Date   
Re: Tek Blue Paint

Dave Daniel
 

Sherwin-Williams can do that.

On Mar 24, 2020, at 07:50, Li Gangyi <li.gangyi@...> wrote:

Can't somebody go get it specteophotometered for a close match like with
custom car colors? I know where I was previously the English color near me
had that tool.

Finally an old lady with a good eye matched the thing by eye till I
couldn't tell a difference. Granted it was a flat color though.


On Tue, Mar 24, 2020, 12:42 PM Dennis Tillman W7PF <@Dennis_Tillman_W7pF>
wrote:

Hi Steve and Brendan,
Stan Griffiths used to sell Tek paint in spray cans and other ways. I got
4 of the last cans he had in October. He only had a few left at that time.

This might be what you are looking for:
Dennis Tillman W7pF


-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
snapdiode via Groups.Io
Sent: Thursday, April 19, 2018 5:12 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Tek blue tyouch up paint?


https://www.sherwin-williams.com/store-locator/product-finishes-facility/portland/or/4383

phone 1-503-249-0222

You want L61 opex lacquer
L61xxcl42
Tek Blue

Or just call Tektronix, they used to have a part number just for that, in
a 7oz spray can.




--
Dennis Tillman W7PF
TekScopes Moderator




Re: Mr Carlson's Patreon and test tool designs - was Re: [TekScopes] enclosures for ESR meters

Lawrance A. Schneider
 

I agree!

Re: fuzzy trace, weakish trace, CURED

aldue
 

Hi Roy, 464 now has a shaper trace. Test Point 1443 was supposed to read +27 Volts. He was about 22 Volts after replacing Q1436, Q1432 and R1437. I learned that I can not trust my DVM to measure ripple also. I had replaced R1437 ,910 Ohms, with a 9.1 K and R1443 ,220 Ohms, had grown to about 12K. The drawer with about 100 ,910 Ohm resistors had 2, 9100 Ohmers. Replacing the resistors raised TP1443 to 27.48 V and resulted in a bright sharp trace with noise. Putting the case on cured the noise.
The bad news. I must have bumped a cable or ?, the sweep is free running. A mission for another day. thank you, aldue

Re: Tek Blue Paint

Li Gangyi
 

Can't somebody go get it specteophotometered for a close match like with
custom car colors? I know where I was previously the English color near me
had that tool.

Finally an old lady with a good eye matched the thing by eye till I
couldn't tell a difference. Granted it was a flat color though.


On Tue, Mar 24, 2020, 12:42 PM Dennis Tillman W7PF <@Dennis_Tillman_W7pF>
wrote:

Hi Steve and Brendan,
Stan Griffiths used to sell Tek paint in spray cans and other ways. I got
4 of the last cans he had in October. He only had a few left at that time.

This might be what you are looking for:
Dennis Tillman W7pF


-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
snapdiode via Groups.Io
Sent: Thursday, April 19, 2018 5:12 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Tek blue tyouch up paint?


https://www.sherwin-williams.com/store-locator/product-finishes-facility/portland/or/4383

phone 1-503-249-0222

You want L61 opex lacquer
L61xxcl42
Tek Blue

Or just call Tektronix, they used to have a part number just for that, in
a 7oz spray can.




--
Dennis Tillman W7PF
TekScopes Moderator



Re: TEKTRONIX 491 measuring wifi signals

Miguel Work
 

My Pansonic microwave oven is working since late 80s, is one of the first micro controlled, the keyboard has no signs of wear 30 years after, has survaived my four brothers family!
Using it every day and still working. It has a double shield.

It costs about 800$

Regards!




-----Mensaje original-----
De: TekScopes@groups.io [mailto:TekScopes@groups.io] En nombre de Chuck Harris
Enviado el: martes, 24 de marzo de 2020 13:44
Para: TekScopes@groups.io
Asunto: Re: [TekScopes] TEKTRONIX 491 measuring wifi signals

When the first commercial microwave ovens were made, they had simple mechanical timers, and no "heat" settings. The next generation had simple mechanical timers, and thermal timers similar to turn signal "clickers" to adjust the on vs off time. Every enhancement since has been simply refinements of the same basic formula: Turning mechanical timers into electronic timers, into microprocessor timers.
Turning mechanical bells into electronic bells. Turning linear transformers into switching power supplies...

