Re: Recommendations for a synthesized 20GHz+ RF gen
?
For more years than I can now remember, I repaired and calibrated 8566Bs.? After using sweepers and generators to adjust the band gain and offset adjustments that way, I switched over to using a comb generator that was salvaged out of a 8569x.? Using the comb generator made the band gain and associated adjustments down right easy.? I still used a calibrated sweep generator to do the final level cal. Interesting - I don't foresee calibrating more than the one, but this is good to know - thanks.?
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Re: Recommendations for a synthesized 20GHz+ RF gen
Hey Vladan,
the 8341 looks quite interesting, but boy it looks like a beast. Has the look of a mountain fortress :). I'll be sure to keep an eye out for one of those.
Siggi
?
Bob Dildine is correct and if you feel the same way, then the 8341 may be your best choice. (It's almost the same as the 8340.) It has two downsides. It's extremely heavy - probably the heaviest piece of test equipment from that era. And it is really loud.
But, it goes from 10 MHz to 20GHz and it doesn't require software for adjustments. BTW, the 8341 can be made to go to 26.5 GHz, you will have to align it in that last band and push some keys on the front panel to enable that feature.
BTW, I think I once aligned the 8566 front end using a 321.4 MHz source, the first LO and a mixer. Obviously, it wasn't a great job, but if you have no other equipment, you can get things going that way.
Vladan
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Re: [TekScopes] Re: Why is Mu Metal used?
I don't know about that being the "primary" but ya that too!
-----Original Message-----
From: Chuck Harris cfharris@... [hp_agilent_equipment]
To: hp_agilent_equipment
Sent: Sat, Feb 20, 2016 3:54 pm
Subject: Re: [hp_agilent_equipment] Re: [TekScopes] Re: Why is Mu Metal used?
?
Because 60Hz isn't the primary reason for the mumetal shield.
The primary reason is the Earth's magnetic field deflecting
the beam in annoying ways.
-Chuck Harris
'cheater00 .' cheater00@... [hp_agilent_equipment] wrote:
> I understand a changing magnetic field would induce a current in the
> copper foil, and so the magnetic field would effectively be "used up"
> by the copper foil, though. Why is copper shielding not effective
> against 60 Hz? That's not DC after all.
>
> Thanks a lot
>
> I'm only learning about EM theory
>
> On Sat, Feb 20, 2016 at 7:57 PM, snapdiode@... [TekScopes]
> < TekScopes@...> wrote:
>> grounded copper foil would do precisely zero against a dc field
>>
>> Mu-metal - Wikipedia, the free encyclopedia
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Re: Recommendations for a synthesized 20GHz+ RF gen
Hey Ancel,
that's a very interesting device. See <>. Looks like a combo RF synthesizer from 35MHz to 4.4GHz and power meter. Doesn't quite go where I'd need it to, but thanks all the same.
Siggi
?
Perhaps this?
Ebay #
201522528149
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Re: Recommendations for a synthesized 20GHz+ RF gen
Hey Bob,
thanks for the tips - I'll read up on those for sure. It's sad to see otherwise perfectly good instruments going off due to the calibration software. The Tek TDS scopes have similar problems, though I've seen a couple of people mention hacking dosemu to allow running the Tek field adjust software in emulation. I noticed there's a HP series 200 emulation project linked off the HP museum page <>. Hopefully this sort of thing will allow keeping these old beauties going...
Siggi
?
Siggi,
I have both an HP 8672A (2-18 GHz) and an HP 83732A (10 MHz - 20 GHz).
I'm partial to the HP 8672A because that was my first project of my 30
year career at HP but I really like the HP 83732A. However, the 83732
requires specialized service software that runs on the HP series 200 or
300 computers to make any adjustments. This software writes calibration
constants into ROM. I'm stuck with uncalibrated power output (it's off
by 4-6 dB and not monotonic) and no way to correct it. The 8672 was done
before the era of computers and all of its adjustments are done manually
as outlined in the manual.
