Tektronix 24xx series and U800 problems

[Jose V. Gavila]

Hello!

After reading lots of old messages regarding Tektronix 24xx problems
(mainly on 2465 variants) with the dreaded U800 Horizontal Amplifier, I
have not yet found any definitive (if there is one ;-) ) answer to why
do they fail and the correlation with oscilloscope types, U800 reference
and failure rate.

I guess it could fail more in later units (2465A and B), as they have
perhaps higher requirements on the chip... but I am just guessing.

So I wonder if you could help me correlating all that information. I
think it would be fine to get info also on working units.

* Type (2465, 2465A, 2465B, 2445, ...)
* U800 reference (155-0241-01, 155-0241-02 or 155-0241-55, if known)
* Manufacture date (if known) or serial number (just first digits)
* If U800 is gone, how did it fail? (i.e. heat related (after long time
use), just after powering on?)
* Comments


Hope this helps to clarify a bit this recursive topic.

Thanks for your help and best regards,

JOSE

--
----------------------------------------------------------------------
73 EB5AGV / EC5AAU - JOSE V. GAVILA
La Canyada - Valencia (SPAIN)

Vintage Radio: http://jvgavila.com
Vintage Test Equipment: http://jvgavila.com/testeq.htm

 

[Jim Yanik]

"Jose V. Gavila" <eb5agv@ctv.es> wrote in news:406439C2.5020305@ctv.es:

Hello!

After reading lots of old messages regarding Tektronix 24xx problems
(mainly on 2465 variants) with the dreaded U800 Horizontal Amplifier, I
have not yet found any definitive (if there is one ;-) ) answer to why
do they fail and the correlation with oscilloscope types, U800 reference
and failure rate.

I guess it could fail more in later units (2465A and B), as they have
perhaps higher requirements on the chip... but I am just guessing.

So I wonder if you could help me correlating all that information. I
think it would be fine to get info also on working units.

* Type (2465, 2465A, 2465B, 2445, ...)
* U800 reference (155-0241-01, 155-0241-02 or 155-0241-55, if known)
* Manufacture date (if known) or serial number (just first digits)
* If U800 is gone, how did it fail? (i.e. heat related (after long time
use), just after powering on?)
* Comments


Hope this helps to clarify a bit this recursive topic.

Thanks for your help and best regards,

JOSE

I don't believe that TEK bothered to find out why the U800 IC's were
failing.all they knew is that they couldn't get new ones made,and that the
2400 series was a dead duck.

Unless you get a number of failed ICs,open them up and check them with an
electron microscope,you probably will not really know the true reason they
failed.It could be process contamination at some construction step,poor
architecture,marginal IC feature geometries,static damage,......
--
Jim Yanik
jyanik-at-kua.net

 

[Jose V. Gavila]

Hello Jim,

Thanks for your comments!

Jim Yanik wrote:

I don't believe that TEK bothered to find out why the U800 IC's were
failing.all they knew is that they couldn't get new ones made,and that the
2400 series was a dead duck.

Unless you get a number of failed ICs,open them up and check them with an
electron microscope,you probably will not really know the true reason they
failed.It could be process contamination at some construction step,poor
architecture,marginal IC feature geometries,static damage,......

Well, so what do you think about buying a 2465 scope?. Is it too risky?.
Would you prefer to get, let's say, a 485?

Best regards,

JOSE

--
----------------------------------------------------------------------
73 EB5AGV / EC5AAU - JOSE V. GAVILA
La Canyada - Valencia (SPAIN)

Vintage Radio: http://jvgavila.com
Vintage Test Equipment: http://jvgavila.com/testeq.htm

 

[mike]

Jose V. Gavila wrote:

Hello Jim,

Thanks for your comments!

Jim Yanik wrote:

I don't believe that TEK bothered to find out why the U800 IC's were
failing.all they knew is that they couldn't get new ones made,and that
the 2400 series was a dead duck.
Unless you get a number of failed ICs,open them up and check them with
an electron microscope,you probably will not really know the true
reason they failed.It could be process contamination at some
construction step,poor architecture,marginal IC feature
geometries,static damage,......


