Topics

Building an HV Multiplier for 455/465M


Michael W. Lynch
 

I have a 455 with a defective HV Multiplier (part of U550). The TEKTRONIX specification calls for a 1 1/2 times multiplier with a "3M Series Resistance". I have built a 1 1/2 times multiplier (that is pretty simple), but am unsure of how to properly get that 3M of series resistance? If this is a simple matter of soldering a suitable sized resistor into the Anode lead? What watt rating for the resistor? I have a 3M Ohm carbon composite resistor, but it is only 1/2 watt. I'm afraid this resistor is too small to do the job. I suppose I just do not completely understand the principals involved? How to get the right answer is the bigger question?
--
Michael Lynch
Dardanelle, Arkansas


 

It is in series with the HV lead. I have seen 1 M resistors used also. Not critical. A 1/2 watt Carbon will be fine.

Regards

On 6/16/2020 5:35 PM, Michael W. Lynch via groups.io wrote:
I have a 455 with a defective HV Multiplier (part of U550). The TEKTRONIX specification calls for a 1 1/2 times multiplier with a "3M Series Resistance". I have built a 1 1/2 times multiplier (that is pretty simple), but am unsure of how to properly get that 3M of series resistance? If this is a simple matter of soldering a suitable sized resistor into the Anode lead? What watt rating for the resistor? I have a 3M Ohm carbon composite resistor, but it is only 1/2 watt. I'm afraid this resistor is too small to do the job. I suppose I just do not completely understand the principals involved? How to get the right answer is the bigger question?
--
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Michael W. Lynch
 

Tom,

Thanks! So it seems that I was drastically overthinking the problem?

--
Michael Lynch
Dardanelle, Arkansas


Glenn Little
 

It is not the wattage as much as the voltage.
Resistors have a voltage rating.

Glenn

On 6/16/2020 5:35 PM, Michael W. Lynch via groups.io wrote:
I have a 455 with a defective HV Multiplier (part of U550). The TEKTRONIX specification calls for a 1 1/2 times multiplier with a "3M Series Resistance". I have built a 1 1/2 times multiplier (that is pretty simple), but am unsure of how to properly get that 3M of series resistance? If this is a simple matter of soldering a suitable sized resistor into the Anode lead? What watt rating for the resistor? I have a 3M Ohm carbon composite resistor, but it is only 1/2 watt. I'm afraid this resistor is too small to do the job. I suppose I just do not completely understand the principals involved? How to get the right answer is the bigger question?
--
-----------------------------------------------------------------------
Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIV wb4uiv@... AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI LM NRA LM SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"


Chuck Harris
 

That is true, but in this case, normal operation isn't going
to have enough current to present a significant voltage across
the resistor. It is going to be the same voltage on each end,
floating on top of a whole lot of KV.

The resistor's purpose is manifold:

1) it limits the current that could affect a subject that
comes across the power supply with charged capacitors.
2) it limits the current charging the CRT's anode capacitance
3) it adds an R component to the inherent RC filter created by
the anode capacitance.. reducing any flicker induced by the
supply's ripple.

#1 is probably the most important reason for its being.

-Chuck Harris


Glenn Little wrote:

It is not the wattage as much as the voltage.
Resistors have a voltage rating.

Glenn

On 6/16/2020 5:35 PM, Michael W. Lynch via groups.io wrote:
I have a 455 with a defective HV Multiplier (part of U550).  The TEKTRONIX
specification calls for a 1 1/2 times multiplier with a "3M Series Resistance".   I
have built a 1 1/2 times multiplier (that is pretty simple), but am unsure of how
to properly get that 3M of series resistance?  If this is a simple matter of
soldering a suitable sized resistor into the Anode lead?  What watt rating for the
resistor?  I have a 3M Ohm carbon composite resistor, but it is only 1/2 watt.  I'm
afraid this resistor is too small to do the job.  I suppose I just do not
completely understand the principals involved?   How to get the right answer is the
bigger question?


 

It also limits the short circuit current through the diodes in the event the HV lead comes to ground.

On 6/16/2020 11:04 PM, Chuck Harris wrote:
That is true, but in this case, normal operation isn't going
to have enough current to present a significant voltage across
the resistor. It is going to be the same voltage on each end,
floating on top of a whole lot of KV.

