I have the opportunity to purchase a Tektronix 2445 4-channel 150 MHz
oscilloscope with 2 probes and the user manual from a friend for $250.
While I believe this is a good deal, I'm concerned about two issues.

1) The second channel is slightly noisy - perhaps a tenth of a division
of something that looks like a logic signal. Just enough to notice.

2) Per UseNet searches, there appear to be known problems with some
custom chips failing (like the U800 horizontal amp chip) in the 2445. The
chips are no longer available and can only be had by scavenging scrap
scopes of the same series.

Is anyone familiar with the "slightly noisy" channel problem described
above? It is probably something I can learn to live with if it is not
relatively easy to fix.

What is the reliability of the 2445 with respect to the custom chip
failures?

I am an Amateur Radio operator and electronic hobbiest. The scope would
be used for troubleshooting radios and other equipment, aligning radios,
and furthering my eletronics knowledge. I was initially planning on
hunting-down a Tektronix 2236 because of its automatic counter/DMM
functionality when I became aware of my friend's 2445. I really like the
2236's counter/DMM functionality. However, the current state of the 2245
is a known quantity whereas I can't be too sure what I'll get in the way
of a 2236 off of Ebay or a classifieds site.

Any and all input would be appreciated!

-Michael, N9BDF,

"Michael J. Linden, N9BDF" wrote in
:

I have the opportunity to purchase a Tektronix 2445 4-channel 150
MHz
oscilloscope with 2 probes and the user manual from a friend for $250.
While I believe this is a good deal,

Yes,IMO,it is.

I'm concerned about two issues.

1) The second channel is slightly noisy - perhaps a tenth of a
division of something that looks like a logic signal. Just enough to
notice.

Could be bad decoupling caps, a bad Ch.2 input hybrid,a bad BNC.Even a
loose or missing ground screw.

2) Per UseNet searches, there appear to be known problems with some
custom chips failing (like the U800 horizontal amp chip) in the 2445.
The chips are no longer available and can only be had by scavenging
scrap scopes of the same series.

Is anyone familiar with the "slightly noisy" channel problem
described
above? It is probably something I can learn to live with if it is not
relatively easy to fix.

What is the reliability of the 2445 with respect to the custom chip
failures?

You pay your money,you takes your chances.Some older scopes had Horizontal
ICs that never failed,and are still working fine,some 2400 scopes got the
IC replaced and worked fine ever since,and some went thru IC's again and
again;it was never traced down to any batch problems,no specific IC numbers
to avoid.
Somem people have added heat sinks to keep the IC cooler under the premise
that heat is bad for ICs.It certainly cannot hurt,if installed
right(attention to cabinet clearance and isolation)


I am an Amateur Radio operator and electronic hobbiest. The scope
would
be used for troubleshooting radios and other equipment, aligning
radios, and furthering my eletronics knowledge. I was initially
planning on hunting-down a Tektronix 2236 because of its automatic
counter/DMM functionality when I became aware of my friend's 2445. I
really like the 2236's counter/DMM functionality. However, the current
state of the 2245 is a known quantity whereas I can't be too sure what
I'll get in the way of a 2236 off of Ebay or a classifieds site.

Any and all input would be appreciated!

-Michael, N9BDF,




I would avoid 2245 series scopes. 2213/15/35/36 series are OK,but not the
2245/46/47's.

2236 is passably OK,but for a counter or DMM,I'd rather have a separate
one(better performance).

--
Jim Yanik
jyanik
at
kua.net

Whoops! I never meant to refer to the 2245 (below) -- I really meant the
2445

"However, the current state of the 2245 is a known quantity whereas I can't
be too sure what I'll get in the way of a 2236 off of Ebay or a classifieds
site."

From your perspective, what makes the 2445 a better scope than the 2236,
aside from the number of channels and bandwidth?

Thanks, Michael


In article , .
says...


"Michael J. Linden, N9BDF" wrote in
:

I have the opportunity to purchase a Tektronix 2445 4-channel 150
MHz
oscilloscope with 2 probes and the user manual from a friend for $250.
While I believe this is a good deal,

Yes,IMO,it is.

I'm concerned about two issues.

1) The second channel is slightly noisy - perhaps a tenth of a
division of something that looks like a logic signal. Just enough to
notice.

Could be bad decoupling caps, a bad Ch.2 input hybrid,a bad BNC.Even a
loose or missing ground screw.

2) Per UseNet searches, there appear to be known problems with some
custom chips failing (like the U800 horizontal amp chip) in the 2445.
The chips are no longer available and can only be had by scavenging
scrap scopes of the same series.

Is anyone familiar with the "slightly noisy" channel problem
described
above? It is probably something I can learn to live with if it is not
relatively easy to fix.

What is the reliability of the 2445 with respect to the custom chip
failures?

You pay your money,you takes your chances.Some older scopes had Horizontal
ICs that never failed,and are still working fine,some 2400 scopes got the
IC replaced and worked fine ever since,and some went thru IC's again and
again;it was never traced down to any batch problems,no specific IC numbers
to avoid.
Somem people have added heat sinks to keep the IC cooler under the premise
that heat is bad for ICs.It certainly cannot hurt,if installed
right(attention to cabinet clearance and isolation)


I am an Amateur Radio operator and electronic hobbiest. The scope
would
be used for troubleshooting radios and other equipment, aligning
radios, and furthering my eletronics knowledge. I was initially
planning on hunting-down a Tektronix 2236 because of its automatic
counter/DMM functionality when I became aware of my friend's 2445. I
really like the 2236's counter/DMM functionality. However, the current
state of the 2245 is a known quantity whereas I can't be too sure what
I'll get in the way of a 2236 off of Ebay or a classifieds site.

Any and all input would be appreciated!

-Michael, N9BDF,




I would avoid 2245 series scopes. 2213/15/35/36 series are OK,but not the
2245/46/47's.

2236 is passably OK,but for a counter or DMM,I'd rather have a separate
one(better performance).

--
Jim Yanik
jyanik
at
kua.net

"Michael J. Linden, N9BDF" wrote in
:

Whoops! I never meant to refer to the 2245 (below) -- I really meant
the
2445

"However, the current state of the 2245 is a known quantity whereas I
can't
be too sure what I'll get in the way of a 2236 off of Ebay or a
classifieds site."

From your perspective, what makes the 2445 a better scope than the
2236,
aside from the number of channels and bandwidth?

Thanks, Michael


2445/65 series scopes were the most accurate analog scopes made.Better
triggering.It has nifty cursor measurement modes,too.The 2445/65 series
were essentially lab quality portable scopes.They were meant as a
replacement for the 485,with added features.

There also were some very useful options,and the counter-timer option was
more accurate than the counter in the 2236. The 2245/65 DMM option was far
better than the 2236 DMM. 2445/65 had a TV trigger option with line
counting.When it concerns counters,one has to consider the time-base
accuracy,otherwise all those digits are meaningless.


The 2200 series was intended as low-cost,high production volume scope,with
poorer triggering than a 465/475 series scope. The DMM counter module was
for field service people so they would not have to carry a DMM and a
counter with the scope,reducing their equipment load,reminiscent of the 213
1Mhz portable scope/DMM,but muuch more useable.
--
Jim Yanik
jyanik
at
kua.net