Date   
Re: What have i here ? (Tek TDS 540 )

 

On Sat, Dec 8, 2018 at 09:26 PM, mattko87 wrote:


What is meaning VER2 ?
Version 2 Firmware.

/Håkan

Re: TIP: Current Probes ...

stefan_trethan
 

If you only need low frequency the LEM brand hall effect sensors, I
believe Allegro also makes chip based ones, can be an option.
Also remember you can put 10 turns through if you need more
sensitivity (insertion impedance permitting).

ST

On Sun, Dec 9, 2018 at 6:30 PM David Slipper <softfoot@...> wrote:


I quite often have a need to sense small currents (~10-200mA) and have
always wanted a clamp on current probe but even the used ones for a
scope are out of my budget.

A series resister is one solution but it is rather intrusive and
sometimes the circuit cannot tolerate the voltage drop.

Recently, at a garage sale I came across an old RS current clamp
intended to be used with a multimeter, it is a Hall effect device so
it's good for DC too, so just as an experiment I attached it to my scope
with a "banana<--->BNC" adapter and it works a treat :-)

The sensitivity is 1mV for 10mA and the bandwidth seems adequate for my
needs. If I need better sensitivity I just wind the wire 10 times around
the sensor clamp which gets me 1mV per 1mA.

Since I'm trying to get an Arduino and ESP8266 WiFi adapter to run on
batteries it is proving invaluable.

It may not have the bandwidth of a purpose built 'scope current probe
but it seems OK for my needs.

Dave




Re: A cautionary tale ...

Vincent Trouilliez
 

On Sat, Dec 8, 2018 at 04:57 AM, David Slipper wrote:
Everything was OK but I did find a loose screw rolling around in the PSU
area !!!

I am very glad I gave the thing a "once-over" or I would have allowed
the "magic smoke" to escape !!!

I seem to remember someone else finding loose screws.
Talk about it ! :-/

I had my 2232 for a year, was working just fine. Then I had to do some work on it, UNrelated to the PSU. Once I was done, put it back together, went for a test drive to make sure all was well.. and it was... for a few minutes. Then out of the blue, magic smoke escaped from that scope that was working just fine a second before ! Turned out to be a loose screw in the PSU... I guess I must have dislodged it while working on the scope, argh... well at least it was an opportunity to work on these 22XX PSUs , learn about them and get some hands on experience... made fixing the PSU of a later acquired 2215A, incredibly easy and fast. So I try to see the bright side of things....



Vincent Trouilliez

Re: TIP: Current Probes ...

David Slipper
 

Mine has a bandwidth of 20KHz (probably 1/2 that is usable) which is
more than adequate for my needs.

The only problem with it is the zero drifts, but I can live with that.

Dave

Re: TIP: Current Probes ...

Bob Albert
 

I checked on ebay and the cheapest adapter I could find was almost $20; not very sensitive (1 mV per Ampere) and no idea of bandwidth.
If anyone knows of a project to create a current probe I would be interested.
Bob

On Sunday, December 9, 2018, 11:06:03 AM PST, David Slipper <softfoot@...> wrote:

Mine has a bandwidth of 20KHz (probably 1/2 that is usable) which is
more than adequate for my needs.

The only problem with it is the zero drifts, but I can live with that.

Dave

Re: TIP: Current Probes ...

David Slipper
 

I did look at making one with a Hall sensor - the electronics isn't a
problem but the difficulty arises (for me at least) in cutting the slot
in a ferrite ring to put the sensor in or even splitting the core to
make a clamp.  I guess it's easier if you have access to the right tools.

Any ways, this works well for me :-)

On 09/12/2018 18:52, stefan_trethan wrote:
If you only need low frequency the LEM brand hall effect sensors, I
believe Allegro also makes chip based ones, can be an option.
Also remember you can put 10 turns through if you need more
sensitivity (insertion impedance permitting).

Re: TIP: Current Probes ...

stefan_trethan
 

The LEM sensors come complete with core, and I believe some even split open.
The Allegro sensors are just ICs that sit over a PCB trace without
magnetic circuit, I don't believe they are as good for what we want to
do.

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

Are there any cheap approximations of the Iprober 520 fluxgate sensor
current probe?
Maybe some sort of IC?

ST

On Sun, Dec 9, 2018 at 8:19 PM David Slipper <softfoot@...> wrote:


I did look at making one with a Hall sensor - the electronics isn't a
problem but the difficulty arises (for me at least) in cutting the slot
in a ferrite ring to put the sensor in or even splitting the core to
make a clamp. I guess it's easier if you have access to the right tools.

Any ways, this works well for me :-)

On 09/12/2018 18:52, stefan_trethan wrote:
If you only need low frequency the LEM brand hall effect sensors, I
believe Allegro also makes chip based ones, can be an option.
Also remember you can put 10 turns through if you need more
sensitivity (insertion impedance permitting).


