|
Hello, I've seen a 7704A, the seller is selling it as
non working unit, he has no plugins, so simply powered it up.
He says that the scope powers up and it's visible the point
on the screen, the intensity control doesnt work.
A pair of questions:
should this mainframe show a point without plugins installed?
Will be it easy to repair in case of major failures?
(at least the tube seem to be working ok).
I have an R7103, since I started using it I decided that I'll
use the 7000 series as main scope, it's like driving a luxury
car, it can be old, but it's a joy to drive.
Also someone said that nobody is known to have lived long owning
only one 7k mainframe, so... :)
I dont want to stress the 7103 tube, it will be used only
when needed (rarely) so now I'm searching for an everyday scope.
I'd like good screen with a well defined trace.
Will be used with a pair of 7A26 and or 7A22 and I'm searching
a 7A13 also.
I'm considering also a 7844 (I like the "dual scope in one" concept)
but it is much more costly. If the 7704A is able to use most of the
bw of the 7A26 and 7A13 with a pleasant trace I'll go
for it, what do you think?
Fabio.
|
On Wed, 27 Jun 2012 17:30:49 -0000, "fabio_tele" <fabioeb@...> wrote: Hello, I've seen a 7704A, the seller is selling it as
non working unit, he has no plugins, so simply powered it up.
He says that the scope powers up and it's visible the point
on the screen, the intensity control doesnt work. Almost all of my 7000 series oscilloscopes had intensity control problems before I disassembled, cleaned, and lubricated the intensity control potentiometers. A pair of questions:
should this mainframe show a point without plugins installed?
Will be it easy to repair in case of major failures?
(at least the tube seem to be working ok). I would expect it to but I just tested a working 7834 and 7904. Without any plug-ins, they do not display a dot. With one plug-in, one axis was moved to be visible but the other was still off screen. I have an R7103, since I started using it I decided that I'll
use the 7000 series as main scope, it's like driving a luxury
car, it can be old, but it's a joy to drive.
Also someone said that nobody is known to have lived long owning
only one 7k mainframe, so... :)
I dont want to stress the 7103 tube, it will be used only
when needed (rarely) so now I'm searching for an everyday scope.
I'd like good screen with a well defined trace.
Will be used with a pair of 7A26 and or 7A22 and I'm searching
a 7A13 also.
I'm considering also a 7844 (I like the "dual scope in one" concept)
but it is much more costly. If the 7704A is able to use most of the
bw of the 7A26 and 7A13 with a pleasant trace I'll go
for it, what do you think? I am not sure about the differences and desirability between the 7704, 7704A, 7904, and 7904A. Of those, I just recently acquired a 7904. I understand the advantages of the 7844 but I am not convinced the extra complexity is worth it except in very special cases.
|
The 7844 is a great scope (I have a bunch of them), but unless you use it all the time and fully understand how to set it up, it can be confusing- too many ways to configure the signals.
?
As to the differences between the non-A and -A scopes, I've found the -A units more reliable (especially the power supplies)?and easier to work on.
?
If you really like fine traces, consider a 5xx series tube scope.? They have much nicer displays.
?
-Dave
From: "David" To: TekScopes@... Sent: Wednesday, June 27, 2012 12:10:23 PM Subject: Re: [TekScopes] 7704A, should I go for it?
?
On Wed, 27 Jun 2012 17:30:49 -0000, "fabio_tele" <fabioeb@...>
wrote:
>Hello, I've seen a 7704A, the seller is selling it as
>non working unit, he has no plugins, so simply powered it up.
>He says that the scope powers up and it's visible the point
>on the screen, the intensity control doesnt work.
Almost all of my 7000 series oscilloscopes had intensity control
problems before I disassembled, cleaned, and lubricated the intensity
control potentiometers.
>A pair of questions:
>should this mainframe show a point without plugins installed?
>Will be it easy to repair in case of major failures?
>(at least the tube seem to be working ok).
I would expect it to but I just tested a working 7834 and 7904.
Without any plug-ins, they do not display a dot. With one plug-in,
one axis was moved to be visible but the other was still off screen.
>I have an R7103, since I started using it I decided that I'll
>use the 7000 series as main scope, it's like driving a luxury
>car, it can be old, but it's a joy to drive.
>Also someone said that nobody is known to have lived long owning
>only one 7k mainframe, so... :)
>I dont want to stress the 7103 tube, it will be used only
>when needed (rarely) so now I'm searching for an everyday scope.
>I'd like good screen with a well defined trace.
>Will be used with a pair of 7A26 and or 7A22 and I'm searching
>a 7A13 also.
