Driver to drive?

[josephkk]

On Tue, 24 Jun 2014 09:32:43 +0300, upsidedown@downunder.com wrote:

On Tue, 24 Jun 2014 05:18:51 GMT, Jan Panteltje <panteltje@yahoo.com
wrote:

On a sunny day (Mon, 23 Jun 2014 13:34:19 -0700 (PDT)) it happened
makolber@yahoo.com wrote in
a622ac70-833b-47ba-ad41-ad1322c66375@googlegroups.com>:


I would like to build a 50Hz sharp notch filter for an instrumentation amp.

It seems that all low pass and high pass filters create varying degrees
of phase and time distortion. Since I want to avoid this effect, does it
also apply to notch filters?

any filter with sharp transitions in the freq domain will have ugly artifac>>>ts in the time domain. You can equalize the phase response or use FIR typ>>>e filters with linear phase. This will linearize the phase at the expense >>>of overall time delay or latency. BUT...even if you do this, there will st>>>ill be nasty ringing and other artifacts in the time domain.

If is a fundamental fact of nature that you cannot sharply filter in one do>>>main without screwing up the other domain.

If for example, you create a sharp 50 Hz notch to block mains hum for examp>>>le, you WILL introduce 50 Hz ringing into the step response. No way around >>>it.

Mark

But you could add 50 Hz in anti phase.
You can make that 50 Hz by using a small notch filter on the signal.
The real signal does not pass the noth filter.
Shift phase all you want on the 50 Hz you make, change amplitude too,
make harmonics needed.

Just an idea.

I guess that you should also get at least the 150 Hz harmonics "off
the air" in addition to the 50 Hz fundamental and not try to generate
the harmonics from the fundamental.

While in a single phase environment, using a very narrow band PLL to
generate the antiphase fundamental should work, things can get quite
ugly in a three phase environment. If the input signal is moved from
close to one mains line phase to an other mains phase, the resultant
hum signal will experience a 120 degree phase shift. A too narrow PLL
might not be able to track this movement.

Actually, rectified mains (50/60 Hz) is one major component of hum. The
second harmonic and odd multiples of it are part of the problem. You can
notch or balance out an many as you wish. It is still part of the
equation.

?-)

 

[Jim Thompson]

On Tue, 24 Jun 2014 09:32:43 +0300, upsidedown@downunder.com wrote:

On Tue, 24 Jun 2014 05:18:51 GMT, Jan Panteltje <panteltje@yahoo.com
wrote:

On a sunny day (Mon, 23 Jun 2014 13:34:19 -0700 (PDT)) it happened
makolber@yahoo.com wrote in
a622ac70-833b-47ba-ad41-ad1322c66375@googlegroups.com>:


I would like to build a 50Hz sharp notch filter for an instrumentation amp.

It seems that all low pass and high pass filters create varying degrees
of phase and time distortion. Since I want to avoid this effect, does it
also apply to notch filters?

any filter with sharp transitions in the freq domain will have ugly artifac=
ts in the time domain. You can equalize the phase response or use FIR typ=
e filters with linear phase. This will linearize the phase at the expense =
of overall time delay or latency. BUT...even if you do this, there will st=
ill be nasty ringing and other artifacts in the time domain.

If is a fundamental fact of nature that you cannot sharply filter in one do=
main without screwing up the other domain.

If for example, you create a sharp 50 Hz notch to block mains hum for examp=
le, you WILL introduce 50 Hz ringing into the step response. No way around =
it.

Mark

But you could add 50 Hz in anti phase.
You can make that 50 Hz by using a small notch filter on the signal.
The real signal does not pass the noth filter.
Shift phase all you want on the 50 Hz you make, change amplitude too,
make harmonics needed.

Just an idea.

I guess that you should also get at least the 150 Hz harmonics "off
the air" in addition to the 50 Hz fundamental and not try to generate
the harmonics from the fundamental.

While in a single phase environment, using a very narrow band PLL to
generate the antiphase fundamental should work, things can get quite
ugly in a three phase environment. If the input signal is moved from
close to one mains line phase to an other mains phase, the resultant
hum signal will experience a 120 degree phase shift. A too narrow PLL
might not be able to track this movement.

You've never built an actual PLL, have you?

