?

I’ve had some success coupling the counter’s 10Mz. signal to the SW receiver’s input (just a wire in close proximity – minimum coupling to the counter to avoid pulling the oscillator). If you can get the counter’s signal and the WWV signal reasonably close in amplitude, you should be able to tune the counter’s trimmer to zero-beat with the WWV carrier. Is this what you’re doing? When I tried it, I could hear the WWV signal fluctuate at the beat frequency well below a few Hertz.

?

Chuck Lewis

?

From: TekScopes@... [mailto:TekScopes@...] On Behalf Of amxcoder
Sent: Thursday, October 11, 2012 9:44 AM
To: TekScopes@...
Subject: [TekScopes] How to calibrate a frequency counter (on the cheap)

?

?

I have three frequency counters. Two have oven standards. They are old and
purchased from ebay. They all disagreed about what frequency was what. They all
have 10 mhz frequency oscillators. I have tried calibrating them with WWV before
and been only moderately successful. Short wave receivers simply do not produce
audio below 100 hz. I needed to get much closer than that. What I had going was
three freq counters that might be as much as 45 hz off from each other on 10
mhz.

Then I had an inspiration. I realized that at the receiver detector, there is
nothing to limit frequency response. I got out my old DX160 receiver and a
schematic. I found the diode (D3) that did the detecting. I put a scope probe on
this. I then tuned in WWV. I put a little antenna on the BNC output of the
counters 10 mhz clock. Presto, I had a hetrodyne sine wave from the detector
that gave me the clock error. I moved the counter freq adjust up and down past
the null. I had to do this to be sure I was actually finding a null. I had to
slow down the scope horizontal sweep speed a whole lot to see the resulting sine
wave. I could actually see a 1 hz sine wave. I let the oven warm up for a half
an hour. I set it for a "perfect" null. You still cannot be perfect at this. I
had my scope on DC input. I could watch the error signal drift up and down as
much a 1 hz as the oven and crystal drifted. I then set the rest of counters to
my new standard.

BTW there was no sound of this mixed signal coming out of my DX160. It was just
too low to be reproduced.

This procedure is much cheaper than sending your counter into a lab to be
calibrated and finally I can trust the readings on my frequency counters. This
is pretty important when you are trying to receive and transmit SSB. A 30 hz
error is pretty apparent when you are listening to it. One of my counters was 45
hz off at 10 mhz! Yikes.

?

?

A man with one counter always knows what frequency he is on ...a man
with two counters is never quite sure :-)

Dave
NR1DX
ArtekManuals.com

On 10/11/2012 9:44 AM, amxcoder wrote:

I have three frequency counters. Two have oven standards. They are old and
purchased from ebay. They all disagreed about what frequency was what.
They all
have 10 mhz frequency oscillators. I have tried calibrating them with
WWV before
and been only moderately successful. Short wave receivers simply do
not produce
audio below 100 hz. I needed to get much closer than that. What I had
going was
three freq counters that might be as much as 45 hz off from each other
on 10
mhz.

Then I had an inspiration. I realized that at the receiver detector,
there is
nothing to limit frequency response. I got out my old DX160 receiver and a
schematic. I found the diode (D3) that did the detecting. I put a
scope probe on
this. I then tuned in WWV. I put a little antenna on the BNC output of the
counters 10 mhz clock. Presto, I had a hetrodyne sine wave from the
detector
that gave me the clock error. I moved the counter freq adjust up and
down past
the null. I had to do this to be sure I was actually finding a null. I
had to
slow down the scope horizontal sweep speed a whole lot to see the
resulting sine
wave. I could actually see a 1 hz sine wave. I let the oven warm up
for a half
an hour. I set it for a "perfect" null. You still cannot be perfect at
this. I
had my scope on DC input. I could watch the error signal drift up and
down as
much a 1 hz as the oven and crystal drifted. I then set the rest of
counters to
my new standard.

BTW there was no sound of this mixed signal coming out of my DX160. It
was just
too low to be reproduced.

This procedure is much cheaper than sending your counter into a lab to be
calibrated and finally I can trust the readings on my frequency
counters. This
is pretty important when you are trying to receive and transmit SSB. A
30 hz
error is pretty apparent when you are listening to it. One of my
counters was 45
hz off at 10 mhz! Yikes.

--
Dave Henderson
Manuals@...
www.Artekmanuals.com
PO Box 175
Welch,MN 55089
651-269-4265

I don't think there is any Doppler shift associated with two points that aren't
in motion realitive to each other.



"With a soldering iron in one hand, a schematic in the other, and a puzzled look
on his face..."

