Date   

Re: TEK 453 Vert Amp - not 453A

Mark Wendt <mark.wendt@...>
 

Tom,

I'm probably being really dense, but which line are you saying should be dashed? I'm seeing five of those demarks around components Q84 and the R75 pot that look like they are tying those circuit traces together. Should those be little "hoops" that show a crossing but not connection point? If so, then the ground point in this instance wouldn't make a whole lot of sense showing where it is the schematic.

On 05/20/2013 08:28 AM, Tom Miller wrote:
That line should have been dashed. Print it out and trace over it with a red
pencil and it will make a lot more sense.

If you put the whole schematic together, you can follow the line completely
around the circuit. It is there to identify all the board mounted parts.

I have seen it done the same on a few other Tek manuals.

Tom


Tek 7000 Series deflection plate precision?

 

Hi guys,
could someone chime in on how precise the deflection in a Tek 7000 can be?

I'm very new to vacuum tubes and the idea of electrostatic deflection,
so please bear with any stupid questions...

My main consideration is: with modifications, would it be suitable to
jury rig an SEM (Scanning Electron Microscope)?

I am trying to do something inspired by Ben Krasnow's SEM design. If
you don't know it, he has some info here on how he made an SEM
himself:

http://benkrasnow.blogspot.de/2011/03/diy-scanning-electron-microscope.html
http://benkrasnow.blogspot.de/2011/03/diy-scanning-electron-microscope_26.html

He made the raster generator and deflection assembly and amplifiers
himself. It was my idea to use a broken 7000 series tube and hook it
up to a working 7000 scope configured with two time bases in a raster
generator setup. Of course I'd need a Tungsten filament, the one in
the 7000 CRT would be broken by having been exposed to air.

What happens in an SEM is that the electron beam *scans* a rectangular
area on the thing you're zooming in on. It moves in a raster image,
just like on a TV, or an oscilloscope in raster config. This rectangle
has to be very small, let's say 2mm across. You'd start out with a
fairly big rectangle, say 2x2 cm, to see the overall shape of the
object, then you zoom in a bit so that the rectangle is 1x1cm and pan
a little, then zoom and pan again, and so on. Think CSI: Miami
("enhance"). You might end up with a square of 2mm or even smaller.


Here's my question: the deflection needs to be precise, so e.g. if
you're horizontally 5% of the way, it still needs to be this far
across, and not erratically in some other place.

It would be bad if it e.g. jumped from 0% to 10% to 20% and so on to
100% while skipping the intermediates.

It would also be bad if it e.g. centered around that 5%, but noise and
interference meant the beam would randomly err between 1% and 9% with
5% at its center.

The rectangle as a whole needs to be moved at least in this area of
1cm or 2cm as well. It would be fairly bad if the rectangle as a whole
drifted or if the position were shaky.

How would one modify the deflection circuitry and assembly in a Tek
7000 to achieve such a small scan area? Is the circuitry going to be
low-noise and/or linear enough so that deflection precision is
retained?

How *wide* across can the electron beam be?

Thanks,
Damian


Re: TEK 453 Vert Amp - not 453A

 

That line should have been dashed. Print it out and trace over it with a red pencil and it will make a lot more sense.

If you put the whole schematic together, you can follow the line completely around the circuit. It is there to identify all the board mounted parts.

I have seen it done the same on a few other Tek manuals.

Tom

----- Original Message -----
From: "Mark Wendt" <mark.wendt@nrl.navy.mil>
To: <TekScopes@yahoogroups.com>
Sent: Monday, May 20, 2013 5:49 AM
Subject: Re: [TekScopes] TEK 453 Vert Amp - not 453A


On 05/19/2013 02:21 PM, Tom Miller wrote:


That line is the demark for the parts on the PC board. The black dot
or the circle is a wire or pin that connects to a part not located on
the PC board. I.e. a chassis mounted control.
Tom
Still doesn't seem to make much sense though. Following the circuit
back from the base of Q84, you hit the first of those "demarks", which
looks like it ties the base of Q84 to R61 and R71, then it goes to
ground (shown off one end of R76). Thinking that ground symbol might be
there by mistake.