Well, so what do you think about buying a 2465 scope?. Is it too risky?.
Would you prefer to get, let's say, a 485?

Price matters...A LOT!!! If you have the space, get a 7704. If you
stand around long enough, someone will give you one...and a second one
for spare parts. To get a 485, you're gonna have to compete with the
rest of the world and pay money. ;-)
mike

Best regards,

JOSE

--
Return address is VALID.
Bunch of stuff For Sale and Wanted at the link below.
Toshiba & Compaq LiIon Batteries, Test Equipment
Honda CB-125S $800 in PDX
Yaesu FTV901R Transverter, 30pS pulser
Tektronix Concept Books, spot welding head...
http://www.geocities.com/SiliconValley/Monitor/4710/

 

[Mike Harrison]

On Fri, 26 Mar 2004 10:58:35 -0800, mike <spamme0@juno.com> wrote:

Jose V. Gavila wrote:
Hello Jim,

Thanks for your comments!

Jim Yanik wrote:

I don't believe that TEK bothered to find out why the U800 IC's were
failing.all they knew is that they couldn't get new ones made,and that
the 2400 series was a dead duck.
Unless you get a number of failed ICs,open them up and check them with
an electron microscope,you probably will not really know the true
reason they failed.It could be process contamination at some
construction step,poor architecture,marginal IC feature
geometries,static damage,......


Well, so what do you think about buying a 2465 scope?. Is it too risky?.
Would you prefer to get, let's say, a 485?

Price matters...A LOT!!! If you have the space, get a 7704. If you
stand around long enough, someone will give you one...and a second one
for spare parts. To get a 485, you're gonna have to compete with the
rest of the world and pay money. ;-)
mike


The impression I get is that it's not that these ICs fail very often, just that it's terminal whan

they do. It would be interesting to find some figures on failures over time to see if tehers a
pattern (e.g. if age and hours used has an influence) - if it's the case that it was a bad batch, it
could be that most of the ones that were going to fail already have done so.

 

[Walter Harley]

"Mike Harrison" <mike@whitewing.co.uk> wrote in message
news:ku1960t0buh5o4c0m94shj0vag7pr5ardo@4ax.com...

The impression I get is that it's not that these ICs fail very often,
just that it's terminal whan
they do. It would be interesting to find some figures on failures over
time to see if tehers a
pattern (e.g. if age and hours used has an influence) - if it's the case
that it was a bad batch, it
could be that most of the ones that were going to fail already have done
so.

The bottom line seems to be that many people, including many on this group
(including me) have got 2465's and use them and love them. As you suggest,
the failure doesn't seem to be so widespread that the scopes have all died.

I bet my 2465A will still be going strong when all the TDSxxx folks can no
longer get replacement modules. If I find another scope that's got a
working U800 in it, maybe I'll buy it as an insurance policy - two used
2465's would still be cheaper than a new scope of comparable quality and
usefulness.

 

[Jose V. Gavila]

Hello Walter,

Walter Harley wrote:

The bottom line seems to be that many people, including many on this group
(including me) have got 2465's and use them and love them. As you suggest,
the failure doesn't seem to be so widespread that the scopes have all died.

I bet my 2465A will still be going strong when all the TDSxxx folks can no
longer get replacement modules. If I find another scope that's got a
working U800 in it, maybe I'll buy it as an insurance policy - two used
2465's would still be cheaper than a new scope of comparable quality and
usefulness.

This is what I wanted to hear ;-)!. There is some hope a 2465 _could_
last some time.

In my small test equipment collection, I have several 7000 series
mainframes (7704, 7633 (2), 7603, R7603) and also some 4xx units (475,
466/DM44, 485). Also a venerable 545B (and a Lavoie clone of the 545A!).
Recently, I got a 2230. And, just a couple days ago, I could not pass a
2465DMM for just US$400.

But some weeks ago, a friend asked me about repairing a 2465... which
seems to have a blown U800. I have not a complete Service Manual for it,
just a partial copy (without schematics) but I am pretty sure it had
that fault.