But the basic on/off, "bang-bang" method of controlling the heat has remained intact: how many seconds on, out of 10 seconds, determines the "heat" from the oven.

Some researchers wanted to take the microwave oven into the realm of laboratory heating, and found the "bang-bang" style of heat adjustment way too brutal. For instance, if you wanted to heat a saline solution in a watch glass, it would explode around the edges where the water was so very thin, even though the "heat" was on low... even one second at full power followed by 9 seconds of being off was too brutal.

So, a colleague of mine developed a precision microwave that took the duty cycle modulation of the magnetron from seconds on out of 10 seconds, to power line cycles on out of 10 power line cycles. And, even balanced the distribution of on cycles so that if you were at 50%, it was every other cycle of the 60Hz power, (that may have been my suggestion, I don't remember anymore) ... Saline in a watch glass was his standard test.

Heading back to 491's, and wifi signals:

Modern microwave ovens have replaced the heavy, and copper laden, power transformers with switching power supplies...
which is why they are now available for less than $100.

There is a big cost, however. High voltage capacitors are still expensive, so the new supplies aren't at all well filtered, and end up modulating the 2450MHz nominal magnetron output at the switching supply rate, and the switching supply rate is not at all stabilized, so it changes with load. This wreaks havoc with wifi routers which occupy the same ISM band as do the ovens.... Only the ovens leak way more power than the routers put out.

A friend once asked me why his "smart" house, and his cordless phones, stopped working every so often... I asked him if he had a microwave oven. He said yes. I asked him to notice if his wife was using the microwave oven when his "smart"
house stopped being so "smart".

You should be able to see this wandering RF noise fest on your
491 whenever the microwave oven is running.

-Chuck Harris
on off timer that im Ford wrote:

I stand corrected (not all that unusual).  Thanks, Chuck.  My guess
would be that microwave oven manufacturers either don't know about or
don't want to deal with the subtleties of magnetron anode and filament
voltages and currents.JimSent from my Verizon, Samsung Galaxy
smartphone

Re: TEKTRONIX 491 measuring wifi signals

greenboxmaven
 

Is there a limit to how fast a magnetron can get the swirling electrons "up to speed" and begin producing an output? Radar sets do use some sharp pulses, do accommodations have to be made for the magnetron's response?

Bruce Gentry, KA2IVY

On 3/24/20 8:44 AM, Chuck Harris wrote:

Heading back to 491's, and wifi signals:

Modern microwave ovens have replaced the heavy, and copper
laden, power transformers with switching power supplies...
which is why they are now available for less than $100.

There is a big cost, however. High voltage capacitors are
still expensive, so the new supplies aren't at all well
filtered, and end up modulating the 2450MHz nominal magnetron
output at the switching supply rate, and the switching
supply rate is not at all stabilized, so it changes with
load. This wreaks havoc with wifi routers which occupy the
same ISM band as do the ovens.... Only the ovens leak way
more power than the routers put out.



-Chuck Harris
on off timer that im Ford wrote:
I stand corrected (not all that unusual). Thanks, Chuck. My guess would be that microwave oven manufacturers either don't know about or don't want to deal with the subtleties of magnetron anode and filament voltages and currents.JimSent from my Verizon, Samsung Galaxy smartphone

Fixtures for 7CT1N/5CT1N

Szabolcs Szigeti
 

Hi,

Apparently posting this in the ESR meter thread was a no-no and got
caught by moderation, so I repeat the important part here if anyone is
interested in some collaboration.

"
Good that you mentioned the 7CT1N, as this has been a long time plan
for me to make some fixtures for my 5CT1N, especially seeing the price
these are being sold on eBay. I have just started to sketch up some
design and look for parts. So I would be gladly helping with coming up
with a design. I can do the PCB, but this could be a good group effort
as it would be nice to have some 3D printed enclosures for it. Of
course it can be simple small PCB with 3 plugs and some zif socket,
but why not make it really fancy if we have the knowledge and tools.
"

Szabolcs

Re: TEKTRONIX 491 measuring wifi signals

Chuck Harris
 

When the first commercial microwave ovens were made, they
had simple mechanical timers, and no "heat" settings. The
next generation had simple mechanical timers, and thermal
timers similar to turn signal "clickers" to adjust the on
vs off time. Every enhancement since has been simply
refinements of the same basic formula: Turning mechanical
timers into electronic timers, into microprocessor timers.
Turning mechanical bells into electronic bells. Turning
linear transformers into switching power supplies...

