<https://www.dropbox.com/s/rddddzpkwqo44sc/TransformerWiring.jpg?dl=0>

Shows how the power transformer is directly wired to two separate
boards. Not sure how, or why, they'd want to do that.

<https://www.dropbox.com/s/nlzx6f0w5deomb1/SolderThroughHere.jpg?dl=0>

Shows the hole through which the transistor has to be soldered. Note the
two resistors in plastic tubing that have one end soldered to this
board, and the other end soldered to a board at the back of the tube.
Also a wire directly soldered to the board that also goes there.

<https://www.dropbox.com/s/degb7topima7yle/TransistorLeads.jpg?dl=0>

Shows the formed leads for the transistors. Fortunately, I now have a 3D
printer and have been able to make a template for bending the leads. Not
sure whether the white stand-offs have any useful thermal properties.
They have to withstand about 170 volts.

Another oddity is the two leads covered in yellow insulation. They are
only connected at one end, and are marked on the schematic as "wired
capacitors" across the resistors that lead to the tube X axis plates. No
doubt they do produce some capacitance, but I can't imagine it's much.
Anyone know what the purpose would be?

Sylvia.

On Mon, 23 Aug 2021 12:30:08 +1000, Sylvia Else <sylvia@email.invalid>
wrote:

><https://www.dropbox.com/s/rddddzpkwqo44sc/TransformerWiring.jpg?dl=0>
>
>Shows how the power transformer is directly wired to two separate
>boards. Not sure how, or why, they'd want to do that.
>
><https://www.dropbox.com/s/nlzx6f0w5deomb1/SolderThroughHere.jpg?dl=0>
>
>Shows the hole through which the transistor has to be soldered. Note the
>two resistors in plastic tubing that have one end soldered to this
>board, and the other end soldered to a board at the back of the tube.
>Also a wire directly soldered to the board that also goes there.
>
><https://www.dropbox.com/s/degb7topima7yle/TransistorLeads.jpg?dl=0>
>
>Shows the formed leads for the transistors. Fortunately, I now have a 3D
>printer and have been able to make a template for bending the leads. Not
>sure whether the white stand-offs have any useful thermal properties.
>They have to withstand about 170 volts.
>
>Another oddity is the two leads covered in yellow insulation. They are
>only connected at one end, and are marked on the schematic as "wired
>capacitors" across the resistors that lead to the tube X axis plates. No
>doubt they do produce some capacitance, but I can't imagine it's much.
>Anyone know what the purpose would be?
>
>Sylvia.

Poor planning ?

Sylvia Else wrote:
==============

>
> Another oddity is the two leads covered in yellow insulation. They are
> only connected at one end, and are marked on the schematic as "wired
> capacitors" across the resistors that lead to the tube X axis plates.

** Not what the shem shows.

There are two 111k resistors ( for each X plate) in parallel plus the "trick capacitor" in a feedback path to the base of a BF119.
Likely purpose is frequency compensation for a bit of L in the Rs.
Sometimes you see two plastic coated wires gently twisted for the same job.

....... Phil

On 23-Aug-21 12:52 pm, Phil Allison wrote:
> Sylvia Else wrote:
> ==============
>
>>
>> Another oddity is the two leads covered in yellow insulation. They are
>> only connected at one end, and are marked on the schematic as "wired
>> capacitors" across the resistors that lead to the tube X axis plates.
>
> ** Not what the shem shows.

No, not sure why I misread that.

t.>
> There are two 111k resistors ( for each X plate) in parallel plus the "trick capacitor" in a feedback path to the base of a BF119.
> Likely purpose is frequency compensation for a bit of L in the Rs.
> Sometimes you see two plastic coated wires gently twisted for the same job.
>
> ...... Phil
>

Sylvia.