Mark


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

Yahoo! Groups Links



Re: Anyone have experience shipping to France?

Craig Sawyers <c.sawyers@...>
 

UK and Ireland are a disappointment as
many packages get lost or returned --
I've bought hundreds of things from the US, and only had a single screw up
in the UK when a large box was returned to the US. Parcel Force refunded
all shipping and re-shipping charges.

If something is sent via USPS it always comes into the UK via Parcel Force.
They clear the parcel through customs, and let you know so that you can pay
the tax. They then try to deliver three times, leaving a post card each
time. They then retain the parcel for a further 16 calendar days before
returning to the sender.

So they return to sender about three weeks after they get the parcel from
Customs, so probably about five weeks after it was shipped.

Their claim for loss, damage or other cause is here
http://www.parcelforce.com/help-information/frequently-asked-questions/claim
-compensation . I've only had to claim twice in 20 years - one for the box
returned to the US, and once for a Tormek wet grinding machine (a sizable
and rugged machine) for sharpening chisels and plane irons etc. That as
only coming a hundred miles or so, and it looked like it has been run over
with a truck (even the 12 mm drive shaft was bent). Total claim was for
over £400, which they paid without protest. I've never had anything lost
coming in.

Craig


Re: Anyone have experience shipping to France?

Don Black <donald_black@...>
 

I'm waiting for some connectors sent from the US to Australia on the 3rd May, I expect them any day. I've had good service getting items from the US via the post office, usually it's about 1 week, sent by the most economical rate. I did buy a book from Amazon and selected their cheapest rate which was supposed to be by surface mail, expected time 2 months or so. I was delighted when it arrived within a fortnight.

Don Black.

On 20-May-13 9:18 PM, Mike wrote:
 

US postal service Priority mail is the only economical option that I have found for international shipping. I haven't had significant issues mailing stuff across the pond, once I figured out some basic stuff.

1) I list actual value on Customs form. Receiver of package will have to pay duty. What do they say about Taxes and Death.
2) Put an invoice inside the package.
3) Be patient - 2 weeks minimum - 3 or 4 weeks wouldn't be surprising.

regards,
Mike W.

--- In TekScopes@..., "Dennis Tillman" wrote:
>
> I sent something valuable to a buyer in France.
>
> When I mailed it I was told it could not be insured for more than $100 (due
> to some French regulation) if sent by the US Post Office.
>
> As an alternative I chose to require a signature so that I would know it was
> delivered safely. That also means the USPS tracks the package.
>
> Although it was not a big or heavy package the shipping charges still came
> to about $100.
>
>
>
> The USPS tracking kept me informed as the package moved into French Customs
> and then as it was handed off from customs into the French Postal System.
> That was on May 6th. The buyer still has not received the package and is
> getting worried.
>
>
>
> Yesterday I received this notice from the USPS:
>
> In response to your request dated May 14, 2013, we regret to inform you that
> we were
>
> unable to locate any delivery information in our records regarding your item
> number.
>
>
>
> Does anyone have any suggestions on what is going on or what I can do to
> find out what happened to the package?
>
>
>
> Dennis
>



Re: Anyone have experience shipping to France?

Mike
 

US postal service Priority mail is the only economical option that I have found for international shipping. I haven't had significant issues mailing stuff across the pond, once I figured out some basic stuff.

1) I list actual value on Customs form. Receiver of package will have to pay duty. What do they say about Taxes and Death.
2) Put an invoice inside the package.
3) Be patient - 2 weeks minimum - 3 or 4 weeks wouldn't be surprising.

regards,
Mike W.

--- In TekScopes@yahoogroups.com, "Dennis Tillman" <dennis@...> wrote:

I sent something valuable to a buyer in France.