So whatever you choose, be aware that a fixer upper might require
service software that is now unobtainable and runs on computers that are
old and obsolete.
Regards,
Bob Dildine
w6sfh at sonic dot net
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Re: eBay buyer protections are poor
| Daniel
I think you have missed the point of my comment. Why do some items cost 3 times as much to ship as the other same item?? And you are wrong - ten years ago USPS were quite reasonable. It seems they have now jumped onto the "Ebay make a quick buck" bandwagon.
Cheers Peter - VK2AN
| From:"daniel@... [hp_agilent_equipment]"
Date:Sat, Feb 20, 2016 at 23:53
Subject:Re: [hp_agilent_equipment] Re: eBay buyer protections are poor
?
>Sure, I got a few dodgy items, but when you are buying 100 resistors for $2.95 including shipping, what do you expect?
You can get 100 resistors for cheaper than that from Digi-Key; why would you buy junky no-name Chinese resistors and wait a month for that price?
>By the way, I have had a few dodgy items from the good old USofA too,
and unfortunately the biggest downer for those of us who dont live in
the States now is the big USPS ripoff. If you dont believe me,
do a search on some HP test gear and check the crazy range of shipping
charges for the same piece of kit. I actually came across one bit of
gear the other day that had $975 as the shipping cost for a 50lb item!
That's what you get for shipping heavy items via USPS.? They've always been expensive for that; you have to ship that stuff by some other method.? USPS is only good for lightweight stuff.? For anything over 5 pounds, they're not competitive.? If you can't be bothered to look for alternatives, you have no right to complain about
USPS's prices.
| |
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Re: [TekScopes] Re: Why is Mu Metal used?
Because 60Hz isn't the primary reason for the mumetal shield.
The primary reason is the Earth's magnetic field deflecting
the beam in annoying ways.
-Chuck Harris
'cheater00 .' cheater00@... [hp_agilent_equipment] wrote:
toggle quoted message
Show quoted text
I understand a changing magnetic field would induce a current in the
copper foil, and so the magnetic field would effectively be "used up"
by the copper foil, though. Why is copper shielding not effective
against 60 Hz? That's not DC after all.
Thanks a lot
I'm only learning about EM theory
On Sat, Feb 20, 2016 at 7:57 PM, snapdiode@... [TekScopes]
<TekScopes@...> wrote:
grounded copper foil would do precisely zero against a dc field
Mu-metal - Wikipedia, the free encyclopedia
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Re: eBay buyer protections are poor
Precisely why, when the cards are stacked against me, my ONLY option is to refuse to play the game!
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Re: [TekScopes] Re: Why is Mu Metal used?
And this applies above power line frequencies.
I have personal experience with this on the 7834 oscilloscope which
uses a switching power supply. This particular 7834 has a geometry
issue and one of the tests I did was to operate it without the mu
metal shield in place. The result was that the display on the CRT was
so smeared as to be unusable and barely even recognizable.
Some oscilloscopes do get away with just using a metal shield.
toggle quoted message
Show quoted text
On Sat, 20 Feb 2016 20:55:01 +0100, you wrote: Ahh ok, now THAT makes sense and tells me a lot + gives me some
keywords to follow up on. Thank you very much!
On Sat, Feb 20, 2016 at 8:27 PM, kmec@... [hp_agilent_equipment]
<hp_agilent_equipment@...> wrote:
The skin depth for copper at 60 Hz is large enough that significant field energy can penetrate through material thin enough to be practical, resulting in interference. Mu metal (iron that has been annealed (degaussed) in a reducing atmosphere, usually hydrogen)) acts to divert magnetic field lines around the shielded object without add any remanent field of its own. I am sure others can/will add more.
73
Jeff Kruth
WA3ZKR
|
Re: Why is Mu Metal used?
