The effectiveness of the ferrite is a matter of the characteristics of the
ferrite and the wave impedance (the ratio of the total voltage [forward
and reverse waves] to total current [again, forward and reverse waves]) at
the point along the wire where the ferrite is placed. For example, if
No, this is not correct. The 8566 in either version covers 100 Hz to 22
GHz. I think Gaby is confusing the 8566 with the 8568, which in both A and
B models covers 100 Hz to 1.5 GHz.
I am going from memory right now, but I believe the B models of both
spectrum analyzers have the capability
I think the passive, dumb RF antitheft tags are simply 915 MHz dipoles with
a diode at the center. The scanners pick up a harmonic generated when a 915
MHz field is applied.
Don Borowski
Schweitzer Engineering Labs
Pullman, WA
When I think of a network analyzer, I think of a device that injects a
signal into a network, and then receives the signal after processing by the
network using a receiver tuned to the original frequency. This type of
network analyzer rejects harmonics.
There are some inexpensive network
The easiest way to generate harmonics would be to hook up a pair of
Schottky low capacitance (usually also low breakdown voltage) diodes in an
antiparallel arrangement, and then connect the pair either shunting the RF
signal, or in series with the RF signal. One way may be more successful
You might want to check out negative commentary about the proposal on the
American Radio Relay League (ARRL) web site:
http://www.arrl.org/news/features/2003/07/08/
BPL could have a big negative impact on radio amateurs and other users of
HF spectrum.
Don Borowski
WA6OMI
Schweitzer
Loading up the PCI slots puts more capacitance on the PCI bus, slowing the
logic transistions and thus reducing emissions. Quite likely loading up the
ISA slots will do the same thing, though emissions could go up.
To reduce keyboard emissions, try wrapping the cable multiple times through
If installation is normal usage, then should all those bare boards
installed in PCs should be tested for ESD resistance in their bare state?
Or is the distinction between a product and a component that goes into a
product (though some may argue that, for example, a modem board is a
I think the local test lab is correct, since the product will be accessed
only for installation or maintenance. This is similar to the situation
where the covers are off a device for servicing - ESD testing is not
required for the internal circuitry of a device with the covers off.
Having
I have Word 2000 here at work, and it suggests maw, jaw, jaws, maws, and
jowl. I have Word 97 at home. Maybe it will come up with something more
interesting.
John Woodgate
When the model says something does not work, I believe it. When the model
says something works, I take it with the several grains of salt.
Don Borowski
Schweitzer Engineering Labs
Pullman, Washington
USA
Dave Cuthbert wrote on 06/19/2003 02:45:40 PM:
Ran some more simulations. This is
It has been a while since I looked at the standard. While the ESD levels
for road vehicles may be the same, the generator is a bit different - the
size of the capacitor is larger. If I remember correctly, it is something
like 300 or 330 pF, about double the size of the capacitor in the
rbus...@es.com wrote on 06/03/2003 08:56:53 AM:
I have a customer that wants to remove the power plug (and IEC 309
style) from our equipment and connect the wires to a power distribution
system beneath the computer floor. This distribution system uses an IEC
style din rail type of
David Heald hea...@symbol.com wrote on 06/02/2003 11:51:50 AM:
Most UPS's use a stepped approximation of a sine wave when in battery
mode. While most switching supplies don't care (and are the intended
loads for these UPS's), surge suppressors can cause real issues - It has
something
This seems to be a problem of semantics. In the case of a fuse, a failure
is a success - the fuse succeeded in protecting the circuit (neglecting the
cases where the fuse failed to do its job, discussed elsewhere).
I clearly recall some ads for Timken Steel in the 1960s which discussed the
Let me offer a possible explanation from my limited knowedge of vacuum
tubes and mercury vapor rectifiers in particular.
In a mercury vapor rectifier, the voltage drop is fairly constant (10 to 15
volts) no matter what the current. The reason is that it takes an electron
of 10 to 15 eV to
The other thing that can happen is that the discharge can take a different
path. I have seen a technician succesfully discharge an ESD gun onto the
connector pins of a sub-min D connector at low voltage, but only be able to
hit the shell at higher voltage.
Don Borowski
Schweitzer
The usual solution is to have the ground connection for the protection
devices (varistor and gas tube) provided by a screw that can be removed for
testing purposes, and then replaced after the test.
Donald Borowski
Schweitzer Engineering Labs
Pullman, WA
To efficiently radiate heat, the radiator needs to appear black at the
wavelength of the radiation. For electronic devices, the wavelength of
radiation is well into the infrared region. It turns out that almost any
organic coating will work well. Paints are organic coatings. The color of
the
I think there is a difference.