When I mailed it I was told it could not be insured for more than $100 (due
to some French regulation) if sent by the US Post Office.

As an alternative I chose to require a signature so that I would know it was
delivered safely. That also means the USPS tracks the package.

Although it was not a big or heavy package the shipping charges still came
to about $100.



The USPS tracking kept me informed as the package moved into French Customs
and then as it was handed off from customs into the French Postal System.
That was on May 6th. The buyer still has not received the package and is
getting worried.



Yesterday I received this notice from the USPS:

In response to your request dated May 14, 2013, we regret to inform you that
we were

unable to locate any delivery information in our records regarding your item
number.



Does anyone have any suggestions on what is going on or what I can do to
find out what happened to the package?



Dennis


Re: Anyone have experience shipping to France?

caveteursus
 

I shipped amplifier kits and parts to Europe and find France, Norway, Denmark, Sweden and Holland to be among the best, next is Spain. For Germany, routine shipments of components, whether shipped to an individual or company, always seem to get held up in customs. Italy, despite the horror stories, seems to be OK. UK and Ireland are a disappointment as many packages get lost or returned --

--- In TekScopes@yahoogroups.com, Druid Noibn <druid_noibn@...> wrote:

Hi
 
Just curious, thanks.  I keep hearing stories about the uncooperative postal folks in the UK, France and Italy.
 
Be well and best of luck to all,
DBN

--- On Sun, 5/19/13, Craig Sawyers <c.sawyers@...> wrote:


From: Craig Sawyers <c.sawyers@...>
Subject: RE: [TekScopes] Anyone have experience shipping to France?
To: TekScopes@yahoogroups.com
Date: Sunday, May 19, 2013, 8:32 PM



 





I think I probably used Parcel Farce.
 
Craig
 

 





Hi,

 

Did you use the postal system or courier service?

 

Be well,

DBN


 


Re: 576 curve trace scope problem

Dave / NR1DX
 

Better yet scan a copy and post it to KO4BB.com

Dave
ArtekManuals.com
On 5/20/2013 12:38 AM, drawding@... wrote:
 

Chuck,

Per your response below, it appears that you have access to the 576 HV transformer winding sheet. Would you be kind enough to send me a copy or let me know where you got it?

