Date   

Re: Interesting "new" refrigerant

Ed Breya
 

Yes, it's kind of arbitrary, since lots of things can be used as refrigerants, and are classified with R-numbers for use in that context. For example, R-290 is "clean" propane used for refrigeration, not fuel. Even water is classified - R-718.

Ed

--- In TekScopes@yahoogroups.com, Don Black <donald_black@...> wrote:

Fair enough Ed, I thought it was first mentioned as a refrigerant (to
make cold) not as a freon replacement in probes.

Don Black.

On 11-Jun-13 11:45 PM, Ed Breya wrote:

If it boiled at -60, it wouldn't have been "interesting," and I
wouldn't have mentioned it in the first place, and we wouldn't be
talking about it. Boiling near room temperature allows for a whole new
set of applications, since refrigeration (or really heat transport)
depends on changing between gas and liquid phases at suitable
temperatures and pressures.

The P vs T and enthalpy charts show how the different refrigerants
work and why there are different ones for various applications.

The higher boiling point means lower pressure near room temperature,
so using it in a P6015, for example, means that the pressure won't get
very high at normal temperature - otherwise it could blow a gasket or
burst the container - the probe housing in this case. The chart shows
that at a maximum ambient of say 120 deg F, P will be 34 PSIG. A more
conventional refrigerant like R134a would be around 100 PSIG or so.

The downside is that R-245fa will actually create a relative vacuum
below its boiling point of 60 deg F - it still must exist at a
positive absolute pressure at low density, but it will be a negative
gauge pressure, with respect to atmosphere, so the seals of the
container may not work the same and possibly leak. The lower density
as it approaches true vacuum (at around 30 deg F) also means that it
won't serve its purpose as a dielectric anymore - there won't be
enough of its gaseous form.

Ed

--- In TekScopes@yahoogroups.com <mailto:TekScopes%40yahoogroups.com>,
Don Black <donald_black@> wrote:

Thanks, my original comments still apply. Maybe there's a refrigeration
Guru here who can shed more light on its use in refrigeration.

Don Black.

On 11-Jun-13 7:00 PM, Albert wrote:

+59.5 F (15 C) according to MSDS.
Albert

Does it boil at 60 deg F or -60 deg F at atmospheric pressure?
60 deg
doesn't sound like a great refrigerant unless perhaps used in a low
pressure system.

Don Black.


Re: 7834 non-storage mode readout brightness (or lack thereof)

Ed Breya
 

I fired it up last night to look at the problems again, and two very interesting things happened.

First, other than a big blotch near the center of the screen from the power-up transients, the image that was on the screen two days before was still there. I had left it in SAVE mode when I turned it off, and it kept it all that time even with no power.

The other thing is that the non-storage readout now seems to work OK - it's plenty bright enough, and the RO intensity adjustment range seems normal. It makes a smooth transition between modes, with consistent brightness. Maybe running for those few hours the other day, and sitting for a while was enough to rejuvenate something (like maybe a leaky cap?). Of course, whatever the cause, it may come back, since I don't know what it was.

So, I just have to tweak the RO to set it to the right spots, and thoroughly work it over operationally, and it should be all set - for now. Thanks all, for the advice and comparison info.

BTW I'm really liking this scope - it has the nicest looking display of all that I have. It is brightness-limited, but the traces are quite sharp for a DVST, and the RO is rock-solid - no setup or signal extremes I have applied so far seem to affect the shape or position of the RO characters, unlike the jiggliness and shifting that I've seen in my other 7K scopes.

Ed

--- In TekScopes@yahoogroups.com, "Craig Sawyers" <c.sawyers@...> wrote:

That seems high to me, but I'll check my 7623A when I get home this
afternoon. Are you talking about the setting in normal or storage mode?
Normal. And that is on a 7623B that came sealed in the original double
cartons, with accessories in sealed bags straight from Beaverton, so it only
has about 20 hours use with all of them by me.

Craig


Re: I killed it... DM40 on a 466

Herbert
 

Look here

http://www.qservice.tv/vpasp/shopexd.asp?id=755&bc=no

Best regards

Herbert


Am 11-06-2013 15:01, schrieb Cliff White:

 

I guess that means I need to get the schematic... I'll work on that. :)

The plug that was installed backwards was a 5 pin flat connector at the back of the board (P2651). It has ground, +5, +12 and two look to be unused. When it was reversed the +5 and ground got switched, and the +12 went to an unused pin.


