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I was there when the 453 was introduced to the world. No doubt about it . . . it
was revolutionary. You have to put it in the context of the other instruments
available on the market at the time. Nothing could touch it. IBM was certainly
in love with it . . .

Stan
w7ni@...

Michael wrote:

Hi again all... :)

Sometime on Mon, 02 Oct 2000, you wrote:

margo.student.utwente.nl has the IP address 130.89.221.72

FOUND IT!!!

Thanks for that. Looks like it was a nameserver problem after all... Great
pages, but I take issue with your comment that the 453 "doesn't belong in the
list of the great tek scopes..." The 453 was my scope of choice as soon as I
could get my hands on it! And the first thing I did was throw away the mesh
filter and fit a blue one. Lovely! :)

In my mind, the 453 is the "classic portable" oscilloscope.

Cheers,
:)
Michael

Hi Michael,

margo.student.utwente.nl has the IP address 130.89.221.72

and if that works, then I probably know what went wrong: the IP address used
to be different, and maybe changes haven't filtered around to the other side
of the world yet..


Regards,

Arnoud.

Sometime on Sun, 01 Oct 2000, you wrote:

I already wrote one book about Tek scopes: "OSCILLOSCOPES--Selecting and
Restoring a Classic". There is more about this on the web page at
<>. My first book, published in 1992, covered Tek scopes
and plugins from 1947 (the beginning) to the end of 1969. The second volume
(under construction for several years now) will cover the scopes and plugins
introduced by Tek in the decade of the 70's. I still have a couple of hundred
copies of the first book if you find it interesting after you read the review of
it on the web page.

That's one book I will be ordering, when I can afford it. (and when the $A/$US
exchange rate is a little more favourable...)

Cheers,
:)
Michael

Hiya Stan, :)

Sometime on Sun, 01 Oct 2000, you wrote:

I may be all wet here but I think your server has to know about the URL you wish to
go to or it won't let you go there. Maybe your server just does not recognize the
web address you are trying to reach. As I understand it, when a new URL comes on
board, the owner has to let the world (internet) know about it so the various
servers of the world can recongnize and find it. The servers are constantly
updating their database of valid URL's and maybe the one you are looking for never
got into your server's database. If not, your server could not find it, but
others still could . . .

But I may be completely off base on this one. It makes sense to me . . .

Hmmm... I'm not prepared to say you're wrong, but I'm not certain you're right
either. I just don't really know. Either way, it's a pity, as I'd like to see
the site. Oh well... Never mind.

Cheers,
:)
Michael

Hiya Arnoud,

I'm not gonna give up... <g>

Can you supply me with the ip address of margo.student.utwente.nl ? (there's
more than one way to do almost anything... :)

Cheers,
:)
Michael

--

Michael VK2XMD 0404-478-205
I used to have a handle on life, but it broke ...

HI Michael,

I already wrote one book about Tek scopes: "OSCILLOSCOPES--Selecting and
Restoring a Classic". There is more about this on the web page at
<>. My first book, published in 1992, covered Tek scopes
and plugins from 1947 (the beginning) to the end of 1969. The second volume
(under construction for several years now) will cover the scopes and plugins
introduced by Tek in the decade of the 70's. I still have a couple of hundred
copies of the first book if you find it interesting after you read the review of
it on the web page.

Tube with part numbers beginning with "157-" are checked for various parameters.
Some are matched for gm. Some are checked for grid current or microphonics.
There are other parameters they are checked for as well. And, yes, I almost hate
to say it, I know what those parameters are. The reason I hate to say it is that
if it were generally known that I know this stuff, I would be buried under
requests for the info . . . I just don't have the time to handle the requests.
The plan was to publish a database with checked tube part numbers and the
parameters they are checked for but so far, there just has not been time to do
it. Believe it or not, there are a couple of other even more important databases
to publish if we have time for them, like a cross reference from "152-" (diode)
part numbers to generic (1N) diode numbers. There are also checked transistors
and diodes ("153-") part numbers and we could do a database on those too. There
is literally TONS of good data to be published. I could very easily spend the
rest of my life doing this . . . and that is not really a bad idea as I am sure
there are a lot of guys and gals out there who would appreciate and use the data.