>
>I'm considering also a 7844 (I like the "dual scope in one" concept)
>but it is much more costly. If the 7704A is able to use most of the
>bw of the 7A26 and 7A13 with a pleasant trace I'll go
>for it, what do you think?
I am not sure about the differences and desirability between the 7704,
7704A, 7904, and 7904A. Of those, I just recently acquired a 7904. I
understand the advantages of the 7844 but I am not convinced the extra
complexity is worth it except in very special cases.
|
The one big difference I did notice between the 7904 and my other 7000
oscilloscopes is that it has no fan so is completely silent.
toggle quoted message
Show quoted text
On Wed, 27 Jun 2012 20:31:46 +0000 (UTC), d.seiter@... wrote: The 7844 is a great scope (I have a bunch of them), but unless you use it all the time and fully understand how to set it up, it can be confusing- too many ways to configure the signals .
As to the differences between the non-A and -A scopes, I've found the -A units more reliable (especially the power supplies) ?and easier to work on.
If you really like fine traces, consider a 5xx series tube scope.? They have much nicer displays.
-Dave
----- Original Message -----
From: "David" <davidwhess@...>
To: TekScopes@...
Sent: Wednesday, June 27, 2012 12:10:23 PM
Subject: Re: [TekScopes] 7704A, should I go for it?
?
On Wed, 27 Jun 2012 17:30:49 -0000, "fabio_tele" < fabioeb@... >
wrote:
Hello, I've seen a 7704A, the seller is selling it as
non working unit, he has no plugins, so simply powered it up.
He says that the scope powers up and it's visible the point
on the screen, the intensity control doesnt work. Almost all of my 7000 series oscilloscopes had intensity control
problems before I disassembled, cleaned, and lubricated the intensity
control potentiometers.
A pair of questions:
should this mainframe show a point without plugins installed?
Will be it easy to repair in case of major failures?
(at least the tube seem to be working ok). I would expect it to but I just tested a working 7834 and 7904.
Without any plug-ins, they do not display a dot. With one plug-in,
one axis was moved to be visible but the other was still off screen.
I have an R7103, since I started using it I decided that I'll
use the 7000 series as main scope, it's like driving a luxury
car, it can be old, but it's a joy to drive.
Also someone said that nobody is known to have lived long owning
only one 7k mainframe, so... :)
I dont want to stress the 7103 tube, it will be used only
when needed (rarely) so now I'm searching for an everyday scope.
I'd like good screen with a well defined trace.
Will be used with a pair of 7A26 and or 7A22 and I'm searching
a 7A13 also.
I'm considering also a 7844 (I like the "dual scope in one" concept)
but it is much more costly. If the 7704A is able to use most of the
bw of the 7A26 and 7A13 with a pleasant trace I'll go
for it, what do you think? I am not sure about the differences and desirability between the 7704,
7704A, 7904, and 7904A. Of those, I just recently acquired a 7904. I
understand the advantages of the 7844 but I am not convinced the extra
complexity is worth it except in very special cases.
|
On 6/27/2012 4:31 PM, d.seiter@... wrote: The 7844 is a great scope (I have a bunch of them), but unless you use
it all the time and fully understand how to set it up, it can be
confusing- too many ways to configure the signals.
As to the differences between the non-A and -A scopes, I've found the -A
units more reliable (especially the power supplies) and easier to work on.
If you really like fine traces, consider a 5xx series tube scope. They
have much nicer displays. Hello, Dave and the group-- 5xx scopes, indeed... I worked with a tech who swore that he could enjoy a really good shave with the trace of a 547's CRT <g>. 73-- Brad AA1IP
|
The 7704A is fan-free too... except for one I have which also has "focused vent holes" on the side panels, similar to the 7104, etc.? I've been told the 7704A never had a fan, but this one looks like it came from the factory.
?
-Dave
From: "David" To: TekScopes@... Sent: Wednesday, June 27, 2012 1:50:41 PM Subject: Re: [TekScopes] 7704A, should I go for it?
?
The one big difference I did notice between the 7904 and my other 7000
oscilloscopes is that it has no fan so is completely silent.
On Wed, 27 Jun 2012 20:31:46 +0000 (UTC), d.seiter@... wrote:
>The 7844 is a great scope (I have a bunch of them), but unless you use it all the time and fully understand how to set it up, it can be confusing- too many ways to configure the signals .
>
>As to the differences between the non-A and -A scopes, I've found the -A units more reliable (especially the power supplies) ?and easier to work on.
>
>If you really like fine traces, consider a 5xx series tube scope.? They have much nicer displays.