Respectfully,
Cliff White, W5CNW
w5cnw@...
On 06/10/2013 07:43 PM, David wrote:
 

I would go through the schematics and mark everything that had reverse
voltage applied. It is possible something replaceable self destructed
and crow-barred the power supply protecting everything else.

If I could not find a specific problem, then I would start swapping
the unknown chips for good ones starting with the least expensive.

On Mon, 10 Jun 2013 18:15:08 -0500, Cliff White
<cn.white@...> wrote:

>I'm not sure this went through the first time. If not, here it is again.
>And: I've since tested the volts and ohms functions and they suffer the
>same symptoms as the time function. Ideas anyone?
>
>
>Respectfully,
>Cliff White, W5CNW
>w5cnw@... w5cnw@...>
>On 06/10/2013 07:46 AM, Cliff White wrote:
>>
>> When I was reinstalling the DM40 meter back onto my 466, I apparently
>> got the power connector on backwards. (Why do they let THAT
>> happen???). After switching it back around, the LCD comes on, but
>> there's no usable data on it. In Time mode, the ms/us lights work as
>> expected depending on the sweep speed. But the LCD always shows a
>> fluctuating number around 200, which the Delay knob and Zero button do
>> not affect.
>>
>>
>> --
>> Respectfully,
>> Cliff White, W5CNW
>> w5cnw@... w5cnw@...>
>>




Re: Interesting "new" refrigerant

Don Black <donald_black@...>
 

Fair enough Ed, I thought it was first mentioned as a refrigerant (to make cold) not as a freon replacement in probes.

Don Black.

On 11-Jun-13 11:45 PM, Ed Breya wrote:
 

If it boiled at -60, it wouldn't have been "interesting," and I wouldn't have mentioned it in the first place, and we wouldn't be talking about it. Boiling near room temperature allows for a whole new set of applications, since refrigeration (or really heat transport) depends on changing between gas and liquid phases at suitable temperatures and pressures.

The P vs T and enthalpy charts show how the different refrigerants work and why there are different ones for various applications.

The higher boiling point means lower pressure near room temperature, so using it in a P6015, for example, means that the pressure won't get very high at normal temperature - otherwise it could blow a gasket or burst the container - the probe housing in this case. The chart shows that at a maximum ambient of say 120 deg F, P will be 34 PSIG. A more conventional refrigerant like R134a would be around 100 PSIG or so.

The downside is that R-245fa will actually create a relative vacuum below its boiling point of 60 deg F - it still must exist at a positive absolute pressure at low density, but it will be a negative gauge pressure, with respect to atmosphere, so the seals of the container may not work the same and possibly leak. The lower density as it approaches true vacuum (at around 30 deg F) also means that it won't serve its purpose as a dielectric anymore - there won't be enough of its gaseous form.

Ed

--- In TekScopes@..., Don Black wrote:
>
> Thanks, my original comments still apply. Maybe there's a refrigeration
> Guru here who can shed more light on its use in refrigeration.
>
> Don Black.
>
> On 11-Jun-13 7:00 PM, Albert wrote:
> >
> > +59.5 F (15 C) according to MSDS.
> > Albert
> >
> > > Does it boil at 60 deg F or -60 deg F at atmospheric pressure? 60 deg
> > > doesn't sound like a great refrigerant unless perhaps used in a low
> > > pressure system.
> > >
> > > Don Black.
> >
> >
>



Re: I killed it... DM40 on a 466

Cliff White
 

I guess that means I need to get the schematic... I'll work on that. :)

The plug that was installed backwards was a 5 pin flat connector at the back of the board (P2651). It has ground, +5, +12 and two look to be unused. When it was reversed the +5 and ground got switched, and the +12 went to an unused pin.


Respectfully,
Cliff White, W5CNW
w5cnw@...

On 06/10/2013 07:43 PM, David wrote:
 

I would go through the schematics and mark everything that had reverse
voltage applied. It is possible something replaceable self destructed
and crow-barred the power supply protecting everything else.

If I could not find a specific problem, then I would start swapping
the unknown chips for good ones starting with the least expensive.

