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I saw this 577 Curve Tracer show up on eBay and it sold for $256. Not sure if that power-up trace indicates an issue (not having had or operated a curve tracer, I don't know what the power-up trace should look like). Following-on to conversations in this forum about the the 576, I've been keeping my eyes out for a 576. Is there a significant difference between the two?

The 576 was based on the original 7000 series,
and the 577 was based on the modular 5000 series.

The 576 was intended to do everything discrete
semiconductor wise.

The 577 was geared towards low current discretes,
opamps, and 3 terminal regulators.

They are complementary instruments, each covering
a different part of the V-I spectrum, but do not
fully replace each other.

-Chuck Harris

David Berlind wrote:

On Mon, May 14, 2018 at 06:23 am, Chuck Harris wrote:

The 576 was based on the original 7000 series,
and the 577 was based on the modular 5000 series.

In what way would you say 576 is based on the 7000 series ?

/H?kan

Just chiming in...
I would agree with Chuck on this. Some other factors...
A 576 is way more complex inside with all the display lighting and control.
If something fails, you have a lot more work to do. I just sold a 576 for $750 and I think, for a fully working unit, it was a buyer bargain. The owner just wanted it gone....

I use a 577 for just about anything discrete. I have a dozen fixtures. (No IC testing though as mine has the 177 fixture) . Both are versatile, and you can build fixtures to do things Tek didn't anticipate or support. I'm working on a fixture to test Nuvistors.. A work in progress though.

One caution (among many) If you get one and then go looking for fixtures, be ware that many of the Tek plug-in fixtures have reached EOL. The covers are screwed into bosses in the base boxes. Both the threaded bosses and the covers themselves are now failing. As the plastics aged they became brittle and the stresses have fractured the bosses and the covers now pull away from the base. I have seen top covers laced with hairline cracks causing the top to break up like a jig-saw puzzle. So take a good look at what you are buying.

kjo

David Berlind wrote:
. . .
I saw this 577 Curve Tracer show up on eBay and it sold for $256. Not sure if that power-up trace indicates an issue (not having had or operated a curve tracer, I don't know what the power-up trace should look like). Following-on to conversations in this forum about the the 576, I've been keeping my eyes out for a 576. Is there a significant difference between the two?

My main interest in a curve tracer would be for tube testing/matching. A
few months back, I believe there was discussion of a home-grown 576 fixture
for that. For now, one of my upcoming projects is to build my own tube
testing rig. For example, I'd wire up a single socket to some voltage and
amperage gauges and power the rig with an external DC supply across a
mixture of plate voltage and cathode resistance ranges. But that's a a lot
of work for each tube. I've seen a few hacks that convert old oscilloscopes
into curve tracers but haven't really studied any of them.

I just sold a 576 for $750 and I think, for a fully
working unit, it was a buyer bargain. The owner just wanted it gone....

My 576 cost me - precisely zero! Known to have the epoxy HT transformer problem. I rewound it from the
specification sheet, and potted it in wax. Works absolutely perfectly.

Craig

If you're interested primarily in tubes, you should check out the uTracer
which is a very clever implementation using pulsed power supplies and a
computer for the analysis/display. Google uTracer and you'll get a
zillion hits but the home URL is

www.dos4ever.com/uTracer3/uTracer3.html

I do very little with tubes, but I was very impressed with the implementation.
He has a kit available too, which makes construction easy.

Wow, I just checked the web site and there's now a Linux version of the GUI.
The latest version goes up to 400V as well. Extremely impressive. I'm
tempted to get a kit just for the heck of it.

For the record, I have a 576, 577 and a 7ct1n (which is the one that seems to
get used the most since I'm mostly checking small signal transistors).

Paul

--
Paul Amaranth, GCIH | Rochester MI, USA
Aurora Group, Inc. | Security, Systems & Software
paul@... | Unix & Windows

If you're interested primarily in tubes, you should check out the uTracer which is a very clever
implementation using pulsed power supplies and a computer for the analysis/display. Google

uTracer

and you'll get a zillion hits but the home URL is

www.dos4ever.com/uTracer3/uTracer3.html

I do very little with tubes, but I was very impressed with the implementation.
He has a kit available too, which makes construction easy.

Wow, I just checked the web site and there's now a Linux version of the GUI.
The latest version goes up to 400V as well. Extremely impressive. I'm tempted to get a kit just

for the

heck of it.

For the record, I have a 576, 577 and a 7ct1n (which is the one that seems to get used the most

since

I'm mostly checking small signal transistors).

I have all those (although the uTracer, though working, is awaiting a hardware implementation)

Plus a 575mod122C, and another 575 plus 175 high current adaptor (which weighs even more than the
575!)

I have a bit of a thing about curve tracers ;-)

Craig

Based is probably a little to strong of a suggestion.

Definitely siblings, though.