On Mon, 23 Aug 2021 12:30:08 +1000, Sylvia Else <sylvia@email.invalid>
wrote:

><https://www.dropbox.com/s/rddddzpkwqo44sc/TransformerWiring.jpg?dl=0>
>
>Shows how the power transformer is directly wired to two separate
>boards. Not sure how, or why, they'd want to do that.
>
><https://www.dropbox.com/s/nlzx6f0w5deomb1/SolderThroughHere.jpg?dl=0>
>
>Shows the hole through which the transistor has to be soldered. Note the
>two resistors in plastic tubing that have one end soldered to this
>board, and the other end soldered to a board at the back of the tube.
>Also a wire directly soldered to the board that also goes there.
>
><https://www.dropbox.com/s/degb7topima7yle/TransistorLeads.jpg?dl=0>
>
>Shows the formed leads for the transistors. Fortunately, I now have a 3D
>printer and have been able to make a template for bending the leads. Not
>sure whether the white stand-offs have any useful thermal properties.
>They have to withstand about 170 volts.
>
>Another oddity is the two leads covered in yellow insulation. They are
>only connected at one end, and are marked on the schematic as "wired
>capacitors" across the resistors that lead to the tube X axis plates. No
>doubt they do produce some capacitance, but I can't imagine it's much.
>Anyone know what the purpose would be?
>
>Sylvia.

It's a gimmick capacitor, a twisted pair variable cap.

I showed one of my young engineers how to do that last week. We didn't
yet have the code to drive a digital variable capacitor, so she
couldn't tune an oscillator to within phaselock range, so that was a
temporary fix to let us test her FPGA phaselock code.

--

Father Brown's figure remained quite dark and still;
but in that instant he had lost his head. His head was
always most valuable when he had lost it.

On a sunny day (Mon, 23 Aug 2021 12:30:08 +1000) it happened Sylvia Else
<sylvia@email.invalid> wrote in <iogfhiFmhdsU1@mid.individual.net>:

><https://www.dropbox.com/s/rddddzpkwqo44sc/TransformerWiring.jpg?dl=0>
>
>Shows how the power transformer is directly wired to two separate
>boards. Not sure how, or why, they'd want to do that.
>
><https://www.dropbox.com/s/nlzx6f0w5deomb1/SolderThroughHere.jpg?dl=0>

Thin wires mains side? Kept away from sensitive electronics on other board?

>Shows the hole through which the transistor has to be soldered. Note the
>two resistors in plastic tubing that have one end soldered to this
>board, and the other end soldered to a board at the back of the tube.
>Also a wire directly soldered to the board that also goes there.
>
><https://www.dropbox.com/s/degb7topima7yle/TransistorLeads.jpg?dl=0>
>
>Shows the formed leads for the transistors. Fortunately, I now have a 3D
>printer and have been able to make a template for bending the leads. Not
>sure whether the white stand-offs have any useful thermal properties.
>They have to withstand about 170 volts.
>
>Another oddity is the two leads covered in yellow insulation. They are
>only connected at one end, and are marked on the schematic as "wired
>capacitors" across the resistors that lead to the tube X axis plates. No
>doubt they do produce some capacitance, but I can't imagine it's much.
>Anyone know what the purpose would be?

When I worked for Tek we calibrated the V amp to the CRT by bending the wires to the CRT,
that changed C and the frequency response needed to be within some limit.
This insulated wire, if bended, does the same
Maybe the is also some inductor in there?

On 23/08/21 03:30, Sylvia Else wrote:
> Another oddity is the two leads covered in yellow insulation. They are only
> connected at one end, and are marked on the schematic as "wired capacitors"
> across the resistors that lead to the tube X axis plates. No doubt they do
> produce some capacitance, but I can't imagine it's much. Anyone know what the
> purpose would be?

It is a gimmick capacitor, often made with a couple of wires
twisted together to make a ~1pF fiddlable capacitor.

Quite a lot of old Tektronix equipment relied on parasitic
stray capacitance and inductance of circuit tracks. They had
the decency to include the caps on the schematics, and to
indicate they couldn't be seen on the boards.

On 23-Aug-21 4:38 pm, Jan Panteltje wrote:
> On a sunny day (Mon, 23 Aug 2021 12:30:08 +1000) it happened Sylvia Else
> <sylvia@email.invalid> wrote in <iogfhiFmhdsU1@mid.individual.net>:
>
>> <https://www.dropbox.com/s/rddddzpkwqo44sc/TransformerWiring.jpg?dl=0>
>>
>> Shows how the power transformer is directly wired to two separate
>> boards. Not sure how, or why, they'd want to do that.
>>
>> <https://www.dropbox.com/s/nlzx6f0w5deomb1/SolderThroughHere.jpg?dl=0>
>
> Thin wires mains side? Kept away from sensitive electronics on other board?
>

It's not the positioning I'm questioning, but the mode of attachment.
There are plenty of wire-to-board connectors available, and that would
surely have made assembly easier.