On Mon, 10 Jun 2013 18:15:08 -0500, Cliff White
<cn.white@...> wrote:

>I'm not sure this went through the first time. If not, here it is again.
>And: I've since tested the volts and ohms functions and they suffer the
>same symptoms as the time function. Ideas anyone?
>
>
>Respectfully,
>Cliff White, W5CNW
>w5cnw@... w5cnw@...>
>On 06/10/2013 07:46 AM, Cliff White wrote:
>>
>> When I was reinstalling the DM40 meter back onto my 466, I apparently
>> got the power connector on backwards. (Why do they let THAT
>> happen???). After switching it back around, the LCD comes on, but
>> there's no usable data on it. In Time mode, the ms/us lights work as
>> expected depending on the sweep speed. But the LCD always shows a
>> fluctuating number around 200, which the Delay knob and Zero button do
>> not affect.
>>
>>
>> --
>> Respectfully,
>> Cliff White, W5CNW
>> w5cnw@... w5cnw@...>
>>



Re: what to look for in basic Mainframe and plugins

Jim <n6otq@...>
 

Jerry,

We're seeing a decent number of spectrum analyzers coming out of celphone service now that work to about 1.8 GHz, which would be ideal for your 440 MHz need, since they cover up to 4th harmonic.  The pristine units are around $1000.  Less capable, or less pristine units are comparably less expensive, but remember that you don't get what you don't pay for.

73
Jim N6OTQ


From: Jerry Barr
To: "TekScopes@..."
Sent: Tuesday, June 11, 2013 8:32 AM
Subject: Re: [TekScopes] what to look for in basic Mainframe and plugins

hi ure right i didnt mention my intended uses / I am going to be using it for  tuning -repairing a  repeater system   just for personal  test gear not for on the job etc /being retired its jus for fun hobby stuff lol/ and not having used a spec analyzer i cant say what it needs to belike feature wise/ the repeater will or is  440 mghtz/ thanks guys
 
Jerry KJ6NTL


Re: Interesting "new" refrigerant

Ed Breya
 

If it boiled at -60, it wouldn't have been "interesting," and I wouldn't have mentioned it in the first place, and we wouldn't be talking about it. Boiling near room temperature allows for a whole new set of applications, since refrigeration (or really heat transport) depends on changing between gas and liquid phases at suitable temperatures and pressures.

The P vs T and enthalpy charts show how the different refrigerants work and why there are different ones for various applications.

The higher boiling point means lower pressure near room temperature, so using it in a P6015, for example, means that the pressure won't get very high at normal temperature - otherwise it could blow a gasket or burst the container - the probe housing in this case. The chart shows that at a maximum ambient of say 120 deg F, P will be 34 PSIG. A more conventional refrigerant like R134a would be around 100 PSIG or so.

The downside is that R-245fa will actually create a relative vacuum below its boiling point of 60 deg F - it still must exist at a positive absolute pressure at low density, but it will be a negative gauge pressure, with respect to atmosphere, so the seals of the container may not work the same and possibly leak. The lower density as it approaches true vacuum (at around 30 deg F) also means that it won't serve its purpose as a dielectric anymore - there won't be enough of its gaseous form.

Ed

--- In TekScopes@yahoogroups.com, Don Black <donald_black@...> wrote:

Thanks, my original comments still apply. Maybe there's a refrigeration
Guru here who can shed more light on its use in refrigeration.

Don Black.

On 11-Jun-13 7:00 PM, Albert wrote:

+59.5 F (15 C) according to MSDS.
Albert

Does it boil at 60 deg F or -60 deg F at atmospheric pressure? 60 deg
doesn't sound like a great refrigerant unless perhaps used in a low
pressure system.

Don Black.


Re: what to look for in basic Mainframe and plugins

 

Hi Jerry,
have you considered getting a dedicated spec an? Those are found much cheaper than the spec an plugins for tek 7k..

HP, Anritsu, Ono Sokki, Nicolet, Stanford Research are good makes.

You're not looking for an esoteric frequency, so you should find it easy to get something on the cheap.

Cheers,
D.


On Tue, Jun 11, 2013 at 3:32 PM, Jerry Barr <kj6ntl@...> wrote:


hi ure right i didnt mention my intended uses / I am going to be using it for  tuning -repairing a  repeater system   just for personal  test gear not for on the job etc /being retired its jus for fun hobby stuff lol/ and not having used a spec analyzer i cant say what it needs to belike feature wise/ the repeater will or is  440 mghtz/ thanks guys
 
Jerry KJ6NTL
From: cheater00 . <cheater00@...>
To: TekScopes@...
Sent: Tuesday, June 11, 2013 5:41 AM

Subject: Re: [TekScopes] what to look for in basic Mainframe and plugins
 
Craig,
we still don't know what he wants the spec an for.