>
>-Dave
>
>----- Original Message -----
>
>
>From: "David" <davidwhess@...>
>To: TekScopes@...
>Sent: Wednesday, June 27, 2012 12:10:23 PM
>Subject: Re: [TekScopes] 7704A, should I go for it?
>
>?
>
>
>
>
>On Wed, 27 Jun 2012 17:30:49 -0000, "fabio_tele" < fabioeb@... >
>wrote:
>
>>Hello, I've seen a 7704A, the seller is selling it as
>>non working unit, he has no plugins, so simply powered it up.
>>He says that the scope powers up and it's visible the point
>>on the screen, the intensity control doesnt work.
>
>Almost all of my 7000 series oscilloscopes had intensity control
>problems before I disassembled, cleaned, and lubricated the intensity
>control potentiometers.
>
>>A pair of questions:
>>should this mainframe show a point without plugins installed?
>>Will be it easy to repair in case of major failures?
>>(at least the tube seem to be working ok).
>
>I would expect it to but I just tested a working 7834 and 7904.
>Without any plug-ins, they do not display a dot. With one plug-in,
>one axis was moved to be visible but the other was still off screen.
>
>>I have an R7103, since I started using it I decided that I'll
>>use the 7000 series as main scope, it's like driving a luxury
>>car, it can be old, but it's a joy to drive.
>>Also someone said that nobody is known to have lived long owning
>>only one 7k mainframe, so... :)
>>I dont want to stress the 7103 tube, it will be used only
>>when needed (rarely) so now I'm searching for an everyday scope.
>>I'd like good screen with a well defined trace.
>>Will be used with a pair of 7A26 and or 7A22 and I'm searching
>>a 7A13 also.
>>
>>I'm considering also a 7844 (I like the "dual scope in one" concept)
>>but it is much more costly. If the 7704A is able to use most of the
>>bw of the 7A26 and 7A13 with a pleasant trace I'll go
>>for it, what do you think?
>
>I am not sure about the differences and desirability between the 7704,
>7704A, 7904, and 7904A. Of those, I just recently acquired a 7904. I
>understand the advantages of the 7844 but I am not convinced the extra
>complexity is worth it except in very special cases.
|
Take my opinion with a grain of salt as I have been at this stuff less than
a year. Then again as with all things I jumped in with both feet....
In any event, I am working my way through refurbishing, etc. of several 7000
series scopes as a hobby. My favorites in order best to worst so far are
7844, 7904, 7834,7704A, 7613. Obviously all based on personal opinion and
preferences, etc. I will say however that the 7704A is indeed the easiest
to work on and understand, etc. Indeed if my goal was ease of maintenance
and extended mean time between failures (perceived failures not actual as I
do not have enough historical data for my MTBF to have any meaning).... The
7704A would lead the list...
Finally I cannot comment on the 5xx sharpness vs. any of the above examples
( they indeed are all I have experience with) . I will say however one of
the things I have started doing out of route is go through and replace the
electrolytic capacitors in the power supply and on the boards. I also clean
the pots and switches (pots on the front not all i.e. don¡¯t go tweaking pots
on the boards w/o reason but user accessible ones have been noisy so I clean
them with contact cleaner as recommended in this forum)..
I hope this helps. Concisely, a 7704A is a good choice for an everyday scope
and since you already have a 7103 you are well aware of the plug-ins, etc.
So I say "Go for It"
Rob<--who always finds it easy to spend others money *smile *
toggle quoted message
Show quoted text
-----Original Message----- From: TekScopes@... [mailto:TekScopes@...] On Behalf Of David Sent: Wednesday, June 27, 2012 3:51 PM To: TekScopes@... Subject: Re: [TekScopes] 7704A, should I go for it? The one big difference I did notice between the 7904 and my other 7000 oscilloscopes is that it has no fan so is completely silent. On Wed, 27 Jun 2012 20:31:46 +0000 (UTC), d.seiter@... wrote: The 7844 is a great scope (I have a bunch of them), but unless you use it all the time and fully understand how to set it up, it can be confusing- too many ways to configure the signals .
As to the differences between the non-A and -A scopes, I've found the -A
units more reliable (especially the power supplies) ?and easier to work on.
If you really like fine traces, consider a 5xx series tube scope.? They
have much nicer displays.
-Dave
----- Original Message -----
From: "David" <davidwhess@...>
To: TekScopes@...
Sent: Wednesday, June 27, 2012 12:10:23 PM
Subject: Re: [TekScopes] 7704A, should I go for it?
?
