Date   

Re: Spectrum analyzer Tektronix 7L13 on mainframe Tektronix 7603

Attilio
 

Hi Dave,
thanks Dave, I'll go read the posts of the nanovna-users group.

--Cheers
Attilio


Re: Spectrum analyzer Tektronix 7L13 on mainframe Tektronix 7603

Attilio
 

Hi Tom,
you are a great person.
Sometimes the bureaucracy can demoralize you, you must not give up.

I think I will purchase both the nanoVNA and a noise generator to use my 7L13 while waiting to find its TR502 tracking generator.

Happy New Year
Attilio


File archive back up

Bruce Lane
 

Fellow techies,

I'm pleased to announce I've fixed the problems with the Blue Feather file library. It's back up and operating as normal.

For those who have requested the login info, please continue to use the same user/password I supplied you before. There's been no change in that regard.

Thanks for your patience.

--
---
Bruce Lane, ARS KC7GR
http://www.bluefeathertech.com
kyrrin (at) bluefeathertech dot com
"Quando Omni Flunkus Moritati" (Red Green)


Re: Spectrum analyzer Tektronix 7L13 on mainframe Tektronix 7603

Tom Lee
 

Hi Attilio,

If your intention was/is to make frequency-response measurements with your SA in combination with a noise source, the nanoVNA will do that all by itself; no other device needed -- the nano will present a plot of frequency response magnitude and phase. So, think of the nanoVNA as a separate instrument.

There's also a related project, the tinySA, which is in the same form factor as the nanoVNA. The tinySA can also be used as a signal generator, although a rudimentary one. As with the nanoVNA, the tinySA is very inexpensive (order of $40, depending on vendor).

I have no relationship with the designers or vendors of these products, by the way. I've just been evaluating ways to keep my lab courses going in this age of COVID-forced lockdowns and remote teaching. Shipping "real" lab equipment is impractical for many obvious reasons. But the tinySA and nanoVNA go a long way toward enabling students to do all their lab experiments at home, and with a capital outlay that my department can absorb. Ironically, my biggest challenge is to find a suitable oscilloscope of similar price/performance. Getting approval to ship soldering stations and solder turned out to be a bureaucratic nightmare ("But what if students burn down their homes, or eat the solder?"). Solving that problem proved to consume much more time and energy than any other step in the process.

I'll now go back to the bench and solder something as therapy. ;)

-- Felice anno nuovo,
Tom


--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 12/29/2020 04:28, Attilio wrote:
Hi Tom,
wow fantastic this nanoVNA, I saw that there is also a V2 version, maybe I will buy it, but I didn't understand how to use it with my SA (maybe using it as generator ?).

-- Cheers,
Attilio




Re: Comments from Peter Keller on the 500 Series Scopes

Jonathan Pyle
 

My only Tektronix scope is an RM45A (rack-mount 545A) and my interest in 500 series scopes is the only reason I'm here! My favorite feature of the scope is using "B intensified by A," turning the delay multiplier to select a portion of the waveform, and then switching to "A delayed by B."


549 storage does not work

john.looyestijn@...
 

I raised a 549 from the grave and it is now working well, except for the memory function. The storage board is of version 'E' (actually indicated as HE, what must stand for Hoogeveen, The Netherlands type 'E'). If someone has the documentation on this version, that would be very welcome. The problem I now have is that the upper half of the CTR does not light up when the STORE function is activated. When the INTEGRATE TRACES button is pressed, than the upper part of the screen does light up and stays like that even when when STORE is depressed. Ingrate Traces has to be pushed again to get a normal screen. Switching the connections of the UPPER and LOWER on the PCB indicates that the electronics are working fine for upper and lower.
In addition to this, no signal remains on the screen in STORE mode. TP FLOOD CATH is 112 volt (seems to be low) and can not be altered since R1185 is missing. So 2 main questions:
1) why does the upper part of the CTR not light up in STORE mode;
2) why does the memory function not work.