Jerry, care to elaborate?

D.

On Tue, Jun 11, 2013 at 10:22 AM, Craig Sawyers
<mailto:c.sawyers%40tech-enterprise.com> wrote:
> ==============
> Hi Jerry,
> unless you buy the scope refurbished and recapped, avoid persistence storage
> scopes, because 1. you probably don't need it and 2. they're much more
> complex to repair (and you'll have to at some point). However they're good
> as second scopes, and I have this kind of setup as well: a 7704 and a 7613.
> Cheers,
> D.
> =============
>
> The guy wants the frame for adding a spectrum analyser. See my earlier
> comments.
>
> * A non-storage scope is perfect if the analyser has digital storage - the
> 7L5, 7L14 and 7L15. In that case a 7603 is the way to go, with its large
> CRT screen.
> * A storage scope with variable persistence **is essential if the analyser
> does not have digital storage** - the 7L12 and 7L13. Why? If you select a
> narrow resolution bandwidth the scan rate drops to perhaps 1 division per
> second and on a non-storage scope you see absolutely nothing of value.. In
> that case the best choice is a 7613, but a 7623A or 7633 would also do.
>
> Craig
>
>
>
> ------------------------------------
>
> Yahoo! Groups Links
>
>
>




Re: Non-Tek 7k plugins? Plus: what nonexistent plugins would you wis

 

Unless you have a dead, unsalvageable plug-in, why not make rails out of hardwood, like maple ?

 
HankC, Boston
WA1HOS


Re: what to look for in basic Mainframe and plugins

Jerry Barr
 

hi ure right i didnt mention my intended uses / I am going to be using it for  tuning -repairing a  repeater system   just for personal  test gear not for on the job etc /being retired its jus for fun hobby stuff lol/ and not having used a spec analyzer i cant say what it needs to belike feature wise/ the repeater will or is  440 mghtz/ thanks guys
 
Jerry KJ6NTL

From: cheater00 .
To: TekScopes@...
Sent: Tuesday, June 11, 2013 5:41 AM
Subject: Re: [TekScopes] what to look for in basic Mainframe and plugins
 
Craig,
we still don't know what he wants the spec an for.

Jerry, care to elaborate?

D.

On Tue, Jun 11, 2013 at 10:22 AM, Craig Sawyers
<mailto:c.sawyers%40tech-enterprise.com> wrote:
> ==============
> Hi Jerry,
> unless you buy the scope refurbished and recapped, avoid persistence storage
> scopes, because 1. you probably don't need it and 2. they're much more
> complex to repair (and you'll have to at some point). However they're good
> as second scopes, and I have this kind of setup as well: a 7704 and a 7613.
> Cheers,
> D.
> =============
>
> The guy wants the frame for adding a spectrum analyser. See my earlier
> comments.
>
> * A non-storage scope is perfect if the analyser has digital storage - the
> 7L5, 7L14 and 7L15. In that case a 7603 is the way to go, with its large
> CRT screen.
> * A storage scope with variable persistence **is essential if the analyser
> does not have digital storage** - the 7L12 and 7L13. Why? If you select a
> narrow resolution bandwidth the scan rate drops to perhaps 1 division per
> second and on a non-storage scope you see absolutely nothing of value.. In
> that case the best choice is a 7613, but a 7623A or 7633 would also do.
>
> Craig
>
>
>
> ------------------------------------
>
> Yahoo! Groups Links
>
>
>


Re: Interesting "new" refrigerant

Don Black <donald_black@...>
 

Thanks everyone. I was thinking of how to keep my ice cream cold but use on hot transistors makes sense.

Don Black.

On 11-Jun-13 10:08 PM, Peter Gottlieb wrote:
Systems don't need to be low pressure. Electronics are moving to higher
temperature operation (cooling is a major cost of data centers) and the higher
temperature refrigerants are used in phase change heat pipe systems as well as
pumped (not compressed) refrigerant loops. That's what my company had been
experimenting with using HFE-7000.


On 6/11/2013 5:00 AM, Albert wrote:
+59.5 F (15 C) according to MSDS.
Albert

Does it boil at 60 deg F or -60 deg F at atmospheric pressure? 60 deg
doesn't sound like a great refrigerant unless perhaps used in a low
pressure system.