Re: TIP: Current Probes ...

stefan_trethan
 

To answer my own question:
http://www.ti.com/lit/ds/symlink/drv425.pdf

But only 47kHz, I'd like something like that with a couple hundred kHz....

ST

On Sun, Dec 9, 2018 at 8:38 PM stefan_trethan <stefan_trethan@...> wrote:

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

Are there any cheap approximations of the Iprober 520 fluxgate sensor
current probe?
Maybe some sort of IC?

ST

On Sun, Dec 9, 2018 at 8:19 PM David Slipper <softfoot@...> wrote:


I did look at making one with a Hall sensor - the electronics isn't a
problem but the difficulty arises (for me at least) in cutting the slot
in a ferrite ring to put the sensor in or even splitting the core to
make a clamp. I guess it's easier if you have access to the right tools.

Any ways, this works well for me :-)

On 09/12/2018 18:52, stefan_trethan wrote:
If you only need low frequency the LEM brand hall effect sensors, I
believe Allegro also makes chip based ones, can be an option.
Also remember you can put 10 turns through if you need more
sensitivity (insertion impedance permitting).



Resurrection of a 494P...

ulf_r_k
 

I recently acquired a 494P on a flea market.
It had been left in an unheated shed for > 10 years having to
endure the scandinavian climate with cold and moist during
wintertime and heat during the summers. After it was salvaged,
it was turned on and there was a picture on the CRT for 10 seconds.
Then it died and was left for dead. After that it hit a flea market
and I baught it. At first for spare parts, but I decided to give it
a chance.

I started by replacing all electrolytics in the PSU as well as
all the MP capacitors and then also
giving it the treat of replacing the AllenBradley resistors
in the deflection apmlifiers according to KE5FX

When turned on, still no picture, so all HV supply parts was replaced.
I did not have any 2SC3333 som instead a BUX84 was used.

Voila: I got a nice steady picture on the screen.

Initially, it would not lock, and I also got error messages
about non consistent non-volatile memory error but they cleared
themselfes.

Now using spans narrower than 50 MHz the analyzer performs
excellently, but if I try wide spans, apart from my test signal,
there are random visble spurs that occurrs
all over the band in an erratic way.

Also the noise level jumps up and down.

I assume that this can be caused by long term drifts outside
any calibration performed in the past. If the behavior above
is due to a component failure, I would be glad if someone
pointed me in the right direction, where to look first.

If the problem is only related to drift/calibration, I will attempt
a recalibration.

I can go on replacing capacitors and so but if the problem
above is a result of a bad YTO, I doubt that I can find
a replacment unit that won't cost me a fortune.
After all, this is a 30+ year old instrument.

Cheers

Ulf Kylenfall
SM6GXV

Re: Tube test adaptor for Tektroinx 575 was: Re: [TekScopes] FS: miscellaneous Tektronix manuals

Jim Ford
 

Ah, yes, the same idea is used in dual coil guitar pickups, also known as humbuckers.
Jim F


Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: Craig Sawyers <c.sawyers@...> Date: 12/9/18 1:53 AM (GMT-08:00) To: TekScopes@groups.io Subject: Re: Tube test adaptor for Tektroinx 575 was: Re: [TekScopes] FS: miscellaneous Tektronix manuals
A center tapped filament transformer, or a 'hum balance' circuit to create an artificial center tap
will do
even better. That circuit was often no more than a 200 ohm pot across the winding, with the wiper
connected to ground, and both filament leads floating above ground. A 2W pot was common for this
use.


Michael A. Terrell
The other common term (at least on my side of the pond) was hum bucker.

Craig

Re: Russian Tunnel Diodes

David DiGiacomo
 

On Sun, Dec 9, 2018 at 7:52 AM Chuck Harris <cfharris@...> wrote:
I don't want my comments to be a source of disparagement of Leo's
work. I haven't spent a great deal of time studying what he has
done, but in all of the scope pictures he has presented, there is
very significant leading edge overshoot and ripple. To my weathered
eyes the peaking and ripple appears to be 20-30% of the pulse
amplitude.
Leo supplied my (early revision BNC) pulser with a CSA803 screenshot
showing measured rising edge aberrations of 9.4% P-P and falling edge
aberrations of 3.6% P-P. This compares favorably with my S-52s and
other tunnel diode pulsers. I believe he has improved the layout
since that time.

Re: How Many Scopes?

RonC
 

Yea, my ex kept asking why I have more than one o'scope, and figured I need to sell them off. Fact is, they all do something a little different, and you can't get it all rolled into one unit.
I want to buy a digital, but I'm only working on guitar amps and electronics of that nature, so a digital isn't actually necessary.
Here's what I'm sitting on:
Telequipment D54 (my first scope)
Tek 2337
Tek 475A
Tek 454A
(2) HP 1740A
HP 1725A
Phillips PM3212

Re: How Many Scopes?