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: skypeanalog | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Kevin Aylward]

wrote in message news:gh9mq9d2si4npfqrmebldgb8fi4fma5i36@4ax.com...

On Wed, 25 Jun 2014 17:38:39 +0100, "Kevin Aylward"
<ExtractkevinRemove@kevinaylward.co.uk> wrote:

wrote in message news:g7ukq9tmomn0aqj297fv6120rlf5uiphc5@4ax.com...

On Tue, 24 Jun 2014 08:34:32 -0700 (PDT), makolber@yahoo.com wrote:

yes I want to clarify my remarks...

sharp filtering in the frequency domain does create artifacts in the time
domain...but that doesn't mean that a good notch filter won't be effective
at removing single frequency hum.

Usually the artifacts are not audible and are much less objectionable
compared to the hum, so yes build and use a notch filter, or even a comb
filter if the hum has harmonics.

This is a good example of theory vs practice, it does work well in
practice.


Mark



For audio applications, the ear is not very sensitive to sounds below
100 Hz at least at moderate sound levels, say below 80 dB, thus quite
a lot hum is tolerated.

Ahmmmmmmmmmmmmmmmmmmmmm

The low note on a guitar is 82 Hz, the low note on a Bass is 41, sure its
not as sensitive, but if you cant hear that in music, you must be deaf.
60/50 hz hum is bloody annoying indeed in a guitar amplifier.

Take a look at Fletcher Munson curves.

Go and take an actual listen to a Marshall on full gain.

{snip trivial irrelevance}

Mate, I am a guitar player, and been for a rather long time. 60/50 hz hum is
bloody annoying. Many, many amps over the last 40 years, in particular
tube/valve amps can have very, very annoying hums. Period.

Hint: music from instruments isn't continuous, and guitar amps have bloody
HUGE gain to get huge preamp distortion making any minor hum hugely audible.

Kevin Aylward B.Sc.
www.kevinaylward.co.uk
www.anasoft.co.uk - SuperSpice

 

[George Herold]

On Thursday, June 26, 2014 12:36:45 PM UTC-4, Kevin Aylward wrote:

wrote in message news:gh9mq9d2si4npfqrmebldgb8fi4fma5i36@4ax.com...
snip

Mate, I am a guitar player, and been for a rather long time. 60/50 hz hum is
bloody annoying. Many, many amps over the last 40 years, in particular
tube/valve amps can have very, very annoying hums. Period.

Hint: music from instruments isn't continuous, and guitar amps have bloody
HUGE gain to get huge preamp distortion making any minor hum hugely audible

How about ya bag the 50/60 Hz transformers,
Go to a SMPS, smaller magnetics, do it at 100kHz and it's easy to filter.
(and then put some distance between the PS and amp, if you have to.)

George H.

Kevin Aylward B.Sc.

www.kevinaylward.co.uk

www.anasoft.co.uk - SuperSpice

 

[Kevin Aylward]

"George Herold" wrote in message
news:e11468d4-f2fa-4409-8f41-4084bcf17069@googlegroups.com...

On Thursday, June 26, 2014 12:36:45 PM UTC-4, Kevin Aylward wrote:

wrote in message news:gh9mq9d2si4npfqrmebldgb8fi4fma5i36@4ax.com...
snip

Mate, I am a guitar player, and been for a rather long time. 60/50 hz hum
is
bloody annoying. Many, many amps over the last 40 years, in particular
tube/valve amps can have very, very annoying hums. Period.

Hint: music from instruments isn't continuous, and guitar amps have
bloody
HUGE gain to get huge preamp distortion making any minor hum hugely
audible

How about ya bag the 50/60 Hz transformers,
Go to a SMPS, smaller magnetics, do it at 100kHz and it's easy to filter.
(and then put some distance between the PS and amp, if you have to.)

That was just one example illustrating the problem of 50/60hz hum. Its
irrelevant that the ear may be less sensitive to low frequencies, it's still
a major problem.

The whole process of using balanced (differential) signals in a music
recording environment was done to get rid of bloody annoying hum loops and
hum drops.

Much effort has been given to having power amps with balanced inputs,
microphones with balanced inputs and so forth. Its pretty much a given that
when setting up a recording studio that there is some bloody hum that defies
all efforts to eliminate it.