Don Black.
--------------------------------------------------------------------------------

No virus found in this message.
Checked by AVG - www.avg.com<http://www.avg.com>
Version: 10.0.1432 / Virus Database: 3199/5900 - Release Date: 06/10/13

------------------------------------

Yahoo! Groups Links





Re: Interesting "new" refrigerant

Albert Otten
 

Meanwhile I received a copy of this article.
It appears that the data are for fluids only and under rather high pressures (over 1 MPa, 10 atm). Then permittivity of HFC-245fa is well above 6. I have no idea whether this gives a clue about the vapor phase.

Albert

In the search for dielectric fluids for the P6015 this article "Dielectric properties of alternative refrigerants" might be very interesting. HFC-245fa is one of the discussed refrigerants. Someone having access to IEEE publications?

http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=1657961&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D1657961

Albert


Re: what to look for in basic Mainframe and plugins

 

Craig,
we still don't know what he wants the spec an for.

Jerry, care to elaborate?

D.

On Tue, Jun 11, 2013 at 10:22 AM, Craig Sawyers
<c.sawyers@tech-enterprise.com> wrote:
==============
Hi Jerry,
unless you buy the scope refurbished and recapped, avoid persistence storage
scopes, because 1. you probably don't need it and 2. they're much more
complex to repair (and you'll have to at some point). However they're good
as second scopes, and I have this kind of setup as well: a 7704 and a 7613.
Cheers,
D.
=============

The guy wants the frame for adding a spectrum analyser. See my earlier
comments.

* A non-storage scope is perfect if the analyser has digital storage - the
7L5, 7L14 and 7L15. In that case a 7603 is the way to go, with its large
CRT screen.
* A storage scope with variable persistence **is essential if the analyser
does not have digital storage** - the 7L12 and 7L13. Why? If you select a
narrow resolution bandwidth the scan rate drops to perhaps 1 division per
second and on a non-storage scope you see absolutely nothing of value.. In
that case the best choice is a 7613, but a 7623A or 7633 would also do.

Craig



------------------------------------

Yahoo! Groups Links



Re: Non-Tek 7k plugins? Plus: what nonexistent plugins would you wish fo

 

The structure of the rear guides the plugins to align correctly with the pins. If you remove the plastic rear piece. It becomes difficult to insert the plugin.

There are hundreds of plugins setting around waiting for members to sort through.

Jerry Massengale



-----Original Message-----
From: cheater00 .
To: TekScopes
Sent: Tue, Jun 11, 2013 2:45 am
Subject: Re: [TekScopes] Re: Non-Tek 7k plugins? Plus: what nonexistent plugins would you wish fo

 
Given a structural frame that rigidly holds the card in relation to the slot rails, the rear plastic frame shouldn't be necessary, should it? I thought it was only for shock retention during transport - after all those plugins used to cost thou's back in the day - you wouldn't want them to break every time you move them in a mobile shop (the scopes were expensive, so you had one that you moved around the floor, hence the carts). Not a consideration for a bench scope now is it?

D.


On Tue, Jun 11, 2013 at 3:00 AM, Dave Daniel <kc0wjn@...> wrote:


I refreshed my memory of how the rails look.

I think it would be fairly easy to buy some square aluminum stock, cut it to length, end-drill and tap for the front and rear panels and then do something simpler than Tek did for the side shields (screw-on mesh, perhaps buy the stock with pre-cut longitudinal slots for the side covers, etc. That circular slot that Tek made is for the side covers to snap in.

I agree with John that buying used ones is better than making these, but i have often thought about making something simpler. The thing that has always been a problem in my mind is the plastic guide on the rear.

Cheers,
DaveD


On 6/9/2013 8:15 PM, Dave Casey wrote:
 
I concede the point of exactly duplicating the Tek rails being cost prohibitive, but that doesn't mean you couldn't easily make something that would work at a more reasonable cost.

Dave Casey

On 6/9/2013 9:00 PM, Dennis Tillman wrote:
 
Pop the side panel off and the rear shroud off a 7000 plugin and look at the
top and bottom rails.