So, now that I have decided to go for a 2465, I was wondering if it
could become the King on the Bench or just a nice museum piece.

BTW, I am using now the 2230 and 485 as main scopes, and a 7000 series
tower (in a wheel cart) for other uses.

Best regards,

JOSE

--
----------------------------------------------------------------------
73 EB5AGV / EC5AAU - JOSE V. GAVILA
La Canyada - Valencia (SPAIN)

Vintage Radio: http://jvgavila.com
Vintage Test Equipment: http://jvgavila.com/testeq.htm

 

[Jim Yanik]

"Jose V. Gavila" <eb5agv@ctv.es> wrote in news:406472A4.4090607@ctv.es:

Hello Jim,

Thanks for your comments!

Jim Yanik wrote:
I don't believe that TEK bothered to find out why the U800 IC's were
failing.all they knew is that they couldn't get new ones made,and
that the 2400 series was a dead duck.

Unless you get a number of failed ICs,open them up and check them
with an electron microscope,you probably will not really know the
true reason they failed.It could be process contamination at some
construction step,poor architecture,marginal IC feature
geometries,static damage,......

Well, so what do you think about buying a 2465 scope?. Is it too
risky?. Would you prefer to get, let's say, a 485?

Best regards,

JOSE

AACK! I'd stay away from a 485;the switching PS is a ton of problems.
I'd much prefer the 2465.It's the best portable analog scope TEK ever made.
It saddens me to think about all the 2400s with bad Horiz output IC's now
useless.I'd say if the scope has operated for this amount of time,it would
be a fair risk to buy one.

--
Jim Yanik
jyanik-at-kua.net

 

[Jim Yanik]

mike <spamme0@juno.com> wrote in news:40647D5B.1010007@juno.com:

Jose V. Gavila wrote:
Hello Jim,

Thanks for your comments!

Jim Yanik wrote:

I don't believe that TEK bothered to find out why the U800 IC's were
failing.all they knew is that they couldn't get new ones made,and
that the 2400 series was a dead duck.
Unless you get a number of failed ICs,open them up and check them
with an electron microscope,you probably will not really know the
true reason they failed.It could be process contamination at some
construction step,poor architecture,marginal IC feature
geometries,static damage,......


Well, so what do you think about buying a 2465 scope?. Is it too
risky?. Would you prefer to get, let's say, a 485?

Price matters...A LOT!!! If you have the space, get a 7704. If you
stand around long enough, someone will give you one...and a second one
for spare parts. To get a 485, you're gonna have to compete with the
rest of the world and pay money. ;-)
mike

Make that a 7704A,the 7704 is an older,less reliable scope.Or best to get a
7904 or 7904A and 7A29 verticals for the full BW.(7A24 as next-best)

--
Jim Yanik
jyanik-at-kua.net

 

[Jim Yanik]

"Jose V. Gavila" <eb5agv@ctv.es> wrote in news:40649D31.1070405@ctv.es:

Hello Walter,

Walter Harley wrote:
The bottom line seems to be that many people, including many on this
group (including me) have got 2465's and use them and love them. As
you suggest, the failure doesn't seem to be so widespread that the
scopes have all died.

I bet my 2465A will still be going strong when all the TDSxxx folks
can no longer get replacement modules. If I find another scope
that's got a working U800 in it, maybe I'll buy it as an insurance
policy - two used 2465's would still be cheaper than a new scope of
comparable quality and usefulness.

This is what I wanted to hear ;-)!. There is some hope a 2465 _could_
last some time.

In my small test equipment collection, I have several 7000 series
mainframes (7704, 7633 (2), 7603, R7603) and also some 4xx units (475,
466/DM44, 485). Also a venerable 545B (and a Lavoie clone of the
545A!). Recently, I got a 2230. And, just a couple days ago, I could
not pass a 2465DMM for just US$400.

Sounds like a museum collection!

That's a great price on the 2465DMM,too.
Did you get the service manuals for the options?