On Wed, 27 Jun 2012 17:30:49 -0000, "fabio_tele" < fabioeb@... >
wrote:
Hello, I've seen a 7704A, the seller is selling it as non working
unit, he has no plugins, so simply powered it up.
He says that the scope powers up and it's visible the point on the
screen, the intensity control doesnt work. Almost all of my 7000 series oscilloscopes had intensity control
problems before I disassembled, cleaned, and lubricated the intensity
control potentiometers.
A pair of questions:
should this mainframe show a point without plugins installed?
Will be it easy to repair in case of major failures?
(at least the tube seem to be working ok). I would expect it to but I just tested a working 7834 and 7904.
Without any plug-ins, they do not display a dot. With one plug-in, one
axis was moved to be visible but the other was still off screen.
I have an R7103, since I started using it I decided that I'll use the
7000 series as main scope, it's like driving a luxury car, it can be
old, but it's a joy to drive.
Also someone said that nobody is known to have lived long owning only
one 7k mainframe, so... :) I dont want to stress the 7103 tube, it
will be used only when needed (rarely) so now I'm searching for an
everyday scope.
I'd like good screen with a well defined trace.
Will be used with a pair of 7A26 and or 7A22 and I'm searching a 7A13
also.
I'm considering also a 7844 (I like the "dual scope in one" concept)
but it is much more costly. If the 7704A is able to use most of the bw
of the 7A26 and 7A13 with a pleasant trace I'll go for it, what do you
think? I am not sure about the differences and desirability between the 7704,
7704A, 7904, and 7904A. Of those, I just recently acquired a 7904. I
understand the advantages of the 7844 but I am not convinced the extra
complexity is worth it except in very special cases.
|
Sorry, I realized I did not finish the third paragraph. Tag this sentence on
the o the end of it:
Which invariably tightens up the trace and makes it sharper than it was
before I started...
And a final thought,,, If you go the direction of replacing caps. You will
not get by with 85F cheap caps. Take the time and do some research and find
good quality replacements or you won't get the results.
toggle quoted message
Show quoted text
-----Original Message----- From: TekScopes@... [mailto:TekScopes@...] On Behalf Of Rob Sent: Wednesday, June 27, 2012 7:39 PM To: TekScopes@... Subject: RE: [TekScopes] 7704A, should I go for it? Take my opinion with a grain of salt as I have been at this stuff less than a year. Then again as with all things I jumped in with both feet.... In any event, I am working my way through refurbishing, etc. of several 7000 series scopes as a hobby. My favorites in order best to worst so far are 7844, 7904, 7834,7704A, 7613. Obviously all based on personal opinion and preferences, etc. I will say however that the 7704A is indeed the easiest to work on and understand, etc. Indeed if my goal was ease of maintenance and extended mean time between failures (perceived failures not actual as I do not have enough historical data for my MTBF to have any meaning).... The 7704A would lead the list... Finally I cannot comment on the 5xx sharpness vs. any of the above examples ( they indeed are all I have experience with) . I will say however one of the things I have started doing out of route is go through and replace the electrolytic capacitors in the power supply and on the boards. I also clean the pots and switches (pots on the front not all i.e. don¡¯t go tweaking pots on the boards w/o reason but user accessible ones have been noisy so I clean them with contact cleaner as recommended in this forum).. I hope this helps. Concisely, a 7704A is a good choice for an everyday scope and since you already have a 7103 you are well aware of the plug-ins, etc. So I say "Go for It" Rob<--who always finds it easy to spend others money *smile * -----Original Message----- From: TekScopes@... [mailto:TekScopes@...] On Behalf Of David Sent: Wednesday, June 27, 2012 3:51 PM To: TekScopes@... Subject: Re: [TekScopes] 7704A, should I go for it? The one big difference I did notice between the 7904 and my other 7000 oscilloscopes is that it has no fan so is completely silent. On Wed, 27 Jun 2012 20:31:46 +0000 (UTC), d.seiter@... wrote: The 7844 is a great scope (I have a bunch of them), but unless you use
it all the time and fully understand how to set it up, it can be confusing- too many ways to configure the signals .
As to the differences between the non-A and -A scopes, I've found the
-A
units more reliable (especially the power supplies) ?and easier to work on.
If you really like fine traces, consider a 5xx series tube scope.? They
have much nicer displays.
-Dave
----- Original Message -----
From: "David" <davidwhess@...>
To: TekScopes@...
Sent: Wednesday, June 27, 2012 12:10:23 PM
Subject: Re: [TekScopes] 7704A, should I go for it?
?
On Wed, 27 Jun 2012 17:30:49 -0000, "fabio_tele" < fabioeb@... >
wrote:
Hello, I've seen a 7704A, the seller is selling it as non working
unit, he has no plugins, so simply powered it up.