1) You need to write at least two CNC programs since the top rail and the
bottom rail are not the same. Can you write in G-code?
2) Look at the end profile. You have to start with a very thick blank.
Aluminum isn't cheap.
3) Look into the long slot that runs the full length of either side of a top
or bottom rail. It is circular inside and wider inside than the outside
opening of the slot. You would need a ball end mill to do that and since it
is such a small diameter slot you will snap off the end of the mill bit
unless you go very slowly.
4) Each rail requires machining on all 4 sides to make all the cuts. That
requires the blank to be moved by hand unless you have a robot arm do it.
5) When you are all done you will need to send the blank out to be anodized.

My best guess, if you can find a machine shop that will do all of this, is
it shouldn't cost much more than $100 for each rail.

Perhaps someone in the group is currently working in a CNC shop and can give
you a more accurate estimate.

Dennis

-----Original Message-----
From: TekScopes@... [mailto:TekScopes@...] On Behalf
Of Michael A. Terrell
Sent: Sunday, June 09, 2013 6:31 PM
To: TekScopes@...
Subject: Re: [TekScopes] Re: Non-Tek 7k plugins? Plus: what nonexistent
plugins would you wish fo

Dennis Tillman wrote:
>
> The top and bottom rails of the 7000 plugins are unique aluminum
> extrusions.
> Ditto for the TM500/TM5000 plugins
>
> It would be virtually impossible and extremely expensive to try to
> make these out of a blank piece of aluminum. The only realistic
> solution is to create a die for an extruder. That would be
> prohibitively expensive. You would need to make thousands to justify
> the cost of the extrusion die. In addition you would need to make a
> special punch to stamp out the openings in the top and bottom rails
> after you extruded the aluminum into blanks.
>
> By comparison the plastic rear shroud could probably be made on a 3D
> printer although it would be slow going.
>
> John is being realistic when he says:
> "Not interested in duplicating aluminum frames, just reuse old ones".
>

Can't they be duplicated on a CNC machine? I haven't used any 7000
series since the mid '80s, but I don't recall anything that makes them so
unique that they can't be duplicated with today's tooling.

------------------------------------

Yahoo! Groups Links







Re: Interesting "new" refrigerant

Peter Gottlieb <hpnpilot@...>
 

Systems don't need to be low pressure. Electronics are moving to higher temperature operation (cooling is a major cost of data centers) and the higher temperature refrigerants are used in phase change heat pipe systems as well as pumped (not compressed) refrigerant loops. That's what my company had been experimenting with using HFE-7000.

On 6/11/2013 5:00 AM, Albert wrote:

+59.5 F (15 C) according to MSDS.
Albert

Does it boil at 60 deg F or -60 deg F at atmospheric pressure? 60 deg
doesn't sound like a great refrigerant unless perhaps used in a low
pressure system.

Don Black.
--------------------------------------------------------------------------------

No virus found in this message.
Checked by AVG - www.avg.com <http://www.avg.com>
Version: 10.0.1432 / Virus Database: 3199/5900 - Release Date: 06/10/13


Re: eBay Auction: Tek 7854 Oscilloscope with the Waveform Calculator

Craig Sawyers <c.sawyers@...>
 

Well, I should probably have said: The Waveform Calculator is pretty rare
for
us over in Europe. For what it is worth...
I bought mine in the US. $109 plus $63 shipping to the UK. Perfect
cosmetic condition (once the layer of dust was cleaned off).

Craig


Re: eBay Auction: Tek 7854 Oscilloscope with the Waveform Calculator

magnustoelle
 

Well, I should probably have said: The Waveform Calculator is pretty rare for us over in Europe. For what it is worth...

Cheers,

Magnus

--- In TekScopes@yahoogroups.com, "Dennis Tillman" <dennis@...> wrote:

The waveform calculator is not rare at all.
There are currently 6 for sale on Ebay. That is a typical number at any one
time of the waveform calculator keyboards for sale.

Dennis


Re: 7834 non-storage mode readout brightness (or lack thereof)

Craig Sawyers <c.sawyers@...>
 

That seems high to me, but I'll check my 7623A when I get home this
afternoon. Are you talking about the setting in normal or storage mode?
Normal. And that is on a 7623B that came sealed in the original double
cartons, with accessories in sealed bags straight from Beaverton, so it only
has about 20 hours use with all of them by me.

Craig


Re: Source for Tek Blue paint

Mark Wendt <mark.wendt@...>
 

I hate it when that happens.