But some weeks ago, a friend asked me about repairing a 2465... which
seems to have a blown U800. I have not a complete Service Manual for
it, just a partial copy (without schematics) but I am pretty sure it
had that fault.

So, now that I have decided to go for a 2465, I was wondering if it
could become the King on the Bench or just a nice museum piece.

BTW, I am using now the 2230 and 485 as main scopes, and a 7000 series
tower (in a wheel cart) for other uses.

Best regards,

JOSE

The 7000 series scopes are far more versatile than portable scopes.
2 Differential PI's,a curve tracer;7CT1N,3 Spectrum analyzer PIs;all very
useful.

--
Jim Yanik
jyanik-at-kua.net

 

[mike]

Jim Yanik wrote:

mike <spamme0@juno.com> wrote in news:40647D5B.1010007@juno.com:


Jose V. Gavila wrote:

Hello Jim,

Thanks for your comments!

Jim Yanik wrote:


I don't believe that TEK bothered to find out why the U800 IC's were
failing.all they knew is that they couldn't get new ones made,and
that the 2400 series was a dead duck.
Unless you get a number of failed ICs,open them up and check them
with an electron microscope,you probably will not really know the
true reason they failed.It could be process contamination at some
construction step,poor architecture,marginal IC feature
geometries,static damage,......


Well, so what do you think about buying a 2465 scope?. Is it too
risky?. Would you prefer to get, let's say, a 485?

Price matters...A LOT!!! If you have the space, get a 7704. If you
stand around long enough, someone will give you one...and a second one
for spare parts. To get a 485, you're gonna have to compete with the
rest of the world and pay money. ;-)
mike




Make that a 7704A,the 7704 is an older,less reliable scope.Or best to get a
7904 or 7904A and 7A29 verticals for the full BW.(7A24 as next-best)

I suppose...
I don't think I've ever seen a non-A 7704. Maybe they've all died.
What part of FREE are we not understanding? A FREE 7704 (A or non-A)
is better than most anything else I could imagine that was NOT free ;-)
I once had to pay $25 for a working 2465. Almost didn't buy it...too
expensive.
mike

--
Return address is VALID.
Bunch of stuff For Sale and Wanted at the link below.
Toshiba & Compaq LiIon Batteries, Test Equipment
Honda CB-125S $800 in PDX
Yaesu FTV901R Transverter, 30pS pulser
Tektronix Concept Books, spot welding head...
http://www.geocities.com/SiliconValley/Monitor/4710/

 

[Jim Yanik]

mike <spamme0@juno.com> wrote in news:40654656.4090602@juno.com:

Jim Yanik wrote:
mike <spamme0@juno.com> wrote in news:40647D5B.1010007@juno.com:


Jose V. Gavila wrote:

Hello Jim,

Thanks for your comments!

Jim Yanik wrote:


I don't believe that TEK bothered to find out why the U800 IC's
were failing.all they knew is that they couldn't get new ones
made,and that the 2400 series was a dead duck.
Unless you get a number of failed ICs,open them up and check them
with an electron microscope,you probably will not really know the
true reason they failed.It could be process contamination at some
construction step,poor architecture,marginal IC feature
geometries,static damage,......


Well, so what do you think about buying a 2465 scope?. Is it too
risky?. Would you prefer to get, let's say, a 485?

Price matters...A LOT!!! If you have the space, get a 7704. If you
stand around long enough, someone will give you one...and a second
one for spare parts. To get a 485, you're gonna have to compete with
the rest of the world and pay money. ;-)
mike




Make that a 7704A,the 7704 is an older,less reliable scope.Or best to
get a 7904 or 7904A and 7A29 verticals for the full BW.(7A24 as
next-best)


I suppose...
I don't think I've ever seen a non-A 7704.

They were of the same construction as of 7504's.
(and 7503,and the 7514 storage monster)
There also was a 7403,and 7413 (storage) scope.

I would not have any of those,free,or not.

Maybe they've all died.