Kevin Aylward B.Sc.
www.kevinaylward.co.uk
www.anasoft.co.uk - SuperSpice

 

On Fri, 27 Jun 2014 19:51:03 +0100, "Kevin Aylward"
<ExtractkevinRemove@kevinaylward.co.uk> wrote:

"George Herold" wrote in message
news:e11468d4-f2fa-4409-8f41-4084bcf17069@googlegroups.com...

On Thursday, June 26, 2014 12:36:45 PM UTC-4, Kevin Aylward wrote:
wrote in message news:gh9mq9d2si4npfqrmebldgb8fi4fma5i36@4ax.com...
snip

Mate, I am a guitar player, and been for a rather long time. 60/50 hz hum
is
bloody annoying. Many, many amps over the last 40 years, in particular
tube/valve amps can have very, very annoying hums. Period.

Hint: music from instruments isn't continuous, and guitar amps have
bloody
HUGE gain to get huge preamp distortion making any minor hum hugely
audible

Yesterday I attended a guitar music festival playing early 1960's
music with old tube amplifiers such as Vox and Marshalls. Only two
times I noticed some hum issues (both during sound check), once when
the player bent over the amplifier and the guitar touched the
amplifier, so some hum from the transformer was transferred to the
pick-up. The other was the typical raspy sound with lots of harmonics,
when a bad cord was inserted into the amplifier (without proper shield
connection at the amplifier end, the shield, the guitar metallic
parts, the player, the pick-up formed a large capacitive probe).

While supporting a local dance band in the 1970s, I repaired their
equipment and studied their construction. Everyone had at least a
center taped 6.3 V filament winding or a potentiometer across the 6.3
V winding and the slider connected to ground, so you could adjust it
for minimum hum. I remember a Geloso amplifier that used DC filament
for the front end tubes. The amplifier is not a significant problem,
it is the total system.

How about ya bag the 50/60 Hz transformers,
Go to a SMPS, smaller magnetics, do it at 100kHz and it's easy to filter.
(and then put some distance between the PS and amp, if you have to.)

That was just one example illustrating the problem of 50/60hz hum. Its
irrelevant that the ear may be less sensitive to low frequencies, it's still
a major problem.

The whole process of using balanced (differential) signals in a music
recording environment was done to get rid of bloody annoying hum loops and
hum drops.

Now we are getting to the point.

I live in a country, in which previously TN-C electrification was
used, i.e. there was a common PEN connector, both functioning as
Neutral (N) and Protective Earth (PE). Of course any neutral current
would cause voltage drops and hence the chassies of different
equipment were at differential potential, causing big hum currents in
audio/video/computer cable shields if grounded at both ends.

The obvious solution would be to use TN-S (five wire), with separate N
and PE conductors in which PE does not carry any current in normal
situations, only in earth fault situations. In practice, most systems
are TN-C-S in which the PEN conductor is split into PE and N at some
point.

While supporting the local dance band in the 1970's I used a single
extension cord with multiple sockets. All audio equipment were then
connected to this single extension cord, forming effectively a TN-C to
TN-S transition. No other equipment, such as SCR controlled stage
lighting, were allowed in this transition. Very little hum problems,
even when playing in schools or other premisses not originally
intended for gigs.

Much effort has been given to having power amps with balanced inputs,
microphones with balanced inputs and so forth. Its pretty much a given that
when setting up a recording studio that there is some bloody hum that defies
all efforts to eliminate it.

Grounding problems "ground loops" are not restricted to audio or video
applications. In a computer room wired as TN-C we had to connect the
14" disk drives to the computer, we had to use a copper braid wider
than the data flat cable for equipotential bonding, since the signals
were just TTL level, with 0.4 V noise margin.

In our office with two staircases, each with its own power feeder and
hence quite a lot of voltage difference between the PEN connectors, I
had to put an RS-232/ethernet terminal server to serve the offices at
the other staircase. Ethernet has galvanic isolation by design.

When working with balanced RS-422/485 serial communication systems,
this is enough for a few tens of meters, galvanic isolation after that
within a building and optical fiber between buildings, if you expect
to survive a lightning strike.

On the audio side, good quality audio transformers are now available,
so splitting the ground network should not be a problem.