It would certainly have made repair easier, though they probably didn't
care about that. The transistor I have to replace is at the edge of the
board, and can be desoldered and resoldered, albeit with some fiddling.

If I had to replace something closer to the middle of the board [*], I'd
have to unsolder all the soldered wires, and somehow hope to be able to
reconnect them later - perhaps by installing the wire-to-board
connectors the thing should have had in the first place.

[*] Of course, one bodge is cut the defective component off its leads,
and solder the new component to them, hoping that they don't become
unsoldered from the board.

Sylvia.

On a sunny day (Mon, 23 Aug 2021 17:04:41 +1000) it happened Sylvia Else
<sylvia@email.invalid> wrote in <iogvkbFpd32U1@mid.individual.net>:

>On 23-Aug-21 4:38 pm, Jan Panteltje wrote:
>> On a sunny day (Mon, 23 Aug 2021 12:30:08 +1000) it happened Sylvia Else
>> <sylvia@email.invalid> wrote in <iogfhiFmhdsU1@mid.individual.net>:
>>
>>> <https://www.dropbox.com/s/rddddzpkwqo44sc/TransformerWiring.jpg?dl=0>
>>>
>>> Shows how the power transformer is directly wired to two separate
>>> boards. Not sure how, or why, they'd want to do that.
>>>
>>> <https://www.dropbox.com/s/nlzx6f0w5deomb1/SolderThroughHere.jpg?dl=0>
>>
>> Thin wires mains side? Kept away from sensitive electronics on other board?
>>
>
>It's not the positioning I'm questioning, but the mode of attachment.
>There are plenty of wire-to-board connectors available, and that would
>surely have made assembly easier.
>
>It would certainly have made repair easier, though they probably didn't
>care about that. The transistor I have to replace is at the edge of the
>board, and can be desoldered and resoldered, albeit with some fiddling.
>
>If I had to replace something closer to the middle of the board [*], I'd
>have to unsolder all the soldered wires, and somehow hope to be able to
>reconnect them later - perhaps by installing the wire-to-board
>connectors the thing should have had in the first place.
>
>[*] Of course, one bodge is cut the defective component off its leads,
>and solder the new component to them, hoping that they don't become
>unsoldered from the board.
>
>Sylvia.

Yes, but that may degrade the soldering on the board side..
Not easy to service this thing, same for my old Trio scope, although that is a bit better accessible.
Sometimes it helps before taking apart such a wire labyrinth to take a few pictures
so you at least get the colors of the wires right...
Cameras are a great help.

OTOH the less connectors the less problems :-)

Sylvia Else wrote:

=================
>
> [*] Of course, one bodge is cut the defective component off its leads,
> and solder the new component to them, hoping that they don't become
> unsoldered from the board.
>

** What I would do.

Recently had to replace a pair of 5 leg, dual transistors in an old Sansui home amp ( AU5900 )
Saved about 2 hours time and a lot of grief by snipping off the device itself off leaving 5 x 1cm leads behind.

...... Phil

Sylvia Else wrote:
=============
> <https://www.dropbox.com/s/rddddzpkwqo44sc/TransformerWiring.jpg?dl=0>
>
> Shows how the power transformer is directly wired to two separate
> boards. Not sure how, or why, they'd want to do that.

---------------------------------------------------
That power tranny is a regular E-Core with no magnetic shielding or even a copper flux shorting strap.

Surprising it does not cause some trembling of the trace - being so close to the CRT like that.

...... Phil

On Mon, 23 Aug 2021 07:43:10 +0100, Tom Gardner
<spamjunk@blueyonder.co.uk> wrote:

>On 23/08/21 03:30, Sylvia Else wrote:
>> Another oddity is the two leads covered in yellow insulation. They are only
>> connected at one end, and are marked on the schematic as "wired capacitors"
>> across the resistors that lead to the tube X axis plates. No doubt they do
>> produce some capacitance, but I can't imagine it's much. Anyone know what the
>> purpose would be?
>
>It is a gimmick capacitor, often made with a couple of wires
>twisted together to make a ~1pF fiddlable capacitor.
>
>Quite a lot of old Tektronix equipment relied on parasitic
>stray capacitance and inductance of circuit tracks. They had
>the decency to include the caps on the schematics, and to
>indicate they couldn't be seen on the boards.