But the basic on/off, "bang-bang" method of controlling the
heat has remained intact: how many seconds on, out of 10
seconds, determines the "heat" from the oven.

Some researchers wanted to take the microwave oven into the
realm of laboratory heating, and found the "bang-bang" style
of heat adjustment way too brutal. For instance, if you
wanted to heat a saline solution in a watch glass, it would
explode around the edges where the water was so very thin,
even though the "heat" was on low... even one second at full
power followed by 9 seconds of being off was too brutal.

So, a colleague of mine developed a precision microwave that
took the duty cycle modulation of the magnetron from seconds
on out of 10 seconds, to power line cycles on out of 10 power
line cycles. And, even balanced the distribution of on
cycles so that if you were at 50%, it was every other cycle
of the 60Hz power, (that may have been my suggestion, I don't
remember anymore) ... Saline in a watch glass was his
standard test.

Heading back to 491's, and wifi signals:

Modern microwave ovens have replaced the heavy, and copper
laden, power transformers with switching power supplies...
which is why they are now available for less than $100.

There is a big cost, however. High voltage capacitors are
still expensive, so the new supplies aren't at all well
filtered, and end up modulating the 2450MHz nominal magnetron
output at the switching supply rate, and the switching
supply rate is not at all stabilized, so it changes with
load. This wreaks havoc with wifi routers which occupy the
same ISM band as do the ovens.... Only the ovens leak way
more power than the routers put out.

A friend once asked me why his "smart" house, and his cordless
phones, stopped working every so often... I asked him if he
had a microwave oven. He said yes. I asked him to notice
if his wife was using the microwave oven when his "smart"
house stopped being so "smart".

You should be able to see this wandering RF noise fest on your
491 whenever the microwave oven is running.

-Chuck Harris
on off timer that im Ford wrote:

I stand corrected (not all that unusual).  Thanks, Chuck.  My guess would be that microwave oven manufacturers either don't know about or don't want to deal with the subtleties of magnetron anode and filament voltages and currents.JimSent from my Verizon, Samsung Galaxy smartphone

Re: TDS3000B calibration

 

Thank you - that's what I needed to know!

David

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of benj3867 via Groups.Io
Sent: 24 March 2020 11:45
To: TekScopes@groups.io
Subject: Re: [TekScopes] TDS3000B calibration

Looking at the service manual for the TDS3000B, and the specs of the recommended Wavetek 9500 calibrator, the signals one needs are within the following limits:
DC Voltage between 50mV and 70V, +-0.1% amplitude accuracy.
AC Sine waves between 30kHz and 80Mhz, 5mv to 5.5V pk-pk into 50 ohm, 100ppm frequency accuracy, 3% amplitude accuracy.
Fast Rise pulse: <= 1ns rise time, at least -2.2V to 0V amplitude (unloaded), repetition rate may be anything between 100Hz and 1MHz (note that any *one* value in this range is all that is needed).

Re: TEKTRONIX 491 measuring wifi signals

Miguel Work
 

Seeing diagram power Supply of a modern microwave, I suspect that is working with the same principle, on off in seconds intervals.

https://2.bp.blogspot.com/-5XQi-_PGrCY/UEnW1UzTtbI/AAAAAAAAAh4/nmHDUTYpAHg/s1600/4.bmp

Regards!

-----Mensaje original-----
De: TekScopes@groups.io [mailto:TekScopes@groups.io] En nombre de Chuck Harris
Enviado el: martes, 24 de marzo de 2020 3:46
Para: TekScopes@groups.io
Asunto: Re: [TekScopes] TEKTRONIX 491 measuring wifi signals

Microwave oven magnetrons, not transformers... bad brain!

Chuck Harris wrote:

30 years ago, I worked with a company that made power sources out of
commercial microwave oven transformers. I can tell you with out
reservation that magnetrons will work to produce power over a wide
range of anode voltages, and power levels.

