Date   

Re: 7603 CRT

cmjones01
 

On 31/12/2013 21:16, David wrote:
Something I noticed before on my 7603 and confirmed recently while
working on it
is that the longer it is operating, the sharper and brighter the CRT
gets even
after adjusting the focus and astigmatism. It was especially dim and blurred
after being in storage for years.

I have never found any faults in other areas of this oscilloscope so is
there
some specific characteristic of the CRT which would cause this?

None of my other oscilloscopes display this behavior.
This is quite a widely-reported phenomenon with CRTs. It seems very common in the vintage TV world that the CRT in an old TV will take some hours of operation to 'wake up' after having been unused for some years. I've observed it on CRTs in my workshop, too - a 2465A I bought a couple of years ago had a rather disappointing trace when I first started using it, but improved with use.

I don't know whether it's about the cathode emission improving, or impurities in the vacuum (!) getting reabsorbed by the getter and electrodes as they all heat up, or what, but it's real enough.

Chris


Re: For sale DC508(a) display modules

ralflaborenz@...
 

Dear Paul,

First a happy new year and thanks again for the replacement display board for the DC508 counter. This works fine if I use my DC508A as a "normal" frequency counter. I just wanted to let you know that if the DC508A is modified for option 7 and used in a set-up with a 7L14/TR502 (spec.analyzer/tracking generator) for indicating the centre frequency, one needs a decimal point in front of the least significant digit for a 100 kHz resolution. This is not supported by the display board I received, however it can be implemented simply by adding another stage of the circuit you use to generate the decimal point driving signal. I did so using some bare wire, the required transistor and diode.

Cheers,

Ralf


File - Posting Rules

TekScopes@...
 

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Regards,
Michael Dunn
Listowner, TekScopes


Plotters (was OT LOL)

Morris Odell
 

Hi all,

Does anyone still use plotters or pen recorders? I have had one for years
which I originally got to plot PCB patterns on copper using an etchant
resistant felt tip pen. It worked nicely until I went to toner transfer and
has been sitting in the cupboard ever since. I took it out the other day and
put in the recycling pile :-(

It's an old Graphtec A3 size with a non-standard parallel (Centronics)
interface. It has a very nifty magnetic pen selection and holding system. I
had to mess around a lot with an interface converter to get it working years
ago and it would be even more of a pain today. Now I have machine shop
facilities to make pen adaptors but is it worth the trouble?

A search on eBay for flatbed plotters shows there's not much of a market for
this type of machine. XY recorders are different and might be a source of
fun for the hobbyist as long as they don't need special paper.

I also have a an old HP chart recorder which I did use recently to monitor a
GPS controlled oscillator for several days for the hell of it, but that
could just as easily be done electronically. Given that it needs special
paper and the ink plumbing clogs easily I can see it going the same way.....

Morris


Of relevance to the HP group, did anyone notice Paillard is using a
standard ball point pen in a vintage HP plotter? Â Nice trick. Â In
fact, all very nicely done!
.....

Just a lathe? There were little "wings" on the pens that twist-lock
into the holders. I supposed I could start with a rectangular piece of
stock and turn all but the wings. Anyone have one of these little pen
adapters?
.....

I drilled and reamed one of the little stubby felt tip pens out to where
the regular pen was a friction fit.
Not hard to do even with just hand tools.


Re: 2564A preventive maintenance

mosaicmerc
 

Were ALL the traces active?


Re: OT LOL

 

I'm getting really annoyed at aetoulis. I asked him a perfectly legitimate
question about the other amplifier - the one with the volume control
(331094423899) - and he didn't include my question along with the other four
perfectly reasonable questions he was asked. The NERVE!

In his answer to the second question he got he recommended against putting
the amplifier in a box because the capacitance of the box would reduce the
frequency response. So I asked if putting his amplifier in a purely
inductive box (one made of MuMetal or Nitinol) would enhance the frequency
response? Maybe I stumped him!

Dennis

PS Apparently someone was dumb enough to pay aetoulis $29 on Dec-23-13 16:10
for a schematic of the Pleiades Electra Only Tubes & No Other Components
Headphone Amplifier (331079777606) according to aetoulis' feedback. $29 for
30 seconds of work makes me think aetoulis is definitely smarter than me. I
would love to be there to see the look on the buyer's face when he/she
opened the schematic for the very first time.

-----Original Message-----
From: Paul Amaranth, Sent: Tuesday, December 31, 2013 3:57 PM

Now that one is a definately a ripoff. It doesn't have a volume control
and he wants THAT much for it ??!!