They also discovered "hook", the terrible time-domain behavior of FR4
as a capacitor.

--

Father Brown's figure remained quite dark and still;
but in that instant he had lost his head. His head was
always most valuable when he had lost it.

On Mon, 23 Aug 2021 01:10:12 -0700 (PDT), Phil Allison
<pallison49@gmail.com> wrote:

>Sylvia Else wrote:
>=============
>> <https://www.dropbox.com/s/rddddzpkwqo44sc/TransformerWiring.jpg?dl=0>
>>
>> Shows how the power transformer is directly wired to two separate
>> boards. Not sure how, or why, they'd want to do that.
>
>---------------------------------------------------
>That power tranny is a regular E-Core with no magnetic shielding or even a copper flux shorting strap.
>
>Surprising it does not cause some trembling of the trace - being so close to the CRT like that.
>
>
>..... Phil

We did one NMR gradient amp with two power transformers, where proper
placement and phasing made the fields cancel where it mattered.

--

Father Brown's figure remained quite dark and still;
but in that instant he had lost his head. His head was
always most valuable when he had lost it.

On Mon, 23 Aug 2021 12:30:08 +1000, Sylvia Else <sylvia@email.invalid>
wrote:

><https://www.dropbox.com/s/rddddzpkwqo44sc/TransformerWiring.jpg?dl=0>
>
>Shows how the power transformer is directly wired to two separate
>boards. Not sure how, or why, they'd want to do that.
>
><https://www.dropbox.com/s/nlzx6f0w5deomb1/SolderThroughHere.jpg?dl=0>
>
>Shows the hole through which the transistor has to be soldered. Note the
>two resistors in plastic tubing that have one end soldered to this
>board, and the other end soldered to a board at the back of the tube.
>Also a wire directly soldered to the board that also goes there.
>
><https://www.dropbox.com/s/degb7topima7yle/TransistorLeads.jpg?dl=0>
>
>Shows the formed leads for the transistors. Fortunately, I now have a 3D
>printer and have been able to make a template for bending the leads. Not
>sure whether the white stand-offs have any useful thermal properties.
>They have to withstand about 170 volts.
>
>Another oddity is the two leads covered in yellow insulation. They are
>only connected at one end, and are marked on the schematic as "wired
>capacitors" across the resistors that lead to the tube X axis plates. No
>doubt they do produce some capacitance, but I can't imagine it's much.
>Anyone know what the purpose would be?
>
>Sylvia.

It is impressive how much stuff is inside an old analog scope. A cheap
100 MHz 4-channel digital scope is mostly air inside.

Multi-channel traces never worked well in analog scopes. They shared
the tube with alternate traces, or chopped.

Digital scopes often share ADCs, which costs sample rate when
additional channels are enabled. For dual trace, it's better to use 2
and 3, instead of the obvious 1 and 2.

--

Father Brown's figure remained quite dark and still;
but in that instant he had lost his head. His head was
always most valuable when he had lost it.

On 23/08/21 16:05, jlarkin@highlandsniptechnology.com wrote:
> On Mon, 23 Aug 2021 07:43:10 +0100, Tom Gardner
> <spamjunk@blueyonder.co.uk> wrote:
>
>> On 23/08/21 03:30, Sylvia Else wrote:
>>> Another oddity is the two leads covered in yellow insulation. They are only
>>> connected at one end, and are marked on the schematic as "wired capacitors"
>>> across the resistors that lead to the tube X axis plates. No doubt they do
>>> produce some capacitance, but I can't imagine it's much. Anyone know what the
>>> purpose would be?
>>
>> It is a gimmick capacitor, often made with a couple of wires
>> twisted together to make a ~1pF fiddlable capacitor.
>>
>> Quite a lot of old Tektronix equipment relied on parasitic
>> stray capacitance and inductance of circuit tracks. They had
>> the decency to include the caps on the schematics, and to
>> indicate they couldn't be seen on the boards.
>
> They also discovered "hook", the terrible time-domain behavior of FR4
> as a capacitor.