Thank you,
Dave

--- In TekScopes@..., Chuck Harris wrote:
>
> I can do precise weights without problem, but I am somewhat concerned about
> how the silicone resin handles exposure to the air. I read that it has a
> definite shelf life, and that it gets much shorter after opening the can.
>
> I am game to try it, though.
>
> The other issue relative to the silicone RTV potting compound is whether it
> is thin enough to penetrate the windings. In the 561 transformer, tek used
> an epoxy varnish to impregnate the windings, and then potted the transformer
> in an aluminum can filled with clear RTV silicone rubber. The 576 winding
> sheet only says silicone resin and gives the part numbers:
>
> 252-0203-00 and 252-0214-00
>
> Anyone know what the commercial equivalent silicone resin is?
>
> I cannot imagine that beeswax transformers would have any problem at all in the
> 576. It is all solid state, and there is plenty of room for ventilation in
> the EHT compartment. Tek switched from beeswax to epoxy when they modularized
> the HV section... prior to that they used either beeswax, or mineral oil. I think
> the issue, mostly, is whether a beeswax transformer would be well received by
> 576 owners...
>
> -Chuck Harris
>
> Bob Koller wrote:
> > I have used the two component silicones as far back as the mid-'70's.. The mix is
> > by weight (or was then), and small volume was not a problem. I think the silicone
> > is preferable to prevent corona. Weren't most of the beeswax impregnated
> > transformers enclosed in a clear plastic case? I foe one, wouldn't care as long as
> > it works right.
> >
> >
> >
> >
> >
> > ________________________________ From: Chuck Harris To:
> > TekScopes@... Sent: Tuesday, August 2, 2011 5:23 AM Subject: Re:
> > [TekScopes] 576 curve trace scope problem
> >
> >
> >
> > The biggest issue for me, with winding 576 transformers, is the potting. If I am
> > to do the replacements with a nice modern 2 part silicone RTV compound, that will
> > raise the price somewhat... The 2 part RTV's are designed to only be used in full
> > can quantities, and that means potting 10 to 20 coils at a time, with the
> > attending need for a 10 to 20 molds, and a way to process 10 to 20 molds in the
> > vacuum chamber at a time.
> >
> > The problem can be lessened if the 2 part RTV's can be safely and reliably used in
> > smaller quantities... without jeopardizing the quality of the resulting product.
> >
> > Beeswax and paraffin are much less expensive in all respects, but would not make
> > an identical transformer.... assuming that anyone cares.
> >
> > -Chuck Harris
> >
> > tom jobe wrote:
> >> Hi Bob, Do you have any idea what color the later (good?) 576 HV transformer
> >> potting might be? Or what S/N's might be effected? The 576 is such a wonderful
> >> machine, it would be absolutely criminal to have to "part one out" for the lack
> >> of an important part such as the HV transformer. tom jobe...
> >>
> >>
> >>
> >>
> >> ----- Original Message ----- From: "Bob Koller"
> >> To:<TekScopes@...> Sent: Monday, August 01, 2011 2:56 PM Subject:
> >> Re: [TekScopes] 576 curve trace scope problem
> >>
> >>
> >> Pull the cover off the HV section. If the transformer has brown potting, that is
> >> almost certainly the culprit. Common on the older s/n's. Chuck Harris and I
> >> discussed rebuilding these, and I provided the winding details to him, but have
> >> I not pursued it further. Finding an original replacement can be quite
> >> difficult..
> >
> >
>


-- 
Dave Henderson
Manuals@...
www.Artekmanuals.com
PO Box 175
Welch,MN 55089
651-269-4265


Re: TEK 453 Vert Amp - not 453A

Mark Wendt <mark.wendt@...>
 

On 05/19/2013 02:21 PM, Tom Miller wrote:


That line is the demark for the parts on the PC board. The black dot or the circle is a wire or pin that connects to a part not located on the PC board. I.e. a chassis mounted control.
Tom
Still doesn't seem to make much sense though. Following the circuit back from the base of Q84, you hit the first of those "demarks", which looks like it ties the base of Q84 to R61 and R71, then it goes to ground (shown off one end of R76). Thinking that ground symbol might be there by mistake.

Mark


Re: Anyone have experience shipping to France

 

I am shocked. I thought that the Europeans were advanced, but these stories are ridiculous.

In Israel, I use the Post Office for import and export, and it has always been a trouble-free experience and a pleasure. At Customs, nothing is opened, unless the receiver is present, so the chance of pilferage is basically zero.
This is probably due to the high security issues we have here.
Obviously all documents have to be shipshape, which only speeds the processing.

HOWEVER, do your Israeli customer a favor, and DO NOT ship to Israel by EMS, Global Express, or any kind of Express Mail. That's handled not by the Israel Post Office, but by a "co^^upt" subcontractor, which charges exorbitant random commissions to process the goods.

Menahem


Anyone have experience shipping to France

Alessandro Cattaneo
 

Hi,
about the Italian post, I am a fan of Tektronix and U.S.A. and I bought more than 180 between oscilloscopes and replacement parts in the U.S.A., never lost anything and everything arrived in excellent condition (even heavy packs more than 25 Kgr, Tek R7103! ), the Italian post office have changed in recent years.
I believe there is still some office that does not work well but it is wrong to insist that the Italian post office are a mess.
Packages shipped with USPS Priority Mail InternationalTM, arrive in about 8 days, and customs are fast.
I hope this my outburst  serves to re-evaluate the Italian post office and Italy (not everything you read in the papers correspond to the reality of my country),there are many differences between town and town.
Best regards.