The resistor's purpose is manifold:

1) it limits the current that could affect a subject that
comes across the power supply with charged capacitors.
2) it limits the current charging the CRT's anode capacitance
3) it adds an R component to the inherent RC filter created by
the anode capacitance.. reducing any flicker induced by the
supply's ripple.

#1 is probably the most important reason for its being.

-Chuck Harris


Glenn Little wrote:
It is not the wattage as much as the voltage.
Resistors have a voltage rating.

Glenn

On 6/16/2020 5:35 PM, Michael W. Lynch via groups.io wrote:
I have a 455 with a defective HV Multiplier (part of U550).  The TEKTRONIX
specification calls for a 1 1/2 times multiplier with a "3M Series Resistance".   I
have built a 1 1/2 times multiplier (that is pretty simple), but am unsure of how
to properly get that 3M of series resistance?  If this is a simple matter of
soldering a suitable sized resistor into the Anode lead?  What watt rating for the
resistor?  I have a 3M Ohm carbon composite resistor, but it is only 1/2 watt.  I'm
afraid this resistor is too small to do the job.  I suppose I just do not
completely understand the principals involved?   How to get the right answer is the
bigger question?
--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus


Reed Dickinson
 

Hi Tom:
I have a large collection of 4XX series scopes and some have been used for parts.  I have a collection of 3X HV voltage multipliers and I would offer you a known good one for $25 plus shipping.  Or, I would sell you a good 465 or 465B for $100.  I do not have any 455 scopes but the multiplier is the same for the 455 and 465.
Reed Dickinson1705 Stonehenge DriveTustin, CA  92780
reed714@...

On Tuesday, June 16, 2020, 08:57:11 PM PDT, Tom Miller <@tmiller> wrote:

It also limits the short circuit current through the diodes in the event
the HV lead comes to ground.


On 6/16/2020 11:04 PM, Chuck Harris wrote:
That is true, but in this case,  normal operation isn't going
to have enough current to present a significant voltage across
the resistor.  It is going to be the same voltage on each end,
floating on top of a whole lot of KV.

The resistor's purpose is manifold:

1) it limits the current that could affect a subject that
    comes across the power supply with charged capacitors.
2) it limits the current charging the CRT's anode capacitance
3) it adds an R component to the inherent RC filter created by
    the anode capacitance.. reducing any flicker induced by the
    supply's ripple.

#1 is probably the most important reason for its being.

-Chuck Harris


Glenn Little wrote:
It is not the wattage as much as the voltage.
Resistors have a voltage rating.

Glenn

On 6/16/2020 5:35 PM, Michael W. Lynch via groups.io wrote:
I have a 455 with a defective HV Multiplier (part of U550).  The TEKTRONIX
specification calls for a 1 1/2 times multiplier with a "3M Series Resistance".   I
have built a 1 1/2 times multiplier (that is pretty simple), but am unsure of how
to properly get that 3M of series resistance?  If this is a simple matter of
soldering a suitable sized resistor into the Anode lead?  What watt rating for the
resistor?  I have a 3M Ohm carbon composite resistor, but it is only 1/2 watt.  I'm
afraid this resistor is too small to do the job.  I suppose I just do not
completely understand the principals involved?   How to get the right answer is the
bigger question?
--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus


n4buq
 

Is it the same for a 465M as for a 465/465B? I'm thinking they're different but not sure.

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "Reed Dickinson" <reed714@...>
To: TekScopes@groups.io
Sent: Wednesday, June 17, 2020 1:33:37 AM
Subject: Re: [TekScopes] Building an HV Multiplier for 455/465M

Hi Tom:
I have a large collection of 4XX series scopes and some have been used for
parts.  I have a collection of 3X HV voltage multipliers and I would offer
you a known good one for $25 plus shipping.  Or, I would sell you a good 465
or 465B for $100.  I do not have any 455 scopes but the multiplier is the
same for the 455 and 465.
Reed Dickinson1705 Stonehenge DriveTustin, CA  92780
reed714@...


On Tuesday, June 16, 2020, 08:57:11 PM PDT, Tom Miller
<@tmiller> wrote:

It also limits the short circuit current through the diodes in the event
the HV lead comes to ground.