They are not just on and off devices.

The efficiency varies on anode voltage, and the power curve is
anything but linear, but we used them from about 10W to about 900W by
driving the anode transformer with a variac.

The important trick was you had to provide the filament voltage with a
separate transformer, as they won't work if the filament isn't hot.

I used a 491 for several years, and at the first opportunity to ditch
it and replace it with *any* other spectrum analyzer, I did. I chose
an Ailtech 707.

Fundamentally the problem with the 491 is it has a fixed first mixer,
and a swept IF, with an unbalanced mixer.

This means that the IF band gets through the mixer with much less loss
than the desired signal. If you are in an RF rich environment... lots
of TV, public service, and FM radio stations, you will have a
porcupine of fixed position spurs on your screen at all times...
leakage through the mixer to the IF.

On the other hand, it works quite well if you are using one of the
higher bands that doesn't include DC.

-Chuck Harris



Jim Ford wrote:
Yep, a magnetron is completely on or completely off.  No in between. 
A virtue of solid state RF cooking devices touted by NXP and others
is that solid state can be ramped up and down for more even heating. 
I'm sure the new ovens are way more expensive than the magnetron
types after 80 or so years of production of the latter.  Will come
down just like solid state displays did.Jim Ford Sent from my
Verizon, Samsung Galaxy smartphone
-------- Original message --------From: Albert Otten <aodiversen@...> Date: 3/23/20 2:52 PM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] TEKTRONIX 491 measuring wifi signals It's also a nice exercise to catch the leakage radiation of a microwave oven. I tried this after repair of my 491, at minimum magnetron power level. Then  I "discovered" (didn't know) that the power level is controlled by the on/off duty cycle of full power. At minimum power there is no radiation at all most of the time.AlbertOn Sun, Mar 22, 2020 at 10:58 PM, Miguel Work wrote:>> I have made a little video showing the Tektronix 491 with wifi signals, at 2.4> Ghz. I now that is a crude SA, but is nice fast showing these signals compared> with the 7L14 that I have in my workbench.> > https://www.youtube.com/watch?v=fCwKErcqJiY&feature=youtu.be> > Regards!



Re: TEKTRONIX 491 measuring wifi signals

Miguel Work
 

In my Panasonic oven is a on off regulation, in 5 seconds intervals, aprox.

In classic microwave oven there is a big 50hz transoformer, with a HV doubler. The same transformer feeds the anode and the filament, son there is no power regulation.

https://www.eevblog.com/forum/chat/microwave-oven-pwm-frequency/



I have seen newer ovens with pwm HV power supply:

https://dfecd.blogspot.com/2012/09/panasonic-microwave-oven-inverter-hv.html

But I don´t know if is a on off method too.

Regards!









-----Mensaje original-----
De: TekScopes@groups.io [mailto:TekScopes@groups.io] En nombre de Chuck Harris
Enviado el: martes, 24 de marzo de 2020 3:38
Para: TekScopes@groups.io
Asunto: Re: [TekScopes] TEKTRONIX 491 measuring wifi signals

30 years ago, I worked with a company that made power sources out of commercial microwave oven transformers. I can tell you with out reservation that magnetrons will work to produce power over a wide range of anode voltages, and power levels.

They are not just on and off devices.

The efficiency varies on anode voltage, and the power curve is anything but linear, but we used them from about 10W to about 900W by driving the anode transformer with a variac.

The important trick was you had to provide the filament voltage with a separate transformer, as they won't work if the filament isn't hot.

I used a 491 for several years, and at the first opportunity to ditch it and replace it with *any* other spectrum analyzer, I did. I chose an Ailtech 707.

Fundamentally the problem with the 491 is it has a fixed first mixer, and a swept IF, with an unbalanced mixer.

This means that the IF band gets through the mixer with much less loss than the desired signal. If you are in an RF rich environment... lots of TV, public service, and FM radio stations, you will have a porcupine of fixed position spurs on your screen at all times... leakage through the mixer to the IF.

On the other hand, it works quite well if you are using one of the higher bands that doesn't include DC.