Re: Anyone have experience shipping to France?

PA4TIM
 

I'm in Holland, we have the same customs bullshit. A friend sended me a package from the states. It was for free but he insured it for 100 dollars. It took 2 weeks to arrive, the box looked like somebody played football with it and the customs charged 19 euro based on the insured value. Bought a GR bridge, same story with time and taxes.
Later I ordered a LCR meter from IET in th US and asked if they could not mention a value or so on the box but something like "defect, no value, only for parts" They made a fake invoice that stated something like "samples, not for resale" on it, sended it by fedex and it arrived in a few days without problems. They gave a track and trace and stated the expected date and time and fedex deliverred it 2 hours and undammaged before the stated time. That was a very good experience. 

I often buy goods for resale from France and Italy for my business but shipping itself was not often a problem.  French shipping itself seems to go well. The shipper from Lafuma always phones first ( in broken English :-) ) if we have space for a x meter truck, and when the truck is expected to arrive ) The firms however.....Italian firms them self can often be a disaster, they never seem to keep their word, change prices and mess up orders, the problem is they often say that is not true, they just lie. French firms often mean well but allways seem to make a mess out of it anyhow. But they stay honnest, appolegies and trie to correct things ( that often makes even a bigger mess out of things) We bought glasses about 8 years from CeBe and I never received 1 order that was correct. Like they collect orders in their warehouse for several custommers and then random put the adress labels on the boxes.

The worst case took me 2 years, about 3 monthd before finally the more or less the right goods arrived ( but at that time I had a lot of things in twice the number of ordered items, a lot of things not ordered ( and with papers for other customers) and some goods still missing while billed) the rest of the time took it to get the right bill and at the end, after 2 years not paying, I was asked if I could make the bill myself because they did not know what they had delivered :-( (Took me many hours) 

But probably you hope to hear all is great over there. In your case I think it could be customs, holydays ect. Think 3 to 4 weeks around this time of the year could be possible.


Fred PA4TIM

Op 20 mei 2013 om 02:19 heeft Druid Noibn <druid_noibn@...> het volgende geschreven:

 

Hi Jerry,
 
Never had the pleasure, but from the words of many, that is sage advice.
 
When dealing with Italy, our colleagues in France made the arrangements and it rarely went smoothly and that includes on a corporate level.  Again, that is all hearsay on my part. 
 
Be well,
DBN
 


--- On Sun, 5/19/13, jerry massengale <j_massengale@...> wrote:

From: jerry massengale <j_massengale@...>
Subject: Re: [TekScopes] Anyone have experience shipping to France?
To: TekScopes@...
Date: Sunday, May 19, 2013, 8:15 PM

 
Don't even think about shipping to Italy without insurance.


Jerry Massengale



-----Original Message-----
From: Craig Sawyers <c.sawyers@...>
To: TekScopes <TekScopes@...>
Sent: Sun, May 19, 2013 7:09 pm
Subject: RE: [TekScopes] Anyone have experience shipping to France?

 
Shipping to France from the UK was disastrous. I sent a storage scope to a guy who bought it off eBay. First it did not arrive - because of the local service nonsense. Then when the guy was home one day, it turned up. It was such a mess when it arrived that he accused me of selling one item and shipping another. Took high resolution images of the front panel (eBay limit resolution) showing the serial number before the guy was convinced.

Never ever again to France. An accident waiting to happen, regardless of how well it is packed.

Craig


Re: Are deflection plates separate from the tube? Do Tek tubes use w

adrianwebber1
 

CSIRAC is not in working condition.  Is static display only, with
original parts as it was when decommissioned c.1964.  Oldest
working computer in world AFAIK is the 1956 Pegasus in the UK.


schematic for 321A FET-Frontend

mattko87
 

Hello all old shool friends

FET Frontend in 321A is Orginal!
I am looking for Kurt/tekwiki and me.