 

[Joe Gwinn]

In article <ccKdnel2P6iTZjfOnZ2dnUVZ8vadnZ2d@bt.com>, Kevin Aylward
<ExtractkevinRemove@kevinaylward.co.uk> wrote:

wrote in message news:g7ukq9tmomn0aqj297fv6120rlf5uiphc5@4ax.com...

On Tue, 24 Jun 2014 08:34:32 -0700 (PDT), makolber@yahoo.com wrote:

yes I want to clarify my remarks...

sharp filtering in the frequency domain does create artifacts in the time
domain...but that doesn't mean that a good notch filter won't be effective
at removing single frequency hum.

Usually the artifacts are not audible and are much less objectionable
compared to the hum, so yes build and use a notch filter, or even a comb
filter if the hum has harmonics.

This is a good example of theory vs practice, it does work well in
practice.


Mark



For audio applications, the ear is not very sensitive to sounds below
100 Hz at least at moderate sound levels, say below 80 dB, thus quite
a lot hum is tolerated.

Ahmmmmmmmmmmmmmmmmmmmmm

The low note on a guitar is 82 Hz, the low note on a Bass is 41, sure its
not as sensitive, but if you cant hear that in music, you must be deaf.
60/50 hz hum is bloody annoying indeed in a guitar amplifier.

The brain reconstructs the fundamental from the harmonics. It is not
necessary to actually hear the 41 Hz.

...<http://en.wikipedia.org/wiki/Missing_fundamental>

Joe Gwinn

 

[Kevin Aylward]

"Joe Gwinn" wrote in message
news:280620141129111304%joegwinn@comcast.net...

For audio applications, the ear is not very sensitive to sounds below
100 Hz at least at moderate sound levels, say below 80 dB, thus quite
a lot hum is tolerated.

Ahmmmmmmmmmmmmmmmmmmmmm

The low note on a guitar is 82 Hz, the low note on a Bass is 41, sure its
not as sensitive, but if you cant hear that in music, you must be deaf.
60/50 hz hum is bloody annoying indeed in a guitar amplifier.

The brain reconstructs the fundamental from the harmonics. It is not
necessary to actually hear the 41 Hz.

Sure the brain can construct an approximation to having some LF but its
nothing like a Fender Precision generating a real damm thumbing Bass E line.


Kevin Aylward B.Sc.
www.kevinaylward.co.uk
www.anasoft.co.uk - SuperSpice

 

On Sat, 28 Jun 2014 12:31:09 +0300, upsidedown@downunder.com wrote:

On Fri, 27 Jun 2014 19:51:03 +0100, "Kevin Aylward"
ExtractkevinRemove@kevinaylward.co.uk> wrote:

"George Herold" wrote in message
news:e11468d4-f2fa-4409-8f41-4084bcf17069@googlegroups.com...

On Thursday, June 26, 2014 12:36:45 PM UTC-4, Kevin Aylward wrote:
wrote in message news:gh9mq9d2si4npfqrmebldgb8fi4fma5i36@4ax.com...
snip

Mate, I am a guitar player, and been for a rather long time. 60/50 hz hum
is
bloody annoying. Many, many amps over the last 40 years, in particular
tube/valve amps can have very, very annoying hums. Period.

Hint: music from instruments isn't continuous, and guitar amps have
bloody
HUGE gain to get huge preamp distortion making any minor hum hugely
audible

Yesterday I attended a guitar music festival playing early 1960's
music with old tube amplifiers such as Vox and Marshalls. Only two
times I noticed some hum issues (both during sound check), once when
the player bent over the amplifier and the guitar touched the
amplifier, so some hum from the transformer was transferred to the
pick-up. The other was the typical raspy sound with lots of harmonics,
when a bad cord was inserted into the amplifier (without proper shield
connection at the amplifier end, the shield, the guitar metallic
parts, the player, the pick-up formed a large capacitive probe).

While supporting a local dance band in the 1970s, I repaired their
equipment and studied their construction. Everyone had at least a
center taped 6.3 V filament winding or a potentiometer across the 6.3
V winding and the slider connected to ground, so you could adjust it
for minimum hum. I remember a Geloso amplifier that used DC filament
for the front end tubes. The amplifier is not a significant problem,
it is the total system.