Mark

On 06/10/2013 08:55 PM, Tom Miller wrote:


It's missing a screw.
Tom

----- Original Message -----
*From:* vdonisa <mailto:vdonisa@yahoo.com>
*To:* TekScopes@yahoogroups.com <mailto:TekScopes@yahoogroups.com>
*Sent:* Monday, June 10, 2013 8:46 PM
*Subject:* [TekScopes] Re: Source for Tek Blue paint

Nice paint job here:

http://www.ebay.com/itm/261228507175

but why oh why aren't we allowed to see the front panel??????


Re: 549 intensity and HV

cmjones01
 

Thanks for the feedback about the 549 and its uses. The CRT in mine seems to be undamaged - the storage brightness is uniform all across the screen, though the whole thing is nowhere near as bright as my 535A. That's not a surprise given the 4kV anode voltage and storage meshes and so on. I haven't tried adjusting the flood gun yet.

Meanwhile, the repair progresses: I modified the rewound HV transformer, taking 20 turns off the grid winding, and now I have intensity control! I've been documenting the process on my blog:

http://martin-jones.com/2013/06/09/tektronix-549-storage-oscilloscope-part-3/

for those who are interested in the details. I also had to replace a couple of tubes in the delay pickoff circuit to get the delayed timebase to work.

Chris

On 08/06/2013 17:15, tubesnthings@aol.com wrote:
I wanted a 549 for use with a 1L5, which, according to Jim Williams "…is
the only reason to have one." He connected me with, not only a beautiful
lo-time 549, but also my first 1L5. I have rarely used it, but do
treasure it. The auto-erase functionality is not an option, as in the
564, and simply too much fun!

Bernd Schroder

/Sent from my Verizon Wireless Droid/


-----Original message-----

*From: *Steve <ditter2@yahoo.com>*
To: *TekScopes@yahoogroups.com*
Sent: *Sat, Jun 8, 2013 16:01:38 GMT+00:00*
Subject: *[TekScopes] Re: 549 intensity and HV



--- In TekScopes@yahoogroups.com
<mailto:TekScopes%40yahoogroups.com>, Chris Jones <chris@...> wrote:
>
> Update: I've got this scope on the proper workbench and tried
swapping
> over the two transformer windings. Success! I now have a trace,
but the
> intensity range control won't go down low enough to suppress the
blanked
> spot. That's exactly what I would expect if the two transformer
windings
> weren't identical. So now I've got to take the replacement
transformer
> apart and remove some turns from one of the windings.
>
> Apart from that, things are mostly looking good: the horizontal
sweep
> doesn't want to go much left of centre, and timebase B isn't very
happy,
> but I think this one's back from the dead.
>
> Just out of interest, what's the general opinion of the 549? It's
very
> unusual in the 500 series lineup, being the only storage scope,
and it's
> a very late model. I think mine was built in 1970.
>
> Chris
>

The 549 CRT is very susceptible to burning, more so than the 564/B –
the other storage scope available at the time. It uses a different
storage phosphor, designated by Tek as P202. (The 564/B uses either
P200 or P201) The 549 has a much faster writing rate for storage
than the 564/B, which is appropriate for the 30 MHz BW, as even with
the P201 phosphor, the 564 writing rate is very slow. But achieving
it results in a phosphor that is easy to burn. Tek warns the user of
the fragile phosphor in the manual.

Tek figured out how to achieve faster writing rate with the P200
phosphor, and hence the 549 is the only scope that ever used the P202
The scope performance is similar to a 545B, although the circuits
are different.

If you exercise care to avoid burning the phosphor, the scope has
decent performance. The storage is actually usable with reasonable
time base settings. And at the slow end, a 1L5 spectrum analyzer is
only usable with a 549.

I have three 549s. I set out to buy the first, the other two were
bundled with another scope I was after. Despite all the warnings
about the fragile phosphor, they all seem to have good tubes. The
flood gun settings on one is badly adjusted, but this is normal as
the tubes age and I suspect I can get it working when I have time to
adjust it. The horizontal in another is nonlinear, possibly from the
plate pull up resistor being open. I have a 541A that had the same
problem. I wonder how common this is in 53x/54x series? If you
calculate the power, you find that the Tek made resistors don't have
the power rating to survive when the horizontal trace is driven off
screen for extended periods of time. For all the great design in the
500 series scopes, I am surprised how many places the design does
not accommodate fault conditions. There are several places where a
single tube failure would cause several other components to burn up.

- Steve

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