So . . . if you need some specific data about one particular "157" part number, I
might find the time to look it up for you . . . let me know.

Stan
w7ni@...

Hi Michael,

I may be all wet here but I think your server has to know about the URL you wish to
go to or it won't let you go there. Maybe your server just does not recognize the
web address you are trying to reach. As I understand it, when a new URL comes on
board, the owner has to let the world (internet) know about it so the various
servers of the world can recongnize and find it. The servers are constantly
updating their database of valid URL's and maybe the one you are looking for never
got into your server's database. If not, your server could not find it, but
others still could . . .

But I may be completely off base on this one. It makes sense to me . . .

Stan
w7ni@...

Michael Dunn wrote:

My on-line tech museum is still a ways off, but y'all may be interested in eyeing a couple of pics I've taken with my new digicam! Go to:



The Tek pix are clearly named. BTW, the close-up is of a 1A1 2-chan input.

Michael

At 6:15 PM -0700 2000/9/29, Stan or Patricia Griffiths wrote:

Here is an excerpt from the "new" book I am writing. I have been working on
it for several years.

APPENDIX 8

FAN MOTOR REBUILD PROCEDURE

Great stuff Stan! Obviously, a motor rebuilding party is in order here. What is this book of which you speak?

p.s., A few tubes in various scopes have Tek labels on them, and the manual points out that they are specially selected parts. Does anyone know what the selection criteria was? I'm guessing it might vary in different applications...? Xconductance here, HV there, matching...???

-----------------------------------------------------------------
Michael Dunn | Surround Sound Decoder & Stereo Enhancement
Cantares | Self-Amplified Speakers, Test Equipment
74 George St. | Ambisonic Surround Sound CDs and Recording
Waterloo, Ont. | (519) 744-9395 (fax: 744-7129)
N2J 1K7 | mdunn@...
Canada |
-----------------------------------------------------------------

Michael Dunn wrote:

At 8:57 PM +1100 2000/9/28, Michael Dunn wrote:

Ah, I remember repacking many, many fan motors.... <g>

Tell us more please! The fans on our 549s don't work too well -
they start out seized, and as the scope warms up, they start to spin,
eventually reaching a decent speed...

Here is an excerpt from the "new" book I am writing. I have been working on
it for several years.

APPENDIX 8

FAN MOTOR REBUILD PROCEDURE

Not all fan motors found in Tek instruments can be easily rebuilt nor do
they need it. The fan motors typically found in the 530/540/550 scopes with
1/4 inch shafts are the ones that this procedure works for. The same basic
motor is also found in the 502 but it looks different because it has an
extra metal shield around it. Inside the shield, it looks the same as the
others.

1. Inspect the motor wires for breaks in insulation. The insulation tends
to harden over time and flake off of the wires. You may want to replace the
wires at this point by splicing them where they enter the motor windings.
At least you are warned to be very careful with them if the insulation is
brittle.

2. Remove the fan motor from the instrument and mark the ceramic strip
notches so you can return motor wires to the correct place. It has also
been suggested that cutting the motor wires just below the motor and
installing quick disconnect connectors will make the job of cleaning the
motor easier when it has to be done again in the future.

3. Disassemble the motor noting that the oil holes in the bearing pieces
point up and to the right side when you are facing the back of the
instrument. Also note that the wires exit the motor from the bottom and
toward the interior of the instrument. Make sketches so you can get it back
together correctly. There are several wrong ways to reassemble it.

4. Disassemble the motor by removing the bolts holding it together and
remove all of the old bearing washers including the fiber washers. Very
carefully remove the tight-fitting washer on the shaft near the fan blade
since you will need to reinstall this one later and I have not seen a source
for replacements.