How about ya bag the 50/60 Hz transformers,
Go to a SMPS, smaller magnetics, do it at 100kHz and it's easy to filter.
(and then put some distance between the PS and amp, if you have to.)

That was just one example illustrating the problem of 50/60hz hum. Its
irrelevant that the ear may be less sensitive to low frequencies, it's still
a major problem.

The whole process of using balanced (differential) signals in a music
recording environment was done to get rid of bloody annoying hum loops and
hum drops.

Now we are getting to the point.

I live in a country, in which previously TN-C electrification was
used, i.e. there was a common PEN connector, both functioning as
Neutral (N) and Protective Earth (PE). Of course any neutral current
would cause voltage drops and hence the chassies of different
equipment were at differential potential, causing big hum currents in
audio/video/computer cable shields if grounded at both ends.

The obvious solution would be to use TN-S (five wire), with separate N
and PE conductors in which PE does not carry any current in normal
situations, only in earth fault situations. In practice, most systems
are TN-C-S in which the PEN conductor is split into PE and N at some
point.

While supporting the local dance band in the 1970's I used a single
extension cord with multiple sockets. All audio equipment were then
connected to this single extension cord, forming effectively a TN-C to
TN-S transition. No other equipment, such as SCR controlled stage
lighting, were allowed in this transition. Very little hum problems,
even when playing in schools or other premisses not originally
intended for gigs.

Much effort has been given to having power amps with balanced inputs,
microphones with balanced inputs and so forth. Its pretty much a given that
when setting up a recording studio that there is some bloody hum that defies
all efforts to eliminate it.

Grounding problems "ground loops" are not restricted to audio or video
applications. In a computer room wired as TN-C we had to connect the
14" disk drives to the computer, we had to use a copper braid wider
than the data flat cable for equipotential bonding, since the signals
were just TTL level, with 0.4 V noise margin.

In our office with two staircases, each with its own power feeder and
hence quite a lot of voltage difference between the PEN connectors, I
had to put an RS-232/ethernet terminal server to serve the offices at
the other staircase. Ethernet has galvanic isolation by design.

There was something wrong with your power distribution if your grounds
were that far apart in a small space. Though it wasn't TTL, more than
one computer room was measured in acres.

There is also current loop.

When working with balanced RS-422/485 serial communication systems,
this is enough for a few tens of meters, galvanic isolation after that
within a building and optical fiber between buildings, if you expect
to survive a lightning strike.

That's why POTS is fiber? They do remarkably well even in FL.

We did RS422 for 500m. The audio was transformer coupled.

On the audio side, good quality audio transformers are now available,
so splitting the ground network should not be a problem.

Audio transformers were never a problem at line levels. It's not like
there have been silicon-scale advancements in transformer technology
in the last 40 years.

 

On Sat, 28 Jun 2014 12:08:38 -0400, krw@attt.bizz wrote:

On Sat, 28 Jun 2014 12:31:09 +0300, upsidedown@downunder.com wrote:

In our office with two staircases, each with its own power feeder and
hence quite a lot of voltage difference between the PEN connectors, I
had to put an RS-232/ethernet terminal server to serve the offices at
the other staircase. Ethernet has galvanic isolation by design.

There was something wrong with your power distribution if your grounds
were that far apart in a small space.

There was nothing strange about it. Single phase loads are supposed to
be evenly distributed between the phases and thus the neutral current
should cancel and no net current should flow in the feeder cable
neutral. For this assumption, the neutral conductor in the feeder
cable previously had often a smaller cross section area than the phase
conductor.

For even loading, this canceling applies for the fundamental, but not
for the third harmonic, which is _added_ into the neutral conductor.
With a lot of electronic (non PFC rectifier capacitor) loads, such
weak neutral conductors have been severely overloaded due to the
harmonics.

RS-232 has only a few volts of noise margin and is referenced to the
signal ground, which is often connected to the chassis ground, which
is then connected to the PEN conductor. When connecting two RS-232
devices connected to different feeders, some current will flow in the
signal ground causing a voltage drop in signal ground conductor,
dropping the noise margin.