He says that the scope powers up and it's visible the point on the
screen, the intensity control doesnt work. Almost all of my 7000 series oscilloscopes had intensity control
problems before I disassembled, cleaned, and lubricated the intensity
control potentiometers.
A pair of questions:
should this mainframe show a point without plugins installed?
Will be it easy to repair in case of major failures?
(at least the tube seem to be working ok). I would expect it to but I just tested a working 7834 and 7904.
Without any plug-ins, they do not display a dot. With one plug-in, one
axis was moved to be visible but the other was still off screen.
I have an R7103, since I started using it I decided that I'll use the
7000 series as main scope, it's like driving a luxury car, it can be
old, but it's a joy to drive.
Also someone said that nobody is known to have lived long owning only
one 7k mainframe, so... :) I dont want to stress the 7103 tube, it
will be used only when needed (rarely) so now I'm searching for an
everyday scope.
I'd like good screen with a well defined trace.
Will be used with a pair of 7A26 and or 7A22 and I'm searching a 7A13
also.
I'm considering also a 7844 (I like the "dual scope in one" concept)
but it is much more costly. If the 7704A is able to use most of the bw
of the 7A26 and 7A13 with a pleasant trace I'll go for it, what do you
think? I am not sure about the differences and desirability between the 7704,
7704A, 7904, and 7904A. Of those, I just recently acquired a 7904. I
understand the advantages of the 7844 but I am not convinced the extra
complexity is worth it except in very special cases.
------------------------------------ Yahoo! Groups Links
|
On Wed, 27 Jun 2012 19:38:48 -0500, "Rob" <rgwood@...> wrote: In any event, I am working my way through refurbishing, etc. of several 7000
series scopes as a hobby. My favorites in order best to worst so far are
7844, 7904, 7834,7704A, 7613. Obviously all based on personal opinion and
preferences, etc. I will say however that the 7704A is indeed the easiest
to work on and understand, etc. Indeed if my goal was ease of maintenance
and extended mean time between failures (perceived failures not actual as I
do not have enough historical data for my MTBF to have any meaning).... The
7704A would lead the list... I was surprised by the simplicity of the 7904 versus the 7834. It was mostly empty space inside but I should have expected that. Finally I cannot comment on the 5xx sharpness vs. any of the above examples
( they indeed are all I have experience with) . I will say however one of I have a 547 and while it is definitely sharper than my 7834, it would have to compare it side by side with my non-storage oscilloscopes to see much of a difference.
|
I have been using the Nichicon PW series as general replacements since they are inexpensive, long life, low impedance, and available up to 450 volts. Unfortunately I have found no equivalent axial leaded capacitor. I have seen some anomalies in my 7834 and in my 7904 which will probably lead me to changing all of the aluminum electrolytics in the power supplies. On Wed, 27 Jun 2012 19:52:42 -0500, "Rob" <rgwood@...> wrote: Sorry, I realized I did not finish the third paragraph. Tag this sentence on
the o the end of it:
Which invariably tightens up the trace and makes it sharper than it was
before I started...
And a final thought,,, If you go the direction of replacing caps. You will
not get by with 85F cheap caps. Take the time and do some research and find
good quality replacements or you won't get the results.
|
Thank you david and all for your opinions. Yesterday I had problems with personal email and send the messages using online yahoo form, but the second message seem that has gone lost, I cannot find it into the messages list. Anyway I was saying that the noise is important to me for an everyday scope, I was curious if there was a source where I can control if a mainframe has a fan or not. Also as for trace thickness, I prefer remain confined into the 7k series, the plugins flexibility is wondeful. I imagine that it's easier for a lower bandwidth to show a better defined trace, Is there any noticeable difference in the 7k series ? At the end I'll go for it, hoping that it will be an easy enough repair. Rob can you confirm if the 7704A shows any dot without plugins installed? Fabio. David <davidwhess@...> ha scritto: I have been using the Nichicon PW series as general replacements since
they are inexpensive, long life, low impedance, and available up to
450 volts. Unfortunately I have found no equivalent axial leaded ---------------------------------------------------------------- This message was sent using IMP, the Internet Messaging Program.
|
Re trace width- Most, if not all, of the 7K series scopes have an expansion mesh in the CRT which effectively blurs the trace to some degree. ?There has been some debate about whether a mesh-less design would be any sharper at the usually higher frequencies of the 7k scopes, but it's a moot point. Typically, looking at the same signal with a 547 and a 7704A, the 547 will be much sharper. ?From a previous post- Tek even spec'd the spot size of the 547 at .004".