-Chuck Harris



Jim Ford wrote:

Yep, a magnetron is completely on or completely off.  No in between. 
A virtue of solid state RF cooking devices touted by NXP and others is
that solid state can be ramped up and down for more even heating.  I'm
sure the new ovens are way more expensive than the magnetron types
after 80 or so years of production of the latter.  Will come down just
like solid state displays did.Jim Ford Sent from my Verizon, Samsung
Galaxy smartphone
-------- Original message --------From: Albert Otten <aodiversen@...> Date: 3/23/20 2:52 PM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] TEKTRONIX 491 measuring wifi signals It's also a nice exercise to catch the leakage radiation of a microwave oven. I tried this after repair of my 491, at minimum magnetron power level. Then  I "discovered" (didn't know) that the power level is controlled by the on/off duty cycle of full power. At minimum power there is no radiation at all most of the time.AlbertOn Sun, Mar 22, 2020 at 10:58 PM, Miguel Work wrote:>> I have made a little video showing the Tektronix 491 with wifi signals, at 2.4> Ghz. I now that is a crude SA, but is nice fast showing these signals compared> with the 7L14 that I have in my workbench.> > https://www.youtube.com/watch?v=fCwKErcqJiY&feature=youtu.be> > Regards!

Re: TDS3000B calibration

benj3867
 

Looking at the service manual for the TDS3000B, and the specs of the recommended Wavetek 9500 calibrator, the signals one needs are within the following limits:
DC Voltage between 50mV and 70V, +-0.1% amplitude accuracy.
AC Sine waves between 30kHz and 80Mhz, 5mv to 5.5V pk-pk into 50 ohm, 100ppm frequency accuracy, 3% amplitude accuracy.
Fast Rise pulse: <= 1ns rise time, at least -2.2V to 0V amplitude (unloaded), repetition rate may be anything between 100Hz and 1MHz (note that any *one* value in this range is all that is needed).

Re: Mr Carlson's Patreon and test tool designs - was Re: [TekScopes] enclosures for ESR meters

Szabolcs Szigeti
 

Hi,

Yes, the current offerings from China and elsewhere on PCBs just make
it practically nonsensical to DIY PCBs at home. It was a fantastic
feeling when I first ordered my first plated hole, double sided smd
PCB from china, complete with solder mask, silkscreen, etc. This would
have been out of reach for a hobbyist a decade or two ago. I'm not
nostalgic about getting back to etch stuff in ferric chloride,
drilling, filing, etc. even though that I even built a compete
oscilloscope this way back in the poor university student time :-)

I used KiCAD for a lot of stuff now and works like charm. (I have even
shared a very simple TekMate 287 daughterboard design with this group)
Of course if one needs to make a large non-plated hole simple board,
it may be cheaper and you don't end up with 4 additional boards, but
taking the cost of the time for this, it still may be better to have
it fabricated.

Good that you mentioned the 7CT1N, as this has been a long time plan
for me to make some fixtures for my 5CT1N, especially seeing the price
these are being sold on eBay. I have just started to sketch up some
design and look for parts. So I would be gladly helping with coming up
with a design. I can do the PCB, but this could be a good group effort
as it would be nice to have some 3D printed enclosures for it. Of
course it can be simple small PCB with 3 plugs and some zif socket,
but why not make it really fancy if we have the knowledge and tools.

Szabolcs


Harvey White <madyn@...> ezt írta (időpont: 2020. márc.
23., H, 23:55):


Making PC boards is not really a trivial task. Toner transfer needs a
laser printer and some understanding of the process, regardless of
whether or not you use it for an ESR meter or some thing different for a
Tektronix rebuild. Toner transfer can best be used on single sided
boards, but double sided boards are possible. Requires more
understanding and the right tools. The board factories (oshpark and any
of the Chinese board factories, for instance) tend to make boards in
lots (oshpark is $5 per square inch, but you get 3, gold plated (ENIG)
boards. The Chinese factories typically have (IMHO) a 100 mm by 100 mm
maximum size, lots of 5 or 10, and very low prices for HASL (Hot air
solder leveled) boards. A typical cheap price is 10 boards for $5.00,
with about 20 to 25 dollars for shipping.

