 via Groups.Io <benj3867= [email protected]> wrote: Thanks David.
Unfortunately, holding the B-trig during power up makes no difference.
Benjamin
|
Tube test adaptor for Tektroinx 575 was: Re: [TekScopes] FS: miscellaneous Tektronix manuals
On 12/4/2018 4:52 PM, Dan Cordova via Groups.Io wrote: Hi Brad,
Do you have or know anyone selling an adapter/fixture to match tubes on a Tektronix 575?
Or, do you know if there is a schematic I can buy?
Glydeck has a blog about this, but there is no schematic or info to contact him. Hello, Dan and the group-- Thank you for your inquiry. Here's a column I wrote for Test & Measurement World magazine (subsequently absorbed by EDN) which describes my version of a tube-test adaptor for the Tek 575: You can view a schematic and photos here... I used an external tube socket, small PC board and some two-piece surplus connectors to build an adaptor, which suffices for small tubes that don't need plate voltages in excess of what the 575 can deliver. Heater or filament and screen voltages get supplied by "wall warts" or other power supplies In the schematic, J1 and J2 form a "crossover network" to match a particular tube's pinout. This approach requires wiring or rewiring the J1-J2 adaptor to test each tube type and thus is best suited to testing a batch of identically-pinned tubes at once. Newcomers to tube technology may be surprised to learn that many tubes with different part numbers can share a common pinout. For example, JEDEC base code 8BD defines an octal (8-pin) base which applies to the 6SN7-GT, the 6SL7-GT and their heater-voltage cognates along with 25 or so other tube-part numbers. Providing 12 pins accommodates "modern" Compactron tubes. While I noted no spurious oscillations while testing a batch of 6SN7s, you may need to slip ferrite beads onto plate and grid leads if needed for parasitic-oscillation suppression. One point: use care in selecting the grid/base voltage you apply to the tube under test. If the tube manual states "maximum positive grid voltage = 0 volts", believe it! Running the grid voltage positive causes large amounts of grid current to flow can melt the grid. Questions welcomed-- I don't have any spare adaptor boards left over but would investigate making more if there's interest. 73-- Brad aA1IP
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Re: 7T11 horizontal memory
On Wed, Dec 5, 2018 at 08:17 AM, Albert Otten wrote: I might have good news for you.
The real time multivibrator doesn't work when you don't have a 7S11 adjacent
to (or otherwise connected to) the 7T11. So then the memory gate is always
blocked and you have no sweep output at the front panel. Aha! Your news is indeed good :-) I put the 7T11 in to a slot next to my 7S11 and I now have a horizontal sweep in the rea ltime ranges. You mean U512 I suppose. It was U512 when I killed it, but I swapped it with U572 to check that it was actually faulty. My 741 kludge seems to work but I'm not convinced it's perfect. The Tek chip seems specified quite fast (80MHz gain-bandwidth product!) and I think the rather pedestrian 741 may be running out of speed (or slew rate) in the faster real-time ranges. In real time ranges the horizontal amplifier now has
one continuous ramp as input during the whole sweep of the 7T11. It depends on
the time/div setting which outputs of U512 are really used in the amplifier
chain. Not used outputs can be overdriven within short time without any
consequence, and stay at some very high maximum level during the rest of the
sweep . It's what I see happening. Yes, I've observed that in the U512A/B/C/D chain too. The ramp only really makes sense properly after the last stage. The good news is that, coupled with my 7S11, I now have something resembling a working sampling system. I have three rather tired-looking sampling heads in unknown condition (an S-1 and two S-2s, one labelled 50ps risetime and the other labelled 75ps). I have only tried the S-1 but it does actually work. Observations so far: - equivalent time mode works a lot better than real time mode. At least, the waveform I see on the screen in equivalent-time mode looks like what I'd expect. I haven't tried a really fast edge in to the sampling head yet to see how the performance is at the really short time'div settings. - in real time mode, it's hard to get a trace that makes sense. presumably the 50kHz-ish clock from the real time multivibrator limits the display to about one sample every 20us, so some of the faster sweep speeds don't show a lot. Even on the slower sweeps, the edges of my test squarewave exhibit terrible risetime (about half a division) which is puzzling, and very different to the behaviour in equivalent time. Maybe it's something to do with the recovery time of the sampling head, or there's something amiss with the 7S11. I tried adjusting the 'dot response' control and making sure smoothing was switched off, but it didn't improve much. Thank you for your help so far. You can probably tell that I'm new to the 7000-series sampling world. I regularly use my CSA803A/SD24 sampling setup, but that makes it all so easy... Chris
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Re: FS: miscellaneous Tektronix manuals
George,
These are really outstanding!?