Which reminds me; I still need to fire up my main 547 again to see if it's trace has returned. ?I wish days had 30 hours....
-Dave
From: "Fabio Eboli" To: TekScopes@... Sent: Thursday, June 28, 2012 12:21:22 AM Subject: Re: [TekScopes] 7704A, should I go for it?
?
Thank you david and all for your opinions.
Yesterday I had problems with personal email and
send the messages using online yahoo form, but the
second message seem that has gone lost, I cannot find
it into the messages list.
Anyway I was saying that the noise is important
to me for an everyday scope, I was curious if
there was a source where I can control if a mainframe
has a fan or not.
Also as for trace thickness, I prefer remain confined
into the 7k series, the plugins flexibility is wondeful.
I imagine that it's easier for a lower bandwidth to
show a better defined trace, Is there any noticeable
difference in the 7k series ?
At the end I'll go for it, hoping that it will be an
easy enough repair.
Rob can you confirm if the 7704A shows any dot without
plugins installed?
Fabio.
David <davidwhess@...> ha scritto:
> I have been using the Nichicon PW series as general replacements since
> they are inexpensive, long life, low impedance, and available up to
> 450 volts. Unfortunately I have found no equivalent axial leaded
----------------------------------------------------------
This message was sent using IMP, the Internet Messaging Program.
|
A "meshless" CRT would have to be much longer to achieve the same deflection (screen display size) at the bandwidths of the upper 7000 series. The fuzziness and other abberations due to the electron optics are annoying, but that's the tradeoff that was made. There's also more electronic noise as BW goes up, which would be unavoidable even without a mesh. I think the 7600 mainframes, being of much lower bandwidth, are meshless, allowing for much sharper traces and slightly bigger screens.
Ed
toggle quoted message
Show quoted text
--- In TekScopes@..., d.seiter@... wrote:
Re trace width- Most, if not all, of the 7K series scopes have an expansion mesh in the CRT which effectively blurs the trace to some degree. There has been some debate about whether a mesh-less design would be any sharper at the usually higher frequencies of the 7k scopes, but it's a moot point. Typically, looking at the same signal with a 547 and a 7704A, the 547 will be much sharper. From a previous post- Tek even spec'd the spot size of the 547 at .004".
Which reminds me; I still need to fire up my main 547 again to see if it's trace has returned. I wish days had 30 hours....
-Dave
----- Original Message -----
From: "Fabio Eboli" <fabioeb@...>
To: TekScopes@...
Sent: Thursday, June 28, 2012 12:21:22 AM
Subject: Re: [TekScopes] 7704A, should I go for it?
Thank you david and all for your opinions.
Yesterday I had problems with personal email and
send the messages using online yahoo form, but the
second message seem that has gone lost, I cannot find
it into the messages list.
Anyway I was saying that the noise is important
to me for an everyday scope, I was curious if
there was a source where I can control if a mainframe
has a fan or not.
Also as for trace thickness, I prefer remain confined
into the 7k series, the plugins flexibility is wondeful.
I imagine that it's easier for a lower bandwidth to
show a better defined trace, Is there any noticeable
difference in the 7k series ?
At the end I'll go for it, hoping that it will be an
easy enough repair.
Rob can you confirm if the 7704A shows any dot without
plugins installed?
Fabio.
David < davidwhess@... > ha scritto:
I have been using the Nichicon PW series as general replacements since
they are inexpensive, long life, low impedance, and available up to
450 volts. Unfortunately I have found no equivalent axial leaded ----------------------------------------------------------
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My 7603 (100 MHz) CRT has a lot of hours on it but comparing it to my faster 7000 series oscilloscopes, I find that the plug-in matters more than the mainframe as far as noise which is what I would expect. The 7A12 (100 MHz) and 7A18 (100 MHz) both seem about the same on my 7905. The 7A13 (100 MHz/5 MHz) looks the same at 10mV/div and higher but has more noise at 5mV/div because it uses a different internal topology involving a switched x10 stage. The 7A16A and 7A26 (200 MHz/20 MHz) traces are slightly thicker which follows from their higher bandwidth. Switching in bandwidth limiting where available makes a huge difference so where that matters, I use my 7A13, 7A16A, or 7A26. For bandwidths up to 1 MHz the 7A22 should be the best of all but I do not have a good set of probes yet that can be compensated to its 47pF inputs. On Thu, 28 Jun 2012 09:21:22 +0200, Fabio Eboli <fabioeb@...> wrote: Anyway I was saying that the noise is important
to me for an everyday scope, I was curious if
there was a source where I can control if a mainframe
has a fan or not.