Thanks
Matt


Re: 2465B Source code..

victor.silva
 

At a minimum the ON/OFF counter would be incremented.

--Victor

--- In TekScopes@yahoogroups.com, "lazystrings" <casinada@...> wrote:

When I was repairing my 2465B DM I had to program the DS1225AD a few times and each time I plugged in the scope and back into the programmer something changed. I haven't tried to compare it again since I repaired the A5 board. I'm still calibrating the scope.....

--- In TekScopes@yahoogroups.com, "macgregor54" <fauxscot@> wrote:

thanks, lazystrings...

(turns out my new acquaintance is already a member here. this suggests to me that this isn't the best route to locate the SC, but it's my first stop usually on any tek quest.)

your idea is a good one, and i've employed it before. tedious, but it works.

this is also wonderful logic analyzer territory. in conjunction with the cal program, monitoring the NVRAM chip for write activity when any cal factor is committed should show the selected addresses and data. It's not likely that after bootup of the scope that the NVRAM is accessed that much, so writes to it would be infrequent unless you were calibrating. it would take 24 channels and some clock inputs or qualifiers, but that's exactly the kind of thing that logic analyzers are for. they're pretty cheap these days, too, and only a slow one is needed for something like a 6802. so that's a solution, too and not quite so tedious.

thanks for the input!

are any old tek employees from the scope division on the board from the 2465 era that you know of? i haven't been on the group for a long time (everything i have sort of works for the moment.)








--- In TekScopes@yahoogroups.com, "lazystrings" <casinada@> wrote:

You can probably find that using an Eprom programmer reading the contents of the DS1225Y and then go to the calibration routines but perform each CAL individually and see what changes in memory. I don't know if is possible to read the contents of the RAM using the GPIB if you have the option. Lots of things are stored in that RAM and they change each time you turn the Scope on.
You can also read the contents of the Eprom U2360 on the A5 board and disassemble the code. I think that the processor U2140 is a 68A02. That could be a fun project :)

--- In TekScopes@yahoogroups.com, "macgregor54" <fauxscot@> wrote:

Hi folks....

I made an acquaintance from across the pond who is looking to hack his 2465B cal setting so as to avoid having to do the entire calibration routine.

i have managed to obtain actual source code for 2600 series personal Fourier analyzers and I was wondering if anyone here has it for the 2465b? I know it's a long shot, but I managed to get the 2600 code after a multi-year search once i found some principal engineers, and i was hoping to find someone here who perhaps worked on the product line, or who had a map of the cal NVRAM contents.

What say you, wizards of Tek-ness? Any 2465B gurus, former Tekkies, gifted hackers, etc. in the group? I think this is one of their abandoned products, and it would unlikely involve any copyright issues, if that's a concern.

All leads much appreciated.


Re: 576 curve trace scope problem

Chuck Harris <cfharris@...>
 

Hi Dave,

Here is the 576 transformer winding sheet.

The biggest thing that keeps me from volunteering to
wind you a transformer using my manual machine is the
1400T of #40AWG wire. It is bad enough winding 733T
#38.

Don't even think about trying to wind this with level
winding. #40AWG can take even less voltage T-T than
#38. It will arc over.

-Chuck

drawding@pacbell.net wrote:

Chuck,

Per your response below, it appears that you have access to the 576 HV transformer winding sheet. Would you be kind enough to send me a copy or let me know where you got it?

Thank you,
Dave

--- In TekScopes@yahoogroups.com, Chuck Harris <cfharris@...> wrote:

I can do precise weights without problem, but I am somewhat concerned about
how the silicone resin handles exposure to the air. I read that it has a
definite shelf life, and that it gets much shorter after opening the can.

I am game to try it, though.

The other issue relative to the silicone RTV potting compound is whether it
is thin enough to penetrate the windings. In the 561 transformer, tek used
an epoxy varnish to impregnate the windings, and then potted the transformer
in an aluminum can filled with clear RTV silicone rubber. The 576 winding
sheet only says silicone resin and gives the part numbers:

252-0203-00 and 252-0214-00

Anyone know what the commercial equivalent silicone resin is?