On the other hand, grounding a thick cable shield at both ends, will
reduce the voltage difference, but several amps of the neutral load
current on feeder #1 will flow through your data cable shield to the
neutral conductor of feeder #2, which also will cause a lot of harm.

Though it wasn't TTL, more than
one computer room was measured in acres.

There is also current loop.

When working with balanced RS-422/485 serial communication systems,
this is enough for a few tens of meters, galvanic isolation after that
within a building and optical fiber between buildings, if you expect
to survive a lightning strike.

That's why POTS is fiber? They do remarkably well even in FL.

The ordinary is just a current loop with no external connections to
ground at the customer's premisses. The situation gets much more
complicated with answering machines and modems, which also have a
mains connection and possibly a direct connection to PE. There are
countless of examples of a few kilovolt flash over between the
telephone and electric networks, not just destroying the device, but
also sometimes burning down the house around it.

>We did RS422 for 500m. The audio was transformer coupled.

You were lucky if that RS422 was not isolated, perhaps site used
proper TN-S mains wiring with separate PE and N conductors all the
way.

 

[Jim Thompson]

On Sat, 28 Jun 2014 17:05:23 +0100, "Kevin Aylward"
<ExtractkevinRemove@kevinaylward.co.uk> wrote:

"Joe Gwinn" wrote in message
news:280620141129111304%joegwinn@comcast.net...



For audio applications, the ear is not very sensitive to sounds below
100 Hz at least at moderate sound levels, say below 80 dB, thus quite
a lot hum is tolerated.

Ahmmmmmmmmmmmmmmmmmmmmm

The low note on a guitar is 82 Hz, the low note on a Bass is 41, sure its
not as sensitive, but if you cant hear that in music, you must be deaf.
60/50 hz hum is bloody annoying indeed in a guitar amplifier.

The brain reconstructs the fundamental from the harmonics. It is not
necessary to actually hear the 41 Hz.

Sure the brain can construct an approximation to having some LF but its
nothing like a Fender Precision generating a real damm thumbing Bass E line.


Kevin Aylward B.Sc.
www.kevinaylward.co.uk
www.anasoft.co.uk - SuperSpice

If you can't feel it in your lungs, it ain't "bass" ;-)

But it's also why my hearing is seriously degraded... I used to play
British Band Classics at "field" levels

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: skypeanalog | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

On Sat, 28 Jun 2014 14:47:54 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Sat, 28 Jun 2014 17:05:23 +0100, "Kevin Aylward"
ExtractkevinRemove@kevinaylward.co.uk> wrote:

"Joe Gwinn" wrote in message
news:280620141129111304%joegwinn@comcast.net...



For audio applications, the ear is not very sensitive to sounds below
100 Hz at least at moderate sound levels, say below 80 dB, thus quite
a lot hum is tolerated.

Ahmmmmmmmmmmmmmmmmmmmmm

The low note on a guitar is 82 Hz, the low note on a Bass is 41, sure its
not as sensitive, but if you cant hear that in music, you must be deaf.
60/50 hz hum is bloody annoying indeed in a guitar amplifier.

The brain reconstructs the fundamental from the harmonics. It is not
necessary to actually hear the 41 Hz.

Sure the brain can construct an approximation to having some LF but its
nothing like a Fender Precision generating a real damm thumbing Bass E line.


Kevin Aylward B.Sc.
www.kevinaylward.co.uk
www.anasoft.co.uk - SuperSpice

If you can't feel it in your lungs, it ain't "bass" ;-)

At least I felt it in the stomach, when hitting a cord on a bass
guitar just in front of the speaker

But it's also why my hearing is seriously degraded... I used to play
British Band Classics at "field" levels

...Jim Thompson

 

I replied over in SER and I don't crosspost.

A compendium of these specs is nice but cannot tell you the whole story on the device.

 

[Spehro Pefhany]

On Thu, 03 Jul 2014 20:44:08 -0700, Robert Baer
<robertbaer@localnet.com> wrote:

<snipped scammer comms>

LOL.

I received a paper version of this attempted scam the other day.

Sent on letterhead of a genuine South African bank, with a South
African stamp, rather than the usual Nigeria or Benin origin. Signed
in the name of the actual branch manager in a real town, a
hearty-looking white woman who has a Facebook and a Linkedin page.

My half the $9.95 million is probably coming any day now..