Indeed, but they also used the "tricks" where that wasn't
important, e.g. time-domain calibrators where the (nuvistor's)
output is a sinewave.

On 23/08/21 16:12, jlarkin@highlandsniptechnology.com wrote:
> On Mon, 23 Aug 2021 12:30:08 +1000, Sylvia Else <sylvia@email.invalid>
> wrote:
>
>> <https://www.dropbox.com/s/rddddzpkwqo44sc/TransformerWiring.jpg?dl=0>
>>
>> Shows how the power transformer is directly wired to two separate
>> boards. Not sure how, or why, they'd want to do that.
>>
>> <https://www.dropbox.com/s/nlzx6f0w5deomb1/SolderThroughHere.jpg?dl=0>
>>
>> Shows the hole through which the transistor has to be soldered. Note the
>> two resistors in plastic tubing that have one end soldered to this
>> board, and the other end soldered to a board at the back of the tube.
>> Also a wire directly soldered to the board that also goes there.
>>
>> <https://www.dropbox.com/s/degb7topima7yle/TransistorLeads.jpg?dl=0>
>>
>> Shows the formed leads for the transistors. Fortunately, I now have a 3D
>> printer and have been able to make a template for bending the leads. Not
>> sure whether the white stand-offs have any useful thermal properties.
>> They have to withstand about 170 volts.
>>
>> Another oddity is the two leads covered in yellow insulation. They are
>> only connected at one end, and are marked on the schematic as "wired
>> capacitors" across the resistors that lead to the tube X axis plates. No
>> doubt they do produce some capacitance, but I can't imagine it's much.
>> Anyone know what the purpose would be?
>>
>> Sylvia.
>
> It is impressive how much stuff is inside an old analog scope. A cheap
> 100 MHz 4-channel digital scope is mostly air inside.
>
> Multi-channel traces never worked well in analog scopes. They shared
> the tube with alternate traces, or chopped.

I acquired a dual /beam/ analogue storage scope before it
hit the dumpster. After replacing the usual PSU electrolytics,
it still works as well as analogue storage scopes ever did.

Dual beam is particularly useful with a dual channel storage
scope, since ALT mode is pretty useless at capturing fast
transients, and CHOP is only useful at low speeds.

Must sell it sometime.

On Mon, 23 Aug 2021 16:37:26 +0100, Tom Gardner
<spamjunk@blueyonder.co.uk> wrote:

>On 23/08/21 16:12, jlarkin@highlandsniptechnology.com wrote:
>> On Mon, 23 Aug 2021 12:30:08 +1000, Sylvia Else <sylvia@email.invalid>
>> wrote:
>>
>>> <https://www.dropbox.com/s/rddddzpkwqo44sc/TransformerWiring.jpg?dl=0>
>>>
>>> Shows how the power transformer is directly wired to two separate
>>> boards. Not sure how, or why, they'd want to do that.
>>>
>>> <https://www.dropbox.com/s/nlzx6f0w5deomb1/SolderThroughHere.jpg?dl=0>
>>>
>>> Shows the hole through which the transistor has to be soldered. Note the
>>> two resistors in plastic tubing that have one end soldered to this
>>> board, and the other end soldered to a board at the back of the tube.
>>> Also a wire directly soldered to the board that also goes there.
>>>
>>> <https://www.dropbox.com/s/degb7topima7yle/TransistorLeads.jpg?dl=0>
>>>
>>> Shows the formed leads for the transistors. Fortunately, I now have a 3D
>>> printer and have been able to make a template for bending the leads. Not
>>> sure whether the white stand-offs have any useful thermal properties.
>>> They have to withstand about 170 volts.
>>>
>>> Another oddity is the two leads covered in yellow insulation. They are
>>> only connected at one end, and are marked on the schematic as "wired
>>> capacitors" across the resistors that lead to the tube X axis plates. No
>>> doubt they do produce some capacitance, but I can't imagine it's much.
>>> Anyone know what the purpose would be?
>>>
>>> Sylvia.
>>
>> It is impressive how much stuff is inside an old analog scope. A cheap
>> 100 MHz 4-channel digital scope is mostly air inside.
>>
>> Multi-channel traces never worked well in analog scopes. They shared
>> the tube with alternate traces, or chopped.
>
>I acquired a dual /beam/ analogue storage scope before it
>hit the dumpster. After replacing the usual PSU electrolytics,
>it still works as well as analogue storage scopes ever did.
>

The giant Tek with the separate power supply?