I cannot imagine that beeswax transformers would have any problem at all in the
576. It is all solid state, and there is plenty of room for ventilation in
the EHT compartment. Tek switched from beeswax to epoxy when they modularized
the HV section... prior to that they used either beeswax, or mineral oil. I think
the issue, mostly, is whether a beeswax transformer would be well received by
576 owners...

-Chuck Harris

Bob Koller wrote:
I have used the two component silicones as far back as the mid-'70's.. The mix is
by weight (or was then), and small volume was not a problem. I think the silicone
is preferable to prevent corona. Weren't most of the beeswax impregnated
transformers enclosed in a clear plastic case? I foe one, wouldn't care as long as
it works right.





________________________________ From: Chuck Harris<cfharris@...> To:
TekScopes@yahoogroups.com Sent: Tuesday, August 2, 2011 5:23 AM Subject: Re:
[TekScopes] 576 curve trace scope problem



The biggest issue for me, with winding 576 transformers, is the potting. If I am
to do the replacements with a nice modern 2 part silicone RTV compound, that will
raise the price somewhat... The 2 part RTV's are designed to only be used in full
can quantities, and that means potting 10 to 20 coils at a time, with the
attending need for a 10 to 20 molds, and a way to process 10 to 20 molds in the
vacuum chamber at a time.

The problem can be lessened if the 2 part RTV's can be safely and reliably used in
smaller quantities... without jeopardizing the quality of the resulting product.

Beeswax and paraffin are much less expensive in all respects, but would not make
an identical transformer.... assuming that anyone cares.

-Chuck Harris

tom jobe wrote:
Hi Bob, Do you have any idea what color the later (good?) 576 HV transformer
potting might be? Or what S/N's might be effected? The 576 is such a wonderful
machine, it would be absolutely criminal to have to "part one out" for the lack
of an important part such as the HV transformer. tom jobe...




----- Original Message ----- From: "Bob Koller"<testtech@...>
To:<TekScopes@yahoogroups.com> Sent: Monday, August 01, 2011 2:56 PM Subject:
Re: [TekScopes] 576 curve trace scope problem


Pull the cover off the HV section. If the transformer has brown potting, that is
almost certainly the culprit. Common on the older s/n's. Chuck Harris and I
discussed rebuilding these, and I provided the winding details to him, but have
I not pursued it further. Finding an original replacement can be quite
difficult..



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

Yahoo! Groups Links




Re: 576 curve trace scope problem

drawding@pacbell.net
 

Chuck,

Per your response below, it appears that you have access to the 576 HV transformer winding sheet. Would you be kind enough to send me a copy or let me know where you got it?

Thank you,
Dave

--- In TekScopes@yahoogroups.com, Chuck Harris <cfharris@...> wrote:

I can do precise weights without problem, but I am somewhat concerned about
how the silicone resin handles exposure to the air. I read that it has a
definite shelf life, and that it gets much shorter after opening the can.

I am game to try it, though.

The other issue relative to the silicone RTV potting compound is whether it
is thin enough to penetrate the windings. In the 561 transformer, tek used
an epoxy varnish to impregnate the windings, and then potted the transformer
in an aluminum can filled with clear RTV silicone rubber. The 576 winding
sheet only says silicone resin and gives the part numbers:

252-0203-00 and 252-0214-00

Anyone know what the commercial equivalent silicone resin is?

I cannot imagine that beeswax transformers would have any problem at all in the
576. It is all solid state, and there is plenty of room for ventilation in
the EHT compartment. Tek switched from beeswax to epoxy when they modularized
the HV section... prior to that they used either beeswax, or mineral oil. I think
the issue, mostly, is whether a beeswax transformer would be well received by
576 owners...