Any help/suggestions will be appreciated


Re: Tek 465 Negative 8 volt rail issues

Dave Peterson
 

I've added photos (and schematic) of waveforms for C1512 and C1513: https://groups.io/g/TekScopes/album?id=258720

What I realized looking at these is that the unregulated 55v top of C1513 is basically the transformer/rectifier output with no filtering at all. This "noise" is propagated throughout the power supply. The 120v unregulated node is being pulled down by this noise via the C1512 coupling (i.e. it has some remaining capacitance), and the other supplies are also affected because the 55v regulated output is going to the + input of all of the other supplies' comparator input. The 55v regulator cannot compensate for the full swing unfiltered noise of the unregulated node. Note that the 120v unregulated noise is not pulling to ground where the 55v unregulated node is pulling all the way to ground. No cap at all. Thus the conclusion that C1513 is the culprit. And FWIW, the 120v regulated output is reducing the noise pretty well. It's just still too much to remove entirely.

Pulling the caps verified that C1513 is suffering massive internal resistance, and all other caps are suffering large internal R and reduced effective capacitance. C1513 has capacitance, but it's behind the large internal cap. It'll charge and discharge _very_ slowly. It shows about 1uF at the lead, nominal 1200uF.

That aside, what these waveforms illustrate for me is the nature of "ripple current" a DC PS filter cap needs to contend with. Through out its lifetime a filter cap is going to be pulling AC current at source frequency to smooth the DC value. The cap must pull current during these rectifier valleys to maintain the DC value. There are a number of ways to measure this current in-situ, but I'm not going to put a measuring R in the circuit - as interesting as that'd be - and I'm not going to buy a current probe just for this. To me the AC supply current the cap is pulling is the true stress on these caps, and transient, while potentially relatively large, likely doesn't contribute to significant heating and the associated reduction in lifetime.

Thought I'd share the images as they give a nice visceral depiction of what these caps are filtering.

Dave


Re: Rescuing 500s from tube snatchers/scavengers - how much is it worth

Paul Amaranth
 

If anyone's interested, 3 500 series have shown up in the Detroit
Craigslist

515A $200 https://detroit.craigslist.org/mcb/ele/d/grosse-pointe-vintage-tektronix-analog/7229304629.html
535 $75 https://detroit.craigslist.org/wyn/msg/d/livonia-tektronix-535-vintage-tube/7248044737.html
includes manual, probe and cart
547 $200 https://detroit.craigslist.org/wyn/ele/d/grosse-pointe-tektronix-type-547/7252700669.html
Manual, probe, 1A2 plugin

No connection to any of the above.

Paul

--
Paul Amaranth, GCIH | Manchester MI, USA
Aurora Group of Michigan, LLC | Security, Systems & Software
paul@AuroraGrp.Com | Unix/Linux - We don't do windows


Re: Tektronix 1A7 and 1A7A Plug-ins

Dave Wise
 

Sounds like your instrument had a Mod Kit field-installed. The VintageTek Museum has lots of microfilm, maybe they have the Mod Summary documentation for it.

Mod Kits are sometimes different from the late-production design, as the Mod Kit has to fit into the early circuitry.


Dave Wise

________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of um-gs via groups.io <um-gs=arcor.de@groups.io>
Sent: Tuesday, December 29, 2020 2:54 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Tektronix 1A7 and 1A7A Plug-ins

Thanks,
but that doesn't solve my request. The 1A7 manual shows the original pre-amp with 4 Nuvistors, and not the modified pre-amp installed in my 1A7 version as described above.


Re: Tek 453A

Tom Lee
 

I have occasionally looked inside scopes.

Your calculation is correct as far as it goes, but your accounting fails to comprehend storage costs. I modulate my offering price to achieve a net zero rate of domestic mass transfer, otherwise the capacitor that is my home will exceed breakdown. I will tell you, with a straight face, that some scopes are not even worth $5 to me. Such calculations will, of course, lead to different decisions for those with different constraints and wants.