What part of FREE are we not understanding? A FREE 7704 (A or non-A)
is better than most anything else I could imagine that was NOT free
;-) I once had to pay $25 for a working 2465. Almost didn't buy
it...too expensive.
mike

True,one cannot beat free. (depends on what condition the 7704 is in,too)

Although a 'free' 500 series tube scope would not be any great gift. ;-)

--
Jim Yanik
jyanik-at-kua.net

 

[Jose V. Gavila]

Hello Jim,

Jim Yanik wrote:

In my small test equipment collection, I have several 7000 series
mainframes (7704, 7633 (2), 7603, R7603) and also some 4xx units (475,
466/DM44, 485). Also a venerable 545B (and a Lavoie clone of the
545A!). Recently, I got a 2230. And, just a couple days ago, I could
not pass a 2465DMM for just US$400.

Sounds like a museum collection!

Well, more or less. By the way, I have a 7704A, not a plain 7704, as I
wrote. I remembered it was not the last 7704 version but it is in fact a
low S/N 7704A.

That's a great price on the 2465DMM,too.
Did you get the service manuals for the options?

No, in fact I have not any service manual for the 2465. I like to have
manuals for all the test and radio gear I own (so my library is getting
large!), but in this case I still need to locate suitable manuals. In
case somebody has them in PDF, I have lots of manuals to swap.

The 7000 series scopes are far more versatile than portable scopes.
2 Differential PI's,a curve tracer;7CT1N,3 Spectrum analyzer PIs;all very
useful.

I have a 7CT1N and it is very nice. About spectrum analyzers, I got some
HP140 series plug-ins (8552B (3), 8553L, 8553B, 8554B, 8556A) and a
couple mainframes (140T and 141A) and they fulfill my needs now... but,
of course, I would love to have some 7L plug-ins !

Yes, I think the test-equipment bug has bitten me... check my WEB
(http://jvgavila.com/testeq.htm) for details !

Regards,

JOSE

--
----------------------------------------------------------------------
73 EB5AGV / EC5AAU - JOSE V. GAVILA
La Canyada - Valencia (SPAIN)

Vintage Radio: http://jvgavila.com
Vintage Test Equipment: http://jvgavila.com/testeq.htm

 

[Jose V. Gavila]

Hello!

Jim Yanik wrote:

AACK! I'd stay away from a 485;the switching PS is a ton of problems.
I'd much prefer the 2465.It's the best portable analog scope TEK ever made.
It saddens me to think about all the 2400s with bad Horiz output IC's now
useless.I'd say if the scope has operated for this amount of time,it would
be a fair risk to buy one.

My unit was bought for the incredible sum of 50 UK Pounds (+shipping to
Spain). It was a non-working unit, of course. But finally failure was
just a broken power button plastic extension and a missing tunnel diode,
which was replaced with an original unit. Later I found that one of the
attenuators was damaged so I got also a replacement. But, all in all, I
like that scope and, for me, is a keeper.

Regards,

JOSE

--
----------------------------------------------------------------------
73 EB5AGV / EC5AAU - JOSE V. GAVILA
La Canyada - Valencia (SPAIN)

Vintage Radio: http://jvgavila.com
Vintage Test Equipment: http://jvgavila.com/testeq.htm

 

[Jeff W]

My personal experience is with an early 2465, I don't remember the
serial but it was around 20K or so. After sitting for perhaps 4
months of non-use, I turned it on and it ran for maybe one minute
before the readout started jumping, then flashing, then all display
was lost. For the next few times I turned it on, it would run for
maybe 30 seconds before losing the display. Pressing the beam find
button resulted in a minature display in the center of the screen,
which was wobbly & jumpy.

On investigation, the electrical failure seems to be that one of the
diff plate drive outputs of the U800 chip developed an internal
leakage path to its respective voltage rail, thereby pulling the
horizontal display off hard to one side.

Given that the scope was sitting for a long time, and developed the
fault early on start up, I don't think the primary failure mechanism
was due to heat. ( although it could have been weakened seriously by
past heat events, of course) So it appears to me that time alone may
be a key factor, which means that keeping your 2465 cool, using it
sparingly, etc, may not be a strategy that will preserve it in the
long run.

