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