As to keeping scopes out of the skip, that's certainly a worthy goal, which is one reason I have a couple hundred. But again, storage space is a factor. Over the years I've given away many scopes (and other instruments) to interested students. But the rate has gone down markedly over the years, as the youngest are accustomed to handheld battery-operated devices with touchscreens. There is, thankfully, a nonzero percentage who are fascinated by crts and Nixies, but overall, the percentage has been decreasing. And I have to be wary of those who want my Nixies merely to make clocks.

Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 12/29/2020 06:31, Chuck Harris wrote:
Take a look inside of your 453A, make note that gold is almost
$1900/oz, and tell me, with a straight face, that it is only
worth $5-10 in a not working condition. Even a broken jug has
$5 worth of gold in it.

If we want these scopes to remain available, we are going to
have to start offering higher prices than the scrap dealers.

Believe me, the scrappers know exactly what they are worth.

-Chuck Harris (Just say'n...)

Tom Lee wrote:
Hi Maurice,

These contain no proprietary ICs (no ICs!). The only sort-of unobtainium parts are
the tunnel diodes used in the trigger circuits. These scopes are highly repairable as
long as the jug isn't dead. But not showing a trace could mean anything from a bad
filter cap to a bad crt, so you're taking a higher than average risk. I'm infamously
cheap, and wouldn't pay more than $5-$10 for one in that condition. I might stretch
that to double that amount if the crt showed some kind of glow and if the scope were
complete and in good cosmetic shape.

-- Cheers,
Tom


Re: Yet another 'replacing carbon resistors with metal film' question....

Glenn Little
 

The carbon comp can absorb much more transient energy than a film resistor.
The carbon comp is a mass with leads on it, the film is a film deposited on an insulator, much less mass to absorb transients.

Each has its place.
Carbon comps have been replaced with ceramic comps.

Glenn

On 12/29/2020 12:35 PM, fiftythreebuick wrote:
Probably not a factor in this case, but in some cases we have found that metal film resistors (of the same value/wattage as the original carbon comp resistors) would blow open when exposed to high inrush current transients while carbon comp resistors would live in the same environment just fine. We first discovered this when working on the power supply of a 555. Multiple metal film resistors blew while a used carbon comp from a junker instrument stayed in there just fine.

Just for what it's worth....

Tom



--
-----------------------------------------------------------------------
Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIV wb4uiv@arrl.net AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI LM NRA LM SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"


Re: Tek 465 Negative 8 volt rail issues

Bob Albert
 

It shouldn't be a big deal to measure ripple current.  The tough part is access to the component without changing the ripple current.  My HP 428B could probably measure it if the probe could be made to fit.
A sensing resistor would work if it's a whole lot lower resistance than the ESR.
The ripple current would be much higher during turn on of the scope; does that count?
Bob

On Tuesday, December 29, 2020, 10:56:48 AM PST, Dave Peterson via groups.io <davidpinsf=yahoo.com@groups.io> wrote:

Spent a good amount of time yesterday studying available caps and Nichicon documentation. Came across this:

https://www.nichicon.co.jp/english/products/pdf/aluminum.pdf Section 2-9 "Life and Reliability".

"if a capacitor is used ... at the maximum operating temperature or below ...  the life doubles for each 10deg C drop in temperature." (Ft)

"The degree that applied voltage effects the life of the capacitor when used below the rated voltage is small, compared to the degree that ambient temperature and ripple current effects life. Therefore, when estimating the life of a capacitor, the voltage coefficient to the applied voltage (Fu) is calculated as 1."