Both were developed in the same time frame,
both were designed to host a fiber optic readout system.
Both are an early adoption of a mix of semiconductor
and IC circuitry. Both fit in about the same footprint.
Both had flat, rectangular, internally ruled graticules,
on rectangular ceramic funnel section CRTs. Both used
epoxy potted EHT transformers in the anode section.
Both have convection cooled linear regulators plating the
back of the instrument.

Put a 7454 and a 576 side by side, and the familial
resemblance is hard to dismiss.

If Gilbert hadn't developed his superior on screen readout
system, The 7000 series would have been a carbon copy of
what you see in the 576.

-Chuck Harris


zenith5106 wrote:

On Mon, May 14, 2018 at 08:28:10PM +0100, Craig Sawyers wrote:

For the record, I have a 576, 577 and a 7ct1n (which is the one that seems to get used the most

since

I'm mostly checking small signal transistors).

I have all those (although the uTracer, though working, is awaiting a hardware implementation)

Plus a 575mod122C, and another 575 plus 175 high current adaptor (which weighs even more than the
575!)

I have a bit of a thing about curve tracers ;-)

Craig

I try to draw the line on whether or not I can lift it without assistance :-)

Paul

--
Paul Amaranth, GCIH | Rochester MI, USA
Aurora Group, Inc. | Security, Systems & Software
paul@... | Unix & Windows

Hi David,

A little over a year ago I completed my Vacuum Tube Curve Tracer adapter which worked with ALL Tek curve tracers. After seeing the beautiful job Glydeck did on his simple triode curve tracer adapter for a 576 I decided I must make one myself if I ever got a 576.


Then one day a 576 fell into my lap for $25 and I set to work. My goal gradually evolved past Glydeck's. I wanted to test all kinds of tubes, not just a few triodes. With great advice from George Lydecker (Glydeck) I came up with a low cost solution for an easy to make adapter that, in conjunction with an inexpensive tube tester, would test any tube on any Tek curve tracer.

My goal was to make something anyone with a curve tracer could build at the absolute lowest cost that would test the greatest number of tubes. It had to work on any Tek curve tracer without modification (575, 576, 577, 7CT1N, 5CT1N) and perform most of the tests the original Tek 570 tube tester could do. Those were pretty aggressive goals but I met most of them and wrote about how I did it in a very detailed 29 page paper complete with parts lists and schematics. It may help guide you in your design. You can download a copy from:


To my amazement I almost immediately got requests from 75+ members of Tekscopes for the PC Board I made for the VTCT Adapter. I gave a talk on the adapter at SeaPac last June and I sold 10 more there. I have sold about 105 of them all total by now including a few completely assembled units and a few kits that include all the parts.

In between everything else I am doing I'm investigating what it would take to design a new version that would be capable of testing tubes under the exact conditions in a Williamson amplifier and its derivatives that many audiophiles will tell you is the ultimate in tube amplifiers.


Dennis Tillman W7PF

I try to draw the line on whether or not I can lift it without assistance :-)

Paul

<grin>

The 175 is an insane unit. It is wired internally with welding cable and has an exceptionally
serious power transformer. All the switching is done using major-league relays. It has a 200A peak
collector current and 12A base current. It also has very, very large current sensing resistors.

When I first got it, I made up an umbilical to connect it to the 575 and fired it up. Just to test
it out, I wired in a random TO220 package transistor. There was a loud crack is it exploded into hot
shrapnel without very much effort at all. The tab burned into the carpet. "What is this mark on the
carpet? It looks like a burn" "No idea, dear...."

Craig,

Many have come to this forum looking for a solution to the epoxy failing on the 576 HT transformers. I went the route of having a run of 5 make by a professional custom transformer supply company. It was not the most economical solution, but it did keep at least five 576s out of the recycle bin.

That said, you and maybe one other that has posted here, where successful in winding one from "scratch". Would there be any possibility of you putting together a how-to post with pictures or a YouTube video of the method you used?

Thanks,
Dave

Many have come to this forum looking for a solution to the epoxy failing on the 576 HT transformers.
I
went the route of having a run of 5 make by a professional custom transformer supply company. It
was not the most economical solution, but it did keep at least five 576s out of the recycle bin.

That said, you and maybe one other that has posted here, where successful in winding one from
"scratch". Would there be any possibility of you putting together a how-to post with pictures or a
YouTube video of the method you used?