On Tue, Dec 31, 2013 at 03:18:14PM -0800, Leon Robinson wrote:
Here is one with wires in it.

http://www.ebay.com/itm/Battery-Tube-Only-Headphones-Amplifier-for-Sennheise
r-HD-580-600-650-Beyer-DT880-/331096206110?pt=US_Pro_Audio_Amplifiers&hash=i
tem4d16df2b1e

Leon Robinson    K5JLR

Political Correctness is a Political Disease.
--
Paul Amaranth, GCIH | Rochester MI, USA
Aurora Group, Inc. | Security, Systems & Software
paul@AuroraGrp.Com | Unix & Windows


Re: 2564A preventive maintenance

af7u@...
 

Tom,

I can't speak to specific sweep speeds, I was just doing general testing under various conditions...  I remember evaluating the beam modulation that I saw at low sweep speeds, then I fed a signal from my HP 8648B and tested bandwidth at higher sweep speeds up to it's upper limit.  Seems like I magnified the sweep a few times just for giggles but not for long periods.  Not a very comprehensive test for certain but just twisting knobs and pushing buttons.  I just got it up after fixing issues and was just checking it out when I noticed U800 not heating...  I am thinking of adding additional sinking anyway...


~Michael - AF7U


Re: OT LOL

stefan_trethan
 

I drilled and reamed one of the little stubby felt tip pens out to
where the regular pen was a friction fit.
Not hard to do even with just hand tools.

ST

On Tue, Dec 31, 2013 at 4:03 PM, Daniel Koller <kaboomdk@yahoo.com> wrote:
Chuck is correct. The relevant footage is near the end of the video where he tests the tube. Link is here in case Yahoo lost it for you: http://www.youtube.com/watch?v=EzyXMEpq4qw

Just a lathe? There were little "wings" on the pens that twist-lock into the holders. I supposed I could start with a rectangular piece of stock and turn all but the wings. Anyone have one of these little pen adapters?

Dan


Re: OT LOL

Don Black <donald_black@...>
 

Come on, look on the bright side. Perhaps he can't speak English.

Happy New Year.
Don Black.

On 01-Jan-14 3:56 PM, Dennis Tillman wrote:
 

Damn! Everytime I think I have everything, someone has to show me something like this video to make me realize I need to live another hundred years to be able to do all the things I want to do.

In addition to a very complete machine shop he appears to have a professional glassblowing laboratory, and a knowledge of electronics. Plus, he speaks French!

Sigh! How I am going to explain that I need a glassblowing laboratory to my wife?

Dennis

PS Clearly, if he can make a vacuum tube he can adapt a pen to fit a plotter. I don't think it took him more than a minute to figure out how to do that. The only question I have is whether he thought about making the holder out of blown glass or out of machined metal. He probably could have done either.

-----Original Message-----
From: Daniel Koller, Sent: Tuesday, December 31, 2013 7:03 AM

Chuck is correct. The relevant footage is near the end of the video where he tests the tube. Link is here in case Yahoo lost it for you: http://www.youtube.com/watch?v=EzyXMEpq4qw

Just a lathe? There were little "wings" on the pens that twist-lock into the holders. I supposed I could start with a rectangular piece of stock and turn all but the wings. Anyone have one of these little pen adapters?

Dan

On Tuesday, December 31, 2013 9:21 AM, Chuck Harris wrote:

>He is referring to the little video on the making of a triode
>in Paillard's home shop. In the video he draws the traces of
>the new triode using a home made manual curve tracer, and an
>HP flat bed plotter. I think the pen is not a ball point, but
>rather a felt tip, or roller ball pen. HP used to make an adapter
>to the old Flair (tm) style... an easy job if you have a lathe.
>
>-Chuck Harris
>
>gerard_constant wrote:
>>
>> --- In TekScopes@..., Daniel Koller wrote:
>>>
>>> Of relevance to the HP group, did anyone notice Paillard is using a standard
>>> ball point pen in a vintage HP plotter? Â Nice trick. Â In fact, all very
>>> nicely done!
>>>
>>> Â Dan
>>
>> Interesting !! Where did you find that ?? A quick web browsing does not show me
>> anything useful ?? Thanks





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Re: OT LOL

 

Damn! Everytime I think I have everything, someone has to show me something like this video to make me realize I need to live another hundred years to be able to do all the things I want to do.

In addition to a very complete machine shop he appears to have a professional glassblowing laboratory, and a knowledge of electronics. Plus, he speaks French!

Sigh! How I am going to explain that I need a glassblowing laboratory to my wife?

Dennis

PS Clearly, if he can make a vacuum tube he can adapt a pen to fit a plotter. I don't think it took him more than a minute to figure out how to do that. The only question I have is whether he thought about making the holder out of blown glass or out of machined metal. He probably could have done either.