>Dual beam is particularly useful with a dual channel storage
>scope, since ALT mode is pretty useless at capturing fast
>transients, and CHOP is only useful at low speeds.

Analog storage never worked well. The secondary-emission tubes wore
out. The mesh things had low writing rates. All primitive.

We have a 7104, the 1 GHz microchannel scope, but we don't use it any
more. That display shuts off about once a minute to extend tube life.
Nuisance.

It's distributed deflection, sort of like these, but ceramic so you
can't see inside:

https://www.dropbox.com/s/evoq6p2nvzyl6wo/547_crt.JPG?dl=0

https://www.dropbox.com/s/r6c3zkwlqrayt53/519_CRT.JPG?dl=0

--

Father Brown's figure remained quite dark and still;
but in that instant he had lost his head. His head was
always most valuable when he had lost it.

jla...@highlandsniptechnology.com wrote:

====================================
>
> It is impressive how much stuff is inside an old analog scope.

** Only true of expensive ones like Tek and HP.

> A cheap 100 MHz 4-channel digital scope is mostly air inside.

** DSOs are chock full of SMD, with a SMPS and a flat screen.
Not really "scopes " at all.

OTOH:

My 50Mhz, dual trace is a steel box 90% full of air.
Has to be deep enough to accommodate the PDA tube = 14 inches.
The front panel has to fit all the controls comfortably = 10 x 7 inches.
Easy to carry in one hand and uses only 14 watts of power.
No need for a stupid, dust clogging fan.

Purchased on the 19/9/1985.
Never out of use.

....... Phil

On Mon, 23 Aug 2021 15:33:47 -0700 (PDT), Phil Allison
<pallison49@gmail.com> wrote:

> jla...@highlandsniptechnology.com wrote:
>
>====================================
>>
>> It is impressive how much stuff is inside an old analog scope.
>
>** Only true of expensive ones like Tek and HP.
>
>> A cheap 100 MHz 4-channel digital scope is mostly air inside.
>
>** DSOs are chock full of SMD, with a SMPS and a flat screen.
> Not really "scopes " at all.
>
>OTOH:
>
>My 50Mhz, dual trace is a steel box 90% full of air.

20% is full of vacuum!

John Larkin wrote:
==============
>
> >My 50Mhz, dual trace is a steel box 90% full of air.
>
> 20% is full of vacuum!

** There is some stuff in there as well ...

Plus it's no more than 10% of the volume and barely affects the weight .

..... Phil

On 23/08/21 16:46, jlarkin@highlandsniptechnology.com wrote:
> On Mon, 23 Aug 2021 16:37:26 +0100, Tom Gardner
> <spamjunk@blueyonder.co.uk> wrote:
>
>> On 23/08/21 16:12, jlarkin@highlandsniptechnology.com wrote:
>>> On Mon, 23 Aug 2021 12:30:08 +1000, Sylvia Else <sylvia@email.invalid>
>>> wrote:
>>>
>>>> <https://www.dropbox.com/s/rddddzpkwqo44sc/TransformerWiring.jpg?dl=0>
>>>>
>>>> Shows how the power transformer is directly wired to two separate
>>>> boards. Not sure how, or why, they'd want to do that.
>>>>
>>>> <https://www.dropbox.com/s/nlzx6f0w5deomb1/SolderThroughHere.jpg?dl=0>
>>>>
>>>> Shows the hole through which the transistor has to be soldered. Note the
>>>> two resistors in plastic tubing that have one end soldered to this
>>>> board, and the other end soldered to a board at the back of the tube.
>>>> Also a wire directly soldered to the board that also goes there.
>>>>
>>>> <https://www.dropbox.com/s/degb7topima7yle/TransistorLeads.jpg?dl=0>
>>>>
>>>> Shows the formed leads for the transistors. Fortunately, I now have a 3D
>>>> printer and have been able to make a template for bending the leads. Not
>>>> sure whether the white stand-offs have any useful thermal properties.
>>>> They have to withstand about 170 volts.
>>>>
>>>> Another oddity is the two leads covered in yellow insulation. They are
>>>> only connected at one end, and are marked on the schematic as "wired
>>>> capacitors" across the resistors that lead to the tube X axis plates. No
>>>> doubt they do produce some capacitance, but I can't imagine it's much.
>>>> Anyone know what the purpose would be?
>>>>
>>>> Sylvia.
>>>
>>> It is impressive how much stuff is inside an old analog scope. A cheap
>>> 100 MHz 4-channel digital scope is mostly air inside.
>>>
>>> Multi-channel traces never worked well in analog scopes. They shared
>>> the tube with alternate traces, or chopped.
>>
>> I acquired a dual /beam/ analogue storage scope before it
>> hit the dumpster. After replacing the usual PSU electrolytics,
>> it still works as well as analogue storage scopes ever did.
>>
>
> The giant Tek with the separate power supply?