On 6/16/2020 11:04 PM, Chuck Harris wrote:
That is true, but in this case,  normal operation isn't going
to have enough current to present a significant voltage across
the resistor.  It is going to be the same voltage on each end,
floating on top of a whole lot of KV.

The resistor's purpose is manifold:

1) it limits the current that could affect a subject that
    comes across the power supply with charged capacitors.
2) it limits the current charging the CRT's anode capacitance
3) it adds an R component to the inherent RC filter created by
    the anode capacitance.. reducing any flicker induced by the
    supply's ripple.

#1 is probably the most important reason for its being.

-Chuck Harris


Glenn Little wrote:
It is not the wattage as much as the voltage.
Resistors have a voltage rating.

Glenn

On 6/16/2020 5:35 PM, Michael W. Lynch via groups.io wrote:
I have a 455 with a defective HV Multiplier (part of U550).  The
TEKTRONIX
specification calls for a 1 1/2 times multiplier with a "3M Series
Resistance".   I
have built a 1 1/2 times multiplier (that is pretty simple), but am
unsure of how
to properly get that 3M of series resistance?  If this is a simple matter
of
soldering a suitable sized resistor into the Anode lead?  What watt
rating for the
resistor?  I have a 3M Ohm carbon composite resistor, but it is only 1/2
watt.  I'm
afraid this resistor is too small to do the job.  I suppose I just do not
completely understand the principals involved?   How to get the right
answer is the
bigger question?
--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus








ArtekManuals
 

The 455/465M use a 3X multiplier but there is no HV output level listed on the schematic or in the circuit description section ( odd)

The 465 Uses a different multiplier but no listing of the multiplier factor on the schematic ...8^(

The 465B uses yet ANOTHER multiplier module than the 455 and the 465 and again no multiplier factor listed on the schematic..

Both the 465 and the 465B have an CRT HV of 14-16KV

Content free data

Dave
manuals@...

On 6/17/2020 9:27 AM, n4buq wrote:
Is it the same for a 465M as for a 465/465B? I'm thinking they're different but not sure.

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "Reed Dickinson" <reed714@...>
To: TekScopes@groups.io
Sent: Wednesday, June 17, 2020 1:33:37 AM
Subject: Re: [TekScopes] Building an HV Multiplier for 455/465M

Hi Tom:
I have a large collection of 4XX series scopes and some have been used for
parts.  I have a collection of 3X HV voltage multipliers and I would offer
you a known good one for $25 plus shipping.  Or, I would sell you a good 465
or 465B for $100.  I do not have any 455 scopes but the multiplier is the
same for the 455 and 465.
Reed Dickinson1705 Stonehenge DriveTustin, CA  92780
reed714@...


On Tuesday, June 16, 2020, 08:57:11 PM PDT, Tom Miller
<@tmiller> wrote:

It also limits the short circuit current through the diodes in the event
the HV lead comes to ground.


On 6/16/2020 11:04 PM, Chuck Harris wrote:
That is true, but in this case,  normal operation isn't going
to have enough current to present a significant voltage across
the resistor.  It is going to be the same voltage on each end,
floating on top of a whole lot of KV.

The resistor's purpose is manifold:

1) it limits the current that could affect a subject that
    comes across the power supply with charged capacitors.
2) it limits the current charging the CRT's anode capacitance
3) it adds an R component to the inherent RC filter created by
    the anode capacitance.. reducing any flicker induced by the
    supply's ripple.

#1 is probably the most important reason for its being.

-Chuck Harris


Glenn Little wrote:
It is not the wattage as much as the voltage.
Resistors have a voltage rating.

Glenn

On 6/16/2020 5:35 PM, Michael W. Lynch via groups.io wrote:
I have a 455 with a defective HV Multiplier (part of U550).  The
TEKTRONIX
specification calls for a 1 1/2 times multiplier with a "3M Series
Resistance".   I
have built a 1 1/2 times multiplier (that is pretty simple), but am
unsure of how
to properly get that 3M of series resistance?  If this is a simple matter
of
soldering a suitable sized resistor into the Anode lead?  What watt
rating for the
resistor?  I have a 3M Ohm carbon composite resistor, but it is only 1/2
watt.  I'm
afraid this resistor is too small to do the job.  I suppose I just do not
completely understand the principals involved?   How to get the right
answer is the
bigger question?
--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus







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


Michael W. Lynch
 

Is it the same for a 465M as for a 465/465B? I'm thinking they're different but not sure.
Thanks,
Barry - N4BUQ
Barry,

You are correct, they are not the same as the 465/465B. The 455/465M was endowed with a unique HV Module that includes a 1 1/2x multiplier plus DC restorer and other circuitry inside that single module. The 465/465B obviously does not include that additional circuitry.

