?

And sometimes become a voltage source i.e. they become a battery. That
can really throw out equipments operation. You can measure the voltage
with a voltmeter, it's steady, not just a charge that will leak away.

==================================================

Don Black posted above:

Reply:: Don,and Group members: I've hesitated for a long time to
mention this same
observation here, but Dons given me the courage to say its true for
some Tantalum (bead) caps too !
And not used ones either, but NOS!
Years ago, when people still used transistors for design work
I volunteered to design and make a shaped freq /amplitude response amp
for a medical app.which had to be AC coupled
This was a freeby, but most of the stuff was bought new and a PC board made
The only "old" parts I used were tantalums made by a well know manufacturer
in the UK, blue bead STC tantalums which came in packs of 5 in sealed
waxed paper bags .
I had a few of those bags unopened and used these due to there high
quality reputation (and cost) and as
they were still sealed. On populating the board , test time showed
each transistor either
saturated or near saturation. The amp was simple enough in concept , so
had I assembled the
board wrong? Careful check showed all OK, including correct
polarities fitted
I had pre checked the transistors for gain at 1kHz and leakage and all
other parts except the caps before fitting (being a
medical app) and these were all fine.
The culprit was quickly traced to the Tant caps......each one was a
battery putting out several
hundred millivolts all on their own !
Removing the caps I twisted their leads together while I had dinner.
Returning about an hour later
the caps were still generating about the same voltage after untwisting
their leads., all of which came up withon a few seconds
Putting them in series added the voltages enough to dimly light a
"grain of wheat" filament lamp.
Shorting them overnight they gave , again, the same battery effect when
un-shorted.
IAll the NOS stocks I had of these were the same (blue STC bought at
the same time) The packets of caps would be
around 20 years old when bulk .bought new and left over from an old project
I put them in a matchbox with leads shorted and carried them around for
a while, showing them to various
people at work and in various labs for a year , where most thought it
was some trick of mine,
Few actually believed it.
Eventually, the caps still giving out a steady voltage,. I accidentally
put my trousers in the wash
with the matchbox still in its pocket which corroded off the leads
due to the washing powder used.
Ive often thought that if I had given them to a battery manufacturer
maybe the secret would have been
discovered and "infinite" life batteries might be in use today!!
(and maybe I would have been richer too)

Anyone brave enough to have seen the same effect and talk about it?
Electro chemists might have a rational explanation?
John

Hello Tek Scopes Group:

I need to change the backup battery in my 2245A. I am not aware of any special steps required.

Can I simply remove the old and solder in a new one? Or, will I mess something up when the battery voltage is removed?

I am also looking for a 2245A service manual. The one I found on line is a locked pdf file, so no searches can be performed. Might anyone be aware of a copy that is not a "locked", but a searchable file?

Thanks,

Chuck

Beautiful - thank both of you!
Bernd


In a message dated 1/24/2013 8:20:03 P.M. Pacific Standard Time,
sipespresso@... writes:




Thanks for scanning it! I cleaned it up a bit:
_
()

-Kurt

--- In _TekScopes@... (mailto:TekScopes@...) ,
d.seiter@ wrote:

Here's the scan of the Tentative 647 spec.?? Sorry it's a bit of a

mess!?? I can't figure out how to force?? our copier to scan one 8x11 at a time
instead of what it sees on the scan bed .?? There must be a way, but it's
not obvious.?? If anyone has pdf editing software and wants to fix it, have
at it!

-Dave



----- Original Message -----


From: "mattko87"
To: _TekScopes@... (mailto:TekScopes@...)
Sent: Thursday, January 24, 2013 1:10:51 PM
Subject: [TekScopes] Re: Tentative 647 scan?

??




Yes, i am interested in the scan ;-)

Matt

--- In _TekScopes@... (mailto:TekScopes@...) ,

d.seiter@ wrote:

While I've got it out, is anyone interested in the 647 tentative spec?



-Dave

>

I do not have any in dependant confirmation but I suspect given the
relatively low frequencies involved for the sampling heads up to 5%
loss that they will be very close to ideal. I do not know of a better
way to calibrate for a constant level that does not require something
else already calibrated to a better standard except for a thermal RMS
based design which itself can be calibrated at DC.

If you have even an unleveled microwave signal source, you could use
it to find the first null in the sampler frequency response which
would tell exactly what the sample gate time is.

Do you mean overshoot or blow-by? I know my S-4 sampling heads have a
lot of blow-by aberration or whatever that is at about 10ns but show
ideal pulse response as far as I can test. My working S-1 shows no
blow-by with the same input pulse but my best flat level pulse
generator while clean is not fast enough for the S-4.

On Fri, 15 Feb 2013 22:35:37 -0000, "Albert" <aodiversen@...>
wrote:

Hi David,

In my response to Ed I said something about VSWR; that crossed your message.
Your calculations (indeed needing the famous sin(x)/x) assume a perfect rectangular windowing function. Do you have any reference for how good or bad this approach might be in practice? The overshoot in step response of my S-4 is in conflict with this theoretical approach.

Albert

--- In TekScopes@..., David <davidwhess@> wrote:

I think using a sampling oscilloscope for flatness calibration is a
great idea. The sampling heads are both very high bandwidth and have
a very predictable frequency response. The weakest links will be the
SWR match and termination but that applies to any system. You can do
away with cable losses by using a sampling head extender.