5. Clean all of the old and solidified oil from around the shaft and the
area of the oil reservoirs in both bearing pieces. Mineral spirits work
well to dissolve the old oil and a rag soaked in mineral spirits works well
to wipe the windings and front and rear housings clean of dirt and old oil.
For especially bad cases, you might actually soak the end housings in
mineral spirits for a day, rinse well, blow out all the excess solvent, and
let them dry for a day before reassembly and re-oiling.

6. Put new oil in the reservoirs and place a small amount directly on the
shaft where it enters the bearing pieces. Do not overfill the reservoirs
but do saturate the fiber reservoir filler with oil. Use any medium weight
quality motor oil. Light mineral oil used to lubricate air conditioning and
heating system blowers works well since it does not change viscosity much as
the temperature changes.

7. Put nylon washers on both ends of the shaft such that the shaft has about
1/32 to 1/64 inch of end play when the motor is fully reassembled (and the
bolts are tight) and the rotating part of the motor is centered in the
field. You may need different washers on the front and back to achieve this
and you may not need all of the washers provided. (Tek used to sell a kit
to do this. Sorry, not available now.) This is a "trial and error" process
which may require assembly and disassembly of the motor several times to get
the correct end play. You can find a good assortment of 1/4" nylon washers
in various thicknesses at a well stocked hardware store.

8. Install the fiber washer that fits tightly on the shaft between the motor
and the fan blade to prevent oil from traveling down the shaft to the fan
blade where it will be thrown around the interior of the instrument.

Motors that tend to run slow almost always do not turn freely and this is
almost always due to the bearings being gummed up. Sometimes motors will
start slow and speed up after a few minutes. This indicates that a rebuild
is needed.

* * * * *
I have used this procedure hundreds of times and successfully fixed many
"slow" motors.

Stan
w7ni@...

Hiya. :)

Sometime on Fri, 29 Sep 2000, you wrote:

The link works precisely as typed....
Can't do more for you than that, I'm afraid....

Hmmm... vewwy stwange... might be my end, but I can't imagine why. I was able
to get into the uni server the "front" way, but when I clicked on *some* links,
I got the same message while attempting redirection to ancillary servers.

My guess is the university webmaster doesn't like Aussies...

(I used to be a university webmaster, and I know it's quite feasible to deny
service selectively this way, but I can't imagine why.)

Oh well...

Cheers,
:)
Michael

--

Michael VK2XMD 0404-478-205
I used to have a handle on life, but it broke ...

The link works precisely as typed....

Can't do more for you than that, I'm afraid....

So long,

Arnoud.

Is anyone familiar with the characteristics of Nuvistors? I ask because I do have some data sheets, but the curves don't look like normal tubes or FETs. Instead of a mostly constant-current section, the Nuvistor curves are resistive in nature. The grid voltage seems to modulate the resistance somewhat, and also sets the threshold plate voltage at which the tube starts to conduct! Am I missing something, or are Nuvistors really that different?

thx

-----------------------------------------------------------------
Michael Dunn | Surround Sound Decoder & Stereo Enhancement
Cantares | Self-Amplified Speakers, Test Equipment
74 George St. | Ambisonic Surround Sound CDs and Recording
Waterloo, Ont. | (519) 744-9395 (fax: 744-7129)
N2J 1K7 | mdunn@...
Canada |
-----------------------------------------------------------------

Sometime on Thu, 28 Sep 2000, you wrote:

I just tried it and it is still there!
So the problem does not seem to be on my end of the line....

I just tried again, and same result. :(

By substituting "www" for "margo.student" and dropping the "/~wel/..." I was
able to get to the university, but was unable to get to your page that way. Is
the server name correct...?

Regards,
:)
Michael

--

Michael VK2XMD 0404-478-205
I used to have a handle on life, but it broke ...

Sometime on Thu, 28 Sep 2000, you wrote:

I just tried it and it is still there!
So the problem does not seem to be on my end of the line....
Regards,
Arnoud.

Hmmm... I double-checked the url (I'm having trouble with this mail program and
web addresses), so I wonder what the problem is? I'll try again today...

Regards,
:)
Michael

--

Michael VK2XMD 0404-478-205
I used to have a handle on life, but it broke ...