-----Original Message-----
From: Daniel Koller, Sent: Tuesday, December 31, 2013 7:03 AM

Chuck is correct. The relevant footage is near the end of the video where he tests the tube. Link is here in case Yahoo lost it for you: http://www.youtube.com/watch?v=EzyXMEpq4qw

Just a lathe? There were little "wings" on the pens that twist-lock into the holders. I supposed I could start with a rectangular piece of stock and turn all but the wings. Anyone have one of these little pen adapters?

Dan

On Tuesday, December 31, 2013 9:21 AM, Chuck Harris <cfharris@erols.com> wrote:

He is referring to the little video on the making of a triode
in Paillard's home shop. In the video he draws the traces of
the new triode using a home made manual curve tracer, and an
HP flat bed plotter. I think the pen is not a ball point, but
rather a felt tip, or roller ball pen. HP used to make an adapter
to the old Flair (tm) style... an easy job if you have a lathe.

-Chuck Harris

gerard_constant wrote:

--- In TekScopes@yahoogroups.com, Daniel Koller <kaboomdk@...> wrote:

Of relevance to the HP group, did anyone notice Paillard is using a standard
ball point pen in a vintage HP plotter? Â Nice trick. Â In fact, all very
nicely done!

 Dan
Interesting !! Where did you find that ?? A quick web browsing does not show me
anything useful ?? Thanks


Re: OT LOL

Brad Thompson <brad.thompson@...>
 

On 12/31/2013 6:57 PM, Paul Amaranth wrote:
Now that one is a definately a ripoff. It doesn't have a volume control
and he wants THAT much for it ??!!

On Tue, Dec 31, 2013 at 03:18:14PM -0800, Leon Robinson wrote:
> Here is one with wires in it.
>
>
http://www.ebay.com/itm/Battery-Tube-Only-Headphones-Amplifier-for-Sennheiser-HD-580-600-650-Beyer-DT880-/331096206110?pt=US_Pro_Audio_Amplifiers&hash=item4d16df2b1e
Hello--

Beware of Geeks bearing grifts....

Yours for audio purity, truth in advertising, and the eternal
quest for Something Better (or failing that, something more
expensive). 73, and my best wishes go to all for a happy
New Year--

Brad AA1IP


---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com


Re: OT LOL

Paul Amaranth
 

Now that one is a definately a ripoff. It doesn't have a volume control
and he wants THAT much for it ??!!

On Tue, Dec 31, 2013 at 03:18:14PM -0800, Leon Robinson wrote:
Here is one with wires in it.

http://www.ebay.com/itm/Battery-Tube-Only-Headphones-Amplifier-for-Sennheiser-HD-580-600-650-Beyer-DT880-/331096206110?pt=US_Pro_Audio_Amplifiers&hash=item4d16df2b1e

�
Leon Robinson �� K5JLR

Political Correctness is a Political Disease.
--
Paul Amaranth, GCIH | Rochester MI, USA
Aurora Group, Inc. | Security, Systems & Software
paul@AuroraGrp.Com | Unix & Windows


Re: Tek 7854 Doesn't Come On After EPROM ROM Replacement

Phil Peri
 

Hi all,


I pulled the FPLA and power cycled the unit a few times and I saw traces! Power cycling a couple more times but I never got a trace again.


Here are some images: http://imgur.com/a/q6fOe


So, intermittent issues... !



P.




Re: OT LOL

Leon Robinson
 

Here is one with wires in it.

http://www.ebay.com/itm/Battery-Tube-Only-Headphones-Amplifier-for-Sennheiser-HD-580-600-650-Beyer-DT880-/331096206110?pt=US_Pro_Audio_Amplifiers&hash=item4d16df2b1e
 
Leon Robinson    K5JLR

Political Correctness is a Political Disease.


From: cheater00 .
To: TekScopes@...
Sent: Monday, December 30, 2013 7:05 AM
Subject: Re: [TekScopes] RE: OT LOL

 
On Mon, Dec 30, 2013 at 5:14 AM, Frank DuVal wrote:
>
> Space Charged Tubes. Not for audio output, a germanium transistor would work for that in car radio use.
>
> http://www.junkbox.com/electronics/lowvoltagetubes.shtml
>
> Frank DuVal
> WA4CWM

Thanks a lot for the link, Frank. It was really helpful and it might
get me started building with tubes much more quickly.

Bear in mind that the html file is corrupt - a whole paragraph is
missing. Luckily enough, the amazing Internet Archive has got monthly
backups of the site - and here is the last version of it:

http://web.archive.org/web/20120328124400/http://www.junkbox.com/electronics/lowvoltagetubes.shtml

You can donate to the Internet Archive here: http://archive.org/donate/

Cheers,
D.



7603 CRT

 

Something I noticed before on my 7603 and confirmed recently while working on it
is that the longer it is operating, the sharper and brighter the CRT gets even
after adjusting the focus and astigmatism. It was especially dim and blurred
after being in storage for years.