I really like 2465's, excellent performing scopes, but sold both my
2465's as a precaution.

Jeff

On Fri, 26 Mar 2004 15:10:10 +0100, "Jose V. Gavila" <eb5agv@ctv.es>
wrote:

Hello!

After reading lots of old messages regarding Tektronix 24xx problems
(mainly on 2465 variants) with the dreaded U800 Horizontal Amplifier, I
have not yet found any definitive (if there is one ;-) ) answer to why
do they fail and the correlation with oscilloscope types, U800 reference
and failure rate.

I guess it could fail more in later units (2465A and B), as they have
perhaps higher requirements on the chip... but I am just guessing.

So I wonder if you could help me correlating all that information. I
think it would be fine to get info also on working units.

* Type (2465, 2465A, 2465B, 2445, ...)
* U800 reference (155-0241-01, 155-0241-02 or 155-0241-55, if known)
* Manufacture date (if known) or serial number (just first digits)
* If U800 is gone, how did it fail? (i.e. heat related (after long time
use), just after powering on?)
* Comments


Hope this helps to clarify a bit this recursive topic.

Thanks for your help and best regards,

JOSE

 

[Jamie]

i own a 485 scope. does that make me old?
i also have a 465 and not sure about the specs on that one how ever.
all i know it works.



Jeff W wrote:

My personal experience is with an early 2465, I don't remember the
serial but it was around 20K or so. After sitting for perhaps 4
months of non-use, I turned it on and it ran for maybe one minute
before the readout started jumping, then flashing, then all display
was lost. For the next few times I turned it on, it would run for
maybe 30 seconds before losing the display. Pressing the beam find
button resulted in a minature display in the center of the screen,
which was wobbly & jumpy.

On investigation, the electrical failure seems to be that one of the
diff plate drive outputs of the U800 chip developed an internal
leakage path to its respective voltage rail, thereby pulling the
horizontal display off hard to one side.

Given that the scope was sitting for a long time, and developed the
fault early on start up, I don't think the primary failure mechanism
was due to heat. ( although it could have been weakened seriously by
past heat events, of course) So it appears to me that time alone may
be a key factor, which means that keeping your 2465 cool, using it
sparingly, etc, may not be a strategy that will preserve it in the
long run.

I really like 2465's, excellent performing scopes, but sold both my
2465's as a precaution.

Jeff

On Fri, 26 Mar 2004 15:10:10 +0100, "Jose V. Gavila" <eb5agv@ctv.es
wrote:


Hello!

After reading lots of old messages regarding Tektronix 24xx problems
(mainly on 2465 variants) with the dreaded U800 Horizontal Amplifier, I
have not yet found any definitive (if there is one ;-) ) answer to why
do they fail and the correlation with oscilloscope types, U800 reference
and failure rate.

I guess it could fail more in later units (2465A and B), as they have
perhaps higher requirements on the chip... but I am just guessing.

So I wonder if you could help me correlating all that information. I
think it would be fine to get info also on working units.

* Type (2465, 2465A, 2465B, 2445, ...)
* U800 reference (155-0241-01, 155-0241-02 or 155-0241-55, if known)
* Manufacture date (if known) or serial number (just first digits)
* If U800 is gone, how did it fail? (i.e. heat related (after long time
use), just after powering on?)
* Comments


Hope this helps to clarify a bit this recursive topic.

Thanks for your help and best regards,

JOSE

 

[Jim Adney]

On Sun, 28 Mar 2004 14:01:54 -0800 Jamie
<jamie_5_not_valid_after_5_Please@charter.net> wrote:

i own a 485 scope. does that make me old?
i also have a 465 and not sure about the specs on that one how ever.
all i know it works.

The 465 is a 100 MHz scope.
The 485 is a 350 MHz scope.

Both are very nice scopes, but the 485 has a power supply that is
often a pain to troubleshoot and repair. The good news is that repair
usually requires easy to get parts.