--sp

 

[Robert Baer]

Spehro Pefhany wrote:

On Thu, 03 Jul 2014 20:44:08 -0700, Robert Baer
robertbaer@localnet.com> wrote:

snipped scammer comms

LOL.

I received a paper version of this attempted scam the other day.

Sent on letterhead of a genuine South African bank, with a South
African stamp, rather than the usual Nigeria or Benin origin. Signed
in the name of the actual branch manager in a real town, a
hearty-looking white woman who has a Facebook and a Linkedin page.

My half the $9.95 million is probably coming any day now..

--sp

WOW!
Beats them all.
Well worth framing.
**
Note what i said about my money transfer experience as a counter
against their request for money.
What i said is 100 percent true.
WU funds overseas can, indeed, go into limbo - making it a
hair-puller to straighten out.
In fact,it seems that i have to goose another transfer - maybe change
receiver name.
PS: both the one mentioned in that response, and the present one is
100 percent legit for worthy causes.

 

On Saturday, July 5, 2014 4:47:03 AM UTC+1, Robert Baer wrote:

Note what i said about my money transfer experience as a counter
against their request for money.
What i said is 100 percent true.
WU funds overseas can, indeed, go into limbo - making it a
hair-puller to straighten out.
In fact,it seems that i have to goose another transfer - maybe change
receiver name.
PS: both the one mentioned in that response, and the present one is
100 percent legit for worthy causes.

What happens to the vast amount of wire transferred money that goes missing?


NT

 

[Robert Baer]

meow2222@care2.com wrote:

On Saturday, July 5, 2014 4:47:03 AM UTC+1, Robert Baer wrote:

Note what i said about my money transfer experience as a counter
against their request for money.
What i said is 100 percent true.
WU funds overseas can, indeed, go into limbo - making it a
hair-puller to straighten out.
In fact,it seems that i have to goose another transfer - maybe change
receiver name.
PS: both the one mentioned in that response, and the present one is
100 percent legit for worthy causes.

What happens to the vast amount of wire transferred money that goes missing?


NT

The longer one waits to re-activate a transfer, the harder it is to
find the documentation, and re-activate.

If one does not actively pursue a "dead" transfer within the timeout
period, the paperwork goes into hyperspace.

Net result: Profit to W.U. i think.

 

On Monday, November 25, 1996 3:00:00 AM UTC-5, Thomas N. Lockyer wrote:

In article <57bf57$7rd@mercury.galstar.com> tpappano@galstar.com (Thomas Pappano) writes:
From: tpappano@galstar.com (Thomas Pappano)
Subject: Re: klystron vs. magnetron
Date: 25 Nov 1996 06:42:47 GMT

Bob Armstrong (fcaeng@gnc.net) wrote:
: Christopher Zoeller wrote:
:
: > As a newbie to the radar world, I have at least two questions:
: > 1) What's the difference between a klystron and a magnetron?
: > 2) What are the applications of each and why would one be
: > chosen over the other?
: > Thanks for any help -- it's very much appreciated!!!!!!!
: > Chris Zoeller
:
: In very general terms by the nature of their design, a klystron
: is used as an RF amplifier while a magnetron is limited to use
: as an RF oscillator. In the early days of radar (1950's era) some
: special purpose klystrons were used as oscillators in some very
: unique applications.
: Regards,
: Bob Armstrong
: E-Mail: fcaeng@gnc.net
: Home page: http://dune.globe-net.net/~fcaeng/
: "Man does not live by RF alone."

Can't help but throw in my two cents also

Klystron anps and oscillators were in common use during WWII. The
Sperry/Raytheon 723/2K25 was used as a local oscillator for 10GHZ
radar. Some others like the 2K26 were used for lower bands. These
two are `reflex' klystrons which mean (if I recall correctly) that
they function as an oscillator with without providing a feedback loop
and their output is available on a coaxial or waveguide terminal.

(snip)

Yes, you are dating yourself. I was an AETM3/c in the Navy and also remember
those local oscillators. Yes, they had a bellows that was externally
adjusted to cause the separation between grids that coupled to a resonant
chamber as reflex. BTW, can you still get those tubes? They had an octal
socket with a lead that extended into the waveguide and you just applied
voltage to get them to oscillate.