G'day... :)

Sometime on Fri, 29 Sep 2000, you wrote:

At 8:57 PM +1100 2000/9/28, Michael Dunn wrote:

Ah, I remember repacking many, many fan motors.... <g>

Tell us more please! The fans on our 549s don't work too well -
they start out seized, and as the scope warms up, they start to spin,
eventually reaching a decent speed...

Hmmm... Well, now you're asking! :) It's 25 years since I did one, but It was
simply a matter of removing the fan motor and disassembling it, then cleaning
with Freon TF (not available now, but many substitutes out there) and
reassembling; adding new fibre washers as necessary. I was always amazed that
this had such a dramatic effect.

But it *was* one of those tedious, messy jobs nobody likes much.....

BTW, Chris commented about the muffin fans not being the quietest thing. I
added a 12VDC one to a computer (this computer) and the noise drove me crazy.
So I ran it from the 5V supply, and it's almost inaudible, though it still
pushes the air around. No doubt a noise vs efficiency compromise could be
found in the scope situation. :)

And ditto his comments about engineering. :) My guess is, that's why we're
all here...

Regards,
:)
Michael

--

Michael VK2XMD 0404-478-205
I used to have a handle on life, but it broke ...

At 8:57 PM +1100 2000/9/28, Michael Dunn wrote:

Ah, I remember repacking many, many fan motors.... <g>

Tell us more please! The fans on our 549s don't work too well - they start out seized, and as the scope warms up, they start to spin, eventually reaching a decent speed...

-----------------------------------------------------------------
Michael Dunn | Surround Sound Decoder & Stereo Enhancement
Cantares | Self-Amplified Speakers, Test Equipment
74 George St. | Ambisonic Surround Sound CDs and Recording
Waterloo, Ont. | (519) 744-9395 (fax: 744-7129)
N2J 1K7 | mdunn@...
Canada |
-----------------------------------------------------------------

Hello all!

First post here for me, but I've been lurking for a little while.

I'm the proud owner of a later model 535A, complete with CA plugin, all
manuals, probes, and the scopemobile. After getting it home, pulling off all
the covers, and getting 40 years of tobacco tar residue off of it (thank
goodness for the smoke-free workplace of today), it looks almost brand new.

Firing it up had it working well, but I did track down a bad pass tube in the
power supply, causing a low voltage on one of the supplies. After that, it
works perfectly, and has a very strong CRT.

It was used at Eaton here in Milwaukee in it's former life, and did some pulse
testing, so it has a camera mount in place of the normal round bezel. It also
had the fan replaced with a 5" muffin style unit some years ago, no doubt a
common conversion in the later years as the originals went south. It really
blows some air, but isn't the quietest thing going.

I use the scope for my audio hobby and it's a treat to use. The engineering
that went into it boggles my mind. The quality is amazing, and to have it
function perfectly after all these years is a real testament to what can be
done with "obsolete" technology.

I also have a dead 422 solid state scope (power supply) that's in really nice
cosmetic condition, but I just don't have the time to fiddle with it. If
anyone is looking for one for parts, let me know. I'd be interested in
obtaining a proper round bezel for my 535A in trade.

That's about it! It's nice to see these technical marvels preserved. Sure,
they are hot, noisy, and big, but when I flip that big switch, it is soooo
much more satisfying that pushing the little button on my Hitachi 40MHz
scope.

Chris Beck


____________________________________________________________________
Get your own FREE, personal Netscape WebMail account today at

I also made a 'Tek scopes museum' website one rainy

afternoon, which can

still be seen at margo.student.utwente.nl/~wel/tek.htm but

which hasn't been

updated for (far) more than a year now. A site like that is

a lot of fun to

make and lots of people come by with enthousiastic comments,

interesting

anecdotes, parts, stories and pictures..

I tried to access it, but my browser returned "unable to
locate server". A
pity, as I'd like to have seen it.

I just tried it and it is still there!

So the problem does not seem to be on my end of the line....

Regards,

Arnoud.