So installing the 465/465B module as a "piggy back" to the original module does not work either, as it would provide too much Anode voltage.

Mult. Fact. Input Output series resistance
455/465M uses 152-0635-00 1.5 6.7kV 10kV 3.0MOhms
465/465B uses 152-0552-00 (and others as well) 3.0 5kV 15kV 510.0kOHms
--
Michael Lynch
Dardanelle, Arkansas


Michael W. Lynch
 

Dave,

The Schematics are not always the best source for critical information on these modules. Take a look at the Yellow Cover TEK Cross reference manual on page 281, you can find the unique specs to each device, by part number. This is in addition to the specs that can be gleaned from the schematics and the service manuals.

455/465M uses 152-0635-00 CRT uses 12kV acceleration potential

465/465B uses 152-0552-00 or 152-0552-01 (and others as well) CRT uses 15-16kV acceleration potential.

These parts have unique and completely different specifications. I am sure that TEK felt that the module in the 455/465M was a better solution and probably saves time and $$ in production. They just made it more difficult for us guys, working on this stuff 40-50 years later.

I have built and tested a 1 1/2 multiplier and attached it "piggy back" and dead bug style at this point. Now to print an enclosure, pot the parts and mount it.

I still would like to find an original working module, but the solution above will work for now.

Thanks!

--
Michael Lynch
Dardanelle, Arkansas


n4buq
 

I was fortunate in that when mine went bad, Sphere had a used one that worked. I don't see any stock for those now.

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "Michael W. Lynch via groups.io" <mlynch003=yahoo.com@groups.io>
To: TekScopes@groups.io
Sent: Wednesday, June 17, 2020 9:03:58 AM
Subject: Re: [TekScopes] Building an HV Multiplier for 455/465M

Dave,

The Schematics are not always the best source for critical information on
these modules. Take a look at the Yellow Cover TEK Cross reference manual
on page 281, you can find the unique specs to each device, by part number.
This is in addition to the specs that can be gleaned from the schematics
and the service manuals.

455/465M uses 152-0635-00 CRT uses 12kV acceleration potential

465/465B uses 152-0552-00 or 152-0552-01 (and others as well) CRT uses
15-16kV acceleration potential.

These parts have unique and completely different specifications. I am sure
that TEK felt that the module in the 455/465M was a better solution and
probably saves time and $$ in production. They just made it more difficult
for us guys, working on this stuff 40-50 years later.

I have built and tested a 1 1/2 multiplier and attached it "piggy back" and
dead bug style at this point. Now to print an enclosure, pot the parts and
mount it.

I still would like to find an original working module, but the solution above
will work for now.

Thanks!

--
Michael Lynch
Dardanelle, Arkansas




Bert Haskins
 

On 6/17/2020 10:03 AM, Michael W. Lynch via groups.io wrote:
Dave,

The Schematics are not always the best source for critical information on these modules. Take a look at the Yellow Cover TEK Cross reference manual on page 281, you can find the unique specs to each device, by part number. This is in addition to the specs that can be gleaned from the schematics and the service manuals.

455/465M uses 152-0635-00 CRT uses 12kV acceleration potential

465/465B uses 152-0552-00 or 152-0552-01 (and others as well) CRT uses 15-16kV acceleration potential.

These parts have unique and completely different specifications. I am sure that TEK felt that the module in the 455/465M was a better solution and probably saves time and $$ in production. They just made it more difficult for us guys, working on this stuff 40-50 years later.

I have built and tested a 1 1/2 multiplier and attached it "piggy back" and dead bug style at this point. Now to print an enclosure, pot the parts and mount it.

I still would like to find an original working module, but the solution above will work for now.

Thanks!
Michael, are you in the US?