It’s used to keep magnetic fields out of the path the electrons travel in the CRT. Copper foil will shield electric fields, and to some extent will shield AC or changing fields. Mu metal channels or attracts the magnetic fields into itself more effectively than air or vacuum due to it’s higher permeability. ?It’s permeability is tens of thousands of times that of steel. ?
toggle quoted message
Show quoted text
Hi guys,
Why is Mu Metal used to shield CRTs in scopes, rather than just
grounded copper foil? I never understood the precise reason for that.
Thanks
|
Re: Why is Mu Metal used?
On 2/20/2016 3:36 PM, `Richard Knoppow dickburk@... [hp_agilent_equipment] wrote:
Mu metal is a shield for magnetic fields. It has extremely high permeability, the ability to conduct magnetic fields the Greek letter Mu u is the symbol for permeability.
See:
for more.
Now, if you take a magnet and a piece of soft iron the magnet will attract the iron. If you place even a fairly thick sheet of conductor, like copper or aluminum, between the two the magnet will still attract the iron with little or no reduction in strength. Now if you place a sheet of Mu metal between the attraction will be much reduced depending on the thickness of the Mu metal and its exact type. The use of Mu metal shields around CRTs and transformers prevents the effects of either static or alternating magnetic fields. These can distort or modulate the beam in the CRT or induce hum in a transformer or allow the transformer to induce a field in some other device.
Good conductors like a thick copper shorted winding of either wire or ribbon, are used in power transformers to eliminate eddy currents in the core but this is different than magnetic shielding.
Hello-- One more thing about MuMetal: in practice, you're supposed to reanneal the shield if you make major structural modifications, such as cutting away a portion of, or bending the shield. Otherwise, the shield's permeability decreases. You can supplement the shield by adding a second (steel) shield between the Mu-metal shield and an offending magnetic-field source. This may not always be practical. 73-- Brad AA1IP
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Re: eBay buyer protections are poor
>The key is to use the 3" semi-hard foam (the kind that you can compress
with significant force but it will always return back to its original
shape and size, its usually pink or white, comes with new TV's etc) and
use a bunch of tape to tape this all the way around the perimiter of the
front of the unit, [snip]
This is excellent packing advice, and this is exactly why stuff like new TVs are also packed this way: engineers have researched the issue and come up with this stuff, since a lot of big things like this are shipped directly to peoples' homes these days.
The problem, however, is that while *you* obviously take the time to ship stuff properly like this, you can't count on some random idiot on Ebay to do so.? So, buyer beware: don't bid until you make sure the seller is going to pack it properly.? Don't just buy something for $$$ from some random person, have them ship it internationally, and then bitch and whine about how Americans are all morons who can't pack things when it arrives damaged.
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Re: Why is Mu Metal used?
?? Mu metal is a shield for magnetic fields. It has
extremely high permeability, the ability to conduct magnetic
fields the Greek letter Mu u is the symbol for permeability.
?? See:
for more.
??? Now, if you take a magnet and a piece of soft iron the magnet
will attract the iron. If you place even a fairly thick sheet of
conductor, like copper or aluminum, between the two the magnet
will still attract the iron with little or no reduction in
strength.? Now if you place a sheet of Mu metal between the
attraction will be much reduced depending on the thickness of the
Mu metal and its exact type.? The use of Mu metal shields around
CRTs and transformers prevents the effects of either static or
alternating magnetic fields. These can distort or modulate the
beam in the CRT or induce hum in a transformer or allow the
transformer to induce a field in some other device.
?? Good conductors like a thick copper shorted winding of either
wire or ribbon, are used in power transformers to eliminate eddy
currents in the core but this is different than magnetic
shielding.
On 2/20/2016 10:48 AM, 'cheater00 .'
cheater00@... [hp_agilent_equipment] wrote:
Hi guys,
Why is Mu Metal used to shield CRTs in scopes, rather than just
grounded copper foil? I never understood the precise reason for that.