Jim Ford
 

Ron, I find a digital scope handy for "stopping time", that is, looking at infrequent events and determining their relationship in time.  Glad I have an HP 54504A in addition to my Tek 5110N, 7603, and 7904 analog scopes.  Point is, a DSO can be useful even for analog/low-speed work.
Jim F


Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: "RonC via Groups.Io" <thepostman6801=yahoo.com@groups.io> Date: 12/9/18 2:55 PM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] How Many Scopes?
Yea, my ex kept asking why I have more than one o'scope, and figured I need to sell them off. Fact is, they all do something a little different, and you can't get it all rolled into one unit.
I want to buy a digital, but I'm only working on guitar amps and electronics of that nature, so a digital isn't actually necessary.
Here's what I'm sitting on:
Telequipment D54 (my first scope)
Tek 2337
Tek 475A
Tek 454A
(2) HP 1740A
HP 1725A
Phillips PM3212

Tektronix 221 board parts

scott.2303@...
 

I am trying to find a replacement for the transistor MPS H34
Scott

Tektronix 221 oscilloscope transistor MPS H34

scott.2303@...
 

I am trying to source a SUITABLE REPLACEMENT TRANSISTOR FOR THE

Oscilloscope 221

scott.2303@...
 

I require a substitute transistor for a MPS H34
Regards,Scott Mc Neill

Re: Tektronix 221 board parts

ArtekManuals
 

Scott
Q??? in the 221?
Dave
manuals@...

On 12/9/2018 11:17 AM, scott mc neill via Groups.Io wrote:
I am trying to find a replacement for the transistor MPS H34
Scott


--
Dave
Manuals@...
www.ArtekManuals.com

Re: Oscilloscope 221

Bob Albert
 

BF224 might be a replacement
Bob

On Sunday, December 9, 2018, 4:15:58 PM PST, scott mc neill via Groups.Io <scott.2303=yahoo.co.uk@groups.io> wrote:


I require a substitute transistor for a MPS H34
Regards,Scott Mc Neill

Re: TIP: Current Probes ...

Craig Sawyers <c.sawyers@...>
 

Design a Rogowsky coil. With the right design you can go from about 200Hz to 5MHz. Needs a wideband
active integrator since a Rogowsky output is proportional to dI/di.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of stefan_trethan
Sent: 09 December 2018 19:52
To: TekScopes@groups.io
Subject: Re: [TekScopes] TIP: Current Probes ...

To answer my own question:
http://www.ti.com/lit/ds/symlink/drv425.pdf

But only 47kHz, I'd like something like that with a couple hundred kHz....

ST

On Sun, Dec 9, 2018 at 8:38 PM stefan_trethan <stefan_trethan@...> wrote:

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

Are there any cheap approximations of the Iprober 520 fluxgate sensor
current probe?
Maybe some sort of IC?

ST

On Sun, Dec 9, 2018 at 8:19 PM David Slipper <softfoot@...> wrote:


I did look at making one with a Hall sensor - the electronics isn't
a problem but the difficulty arises (for me at least) in cutting the
slot in a ferrite ring to put the sensor in or even splitting the
core to make a clamp. I guess it's easier if you have access to the right tools.

Any ways, this works well for me :-)

On 09/12/2018 18:52, stefan_trethan wrote:
If you only need low frequency the LEM brand hall effect sensors,
I believe Allegro also makes chip based ones, can be an option.
Also remember you can put 10 turns through if you need more
sensitivity (insertion impedance permitting).



Re: Mod on horizontal plug-in 7B80

Gary Robert Bosworth
 

Thank you Håkan. I am so happy to see vital information. I wanted to know
the extent of the modifications. I do still wonder why Tektronix made the
Modification. I am happy to have extended horizontal sweep which can be
used in my 7104. Perhaps they did it as a special Mod for one particular
customer. There is only slight cost reduction in the manufacture, since the
slower sweep rates have been eliminated. If anyone knows of more "inside"
information about the rationale, please fill me in.

Gary

On Sun, Dec 9, 2018 at 2:08 AM zenith5106 <hahi@...> wrote:

On Sun, Dec 9, 2018 at 04:17 AM, Gary Robert Bosworth wrote:

This is a tough one. I have a Tek Plug-In number 7B80. It is mod GB. I
see no
mention of this modification in the manuals.
It should be quite obvious if compared to an unmodified 7B80.
This is what the mod manual insert says:

//
7B80
MOD GB
This manual insert describes MOD GB as it applies to the Tektronix Time
Base
plug-in unit. MOD GB increases X2 the horizontal preamplifier gain to
extend
the top sweep rate to 5 ns/div and to 0.5 ns/div, magnified. Rates slower
than 10 us/div have been deleted, limiting the TIME/DIV switch to 11
positions
and the front-panel HOLDOFF control has been deleted, and internal circuits
wired to provide minimum holdoff for all ranges.
//

/Håkan



--
Gary Robert Bosworth
@grbosworth
Tel: 310-317-2247