2-9-5 "Ripple Current and Life" is a complex section, but can be summarized as "ripple current causes temperature rise", and this temperature rise reduces lifetime. (Fi)

Section 2-9-6 "Estimated Life" gives lifetime as:

L = Lo x Ft x Fi x Fu

Where Lo = Datasheet lifetime (about 3000h to 10000h for snap-in and radial aluminum electrolytic capacitors). Or:

L = Lo x 2^((To-Tn)/10) x 2^(1-((In/Im)^2)/K) x 1

Fi = 2^(1-((In/Im)^2)/K) is complicated as heck, but note that its value ranges (roughly) from 1 to 2. Suffice it to say, run your ripple current at max at max temperature and Fi approaches 1, but is generally closer to 1.5 to 1.9.

So lifetime, grossly, at worst, is:

L = 3000h x 2^((105-40)/10) x 1 x 1 = 3000h x 2^6.5 = 3000h x 90 = 270,000h = 270,000h / (24h x 365d/y) = 30y

Finally, noted from later in section 2-9-6 "Please note that calculated life time is for reference only and not guaranteed. Typically, fifteen years is generaIIy considered to be the maximum for the estimated life obtained by the above formula." I take this to mean Nichicon does not assure a lifetime of greater than 15 years, in general.

So: given the worst snap cap lifetime of 3000h, run at or below rated voltage, at or below rated ripple current, at approximately 40C (104F) the lifetime of the cap is estimated to be double the guaranteed lifetime of Nichicon caps. You halve the lifetime for every degree above 40C (roughly), and all bets are off if you exceed voltage or ripple current. Run ripple current below rated and you tend to double the lifetime. The "Miniature Type" (U-series) caps do tend to have about double the lifetime and ripple current rating of "Large Can Type" (L-series). But for large cap and voltage values the L-series have more "headroom" with regards to voltage than the U-series.

For the 1200uF, 100v C1513 (the big cap that brought this scope down) I'm going with a snap-cap at 160v. A U-series cap would have been limited to 80v - there's nothing offered in this line above that. The output at this cap is just under 80v, but it's near enough that it gives me pause. And clearly the technology used in U-series is at its limits with this cap, where the L-series is offered in significantly higher voltages. So it doesn't seem as stressed. The big question remains, what is the actual ripple current?

For the 560uF, 100v C1512, the smaller value L-series caps have ripple current specs less than the 2000mA of C1513 above. So I went with a U-series cap for this one. At the lower value this series has a 160v cap available. So why not!? It's ripple current spec is the same, 2000mA, as C1513. The ripple currents for equivalent L-series caps are less than 2000mA.

The low voltage caps are a bit more limited in available capacitance values. The U-series has 5600uF but only at 35v. The L-series has the same at 50v. But then the L-series does not have a 5000uF. It gets complicated going through all the combinations. I found it interesting that in the "465 PS Cap Replacement Guide" used a 5600uF for all three of C1542, C1552, and C1562. I was inclined to do the same as again, the U-series seems to be more against their voltage limits than the L-series. I do wonder about the significance of using a 5600uF cap in place of a 3000uF cap. But these caps are all about biggest C in the space available (at the time), right?

The big unknown that remains is what IS the ripple current to these caps in these supplies? I wonder if I can put together a reasonably accurate simulation. Just to get some sense of order of magnitude.

I didn't come across (yet?) the effect of voltage on the capacitor, besides little to no effect if kept below spec. But common sense suggests a cap operated near its spec is more likely to fail than one that has some head room. The question is what is "some" head room? A good value seems 2x, but it's not well defined. Lifetime suggests no real gain as long as spec is not exceeded and it's just a matter of providing enough head room to ensure spec is not exceeded under all operating conditions.

Here's my final list ordered from Mouser:

C1512, 560uF: UCY2C561MHD, 560uF, 160v, 2130mA, 18mmx40mm, 7.5mm lead spacing.
C1513, 1200uF: LGN2C122MELA40, 1200uF, 160v, 2300mA, 25mmx40mm, 10mm lead spacing.
C1542, C1552, C1562, 5600uF: LGY1H562MELA40, 5600uF, 50v, 2300mA, 25mmx40mm, 10mm lead spacing.