All varies per manufacturer. They want gerber files, but will give you
the algorithms (files) for the CAM manufacturing of their boards from
popular files. I use EAGLE (7.7). These boards are silk screened,
double sided, plated through holes.

Any boards I can make with toner transfer (disassembled the setup, BTW)
would be double sided, tin lead plated, NO plated through holes, NO silk
screening. It took me a while to get there.

I did a LOT of toner transfer boards (laser printer, laminator, special
paper) before my designs got too complex for manual layout and toner
transfer.

There's lots of low cost, low effort PC board techniques. Haven't seen
the target project, so I can't comment. There are a number of projects
directly related to Tektronix that can use PC boards. I'd suggest test
fixtures for the 7CT1N, for example.

Feel free to contact me off list if you want further information.

Harvey


On 3/23/2020 6:34 PM, David Kuhn wrote:
" “He strongly recommends that you make the boards using the toner transfer
method.”

I only have ink jet. Still it's a lot of work and I do not need to learn to
make PCBs. I've always use 4PCB.com for that and I do not want to have to
use chemicals.

On Mon, Mar 23, 2020 at 2:05 PM Eric <ericsp@...> wrote:

I have been a member of Paul’s patron since the beginning. Just to be
transparent. I have seen this question asked many times. Paul’s response is
usually the same. “He strongly recommends that you make the boards using
the toner transfer method.” I have done so personally and have learned a
staggering amount especially in the QA department having to quality check
my own boards. It has also given me a much better understanding of what is
really going on. There is a lot of learning building it completely from
scratch.


-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Abc Xyz
Sent: Monday, March 23, 2020 2:02 PM
To: TekScopes@groups.io
Subject: Re: Mr Carlson's Patreon and test tool designs - was Re:
[TekScopes] enclosures for ESR meters

it would be nice to have a Board.

On Mon, Mar 23, 2020, 10:52 AM David Kuhn <Daveyk021@...> wrote:

" Mr. Carlson does not usually do commercially produced"

So then I suspect he does not have gerber files to download? It would
be possible to lay it out in CircuitMake/TraxMaker, but if the circuit
uses somewhat modern components, then one would have to create macros
for them.
As I said, I think a minimal of 5 proto boards would be needed. So if
the board works, there would be extras. Since it is Paul's i.p. you
would not be able to see those extra boards of five of us wanted to
make the cap tester.

dave

On Sun, Mar 22, 2020 at 10:02 PM Mlynch001 <@mlynch001> wrote:

Dave,

I built one on Proto-Board my first try. It was tedious, but
worked well. You can build on a breadboard, perf-board or etch your
own. Mr.
Carlson does not usually do commercially produced boards and the
practice is discouraged on Patreon, for obvious reasons. I would
not doubt that someone has produced some of these boards, but I do
not know of a source myself.

--
Michael Lynch
Dardanelle, AR











Re: Tek Blue Paint

 

Hi Steve and Brendan,
Stan Griffiths used to sell Tek paint in spray cans and other ways. I got 4 of the last cans he had in October. He only had a few left at that time.

This might be what you are looking for:
Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of snapdiode via Groups.Io
Sent: Thursday, April 19, 2018 5:12 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Tek blue tyouch up paint?

https://www.sherwin-williams.com/store-locator/product-finishes-facility/portland/or/4383

phone 1-503-249-0222

You want L61 opex lacquer
L61xxcl42
Tek Blue

Or just call Tektronix, they used to have a part number just for that, in a 7oz spray can.




--
Dennis Tillman W7PF
TekScopes Moderator

Re: Tek Blue Paint

stevenhorii
 

Years ago, I was able to buy a can of Tektronix blue paint from Tektronix
parts. I presume that the option is long gone.

I suggest looking through Pantone colors as these are standard and many
paints can be made to match them.

Steve

On Mon, Mar 23, 2020 at 11:11 PM Brendan via Groups.Io
<the_infinite_penguin=yahoo.com@groups.io> wrote:

The closest I have been able to come is Bahama Sea by Krylon.