---

From: amxcoder
To: TekScopes@...
Sent: Thursday, October 11, 2012 9:44 AM
Subject: [TekScopes] How to calibrate a frequency counter (on the cheap)

I have three frequency counters. Two have oven standards. They are old and
purchased from ebay. They all disagreed about what frequency was what. They all
have 10 mhz frequency oscillators. I have tried calibrating them with WWV before
and been only moderately successful. Short wave receivers simply do not produce
audio below 100 hz. I needed to get much closer than that. What I had going was
three freq counters that might be as much as 45 hz off from each other on 10
mhz.

Then I had an inspiration. I realized that at the receiver detector, there is
nothing to limit frequency response. I got out my old DX160 receiver and a
schematic. I found the diode (D3) that did the detecting. I put a scope probe on
this. I then tuned in WWV. I put a little antenna on the BNC output of the
counters 10 mhz clock. Presto, I had a hetrodyne sine wave from the detector
that gave me the clock error. I moved the counter freq adjust up and down past
the null. I had to do this to be sure I was actually finding a null. I had to
slow down the scope horizontal sweep speed a whole lot to see the resulting sine
wave. I could actually see a 1 hz sine wave. I let the oven warm up for a half
an hour. I set it for a "perfect" null. You still cannot be perfect at this. I
had my scope on DC input. I could watch the error signal drift up and down as
much a 1 hz as the oven and crystal drifted. I then set the rest of counters to
my new standard.

BTW there was no sound of this mixed signal coming out of my DX160. It was just
too low to be reproduced.

This procedure is much cheaper than sending your counter into a lab to be
calibrated and finally I can trust the readings on my frequency counters. This
is pretty important when you are trying to receive and transmit SSB. A 30 hz
error is pretty apparent when you are listening to it. One of my counters was 45
hz off at 10 mhz! Yikes.




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

Yahoo! Groups Links

<*> To visit your group on the web, go to:
? ?

<*> Your email settings:
? ? Individual Email | Traditional

<*> To change settings online go to:
? ?
? ? (Yahoo! ID required)

<*> To change settings via email:
? ? TekScopes-digest@...
? ? TekScopes-fullfeatured@...

<*> To unsubscribe from this group, send an email to:
? ? TekScopes-unsubscribe@...

<*> Your use of Yahoo! Groups is subject to:
? ?

The confetti,seems to move with the trace,and blink in and out like a
reflection,I'll try to get a pic Friday,the scope(a 464) is not here
at the moment.I haven't looked a the crt closely,can the rods be seen
in the neck of the tube?Does any other tube fit?sorry,I misstyped the
scope is a 464.
--- In TekScopes@..., larrys@... wrote:

Best guess is one of the glass support rods in the crt fractured

and

dropped a few tiny shards of glass inside the tube. These would
damage the expansion mesh creating the "confetti". It's a guess,
but one I've seen more than once. 465 tubes are not hard to come

by.

-ls-



"emilypetersen1991" <s-petersen@...> wrote:

I have been searching posts,and with google and I can't seem

tofind

the answer,My 465 scope seems to be working properly except for

some

sparkles,artifactsn,and reflections on the screen,intensity and

focus

seem to work at it should.It appears to throw confetti on the

screen.

I was wondering where would be a good place to look?is it an

amplifier

problem,or a crt voltage problem?
Thanks,
Scott



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

Yahoo! Groups Links

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

Yahoo! Groups Links

On Wed, 10 Oct 2012, Stefan Trethan wrote:

That explains that then, they measure a few percent lower at 1kHz.
It's unfair to accuse a manufacturer of penny pinching if you don't
meet their specified testing conditions (usually 120Hz).

It gives same readings at 120Hz for capacitance if it can measure it
(>100uF). For 10-100uF range the most accurate results are at 400 Hz. 1KHz
is a convenient test frequency giving wide range with relatively good
accuracy. It might give up to 3% error at the boundary F/C ranges where it
barely measures capacitance (too high F for big C or too low F for small C)
but it is never 20%. If you want to get most of it, sure you have to choose
a proper frequency. But for 3 digits 1KHz is good for measuring almost
anything. Also capacitance itself does not vary that much with frequency.
ESR varies orders of magnitude more.

Saving a few percent of foil is probably not worth the hassle of
having to meet tighter tolerances caused by leaning towards the lower
end. More likely they used to go above nominal with the old caps

It does. And almost all big manufacturers has shown tendency towards saving
a penny risking a buck. It doesn't make sense in a long run but who thinks
farther than a quarter? Does it make sense to lay off the best (those with
highest salaries) to make a nice profit figure? Can you name a company that
did not fell to a temptation of using cheaper chinese capacitors in high
frequency high ripple applications and thus avoided massive failures because
of blown capacitors? Remember, profit of saving a penny is now and this is
when the higher management gets their bonuses for making profit. Failures
are later and they are not punished for those. And no one of them is going
to work for a particular company forever -- they will go to a different one
for making that one more profitable too once they are done with their
current one (i.e. once it is destroyed by making it more profitable.)

because tolerances were asymmetrical back then.