These all fit the adapter boards from the seller on eBay noted above. I bought two sets of both adapters and caps. One as a back-up for my first attempt at installation, and should I succeed without damage I have a second set for my other 465.

This was not as bad to do as I'd feared, and the caps that came out of my "parts" 465 are so bad that I'm kind of a convert now. Leaking is quite evident, though not so much that the A9 board is affected. While I don't have an ESR type meter, I'm able to use the equipment I have to get some kind of capacitance measurement off working caps. It's difficult to impossible to measure the capacitance on the old PS caps as the internal resistance is so high that shorting the leads does not discharge the cap appreciably (C1513 specifically). But the measured cap is less than 1/10th the rated cap. There's a big fat R between the lead and the internal capacitance. I only find it odd that this scope worked at all. I really wish I'd gotten some ripple measurements off the caps of the supplies (before regulation) before it died. I suspect the regulators were compensating until the 55v regulator couldn't take it any more. I'll have to take a look when I get it back working. I wonder if any of the regulator components are affected by the stress.

Sorry for the long write up, but I hope the info is useful to someone down the road.
Dave


Re: Yet another 'replacing carbon resistors with metal film' question....

Richard Knoppow
 

This resistance to pulse current seems to be about the only virtue carbon comp resistors have. I don't know why. Most carbon film resistors will take tremendous overloads but as steady state. I worked in resistor manufacture many years ago. We made mil spec carbon film and established reliability metal film parts. Carbon film resistors would run at red heat without damage.

On 12/29/2020 9:35 AM, fiftythreebuick wrote:
Probably not a factor in this case, but in some cases we have found that metal film resistors (of the same value/wattage as the original carbon comp resistors) would blow open when exposed to high inrush current transients while carbon comp resistors would live in the same environment just fine. We first discovered this when working on the power supply of a 555. Multiple metal film resistors blew while a used carbon comp from a junker instrument stayed in there just fine.

Just for what it's worth....

Tom



--
Richard Knoppow
dickburk@ix.netcom.com
WB6KBL


Re: Tek 465 Negative 8 volt rail issues

Dave Peterson
 

Spent a good amount of time yesterday studying available caps and Nichicon documentation. Came across this:

https://www.nichicon.co.jp/english/products/pdf/aluminum.pdf Section 2-9 "Life and Reliability".

"if a capacitor is used ... at the maximum operating temperature or below ... the life doubles for each 10deg C drop in temperature." (Ft)

"The degree that applied voltage effects the life of the capacitor when used below the rated voltage is small, compared to the degree that ambient temperature and ripple current effects life. Therefore, when estimating the life of a capacitor, the voltage coefficient to the applied voltage (Fu) is calculated as 1."

2-9-5 "Ripple Current and Life" is a complex section, but can be summarized as "ripple current causes temperature rise", and this temperature rise reduces lifetime. (Fi)

Section 2-9-6 "Estimated Life" gives lifetime as:

L = Lo x Ft x Fi x Fu

Where Lo = Datasheet lifetime (about 3000h to 10000h for snap-in and radial aluminum electrolytic capacitors). Or:

L = Lo x 2^((To-Tn)/10) x 2^(1-((In/Im)^2)/K) x 1

Fi = 2^(1-((In/Im)^2)/K) is complicated as heck, but note that its value ranges (roughly) from 1 to 2. Suffice it to say, run your ripple current at max at max temperature and Fi approaches 1, but is generally closer to 1.5 to 1.9.

So lifetime, grossly, at worst, is:

L = 3000h x 2^((105-40)/10) x 1 x 1 = 3000h x 2^6.5 = 3000h x 90 = 270,000h = 270,000h / (24h x 365d/y) = 30y

Finally, noted from later in section 2-9-6 "Please note that calculated life time is for reference only and not guaranteed. Typically, fifteen years is generaIIy considered to be the maximum for the estimated life obtained by the above formula." I take this to mean Nichicon does not assure a lifetime of greater than 15 years, in general.