Re: TEKTRONIX 491 measuring wifi signals

Jim Ford
 

I stand corrected (not all that unusual).  Thanks, Chuck.  My guess would be that microwave oven manufacturers either don't know about or don't want to deal with the subtleties of magnetron anode and filament voltages and currents.JimSent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: Chuck Harris <cfharris@...> Date: 3/23/20 7:37 PM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] TEKTRONIX 491 measuring wifi signals 30 years ago, I worked with a company that made power sourcesout of commercial microwave oven transformers.  I can tell youwith out reservation that magnetrons will work to produce powerover a wide range of anode voltages, and power levels.They are not just on and off devices.The efficiency varies on anode voltage, and the power curve isanything but linear, but we used them from about 10W to about900W by driving the anode transformer with a variac.The important trick was you had to provide the filament voltagewith a separate transformer, as they won't work if the filamentisn't hot.I used a 491 for several years, and at the first opportunityto ditch it and replace it with *any* other spectrum analyzer,I did.  I chose an Ailtech 707.Fundamentally the problem with the 491 is it has a fixedfirst mixer, and a swept IF, with an unbalanced mixer.This means that the IF band gets through the mixer with muchless loss than the desired signal.  If you are in an RF richenvironment... lots of TV, public service, and FM radio stations,you will have a porcupine of fixed position spurs on your screenat all times... leakage through the mixer to the IF.On the other hand, it works quite well if you are using one ofthe higher bands that doesn't include DC.-Chuck HarrisJim Ford wrote:> Yep, a magnetron is completely on or completely off.  No in between.  A virtue of solid state RF cooking devices touted by NXP and others is that solid state can be ramped up and down for more even heating.  I'm sure the new ovens are way more expensive than the magnetron types after 80 or so years of production of the latter.  Will come down just like solid state displays did.Jim Ford Sent from my Verizon, Samsung Galaxy smartphone> -------- Original message --------From: Albert Otten <aodiversen@...> Date: 3/23/20  2:52 PM  (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] TEKTRONIX 491 measuring wifi signals It's also a nice exercise to catch the leakage radiation of a microwave oven. I tried this after repair of my 491, at minimum magnetron power level. Then  I "discovered" (didn't know) that the power level is controlled by the on/off duty cycle of full power. At minimum power there is no radiation at all most of the time.AlbertOn Sun, Mar 22, 2020 at 10:58 PM, Miguel Work wrote:>> I have made a little video showing the Tektronix 491 with wifi signals, at 2.4> Ghz. I now that is a crude SA, but is nice fast showing these signals compared> with the 7L14 that I have in my workbench.> > https://www.youtube.com/watch?v=fCwKErcqJiY&feature=youtu.be> > Regards!> >

Re: Tek Blue Paint

Brendan
 

The closest I have been able to come is Bahama Sea by Krylon.

Re: TEKTRONIX 491 measuring wifi signals

Chuck Harris
 

Microwave oven magnetrons, not transformers... bad brain!

Chuck Harris wrote:

30 years ago, I worked with a company that made power sources
out of commercial microwave oven transformers. I can tell you
with out reservation that magnetrons will work to produce power
over a wide range of anode voltages, and power levels.

They are not just on and off devices.

The efficiency varies on anode voltage, and the power curve is
anything but linear, but we used them from about 10W to about
900W by driving the anode transformer with a variac.

The important trick was you had to provide the filament voltage
with a separate transformer, as they won't work if the filament
isn't hot.

I used a 491 for several years, and at the first opportunity
to ditch it and replace it with *any* other spectrum analyzer,
I did. I chose an Ailtech 707.

Fundamentally the problem with the 491 is it has a fixed
first mixer, and a swept IF, with an unbalanced mixer.

This means that the IF band gets through the mixer with much
less loss than the desired signal. If you are in an RF rich
environment... lots of TV, public service, and FM radio stations,
you will have a porcupine of fixed position spurs on your screen
at all times... leakage through the mixer to the IF.

On the other hand, it works quite well if you are using one of
the higher bands that doesn't include DC.