Thanks,
Dave

Hi Dave

I took alas no photos. But what I did was:

(a) Buy the cheapest manual coil winder from eBay. In US-speak we're talking $20.
(b) Found a regular pot core bobbin that would fit the core centre leg. That fortunately had lots of
pins.
(c) Wound using wind-and-retrace. If you wind back and forth, you get twice the voltage at each end of
the wind (found the technique from a google search).
(d) Covered each winding layer with a layer of thin yellow transformer tape both for insulation and to
level the wind.
(e) The additional core pins came in handy because I broke the 0.08mm winding wire three or four
times. So I took the wire out, terminated at a pin, and kept winding.
(f) On completion I potted it in a mix of paraffin candle wax and beeswax. I used something like two
thirds candle (and I mean that I melted candles) to one third (carpenter's) beeswax - which you get as
a solid stick.
(g) After assembling to the core, I immersed it in the molten wax until bubbles stopped, and let it
soak for 15 minutes more. Then let it drip until cold.

The pot core needed to be modified, because it was too long. So I cut off the end cheek, then reduced
the length of the centre tube and reattached the end cheek with superglue.

Any way you look at it, winding 1400 turns of hair thin wire is a royal pain in the ass ;-)

The first attempt was a learning process. The second one is in the 576 and working perfectly.

Craig

Hi Craig,
Well that is always the issue.
Do you want to build and repair test equipment or use test equipment? It’s a fine line that deserves some thought before action.
Rebuilding an HV switching xfmr is definitely for the former!!! But I have to admit I have fallen into the fixit trap more often than I want to admit. I’d have been better off buying something new!

Kjo

Sent from kjo iPhone

Hi Craig,
Well that is always the issue.
Do you want to build and repair test equipment or use test equipment? It s a fine line that deserves
some thought before action.
Rebuilding an HV switching xfmr is definitely for the former!!! But I have to admit I have fallen
into the
fixit trap more often than I want to admit. I d have been better off buying something new!

Kjo

Well, I don't agree. You cannot buy a new anything that comes remotely close to a 576 curve tracer, at
least anything that costs less than $12,000 (for a refurbished, obsolete, Tek 370A). I shudder to
think what the current Keithley 2600-PCT-4B costs, but think seriously big money. And if your pockets
are that deep - go for it!

But back in the real world, before you get to use the 576 - you have to fix it. And a free 576 is most
certainly worth a day fixing.

Craig

Craig, did you wind right to the edge? If so, how did you keep the wire from sneaking past? If not, what did you use to fill in the edge?

When I rewound my 453 HT, I wound to the edge, laid a bead of corona dope, laid tape, and waited for the dope to set before starting the next layer. There are other tactics, but that's what I did. I had about 300V (peak) between layers. I used Scotch "Magic" tape, which is polypropylene. I staggered the start/end overlap to avoid humping.

Dave Wise
________________________________________
From: [email protected] <[email protected]> on behalf of Craig Sawyers <c.sawyers@...>
Sent: Monday, May 14, 2018 10:18 PM
To: [email protected]
Subject: Re: [TekScopes] Tek 577 sells for $256 on eBay

Many have come to this forum looking for a solution to the epoxy failing on the 576 HT transformers.
I
went the route of having a run of 5 make by a professional custom transformer supply company. It
was not the most economical solution, but it did keep at least five 576s out of the recycle bin.

That said, you and maybe one other that has posted here, where successful in winding one from
"scratch". Would there be any possibility of you putting together a how-to post with pictures or a
YouTube video of the method you used?

Thanks,
Dave

Hi Dave

I took alas no photos. But what I did was:

(a) Buy the cheapest manual coil winder from eBay. In US-speak we're talking $20.
(b) Found a regular pot core bobbin that would fit the core centre leg. That fortunately had lots of
pins.
(c) Wound using wind-and-retrace. If you wind back and forth, you get twice the voltage at each end of
the wind (found the technique from a google search).
(d) Covered each winding layer with a layer of thin yellow transformer tape both for insulation and to
level the wind.
(e) The additional core pins came in handy because I broke the 0.08mm winding wire three or four
times. So I took the wire out, terminated at a pin, and kept winding.
(f) On completion I potted it in a mix of paraffin candle wax and beeswax. I used something like two
thirds candle (and I mean that I melted candles) to one third (carpenter's) beeswax - which you get as
a solid stick.
(g) After assembling to the core, I immersed it in the molten wax until bubbles stopped, and let it
soak for 15 minutes more. Then let it drip until cold.

The pot core needed to be modified, because it was too long. So I cut off the end cheek, then reduced
the length of the centre tube and reattached the end cheek with superglue.

Any way you look at it, winding 1400 turns of hair thin wire is a royal pain in the ass ;-)

The first attempt was a learning process. The second one is in the 576 and working perfectly.

Craig

Good Day,

Thank you for the step-by-step description, Craig - and for the burst of laughs I had over this:

"Any way you look at it, winding 1400 turns of hair thin wire is a royal pain in the ass ;-)"

Cheers,

Magnus

Dennis,

Just wanted to thank you for the detailed reply. I read Glydeck's web page
(the one you linked to) and have yet to start on the 29 page dissertation
but look forward to doing so. I may be your next customer for a board. One
question based on your note,... given that you targeted compatibility with
a range of systems (575, 576, 577, 7CT1N, 5CT1N), is there any reason to
prefer one (or some) over the others as I continue my hunt?