-
-----------------------------------------------
Jim Adney jadney@vwtype3.org
Madison, WI 53711 USA
-----------------------------------------------

 

[TekMan]

Jim Yanik <jyanik@abuse.gov> wrote in message news:<Xns94B97D5607A1jyanikkuanet@204.117.192.21>...

mike <spamme0@juno.com> wrote in news:40654656.4090602@juno.com:

Jim Yanik wrote:
mike <spamme0@juno.com> wrote in news:40647D5B.1010007@juno.com:


Jose V. Gavila wrote:

Hello Jim,

Thanks for your comments!

Jim Yanik wrote:


I don't believe that TEK bothered to find out why the U800 IC's
were failing.all they knew is that they couldn't get new ones
made,and that the 2400 series was a dead duck.
Unless you get a number of failed ICs,open them up and check them
with an electron microscope,you probably will not really know the
true reason they failed.It could be process contamination at some
construction step,poor architecture,marginal IC feature
geometries,static damage,......


Well, so what do you think about buying a 2465 scope?. Is it too
risky?. Would you prefer to get, let's say, a 485?

Price matters...A LOT!!! If you have the space, get a 7704. If you
stand around long enough, someone will give you one...and a second
one for spare parts. To get a 485, you're gonna have to compete with
the rest of the world and pay money. ;-)
mike




Make that a 7704A,the 7704 is an older,less reliable scope.Or best to
get a 7904 or 7904A and 7A29 verticals for the full BW.(7A24 as
next-best)


I suppose...
I don't think I've ever seen a non-A 7704.

They were of the same construction as of 7504's.
(and 7503,and the 7514 storage monster)
There also was a 7403,and 7413 (storage) scope.

I would not have any of those,free,or not.

Maybe they've all died.

you can see them turn-up in ebay occasionally. Most of them have been
decribed as defective

What part of FREE are we not understanding? A FREE 7704 (A or non-A)
is better than most anything else I could imagine that was NOT free
;-) I once had to pay $25 for a working 2465. Almost didn't buy
it...too expensive.
mike


True,one cannot beat free. (depends on what condition the 7704 is in,too)

ACK. But since even for hobby use the scope should be in working
condition, the question of maintenance and where to get spare parts
makes even "free" a costy gift.

Although a 'free' 500 series tube scope would not be any great gift. ;-)

Well, but it a good alternative for a visit to the gym: Lift the 500
ten times per day from first to third floor, and see your muscles grew
)

scnr,
andreas

 

[TekMan]

"Jose V. Gavila" <eb5agv@ctv.es> wrote in message news:<40661248.4040009@ctv.es>...

Hello!

Jim Yanik wrote:
AACK! I'd stay away from a 485;the switching PS is a ton of problems.
I'd much prefer the 2465.It's the best portable analog scope TEK ever made.
It saddens me to think about all the 2400s with bad Horiz output IC's now
useless.I'd say if the scope has operated for this amount of time,it would
be a fair risk to buy one.

My unit was bought for the incredible sum of 50 UK Pounds (+shipping to
Spain). It was a non-working unit, of course. But finally failure was
just a broken power button plastic extension and a missing tunnel diode,
which was replaced with an original unit. Later I found that one of the
attenuators was damaged so I got also a replacement. But, all in all, I
like that scope and, for me, is a keeper.

well, don't all we hobbyists like to keep the goodies we managed to
repair?
But that's okay, because even thirty year old equipment can do a great
job in your home lab.

But I agree with jim: the 2465a/b are "must have" today if you wanna
do real good job in the home lab.

Andreas

 

[mike]

TekMan wrote:

But I agree with jim: the 2465a/b are "must have" today if you wanna
do real good job in the home lab.

Andreas

I suppose you could come up with an application that could only be done
with a 2465, but you'd have to try really hard. "Must have" is a bit of
a reach.
I had one for two years. Couldn't justify the bench space and never
had occasion to take it out of the closet. If you don't need the
portability (home lab), a 7704A is MUCH greater bang for the buck.

mike




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