No! It is a low-end Telequipment DM63 with 2 vertical
plug-in slots. I am still surprised that a "budget"
brand would have a dual beam storage tube.
https://w140.com/tekwiki/wiki/Telequipment_DM63

>> Dual beam is particularly useful with a dual channel storage
>> scope, since ALT mode is pretty useless at capturing fast
>> transients, and CHOP is only useful at low speeds.
>
> Analog storage never worked well. The secondary-emission tubes wore
> out. The mesh things had low writing rates. All primitive.

When digitising scopes became available, everybody heaved
a sigh of relief, tempered only by realising the slow
sampling rate.

The DM63 is 15MHz, but the writing speed isn't up to that.

> We have a 7104, the 1 GHz microchannel scope, but we don't use it any
> more. That display shuts off about once a minute to extend tube life.
> Nuisance.
>
> It's distributed deflection, sort of like these, but ceramic so you
> can't see inside:
>
> https://www.dropbox.com/s/evoq6p2nvzyl6wo/547_crt.JPG?dl=0
>
> https://www.dropbox.com/s/r6c3zkwlqrayt53/519_CRT.JPG?dl=0

The Tek tubes are works of art. I have a wall-mounted gharial
head fashioned as a small shelf. I've mirrored the gharial's
head shape with a Tek CRT that has had the ugly ceramic bit
chopped off.

On a sunny day (Mon, 23 Aug 2021 15:33:47 -0700 (PDT)) it happened Phil
Allison <pallison49@gmail.com> wrote in
<bc0c1351-6666-49dd-ab0d-a3ce39758bcfn@googlegroups.com>:

> jla...@highlandsniptechnology.com wrote:
>
>====================================
>>
>> It is impressive how much stuff is inside an old analog scope.
>
>** Only true of expensive ones like Tek and HP.
>
>> A cheap 100 MHz 4-channel digital scope is mostly air inside.
>
>** DSOs are chock full of SMD, with a SMPS and a flat screen.
> Not really "scopes " at all.
>
>OTOH:
>
>My 50Mhz, dual trace is a steel box 90% full of air.
>Has to be deep enough to accommodate the PDA tube = 14 inches.
>The front panel has to fit all the controls comfortably = 10 x 7 inches.
>Easy to carry in one hand and uses only 14 watts of power.
>No need for a stupid, dust clogging fan.
>
>Purchased on the 19/9/1985.
>Never out of use.

And I wonder if J.Larkin could repair his digital scopes 40 years from now,
especially after WW3 EPMs.

No parts, no chips, no displays (at least not with a compatible driver).

My CRT will work, if need be in emergency drive the deflection plates directly.
Can do analog TV too:
http://panteltje.com/panteltje/scope_tv/index.html

Jan Panteltje wrote:
=================
> >
> >> A cheap 100 MHz 4-channel digital scope is mostly air inside.
> >
> >** DSOs are chock full of SMD, with a SMPS and a flat screen.
> > Not really "scopes " at all.
> >
> >OTOH:
> >
> >My 50Mhz, dual trace is a steel box 90% full of air.
> >Has to be deep enough to accommodate the PDA tube = 14 inches.
> >The front panel has to fit all the controls comfortably = 10 x 7 inches.
> >Easy to carry in one hand and uses only 14 watts of power.
> >No need for a stupid, dust clogging fan.
> >
> >Purchased on the 19/9/1985.
> >Never out of use.
>
> And I wonder if J.Larkin could repair his digital scopes 40 years from now,
> especially after WW3 EPMs.
>
** Was that EMPs ? Take out most semis I believe.