Thanks
------------------------------------
Posted by: "cheater00 ."
------------------------------------
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Re: [TekScopes] Re: Why is Mu Metal used?
Ahh ok, now THAT makes sense and tells me a lot + gives me some keywords to follow up on. Thank you very much! On Sat, Feb 20, 2016 at 8:27 PM, kmec@... [hp_agilent_equipment] <hp_agilent_equipment@...> wrote:
The skin depth for copper at 60 Hz is large enough that significant field energy can penetrate through material thin enough to be practical, resulting in interference. Mu metal (iron that has been annealed (degaussed) in a reducing atmosphere, usually hydrogen)) acts to divert magnetic field lines around the shielded object without add any remanent field of its own. I am sure others can/will add more.
73
Jeff Kruth
WA3ZKR
|
Re: [TekScopes] Re: Why is Mu Metal used?
The skin depth for copper at 60 Hz is large enough that significant field
energy can penetrate through material thin enough to be practical, resulting in
interference. Mu metal (iron that has been annealed (degaussed) in a reducing
atmosphere, usually hydrogen)) acts to divert magnetic field lines around the
shielded object without add any remanent field of its own. I am sure others
can/will add more.
?
73
Jeff Kruth
WA3ZKR
?
In a message dated 2/20/2016 2:10:54 P.M. Eastern Standard Time,
hp_agilent_equipment@... writes:
toggle quoted message
Show quoted text
?
Another reason, the CRT beam is
most?susceptible to magnetic fields as seen in the television deflection
yoke scanning the beam. A sufficient magnetic field close to the CRT will
deflect or modulate the beam even slightly causing poor focus trace quality
inaccuracy
Jack KG6INX
-----Original Message----- From: 'cheater00 .'
cheater00@... [hp_agilent_equipment]
To: TekScopes
; hp_agilent_equipment
Sent: Sat, Feb 20, 2016 11:02
am Subject: [hp_agilent_equipment] Re: [TekScopes] Re: Why is Mu Metal
used?
?
I understand a changing magnetic field would induce a current in
the copper foil, and so the magnetic field would effectively be "used
up" by the copper foil, though. Why is copper shielding not
effective against 60 Hz? That's not DC after all. Thanks a
lot I'm only learning about EM theory On Sat, Feb 20, 2016 at
7:57 PM, snapdiode@...
[TekScopes] < TekScopes@...>
wrote: > grounded copper foil would do precisely zero against a dc
field > > Mu-metal - Wikipedia, the free encyclopedia > > > >
> > > >
Mu-metal - Wikipedia, the free encyclopedia Mu-metal is a
nickel–iron soft magnetic alloy with very high permeability suitable for
shielding sensitive electronic equipment against static or
low-frequen... > > > > > > > >
View on en.wikipedi... > >
Preview by
Yahoo > > > > > > > > > >
Permeability (electromagnetism) - Wikipedia, the free encyclopedia > > > >
> > > >
Permeability (electromagnetism) - Wikip...
In electromagnetism, permeability is the measure of the ability of a material
to support the formation of a magnetic field within itself. Hence, it is the
degree of... > > > > > > > >
View on en.wikipedi... > >
Preview by
Yahoo > > > > > > > > > >
[Non-text portions of this message have been
removed] > > > >
------------------------------------ > Posted by: snapdiode@...>
------------------------------------ > > >
------------------------------------ > > Yahoo Groups
Links > > >
|
Re: eBay buyer protections are poor
I disagree.? I have bought Agilent ESG-DP, 8341B, 8753ES, 4395A, E4440A, Tek CSA8000, R+S misc, and various heavier advantest equipment in the past year or so.? The key is to use the 3" semi-hard foam (the kind that you can compress with significant force but it will always return back to its original shape and size, its usually pink or white, comes with new TV's etc) and use a bunch of tape to tape this all the way around the perimiter of the front of the unit, SECURELY tape it with a lot of tape to keep it from moving at all, then put a flat piece across the faceplate, and fill in any gap between this 2nd piece and the faceplate with paper wrapping, then SECURELY tape this all together and to the body of the unit.? Then stuff the box with paper (or something else that won't migrate and won't compress significantly) so that the rest of the box supports the body of the unit (and there isn't significant force on the front foam from the weight of the unit).? Anywhere there are any BNC/SMA/etc connectors, you must put 3" of the foam mentioned above.