Thermal impedance takes into consideration the thermal masses in the
system. This is important for pulsed thermal loads.
Thermal resistance causes the steady-state temperature rise in response to
a steady-state thermal load.
The two are analogous to AC vs.
Ron-
If you were using thermal grease long in the past, it may have been a
silicone-based grease. The stuff is notorious for migrating easily, getting
into switch contacts and other places causing malfunctions.
Don Borowski
Schweitzer Engineering Labs
Pullman, WA
Ron Pickard
I don't know about any regulatory or safety aspects, but it would be
difficult to have all batteries leave the factory uncharged. Specifically,
lead-acid and lithium cells need to have at least a minimum level of charge
or they will be damaged. NiCd and NiMH cells are OK with no charge.
Donald
You have the noise figure of the filter/preamp combination correct at 5 dB.
However, you may not be able to ignore the contribution of the spectrum
analyzer. Some (many? most?) have rather high noise figures, well over 20
dB. Your amplifier gain is effectively only 19 dB, so the spectrum
Everyone know you can't clean a vacuum - there is nothing there to clean!
Don Borowski
Schweitzer Engineering Labs
Pullman, WA
John Woodgate j...@jmwa.demon.co.uk@majordomo.ieee.org on 03/31/2003
09:22:42 AM
Please respond to John Woodgate j...@jmwa.demon.co.uk
Sent by:
The tuning fork calibration method is the only one I had heard about.
However, the tuning fork calibration method does not work by doppler shift
(a shift in frequency due to the velocity of an object). While the
frequency of the tuning fork is very stable, the amplitude of the
oscillation
Do you need to look at non-fundamental, non-harmonic emissions as well?
There will be such emissions as well. Some will be visible with the source
in CW mode, but there will be others that appear only during frequency
hopping. These latter emissions are harder to find since their frequencies
are
I can think of only two way to reduce flicker, provide the control you
need, and keep harmonics low.
The first you already mentioned - a power factor corrector (really a
harmonic corrector that also corrects power factor at the same time). What
you need should be quite a bit less expensive than
My guess for the reductions: Since the frequency bands are for broadcast
television and FM radio, the sources are not portable, and the field
strength levels at the boarders of the broadcast transmitter location are
regulated and thus known to be at the lower level.
The biggest hazards for
This is a multi-part message in MIME format.
If the load in question is a resistance heating load, I can see two ways
around the problem:
1. Use a circuit much like a triac light dimmer. Make sure the control is
smooth enough that the flicker standard is met - no sudden changes in
current.
If the power supply voltage is stiff, then all you need measure is the
average current. The average current times the voltage will give you the
correct average power.
If the supply voltage is not stiff, then the process is more complex. You
will need to measure the voltage and the current,
I have seen stainless steel used as battery contacts. The contacts
developed an oxide on them that made it difficult to get power from the
battery. Seems to me that some plating could solve that problem however.
There are no good substitues for BeO in all applications. AlN is better
than
We are trying to figure out the applicability of 61000-3-3 Flicker Standard
to the power supply in our product. We have a device that may be hard
wired into the public low voltage (230 V) mains under certain
circumstances, and has no mains switch. Given this, it appears that the
maximum relative
If polymeric hardware can't handle the heat, one could use ceramic
hardware. I just received some product info from a company called Ceramco
www.ceramcoceramics.com that among other things produces a line of
ceramic nuts, bolts and washers.
Don Borowski
Schweitzer Engineering Labs
Pullman, WA
Yes, they are very much used for this sort of thing.
Note however that many measurements have specified measurement bandwidths
(usually specified as impulse bandwidth rather than the usual -3 dB or
noise bandwidth) and specified post-detection signal measurements (e.g.,
the quasi-peak
Anyone out there have the Elliott Labs EMC Tutorial CD-ROM? I got some mail
from the IEEE a couple of weeks ago offering it. I would go for it without
hesitation if it were say $200, but it is pricey - $675 for us IEEE members
($900 otherwise).
I've been making a living doing EMC for the better
-- Forwarded by Don Borowski/SEL on 01/10/2003 10:37 AM
Don Borowski
01/10/2003 10:35 AM
To:Chris Maxwell chris.maxw...@nettest.com
cc:
Subject:RE: Fiber optic cable testing per EN 55022:1998 ? (Document
link: Database 'Don Borowski', View '($Sent)')
OK,
Getting stuff that runs on 130 volts shouldn't be that difficult. Just go
to Mexico. If I remember correctly, the nominal mains voltage is 126 volts,
so 130 volts wouldn't be much of a stretch.
Even here in the USA, some things like 130 volt incandescent light bulbs
aren't too hard to find.
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