Also as for trace thickness, I prefer remain confined
into the 7k series, the plugins flexibility is wondeful.
I imagine that it's easier for a lower bandwidth to
show a better defined trace, Is there any noticeable
difference in the 7k series ?
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Thank you for your input. Even into the 7103 the 7A26 limited to 20MHz shows a thin trace. As for the 7A22 input capacitance, I have two of them recently acquired, and only one old (cheap) 60MHz probe compensates correctly. Probably I will try some ebay cheap 60MHz probe batch to see if they will work, and hope to find pairs that match. Is probes matching a problem? Fabio. David <davidwhess@...> ha scritto: My 7603 (100 MHz) CRT has a lot of hours on it but comparing it to my
faster 7000 series oscilloscopes, I find that the plug-in matters more
than the mainframe as far as noise which is what I would expect.
The 7A12 (100 MHz) and 7A18 (100 MHz) both seem about the same on my
7905. The 7A13 (100 MHz/5 MHz) looks the same at 10mV/div and higher
but has more noise at 5mV/div because it uses a different internal
topology involving a switched x10 stage. The 7A16A and 7A26 (200
MHz/20 MHz) traces are slightly thicker which follows from their
higher bandwidth.
Switching in bandwidth limiting where available makes a huge
difference so where that matters, I use my 7A13, 7A16A, or 7A26. For
bandwidths up to 1 MHz the 7A22 should be the best of all but I do not
have a good set of probes yet that can be compensated to its 47pF
inputs.
On Thu, 28 Jun 2012 09:21:22 +0200, Fabio Eboli <fabioeb@...>
wrote:
Anyway I was saying that the noise is important
to me for an everyday scope, I was curious if
there was a source where I can control if a mainframe
has a fan or not.
Also as for trace thickness, I prefer remain confined
into the 7k series, the plugins flexibility is wondeful.
I imagine that it's easier for a lower bandwidth to
show a better defined trace, Is there any noticeable
difference in the 7k series ? ---------------------------------------------------------------- This message was sent using IMP, the Internet Messaging Program.
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I found that my cheap Chinese AideTek x1/x10 100MHz probes which are rated from 15pF to 35pF actually managed to barely make it to 47pF on my 7A22. For best performance, the probes used for differential measurements should be matched in attenuation and frequency response. When you use an oscilloscope in invert and add mode, you can use the VAR control on one or the other channel to match the gain. With a differential amplifier like the 7A13 or 7A22, attenuating probes really need to have their own adjustment like with the Tektronix P6055 (20 MHz) or P6055A (100 MHz). I suspect the best option for the 7A22 if you can live with the extra probe loading which is likely at 1 MHz and below is just to use x1 probes. Then there is no compensation or gain matching to worry about. On Thu, 28 Jun 2012 21:16:13 +0200, Fabio Eboli <fabioeb@...> wrote: Thank you for your input.
Even into the 7103 the 7A26 limited to 20MHz shows a
thin trace.
As for the 7A22 input capacitance, I have two of them
recently acquired, and only one old (cheap) 60MHz probe
compensates correctly. Probably I will try some ebay
cheap 60MHz probe batch to see if they will work, and hope
to find pairs that match. Is probes matching a problem?
Fabio.
David <davidwhess@...> ha scritto:
My 7603 (100 MHz) CRT has a lot of hours on it but comparing it to my
faster 7000 series oscilloscopes, I find that the plug-in matters more
than the mainframe as far as noise which is what I would expect.
The 7A12 (100 MHz) and 7A18 (100 MHz) both seem about the same on my
7905. The 7A13 (100 MHz/5 MHz) looks the same at 10mV/div and higher
but has more noise at 5mV/div because it uses a different internal
topology involving a switched x10 stage. The 7A16A and 7A26 (200
MHz/20 MHz) traces are slightly thicker which follows from their
higher bandwidth.
Switching in bandwidth limiting where available makes a huge
difference so where that matters, I use my 7A13, 7A16A, or 7A26. For
bandwidths up to 1 MHz the 7A22 should be the best of all but I do not
have a good set of probes yet that can be compensated to its 47pF
inputs.
On Thu, 28 Jun 2012 09:21:22 +0200, Fabio Eboli <fabioeb@...>
wrote:
Anyway I was saying that the noise is important
to me for an everyday scope, I was curious if
there was a source where I can control if a mainframe
has a fan or not.
Also as for trace thickness, I prefer remain confined
into the 7k series, the plugins flexibility is wondeful.