Thank you very much,
Dan
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On Wednesday, December 5, 2018, 6:46:28 AM PST, Glydeck via Groups.Io <glydeck@...> wrote: Dan, Dennis¡¯ curve tracer is the more complete solution, but if you¡¯re interested in the one on my blog its in the file section of TekScopes. /g/TekScopes/files/Tek575TestFixtures.pdfGeorge On Dec 4, 2018, at 11:01 PM, Dennis Tillman W7PF <dennis@...> wrote:
Hi Dan,
I can help you test tubes on your 575.
Like you I was very impressed with George Lydeck's (Glydeck) creativity and when a 575 fell into my lap for $20 it acted as a catalyst for me to build an adapter to test tubes. I went one step further than George: I came up with a way to test any tube on a 575, 576, 577, 7CT1N or 5CT1N.
You can read? about how you can do it in my paper which you can download at
If you want to get one of my adapter boards please contact me off list at dennis at ridesoft dot com.
Dennis Tillman W7PF
-----Original Message-----
From: Dan Cordova via Groups.Io
Sent: Tuesday, December 04, 2018 1:52 PM
Subject: Re: [TekScopes] FS: miscellaneous Tektronix manuals
Hi Brad,
Do you have or know anyone selling an adapter/fixture to match tubes on
a Tektronix 575?
Or, do you know if there is a schematic I can buy? Glydeck has a blog
about this, but there is no schematic or info to contact him.
Thanks,
Dan
--
Dennis Tillman W7PF
TekScopes Moderator
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Re: 7T11 horizontal memory
Hi Chris,
I might have good news for you.
The real time multivibrator doesn't work when you don't have a 7S11 adjacent to (or otherwise connected to) the 7T11. So then the memory gate is always blocked and you have no sweep output at the front panel.
You mean U512 I suppose. In real time ranges the horizontal amplifier now has one continuous ramp as input during the whole sweep of the 7T11. It depends on the time/div setting which outputs of U512 are really used in the amplifier chain. Not used outputs can be overdriven within short time without any consequence, and stay at some very high maximum level during the rest of the sweep . It's what I see happening.
I didn't pay attention to this in my previous post about equivalent time sampling but you essentially have the same situation then.
Albert
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On Wed, Dec 5, 2018 at 03:23 PM, cmjones01 wrote:
I have now replaced the faulty R541 and R542. I also found that U572B, a Tek
special op-amp, was dead, I think due to a careless slip of my scope probe.
For now I've kludged a 741 in its place. Joy of joys, I have a horizontal
sweep in equivalent-time mode! Still blanked in real-time mode. I think
there's still something not right about the horizontal memory, which seems to
only be used in real-time mode (or am I wrong?). Anyhow, when I select a
real-time-mode sweep range, the output of U572B wanders up to about +12V and
stays there. I do have real-time sweep on the way in to the horizontal memory,
though. Will investigate further.
Chris
On Wed, Dec 5, 2018 at 06:07 AM, Albert Otten wrote:
One more suggestion. Set the 7T11 for MANUAL scan. Set the test scope at 5 or
10 us/div, trigger from the 7T11 pulse output. Then probe all TPs 512, 515,
525, 555 of the horizontal amplifier. In each period you will see one
horizontal line at a level determined by the SCAN knob setting. The level
increases from ground to some maximum when you rotate SCAN from left (ccw) to
right (cw). The amounts and ratios depend on the setting of the 7T11 time/div
within its range. At TP555 the maximum should always be 5 V.
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Re: FS: miscellaneous Tektronix manuals
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Show quoted text
On Dec 4, 2018, at 11:01 PM, Dennis Tillman W7PF <dennis@...> wrote:
Hi Dan,
I can help you test tubes on your 575.
Like you I was very impressed with George Lydeck's (Glydeck) creativity and when a 575 fell into my lap for $20 it acted as a catalyst for me to build an adapter to test tubes. I went one step further than George: I came up with a way to test any tube on a 575, 576, 577, 7CT1N or 5CT1N.
You can read about how you can do it in my paper which you can download at
If you want to get one of my adapter boards please contact me off list at dennis at ridesoft dot com.