Thank you again.

On Mon, May 14, 2018 at 4:31 PM, Dennis Tillman W7PF <dennis@...>
wrote:

Hi David,

A little over a year ago I completed my Vacuum Tube Curve Tracer adapter
which worked with ALL Tek curve tracers. After seeing the beautiful job
Glydeck did on his simple triode curve tracer adapter for a 576 I decided I
must make one myself if I ever got a 576.


Then one day a 576 fell into my lap for $25 and I set to work. My goal
gradually evolved past Glydeck's. I wanted to test all kinds of tubes, not
just a few triodes. With great advice from George Lydecker (Glydeck) I came
up with a low cost solution for an easy to make adapter that, in
conjunction with an inexpensive tube tester, would test any tube on any Tek
curve tracer.

My goal was to make something anyone with a curve tracer could build at
the absolute lowest cost that would test the greatest number of tubes. It
had to work on any Tek curve tracer without modification (575, 576, 577,
7CT1N, 5CT1N) and perform most of the tests the original Tek 570 tube
tester could do. Those were pretty aggressive goals but I met most of them
and wrote about how I did it in a very detailed 29 page paper complete with
parts lists and schematics. It may help guide you in your design. You can
download a copy from:


To my amazement I almost immediately got requests from 75+ members of
Tekscopes for the PC Board I made for the VTCT Adapter. I gave a talk on
the adapter at SeaPac last June and I sold 10 more there. I have sold about
105 of them all total by now including a few completely assembled units and
a few kits that include all the parts.

In between everything else I am doing I'm investigating what it would take
to design a new version that would be capable of testing tubes under the
exact conditions in a Williamson amplifier and its derivatives that many
audiophiles will tell you is the ultimate in tube amplifiers.


Dennis Tillman W7PF

-----Original Message-----
From: David Berlind, Sent: Monday, May 14, 2018 12:02 PM

My main interest in a curve tracer would be for tube testing/matching. A
few months back, I believe there was discussion of a home-grown 576

fixture

for that. For now, one of my upcoming projects is to build my own tube
testing rig. For example, I'd wire up a single socket to some voltage and
amperage gauges and power the rig with an external DC supply across a
mixture of plate voltage and cathode resistance ranges. But that's a a

lot

of work for each tube. I've seen a few hacks that convert old

oscilloscopes

into curve tracers but haven't really studied any of them.

On Mon, May 14, 2018 at 2:43 PM, Kevin Oconnor <kjo@...> wrote:

Just chiming in...
I would agree with Chuck on this. Some other factors...
A 576 is way more complex inside with all the display lighting and

control.

If something fails, you have a lot more work to do. I just sold a 576
for
$750 and I think, for a fully working unit, it was a buyer bargain.
The owner just wanted it gone....

I use a 577 for just about anything discrete. I have a dozen fixtures.
(No IC testing though as mine has the 177 fixture) . Both are
versatile, and you can build fixtures to do things Tek didn't
anticipate or support. I'm working on a fixture to test Nuvistors.. A

work in progress though.

One caution (among many) If you get one and then go looking for
fixtures, be ware that many of the Tek plug-in fixtures have reached
EOL. The covers are screwed into bosses in the base boxes. Both the
threaded bosses and the covers themselves are now failing. As the
plastics aged they became brittle and the stresses have fractured the
bosses and the covers now pull away from the base. I have seen top
covers laced with hairline cracks causing the top to break up like a
jig-saw puzzle. So take a good look at what you are buying.

kjo

David Berlind wrote:
. . .
I saw this 577 Curve Tracer show up on eBay and it sold for $256. Not
sure if that power-up trace indicates an issue (not having had or
operated a curve tracer, I don't know what the power-up trace should

look

like).

Following-on to conversations in this forum about the the 576, I've
been keeping my eyes out for a 576. Is there a significant difference
between the two?

--
Dennis Tillman W7PF
TekScopes Moderator

Just wanted to thank you for the detailed reply. I read Glydeck's web page (the one you linked to)
and
have yet to start on the 29 page dissertation but look forward to doing so. I may be your next
customer for a board. One question based on your note,... given that you targeted compatibility with
a
range of systems (575, 576, 577, 7CT1N, 5CT1N), is there any reason to prefer one (or some) over the
others as I continue my hunt?

The main problem over here in the Tek dead-zone that is the UK, is procuring a tube tester for the
project. I chuckled at Denis's estimate, in his thoroughly excellent paper, that a suitable tube
tester could be procured for $30 at a swap meet.

In the UK, such a tester would typically work out at least a factor of ten more than that, and becomes
by far the most expensive part of the project.

Craig