I imagine that it's easier for a lower bandwidth to
show a better defined trace, Is there any noticeable
difference in the 7k series ?
----------------------------------------------------------------
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To kill two birds with one stone if you will I will reply here: ? ¡°Rob can you confirm if the 7704A shows any dot without
plugins installed?¡± After alignment the 7K scopes in general do not display a dot without plugins (on a few I can get the screen to flicker a blurred dot by pressing the beam find w/o plug-ins and the readout turned all the way up). That said, I do not think that the dot in and of its self is an issue. It could be that someone has adjusted the bias up to high or it could also be indicative of a yet undefined ¡®issue¡¯. The only way to know for sure is to put a vertical and horizontal plug-in in and see what the trace (if any) looks like. (as a side bar I suppose there are ways this group could come up with to find out with one or fewer plug-ins, etc). ? In any event, my point is; that pretty much whatever the issue you find (a simple bias adjustment or components needing to be replaced) The expertise exists here to more than likely make whatever might be wrong an inexpensive fix. In fact, the fact that there is a dot w/o plug-ins leads me to believe that most expensive problems are therefore ruled out. (Assuming the dot has not burned the CRT which should be noticeable), ?The scopes HV is working the CRT is good, etc. if a dot is visible. ? Finally, and unfortunately. There is a chance, unless you are willing to go into the market place at some of the aftermarket vendors such a Sphere used to do (they may actually have some still) That you will purchase an expensive lemon... I actually think that aftermarket vendors could be a preferable path for those that unlike me are looking for a good reliable scope. ? It is certain in that case you will be getting a scope that has been professionally gone through, etc. My path in all of this is for the learning and opportunity to work with some amazing equipment of the past. The fact that it may be suitable for its intended purpose afterward is just a bonus. (As I actually and truly have no reason to own a scope)¡ However, even in my case if/when I am ready to place these ?scopes back on the market. I cannot guarantee there longevity nor support that as business such as for example Sphere did or could do. So while at some level these scopes I am working on and recapping may or may not be preferable to a scope in the open market place that comes up and ran for 2 hours and some government guru decided via edict that it had over lived its usefulness..? ? Said another way, there is just inherent risk in the path your looking to walk. You can lower that risk with a higher investment or except it and take a gamble on both your skills and the ashes you hope to turn back into the phoenix it once was. ? Finally, the 7704A¡¯s I have do not have fans, I am not sure if that means they were optional or?? as I seem to recall seeing that some have fans?? Anyway, they are quite and I have observed no ill effects to date due to running fanless. ? I hope this helps and is taken in the spirit intended, Rob P.S. For those a Sphere I apologize if my use of your name as analogy is offensive I could think of no other way to make the point. I am and continue to be a happy customer.
?
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From: TekScopes@... [mailto:TekScopes@...] On Behalf Of d.seiter@...
Sent: Thursday, June 28, 2012 4:19 AM
To: TekScopes@...
Subject: Re: [TekScopes] 7704A, should I go for it??
Re trace width- Most, if not all, of the 7K series scopes have an expansion mesh in the CRT which effectively blurs the trace to some degree. ?There has been some debate about whether a mesh-less design would be any sharper at the usually higher frequencies of the 7k scopes, but it's a moot point. Typically, looking at the same signal with a 547 and a 7704A, the 547 will be much sharper. ?From a previous post- Tek even spec'd the spot size of the 547 at .004". Which reminds me; I still need to fire up my main 547 again to see if it's trace has returned. ?I wish days had 30 hours.... -Dave
From: "Fabio Eboli" <fabioeb@...>
To: TekScopes@...
Sent: Thursday, June 28, 2012 12:21:22 AM
Subject: Re: [TekScopes] 7704A, should I go for it?
? Thank you david and all for your opinions.
Yesterday I had problems with personal email and
send the messages using online yahoo form, but the
second message seem that has gone lost, I cannot find
it into the messages list.
Anyway I was saying that the noise is important
to me for an everyday scope, I was curious if
there was a source where I can control if a mainframe
has a fan or not.
Also as for trace thickness, I prefer remain confined
into the 7k series, the plugins flexibility is wondeful.
I imagine that it's easier for a lower bandwidth to
show a better defined trace, Is there any noticeable
difference in the 7k series ?
At the end I'll go for it, hoping that it will be an
easy enough repair.
Rob can you confirm if the 7704A shows any dot without
plugins installed?
Fabio.
David <davidwhess@...> ha scritto:
> I have been using the Nichicon PW series as general replacements since
> they are inexpensive, long life, low impedance, and available up to
> 450 volts. Unfortunately I have found no equivalent axial leaded
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David Hess