-Chuck Harris

Bob Koller wrote:
I have used the two component silicones as far back as the mid-'70's.. The mix is
by weight (or was then), and small volume was not a problem. I think the silicone
is preferable to prevent corona. Weren't most of the beeswax impregnated
transformers enclosed in a clear plastic case? I foe one, wouldn't care as long as
it works right.





________________________________ From: Chuck Harris<cfharris@...> To:
TekScopes@yahoogroups.com Sent: Tuesday, August 2, 2011 5:23 AM Subject: Re:
[TekScopes] 576 curve trace scope problem



The biggest issue for me, with winding 576 transformers, is the potting. If I am
to do the replacements with a nice modern 2 part silicone RTV compound, that will
raise the price somewhat... The 2 part RTV's are designed to only be used in full
can quantities, and that means potting 10 to 20 coils at a time, with the
attending need for a 10 to 20 molds, and a way to process 10 to 20 molds in the
vacuum chamber at a time.

The problem can be lessened if the 2 part RTV's can be safely and reliably used in
smaller quantities... without jeopardizing the quality of the resulting product.

Beeswax and paraffin are much less expensive in all respects, but would not make
an identical transformer.... assuming that anyone cares.

-Chuck Harris

tom jobe wrote:
Hi Bob, Do you have any idea what color the later (good?) 576 HV transformer
potting might be? Or what S/N's might be effected? The 576 is such a wonderful
machine, it would be absolutely criminal to have to "part one out" for the lack
of an important part such as the HV transformer. tom jobe...




----- Original Message ----- From: "Bob Koller"<testtech@...>
To:<TekScopes@yahoogroups.com> Sent: Monday, August 01, 2011 2:56 PM Subject:
Re: [TekScopes] 576 curve trace scope problem


Pull the cover off the HV section. If the transformer has brown potting, that is
almost certainly the culprit. Common on the older s/n's. Chuck Harris and I
discussed rebuilding these, and I provided the winding details to him, but have
I not pursued it further. Finding an original replacement can be quite
difficult..


Re: Help with Tektronix 2445.

cslim388
 

Yes, Tgyuri59, you are right in saying that someone did convert 2445B to 2465B by changing the A1 motherboard. 
He did that for a long time. There are embedded inductors in the original 2465B motherboard so it is not a totally 
perfect conversion. Anyway, you can do a search and read all the details. The 2465B service manual has the correct A1
board part number. 

cslim 


Tek 575 tube adapter

Julian
 

I need some advice on setting up the 575 to measure some dual triodes like the 12AX7 etc.. I know others on Tekscopes have built adapters for this purpose, so I'm in the right place! I built one which you can see in action here:

http://jjbunn.files.wordpress.com/2013/05/575_adapter.jpg?w=595&h=620

It connects the plate pins to the transistor A/B collectors banana sockets, the grid pins to the A/B bases, and the cathode pins to the A/B emitters (both grounded). There is a switch for selecting between 12V heater tubes like the 12AX7, and 6V heater tubes like the 6DJ8 etc.. The two terminals allow the connection of a heater supply - I'm using a 6VDC wall wart.

I may sound like I know what I'm doing, but that's not clear :-) In particular, I'm not sure how best to set the 575's controls. I suppose it depends what I want to measure, but it seems like the collector/plate voltage range should be on the 200V setting, for example. But what about all the other variables like dissipation resistance etc.? You can see from the photo that I have a set of curves, but I'm not sure what I'm measuring.

So my question is to others who've done this - how do you set up your 575 for tube testing?

Julian


Re: Anyone have experience shipping to France?

Craig Sawyers <c.sawyers@...>
 

Just curious, thanks. I keep hearing stories about the uncooperative postal folks in the UK, France and Italy.
====================

Sending stuff to the UK is fine. Either if it comes from USPS it goes in via Parcel Force. You can either be in when they try to deliver, or you can collect and pay the tax. If it comes via courier, they deliver and then send you a VAT invoice. All works pretty well.

Craig

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