So: given the worst snap cap lifetime of 3000h, run at or below rated voltage, at or below rated ripple current, at approximately 40C (104F) the lifetime of the cap is estimated to be double the guaranteed lifetime of Nichicon caps. You halve the lifetime for every degree above 40C (roughly), and all bets are off if you exceed voltage or ripple current. Run ripple current below rated and you tend to double the lifetime. The "Miniature Type" (U-series) caps do tend to have about double the lifetime and ripple current rating of "Large Can Type" (L-series). But for large cap and voltage values the L-series have more "headroom" with regards to voltage than the U-series.

For the 1200uF, 100v C1513 (the big cap that brought this scope down) I'm going with a snap-cap at 160v. A U-series cap would have been limited to 80v - there's nothing offered in this line above that. The output at this cap is just under 80v, but it's near enough that it gives me pause. And clearly the technology used in U-series is at its limits with this cap, where the L-series is offered in significantly higher voltages. So it doesn't seem as stressed. The big question remains, what is the actual ripple current?

For the 560uF, 100v C1512, the smaller value L-series caps have ripple current specs less than the 2000mA of C1513 above. So I went with a U-series cap for this one. At the lower value this series has a 160v cap available. So why not!? It's ripple current spec is the same, 2000mA, as C1513. The ripple currents for equivalent L-series caps are less than 2000mA.

The low voltage caps are a bit more limited in available capacitance values. The U-series has 5600uF but only at 35v. The L-series has the same at 50v. But then the L-series does not have a 5000uF. It gets complicated going through all the combinations. I found it interesting that in the "465 PS Cap Replacement Guide" used a 5600uF for all three of C1542, C1552, and C1562. I was inclined to do the same as again, the U-series seems to be more against their voltage limits than the L-series. I do wonder about the significance of using a 5600uF cap in place of a 3000uF cap. But these caps are all about biggest C in the space available (at the time), right?

The big unknown that remains is what IS the ripple current to these caps in these supplies? I wonder if I can put together a reasonably accurate simulation. Just to get some sense of order of magnitude.

I didn't come across (yet?) the effect of voltage on the capacitor, besides little to no effect if kept below spec. But common sense suggests a cap operated near its spec is more likely to fail than one that has some head room. The question is what is "some" head room? A good value seems 2x, but it's not well defined. Lifetime suggests no real gain as long as spec is not exceeded and it's just a matter of providing enough head room to ensure spec is not exceeded under all operating conditions.

Here's my final list ordered from Mouser:

C1512, 560uF: UCY2C561MHD, 560uF, 160v, 2130mA, 18mmx40mm, 7.5mm lead spacing.
C1513, 1200uF: LGN2C122MELA40, 1200uF, 160v, 2300mA, 25mmx40mm, 10mm lead spacing.
C1542, C1552, C1562, 5600uF: LGY1H562MELA40, 5600uF, 50v, 2300mA, 25mmx40mm, 10mm lead spacing.

These all fit the adapter boards from the seller on eBay noted above. I bought two sets of both adapters and caps. One as a back-up for my first attempt at installation, and should I succeed without damage I have a second set for my other 465.

This was not as bad to do as I'd feared, and the caps that came out of my "parts" 465 are so bad that I'm kind of a convert now. Leaking is quite evident, though not so much that the A9 board is affected. While I don't have an ESR type meter, I'm able to use the equipment I have to get some kind of capacitance measurement off working caps. It's difficult to impossible to measure the capacitance on the old PS caps as the internal resistance is so high that shorting the leads does not discharge the cap appreciably (C1513 specifically). But the measured cap is less than 1/10th the rated cap. There's a big fat R between the lead and the internal capacitance. I only find it odd that this scope worked at all. I really wish I'd gotten some ripple measurements off the caps of the supplies (before regulation) before it died. I suspect the regulators were compensating until the 55v regulator couldn't take it any more. I'll have to take a look when I get it back working. I wonder if any of the regulator components are affected by the stress.