JL's collection of Chinese DSOs are for use by his paid staff - a tiny cost compared to their wages.
They get to like it or lump it.

> My CRT will work, if need be in emergency drive the deflection plates directly.
> Can do analog TV too:
> http://panteltje.com/panteltje/scope_tv/index.html

** Did that with my home brew 3", 5 tube scope when I was 18.

Hooked up the H, V & Z inputs to suitable spots inside a 17" B&W tube TV set.
Got a quite watchable pic of a Kim Novak movie - all in green.

Lucky I did not get a serious shock in the process.

...... Phil

On a sunny day (Mon, 23 Aug 2021 23:50:51 -0700 (PDT)) it happened Phil
Allison <pallison49@gmail.com> wrote in
<0d662159-b84a-4626-a129-261382366ad9n@googlegroups.com>:

>Jan Panteltje wrote:
>=================
>> >
>> >> A cheap 100 MHz 4-channel digital scope is mostly air inside.
>> >
>> >** DSOs are chock full of SMD, with a SMPS and a flat screen.
>> > Not really "scopes " at all.
>> >
>> >OTOH:
>> >
>> >My 50Mhz, dual trace is a steel box 90% full of air.
>> >Has to be deep enough to accommodate the PDA tube = 14 inches.
>> >The front panel has to fit all the controls comfortably = 10 x 7 inches.
>> >Easy to carry in one hand and uses only 14 watts of power.
>> >No need for a stupid, dust clogging fan.
>> >
>> >Purchased on the 19/9/1985.
>> >Never out of use.
>>
>> And I wonder if J.Larkin could repair his digital scopes 40 years from now,
>> especially after WW3 EPMs.
>>
> ** Was that EMPs ? Take out most semis I believe.

Yep.

>JL's collection of Chinese DSOs are for use by his paid staff - a tiny cost compared to their wages.
>They get to like it or lump it.
>
>> My CRT will work, if need be in emergency drive the deflection plates directly.
>> Can do analog TV too:
>> http://panteltje.com/panteltje/scope_tv/index.html
>
>** Did that with my home brew 3", 5 tube scope when I was 18.
>
> Hooked up the H, V & Z inputs to suitable spots inside a 17" B&W tube TV set.
> Got a quite watchable pic of a Kim Novak movie - all in green.
>
> Lucky I did not get a serious shock in the process.

Ha, my first scope was an old round TV CRT, high voltage came from a car ignition coil
driven by a 4W audio amp that had feedback so it oscillated, rectified by some TV tube on a 1.5V battery,
And the signals on the deflection coil sitting on my bed (no space) in jail^H^H^H^H cell.. well close..
:-)
Where there is a will there is a way my father used to say.

!

Jan Panteltje wrote:
================
>
> >> My CRT will work, if need be in emergency drive the deflection plates directly.
> >> Can do analog TV too:
> >> http://panteltje.com/panteltje/scope_tv/index.html
> >
> >** Did that with my home brew 3", 5 tube scope when I was 18.
> >
> > Hooked up the H, V & Z inputs to suitable spots inside a 17" B&W tube TV set.
> > Got a quite watchable pic of a Kim Novak movie - all in green.
> >
> > Lucky I did not get a serious shock in the process.
>

-------------------------------------------------------------------------------------------------------

> Ha, my first scope was an old round TV CRT, high voltage came from a car ignition coil
> driven by a 4W audio amp that had feedback so it oscillated, rectified by some TV tube on a 1.5V battery,

** Wow !!! Maybe a 1S2 HT rectifier ?

> And the signals on the deflection coil sitting on my bed (no space) in jail^H^H^H^H cell.. well close..
> :-)

** Yep - bedroom shenanigans out of sight from parents.....

> Where there is a will there is a way my father used to say.

** Or a Lawyer.

....... Phil