Nope. Old ones usually fall in the middle of their tolerance range. If it
was +80/-20% the majority of 1,000uF capacitors had 1,300uF capacitance. And
even +/-20% ones rarely went under 100%. It was also understood that it is
better to overshoot than undershoot as far as capacitance goes.

I'll check out the test data to see if the distribution is offset when
I get the chance.

ST

On Wed, Oct 10, 2012 at 10:23 PM, Sergey Kubushyn <ksi@...> wrote:

On Wed, 10 Oct 2012, Stefan Trethan wrote:

At 1kHz that's just about spot on specification for the taiyo yuden part.
The impedance at this frequency will be what, 15, 16 Ohms? Not sure
why you'd worry....

I do not worry. It is not about using it at a particular frequency.

At what frequency did you measure capacitance? Just so that we don't
waste both our time again.

1KHz. And I don't have time to waste too.

ST

On Wed, Oct 10, 2012 at 9:22 PM, Sergey Kubushyn <ksi@...> wrote:

On Wed, 10 Oct 2012, Stefan Trethan wrote:

On Wed, Oct 10, 2012 at 6:59 PM, Sergey Kubushyn <ksi@...> wrote:

There were bunch of 10uF 25V ones
that I was going to replace with 1206 SMD X5R ceramics but to my surprise
those dipped tantalums had something like 300mOhm ESR that is actually
BETTER than ceramics (Taiyo Yuden 10uF 25V 1206 X5R ceramics of recent
manufacturing that I had several reels in my parts bins have something like
350mOhms ESR.)

At what frequency? The ceramic should have well below 10mR at 100kHz
according to specification, and I just don't see how it could be
otherwise considering the construction.

1KHz. This is actual measured values. As for the specifications majority of
manufacturers don't give any values on ESR in their datasheets. It is
"common knowledge" they are "very low ESR" but reality check shows totally
different picture. If you look at e.g. NIC NMC High CV Series datasheet (one
of the few who give data on ESR) you'll see a ESR vs Frequency chart. It
clearly shows that MLCCs are better when going into MHz range but they are
nothing to write home about at lower frequencies.

Regarding the generally low capacitance value on electrolytics, I have
extensive test data for Rubycon and Nippon Chemicon at work and will
check if they are consistently at the lower capacitance tolerance.

Once again, I do NOT have very extensive data, just several hundred
capacitors. It might be not a representative sample but I could not find a
SINGLE one of recent manufacturing that was 100% of stated capacity or
higher. On the old ones I could not find more than couple of pieces that
were under 100%.

ST


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

Yahoo! Groups Links

---
*
* KSI@home KOI8 Net < > The impossible we do immediately. *
* Las Vegas NV, USA < > Miracles require 24-hour notice. *
*


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

Yahoo! Groups Links

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

Yahoo! Groups Links

---
*
* KSI@home KOI8 Net < > The impossible we do immediately. *
* Las Vegas NV, USA < > Miracles require 24-hour notice. *
*


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

Yahoo! Groups Links

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

Yahoo! Groups Links

---
*
* KSI@home KOI8 Net < > The impossible we do immediately. *
* Las Vegas NV, USA < > Miracles require 24-hour notice. *
*


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

Yahoo! Groups Links

This will not fix the problem but may help with diagnosis if there is
a video camera synchronization issue. Fiddle with the trigger A
holdoff control which is located toward the bottom right. Holdoff is
used to increase the time after a sweep before the next trigger will
be accepted.

I would still check the power supply voltages and ripple before
getting too involved with looking for other causes of the problem.

On Thu, 11 Oct 2012 01:07:46 -0000, "dawtesla2" <dawtesla2@...>
wrote:

Here's a new video that could help.
or

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

I noticed that and wonder if the relatively low video camera frame
rate is disguising what is really going on.

On Mon, 08 Oct 2012 22:08:41 -0400, "Tom Miller"
<tmiller11147@> wrote:

I would open it up and check the power supplies for voltage and ripple per the manual. It seems to be jumping sync at a periodic rate.

Best guess is one of the glass support rods in the crt fractured and
dropped a few tiny shards of glass inside the tube. These would
damage the expansion mesh creating the "confetti". It's a guess,
but one I've seen more than once. 465 tubes are not hard to come by.
-ls-



"emilypetersen1991" <s-petersen@...> wrote:

I have been searching posts,and with google and I can't seem tofind
the answer,My 465 scope seems to be working properly except for some
sparkles,artifactsn,and reflections on the screen,intensity and focus
seem to work at it should.It appears to throw confetti on the screen.
I was wondering where would be a good place to look?is it an amplifier
problem,or a crt voltage problem?
Thanks,
Scott



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

Yahoo! Groups Links