If you take the 3db bandwidth numbers I posted earlier and divide by
4, that is the point where the sample head output will be down by 2%.
The second number shown is where they will be down by 1%:

S-1 260 MHz 190 MHz
S-2 1.18 GHz 869 MHz
S-4 3.60 GHz 2.61 GHz
S-6 2.99 GHz 2.17 GHz

I think this is the first time I have had a need to do math involving
a sin(x)/x function.

?

Excellent instructions and thanks Dave for your good wishes.

Don Black.

On 16-Feb-13 7:01 AM, Artekmedia wrote:

?

After several requests I have created a short step by step process for reinstalling the plastic comb bindings on a Tek manual by hand. No expensive machine required. A 2" manual can be done in about 2 minutes or less a smaller manual in less than a? minute. The only item to purchase is a letter opener that fits in the slots . You can use a tie wrap for this step too but the metal opener works better

The photos of the step by step are in the photos area in a folder "Comb Binding by Hand"

I also have this in a PDF ( what else :-) ) , email me for a copy

Dave




On 2/12/2013 11:46 AM, Artekmedia wrote:

When I get time ( yeah right !) I will do a photo tutorial of how to do this without the machine small manual can be done in less than 1 minute by hand a large manual takes 2 minutes worst case

Dave
ArtekManuals

--
Dave Henderson
Manuals@...

PO Box 175
Welch,MN 55089
651-269-4265

"circuitsandcode" <circuitsandcode@...> wrote:

Would prefer to have a variable P/S to ramp up voltage - but went for
broke and shorted across the fuse (using multimeter measuring amps)
and Q5 went out in flames. I've since ordered a handful of 2SK1018
parts to replace.

Might want to make sure the meter didn't take any collateral damage.
-ls-

?

I've had good luck bonding cracks in knobs (and actually reassembling shattered knobs) with cyanoacrylate type glue. Just be sure to get it positioned correctly pretty quickly because the handling time is extremely short.

Hope it works well!

Tom AE5I

--- In TekScopes@..., "danadak" wrote:
>
> The attenuator control only gives two sensitivity settings now, unlike before when it offered many sensitivities in step db.
>
> Anyone have a similar experience ?
>
> Anyone know of a glue that will fuse cracked knobs, in this case the step attenuator knob is cracked ?
>
> Regards Dana,
>

?

?

?

?

The attenuator control only gives two sensitivity settings now, unlike before when it offered many sensitivities in step db.

Anyone have a similar experience ?

Anyone know of a glue that will fuse cracked knobs, in this case the step attenuator knob is cracked ?

Regards Dana,

?

After several requests I have created a short step by step process for reinstalling the plastic comb bindings on a Tek manual by hand. No expensive machine required. A 2" manual can be done in about 2 minutes or less a smaller manual in less than a? minute. The only item to purchase is a letter opener that fits in the slots . You can use a tie wrap for this step too but the metal opener works better

The photos of the step by step are in the photos area in a folder "Comb Binding by Hand"

I also have this in a PDF ( what else :-) ) , email me for a copy

Dave
ArtekManuals.com



On 2/12/2013 11:46 AM, Artekmedia wrote:

When I get time ( yeah right !) I will do a photo tutorial of how to do this without the machine small manual can be done in less than 1 minute by hand a large manual takes 2 minutes worst case

Dave
ArtekManuals

-- 
Dave Henderson
Manuals@...

PO Box 175
Welch,MN 55089
651-269-4265

I think using a sampling oscilloscope for flatness calibration is a
great idea. The sampling heads are both very high bandwidth and have
a very predictable frequency response. The weakest links will be the
SWR match and termination but that applies to any system. You can do
away with cable losses by using a sampling head extender.

If you take the 3db bandwidth numbers I posted earlier and divide by
4, that is the point where the sample head output will be down by 2%.
The second number shown is where they will be down by 1%:

S-1 260 MHz 190 MHz
S-2 1.18 GHz 869 MHz
S-4 3.60 GHz 2.61 GHz
S-6 2.99 GHz 2.17 GHz

I think this is the first time I have had a need to do math involving
a sin(x)/x function.

Albert, I wouldn't use a sampling scope or even an analog one pushing its BW to calibrate RF generators, except maybe for comparing one against another. A power meter like HP848X heads with HP43X meter is a good way to go, but expensive.

You can also roll your own with modern power level detector ICs - they can also be used directly in the generator leveling loops to improve performance. I'm familiar with some from Analog Devices, but I'm sure the usual companies have plenty to choose from too. These are very common ICs used in huge quantities for all the wireless gear out there.

Here's a place to start looking:



It would take quite a bit of investigation and experimenting, but the trick is mostly to get the desired broadband flatness in the coupling of the signal to the IC, and of course, the right dynamic range. Logarithmic and linear responses are available. With linear, you can expand the measurement for better resolution over a small range for calibration purposes, but have less overall dynamic range.

These devices usually measure true RMS voltage over the entire bandwidth, so if your waves have lots of distortion, the harmonic power will be counted too, up to the BW, then diminished. This also could give a quite different result than looking at the p-p envelope even on a perfectly flat scope - another reason to not use a scope, unless p-p voltage is what's wanted.

Ed