Sorry for the long write up, but I hope the info is useful to someone down the road.
Dave


Re: Yet another 'replacing carbon resistors with metal film' question....

fiftythreebuick
 

Probably not a factor in this case, but in some cases we have found that metal film resistors (of the same value/wattage as the original carbon comp resistors) would blow open when exposed to high inrush current transients while carbon comp resistors would live in the same environment just fine. We first discovered this when working on the power supply of a 555. Multiple metal film resistors blew while a used carbon comp from a junker instrument stayed in there just fine.

Just for what it's worth....

Tom


Re: Rescuing 500s from tube snatchers/scavengers - how much is it worth

kim.herron@sbcglobal.net
 

Just a note: I have it on good authority that the inventory
that was in the building Stan was leasing has been
moved, sold, or something. It all went out of state, so I've
heard. I have reason to think that it was the property
owner that had it removed.



On 29 Dec 2020 at 10:00, - wrote:

John said: This is very sad news. Do you know which one of the
brothers
it was? Sad to hear, they have been very helpful in the past with
reasonable prices and good shipping practices. I hope the business
will
carry on.

It was Stan Winston that passed away. I don't know if he had a
brother
or not but I've heard that there is another relative involved that
is
trying to sell the business or sell off the assets. Stan inherited
the
business from his father 20+ years ago so there could be a brother
that's
also part owner. We're all hoping that the business will continue
but it
doesn't look like it will. IMO This would be a good opportunity for
a
foreign investor that wants to own and operate a US business so that
they
could get an immigration visa.

On Mon, Dec 28, 2020 at 3:44 PM John Williams <books4you4@mail.com>
wrote:

This is very sad news. Do you know which one of the brothers it
was? Sad
to hear, they have been very helpful in the past with reasonable
prices and
good shipping practices. I hope the business will carry on.








John Goller, K9UWA & Jean Goller, N9PXF
Antique Radio Restorations
k9uwa@arrl.net
Visit our Web Site at:
http://www.JohnJeanAntiqueRadio.com
4836 Ranch Road
Leo, IN 46765
USA
1-260-637-6426


Last few new Tek goodies up for Stuff Season

 

Our stuff season is getting its last additions today, there's still one hard to find 149-0035-00 fan motor (465/475), some blue CRT filters, and some interesting Tek internal bits including a 2335/6/7 sweep switch, 7903/7904 mod kit and other goodies. You can see everything here:

https://www.sphere.bc.ca/test/stuffday.html

There's also a bunch of new LCD and VFD displays going up later today as soon as all the pics are done. Many thanks to everybody that dropped by the Stuff Season page, it wasn't as much fun as having everybody here in person, but for those far away, it was a lot more convenient.

All our best wishes for a better new year,
walter & susan
Sphere Research Corp.
https://www.sphere.bc.ca/test/index.html


Re: Spectrum analyzer Tektronix 7L13 on mainframe Tektronix 7603

Dave Daniel
 

You need to read the group Wiki. I suggest the one on the nanovna-users group.

DaveD

On 12/29/2020 7:28 AM, Attilio wrote:
Hi Tom,
wow fantastic this nanoVNA, I saw that there is also a V2 version, maybe I will buy it, but I didn't understand how to use it with my SA (maybe using it as generator ?).

-- Cheers,
Attilio



--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus


Re: Rescuing 500s from tube snatchers/scavengers - how much is it worth

-
 

John said: This is very sad news. Do you know which one of the brothers
it was? Sad to hear, they have been very helpful in the past with
reasonable prices and good shipping practices. I hope the business will
carry on.