-Chuck Harris



Jim Ford wrote:
Yep, a magnetron is completely on or completely off.  No in between.  A virtue of solid state RF cooking devices touted by NXP and others is that solid state can be ramped up and down for more even heating.  I'm sure the new ovens are way more expensive than the magnetron types after 80 or so years of production of the latter.  Will come down just like solid state displays did.Jim Ford Sent from my Verizon, Samsung Galaxy smartphone
-------- Original message --------From: Albert Otten <aodiversen@...> Date: 3/23/20 2:52 PM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] TEKTRONIX 491 measuring wifi signals It's also a nice exercise to catch the leakage radiation of a microwave oven. I tried this after repair of my 491, at minimum magnetron power level. Then  I "discovered" (didn't know) that the power level is controlled by the on/off duty cycle of full power. At minimum power there is no radiation at all most of the time.AlbertOn Sun, Mar 22, 2020 at 10:58 PM, Miguel Work wrote:>> I have made a little video showing the Tektronix 491 with wifi signals, at 2.4> Ghz. I now that is a crude SA, but is nice fast showing these signals compared> with the 7L14 that I have in my workbench.> > https://www.youtube.com/watch?v=fCwKErcqJiY&feature=youtu.be> > Regards!



Re: TEKTRONIX 491 measuring wifi signals

Chuck Harris
 

30 years ago, I worked with a company that made power sources
out of commercial microwave oven transformers. I can tell you
with out reservation that magnetrons will work to produce power
over a wide range of anode voltages, and power levels.

They are not just on and off devices.

The efficiency varies on anode voltage, and the power curve is
anything but linear, but we used them from about 10W to about
900W by driving the anode transformer with a variac.

The important trick was you had to provide the filament voltage
with a separate transformer, as they won't work if the filament
isn't hot.

I used a 491 for several years, and at the first opportunity
to ditch it and replace it with *any* other spectrum analyzer,
I did. I chose an Ailtech 707.

Fundamentally the problem with the 491 is it has a fixed
first mixer, and a swept IF, with an unbalanced mixer.

This means that the IF band gets through the mixer with much
less loss than the desired signal. If you are in an RF rich
environment... lots of TV, public service, and FM radio stations,
you will have a porcupine of fixed position spurs on your screen
at all times... leakage through the mixer to the IF.

On the other hand, it works quite well if you are using one of
the higher bands that doesn't include DC.

-Chuck Harris



Jim Ford wrote:

Yep, a magnetron is completely on or completely off.  No in between.  A virtue of solid state RF cooking devices touted by NXP and others is that solid state can be ramped up and down for more even heating.  I'm sure the new ovens are way more expensive than the magnetron types after 80 or so years of production of the latter.  Will come down just like solid state displays did.Jim Ford Sent from my Verizon, Samsung Galaxy smartphone
-------- Original message --------From: Albert Otten <aodiversen@...> Date: 3/23/20 2:52 PM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] TEKTRONIX 491 measuring wifi signals It's also a nice exercise to catch the leakage radiation of a microwave oven. I tried this after repair of my 491, at minimum magnetron power level. Then  I "discovered" (didn't know) that the power level is controlled by the on/off duty cycle of full power. At minimum power there is no radiation at all most of the time.AlbertOn Sun, Mar 22, 2020 at 10:58 PM, Miguel Work wrote:>> I have made a little video showing the Tektronix 491 with wifi signals, at 2.4> Ghz. I now that is a crude SA, but is nice fast showing these signals compared> with the 7L14 that I have in my workbench.> > https://www.youtube.com/watch?v=fCwKErcqJiY&feature=youtu.be> > Regards!

Craigslist; Lynchburg, VA: 7xxx Scope

John Clark
 

Anyone in the Lynchburg, VA area interested in a 7xxx scope with plug-ins? I'm not familiar enough with them to know exactly which model it is from the single picture but looks to be free for the first one to come pick it up. Listing says it works. I've no affiliation with the owner. It just popped up in a saved search I have.

https://lynchburg.craigslist.org/zip/d/lynchburg-tektronix-oscilloscope/7097981758.html
[https://images.craigslist.org/01717_JnH9hntqVw_600x450.jpg]<https://lynchburg.craigslist.org/zip/d/lynchburg-tektronix-oscilloscope/7097981758.html>
Tektronix Oscilloscope - free stuff<https://lynchburg.craigslist.org/zip/d/lynchburg-tektronix-oscilloscope/7097981758.html>
To the best of our knowledge, this works! Will remove listing once someone picks it up. Please...
lynchburg.craigslist.org

John
Charlotte, NC