Rembering many burned fingers from hot 2k25's
Tom Pappano tpappano@galstar.com

Regards: Tom: http://www.best.com/~lockyer

Yes you can still get those tube's, Toshiba sells them for about quarter mill.

 

Crossposted and followup-to sci.electronics.design .

cassiano@gmail.com wrote:

I work at a physics lab and we have some custom hardware that have
been developed by researches along the years. We are trying to fix one
of them, but it uses a component that we are having a hard time to
find: It is a N-channel dual gate GaAs MES FET by Sony called 3SK166A.

Just from Googling, one broker claims to have stock on a 3SK166,
3SK166-1, and 3SK166A. I have never dealt with this broker before.

http://www.utsource.net/3SK166.html

Brokers like this one buy up inventories of old parts from other
suppliers, and/or send out random parts with false part numbers on them.
Sometimes you will get the genuine part at a bargain price, and
sometimes you will get a part that does not work at all.

> We need help finding a compatible replacement for this component.

I have cross-posted this reply to sci.electronics.design, which is much
more active than sci.electronics.components . It also has people
smarter than I am who might be able to suggest a replacement.

What claims to be the Sony datasheet is available at:

http://pdf.datasheetcatalog.com/datasheets/90/206535_DS.pdf
http://cs.utsource.net/goods_files/pdf/46/46558_SONY_3SK166A.pdf

Some of the interesting parameters seem to be: Vds 8 V, Vgs -6 V,
Id 80 mA, Pd 150 mW, gain about 20 dB. The datasheet gives S
parameters and noise figures for a range of 200 to 2,000 MHz. The
package is a Sony M-254; it doesn't list an EIA or JEDEC package code.

Standard disclaimers apply: I don't get money or other consideration
from any companies mentioned.

Matt Roberds

 

On Thursday, July 17, 2014 12:12:48 AM UTC-4, mrob...@att.net wrote:

Crossposted and followup-to sci.electronics.design .

cassiano wrote:

I work at a physics lab and we have some custom hardware that have
been developed by researches along the years. We are trying to fix one
of them, but it uses a component that we are having a hard time to
find: It is a N-channel dual gate GaAs MES FET by Sony called 3SK166A.

Just from Googling, one broker claims to have stock on a 3SK166,
3SK166-1, and 3SK166A. I have never dealt with this broker before.

http://www.utsource.net/3SK166.html

Brokers like this one buy up inventories of old parts from other
suppliers, and/or send out random parts with false part numbers on them.

Sometimes you will get the genuine part at a bargain price, and
sometimes you will get a part that does not work at all.

We need help finding a compatible replacement for this component.

I have cross-posted this reply to sci.electronics.design, which is much
more active than sci.electronics.components . It also has people
smarter than I am who might be able to suggest a replacement.

What claims to be the Sony datasheet is available at:

http://pdf.datasheetcatalog.com/datasheets/90/206535_DS.pdf
http://cs.utsource.net/goods_files/pdf/46/46558_SONY_3SK166A.pdf

Some of the interesting parameters seem to be: Vds 8 V, Vgs -6 V,

Id 80 mA, Pd 150 mW, gain about 20 dB. The datasheet gives S
parameters and noise figures for a range of 200 to 2,000 MHz. The
package is a Sony M-254; it doesn't list an EIA or JEDEC package code.

Standard disclaimers apply: I don't get money or other consideration
from any companies mentioned.

Matt Roberds

Once upon a time similar dual-gate MESFETs were made by CEL (California
Eastern Laboratories), then a subsidiary of NEC.

http://www.cel.com/

DigiKey and Arrow used to carry them.

Here's an ancient link to the NE251, one of my old fave dual-gate MESFETs
in the same ballpark as the 3SK166A:
http://www.electronicproducts.com/Discrete_Semiconductors/GaAs_MESFET%281%29.aspx

It looks like CEL's been sold to Renesas and the dual-gates may be gone.
They're wonderful parts--dunno why they went out of vogue.

GaAs MESFETs:
http://www.cel.com/product.do?command=viewOverviewDetail&group=4&level2=2407

Maybe these clues will set you on the trail? I *might* even have some
NE251xx's in the dungeon (but might've given them away).

HTH,

James Arthur