It was Stan Winston that passed away. I don't know if he had a brother
or not but I've heard that there is another relative involved that is
trying to sell the business or sell off the assets. Stan inherited the
business from his father 20+ years ago so there could be a brother that's
also part owner. We're all hoping that the business will continue but it
doesn't look like it will. IMO This would be a good opportunity for a
foreign investor that wants to own and operate a US business so that they
could get an immigration visa.

On Mon, Dec 28, 2020 at 3:44 PM John Williams <books4you4@mail.com> wrote:

This is very sad news. Do you know which one of the brothers it was? Sad
to hear, they have been very helpful in the past with reasonable prices and
good shipping practices. I hope the business will carry on.






Re: Mechanism of CRT Double Peaking (UPDATED)

Chuck Harris <cfharris@...>
 

That is probably a miss-memory.

What the designer in GE was talking about is a layer of contamination
that boils up to the surface of the normally highly emissive cathode
material. When the layer covers the cathode material, the emission
drops.

There is good evidence that overheating the cathode, and using the
first grid as the anode of a diode to draw much higher than usual
current from the cathode (using much higher voltages than usual)
will break up the contamination layer, and restore some activity to
the cathode... Indeed, all CRT manufacturers do this to activate the
cathodes of new CRT guns, during manufacture.

Zapping is not really agressive to anything but the cathode layer,
certainly not to the first grid, which is a heavy piece of stainless
steel... way more rugged than the cathode.

Raytronic Beamer, Sencore Rejuvinator, B&K ... there were hundreds
of CRT restorers available to the TV repair shops that all worked the
same way. Each was so magnificent that it was head and shoulders
above all of the rest... Each allowed the repairman to go from gently
(and ineffectually) caressing the cathode to kill'em or cure'em levels
of zapping.

-Chuck Harris

greenboxmaven via groups.io wrote:

Some years ago, I had a very fine conversation with a picture tube designer at
General Electric here in Syracuse. One phenomena that could explain the double peak
you see is the electrical interface between the cathode material and the metal cup it
is applied to.  Apparently, a contaminated layer  can  build up that carries current
well up to a point, then passes it poorly until there is enough current demand to
develope a voltage across the layer and cause it to break down. This effect is far
more detrimental for television than it would be for an oscilloscope where the beam
intensity is usually on or off. Decades ago, there was a rejuvinator called the
Raytronic Beamer that was supposedly superior in breaking down this layer.  They were
so effective they raised a great deal of controversy because people would zap dim
jugs and sell them as excellent used or even rebuilt.  I have had mixed success
zapping scope jugs, it made a small improvement for a very dim 453, but worked well
for 5UP1s and other older ones. One thing about zapping a jug must be kept in mind-
it usually enlarges the aperture in the first grid, which enlarges the beam spot. 
That does help brightness, and is usually OK for black and white television, but
would certainly reduce clarity and resolution on a scope or color television.

       Bruce Gentry, KA2IVY


On 12/25/20 8:53, SCMenasian wrote:
This is a very complex subject and the correct explanation of what is going on
depends critically on what type of cathode is involved. I do not know exactly what
types of cathode Tektronix used. They probably used several in various generations
of tubes. Two types, in addition to coated cathodes come to mind. Both can respond
to higher than normal heater current.

The first is the dispenser cathode, familiar to many experimental atomic
physicists. These cathodes (which are extended in nature and probably not suitable
for CRTs) are consist of a pellet of sintered material in which the active electron
emitting oxides are actually in the body of the cathode. The must be "activated" by
raising the temperature high enough to diffuse the active material to the surface.
If, for example, Tektronix developed a dispenser cathode in which, initially, the
activated surface was only a tiny point and, in which, subsequent overheating would
cause active material to diffuse, not only to that point, but to the entire anode
facing surface, the behavior might be as described.

Another cathode material, often used in vacuum tube filaments, is thoriated
tungsten. In this material, thorium is, initially, distributed through the body of
the material and initial (and subsequent) heatings serve to diffuse the thorium to
the surface, with, possibly, similar results.

Stephen Menasian










11761 - 11780 of 187059