Dennis Tillman W7PF
-----Original Message-----
From: Dan Cordova via Groups.Io
Sent: Tuesday, December 04, 2018 1:52 PM
Subject: Re: [TekScopes] FS: miscellaneous Tektronix manuals
Hi Brad,
Do you have or know anyone selling an adapter/fixture to match tubes on
a Tektronix 575?
Or, do you know if there is a schematic I can buy? Glydeck has a blog
about this, but there is no schematic or info to contact him.
Thanks,
Dan
--
Dennis Tillman W7PF
TekScopes Moderator
|
Re: 7T11 horizontal memory
I have now replaced the faulty R541 and R542. I also found that U572B, a Tek special op-amp, was dead, I think due to a careless slip of my scope probe. For now I've kludged a 741 in its place. Joy of joys, I have a horizontal sweep in equivalent-time mode! Still blanked in real-time mode. I think there's still something not right about the horizontal memory, which seems to only be used in real-time mode (or am I wrong?). Anyhow, when I select a real-time-mode sweep range, the output of U572B wanders up to about +12V and stays there. I do have real-time sweep on the way in to the horizontal memory, though. Will investigate further.
Chris
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On Wed, Dec 5, 2018 at 06:07 AM, Albert Otten wrote: One more suggestion. Set the 7T11 for MANUAL scan. Set the test scope at 5 or
10 us/div, trigger from the 7T11 pulse output. Then probe all TPs 512, 515,
525, 555 of the horizontal amplifier. In each period you will see one
horizontal line at a level determined by the SCAN knob setting. The level
increases from ground to some maximum when you rotate SCAN from left (ccw) to
right (cw). The amounts and ratios depend on the setting of the 7T11 time/div
within its range. At TP555 the maximum should always be 5 V.
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Re: 7T11 horizontal memory
Hi Chris,
One more suggestion. Set the 7T11 for MANUAL scan. Set the test scope at 5 or 10 us/div, trigger from the 7T11 pulse output. Then probe all TPs 512, 515, 525, 555 of the horizontal amplifier. In each period you will see one horizontal line at a level determined by the SCAN knob setting. The level increases from ground to some maximum when you rotate SCAN from left (ccw) to right (cw). The amounts and ratios depend on the setting of the 7T11 time/div within its range. At TP555 the maximum should always be 5 V.
Albert
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On Mon, Dec 3, 2018 at 05:13 PM, Albert Otten wrote:
Hi Chris,
It's not so easy to interpret the graphs 26 and 27 the correct way. The shaded
area in 26 actually consists of horizontal lines, the value of which are
sampled when the memory gate conducts. In 27 something similar for the rest
period between end of hold-off and next trigger event.
When probe TP555 at a slow sweep speed, 5 ms/div, trigger from this signal and
play with the SCAN rate of the 7T11, you can get a more or less stable
display. You will recognize the 7T11 sweep as a rising envelope with an
amplitude of 5 V. The output at TP564 is a nice 2X inverted, down going sweep
signal with amplitude 10 V. TP556 shows about the same as TP564 but with small
amplitude.
Albert
On Mon, Dec 3, 2018 at 01:06 PM, cmjones01 wrote:
Now I have healthy gate pulses at the collector of Q546. However, I don't have
any sweep at TP555 in equivalent time mode. Need to look in to this next.
Chris
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Re: Tektronix 475A intermittent / lazy sweep
Hi, From my information, it is actually the Coulsdon Amateur Transmitting Society, not Crawley. The URL below gets you to the CATS Bazaar and there are links:
I, too have no association with the event, but I think I might try to visit next year....
Colin.
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-----Original Message----- From: [email protected] [mailto: [email protected]] On Behalf Of george edmonds via Groups.Io Sent: 23 November 2018 23:59 To: [email protected]Subject: Re: [TekScopes] Tektronix 475A intermittent / lazy sweep Hi All The CATS (Crawley Amateur Transmitting Society) rally is correctly known as the CATS Bazaar, it was not last month but is was held on the 15th November. If you are into Amateur Radio or T&M kit it is a must go to event. Just for the record I have nothing to do with the organising of the event. 73 George G6HIG On Friday, November 23, 2018 8:35 AM, Tom Gardner <tggzzz@...> wrote: On 23/11/18 06:18, Brian Cockburn wrote: At the CATS rally (South London) ... I'm in Cambridge but I'm not familiar with 'CATS Rally'. Googling didn't turn up anything non-feline. Could you elaborate a bit pleas
The canonical source for these rallies is Since the Couldson (Surrey) rally was last month, it no longer appears there.
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Mike Dinolfo
Glydeck