I have never found any faults in other areas of this oscilloscope so is there
some specific characteristic of the CRT which would cause this?

None of my other oscilloscopes display this behavior.


Re: Tek 7854 Doesn't Come On After EPROM ROM Replacement

Phil Peri
 

Hello all,


Thanks for the replies! Shortly after I posted this topic the author of Modular Synthesis, Dave B., got in touch with me and has been walking me through a potential fix over email. Wher we arrive at a solution I will update everyone.


Göran: Excellent document! I will print it out and look at it but already you've stated to *remove* the FPLA, and when I tried that I get some new lights (two red LEDs: 'REMOTE ONLY' and 'ERROR') popped up! So I will look over this document more in-depth and see what I can do to get this going again.


Thanks again, everyone, and I'll update everyone with my progress :)



Philip.


Re: 2564A preventive maintenance

 

Did you do the test under different sweep speeds and magnify? The fast sweep times might require higher power?
 
Tom
 

----- Original Message -----
From: af7u@...
Sent: Tuesday, December 31, 2013 1:47 PM
Subject: [TekScopes] RE: 2564A preventive maintenance

 

 My U800 is *not* getting hot... maybe warm, maybe, but definitely not hot.  Unit left on for hours and temp is mildly warm to touch, touch being full finger contact across length of IC.


This leads me to think one of two things.  Either there is component value shifting in the related circuitry to U800 causing it to over heat, or... some other issue is afoot.  I've read about proper ventilation and such, my test was done  with slide cover removed.


Don't get me wrong, I'm darn grateful for a cool IC, but any thoughts regarding a NON-heating U800?


~Michael _ AF7U


Re: 5113 calibration problem

h_posilovic@...
 

Hello,

 

Thank You all for excellent and very useful advices.

 

You were right; I measured HV at the test point on the CRT socket. The voltage is only 2325 V, and should be 3400 V. Then tried to raise voltage with trim-pot on the HV board, but the voltage das not react at all, stay around 2325 V. There are some soldering traces on this board; it looks like somebody already tried to repair there something. One transistor is marked with black paint. I will try to find schematics in the manual you recommended to me.

 

I wish You Happy New Year and a lot of good waves on your scopes.

 

Hrvoje.


Re: 2564A preventive maintenance

af7u@...
 

<Scratching Head>  My U800 is *not* getting hot... maybe warm, maybe, but definitely not hot.  Unit left on for hours and temp is mildly warm to touch, touch being full finger contact across length of IC.


This leads me to think one of two things.  Either there is component value shifting in the related circuitry to U800 causing it to over heat, or... some other issue is afoot.  I've read about proper ventilation and such, my test was done  with slide cover removed.


Don't get me wrong, I'm darn grateful for a cool IC, but any thoughts regarding a NON-heating U800?


~Michael _ AF7U


Re: 7603 with power supply problems

 

On Tue, 31 Dec 2013 16:44:41 -0000, you wrote:

--- In TekScopes@yahoogroups.com, "Michael A. Terrell" <mike.terrell@...> wrote:

In series, or in cascade?
A series of transistors are used to increase amplification of a signal - each t ransistor has an 'amplification factor' hfe, increasing the emitter-collector current over the emitter-base (input) current.

If transistor 1 has a factor of 200, then a 2 microamp current would become .4 milliamp. That .4 milliamp input to transistor 2 with the same hFE will deliver 80 ma out of the second transistor. A third in a cascade or series, this time with an hfe of 50, produces 4A.

Using a cascade of three transistors magnifies the 2 ua input current to 4a, a two million X amplification that isn't possible with a single transistor (200 x 200 x 50).

Not sure whether there is a distinction between series or cascade, at least not as far as I see right now. Series increases the current or amplification. Parallel as suggested earlier in the thread is used to divide up the total power to ensure that each transistor doesn't exceed its capability.

In the scenario I gave, if the particular voltage involved was 2V meaning the third transistor would have to handle 8W, but the part chosen can only safely handle 5W with a heatsink, then the third stage might be two of the transistors in parallel so that each of the transistors shoulders 4W (2A) of the current.
In the places where Tektronix used parallel transistors without emitter ballast
resistors and apparently without grading, I suspect the reason was to raise the
current gain at high peak currents where a transistor's current gain drops. In
this type of situation, parallel transistors can multiply the current gain at
least 2 to 4 times without a Darlington connection.

One of the claims to fame that Zetex (bought by Diodes Incorporated) has with
their Super E-line of transistors is high current gain at high currents. Older
transistors like the 2N4401 and 2N4403 have much lower current gain at high
currents. Other companies now produce similar transistors for applications
requiring high efficiency.

A transistor like a ZTX690 at 1 watt would make an excellent replacement for a
2N5859 but costs 10 times more than a 2N4401.

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