The problem is with the kickers in the fedex/UPS distribution centers. The boxes rapidly move down conveyers and are scanned, and when they reach the appropriate split/chute, this little wall kicks out *BAM!* and throws it down the other path.? The problem is that with heavy packages, it takes significant force to get the package moving and there will be significant momentary force exerted on wherever it gets kicked.? This will momentarily compress that part of the package.? Packaging that migrates or yields will get compressed and no longer protect after a kick or two.? I have seen BNC connectors punched through 4 layers of cardboard from these kickers, faceplates broken, etc, so I always provide very specific packing instructions to private sellers, and the materials needed are usually cheap if you give them a few different options.
All of? the equipment that I have received damaged was damaged because it was packed in material that yields (compresses but does not return) - such as 1-2" styrofoam (no good for faceplates and most corners, only good for flat sides with no protrusions!!); Bubble wrap (shameful), etc.? The key is to use this foam that takes significant force to compress, can be compressed to about 1/2 its original thickness by significant force, but always returns to original size.? It's the same foam that TV's usually come packed in, computers, new test equipment, etc.
Protect the corners, use very secure taping to make sure the foam WILL NOT move, protect any surface with protruding connectors, and if you really care about the back corners (I often do not as I rarely see damage on rear corners unless they have protruding pillars like advantest and R+S) then use the same foam on those as well.
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Re: [TekScopes] Re: Why is Mu Metal used?
Another reason, the CRT beam is most?susceptible to magnetic fields as seen in the television deflection yoke scanning the beam. A sufficient magnetic field close to the CRT will deflect or modulate the beam even slightly causing poor focus trace quality inaccuracy
Jack KG6INX
-----Original Message-----
From: 'cheater00 .' cheater00@... [hp_agilent_equipment]
To: TekScopes ; hp_agilent_equipment
Sent: Sat, Feb 20, 2016 11:02 am
Subject: [hp_agilent_equipment] Re: [TekScopes] Re: Why is Mu Metal used?
?
I understand a changing magnetic field would induce a current in the
copper foil, and so the magnetic field would effectively be "used up"
by the copper foil, though. Why is copper shielding not effective
against 60 Hz? That's not DC after all.
Thanks a lot
I'm only learning about EM theory
On Sat, Feb 20, 2016 at 7:57 PM, snapdiode@... [TekScopes]
< TekScopes@...> wrote:
> grounded copper foil would do precisely zero against a dc field
>
> Mu-metal - Wikipedia, the free encyclopedia
>
>
>
>
>
>
>
> Mu-metal - Wikipedia, the free encyclopedia Mu-metal is a nickel–iron soft magnetic alloy with very high permeability suitable for shielding sensitive electronic equipment against static or low-frequen...
>
>
>
>
>
>
>
> View on en.wikipedi...
>
> Preview by Yahoo
>
>
>
>
>
>
>
>
>
> Permeability (electromagnetism) - Wikipedia, the free encyclopedia
>
>
>
>
>
>
>
> Permeability (electromagnetism) - Wikip... In electromagnetism, permeability is the measure of the ability of a material to support the formation of a magnetic field within itself. Hence, it is the degree of...
>
>
>
>
>
>
>
> View on en.wikipedi...
>
> Preview by Yahoo
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> ------------------------------------
> Posted by: snapdiode@...
> ------------------------------------
>
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> ------------------------------------
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> Yahoo Groups Links
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>
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Re: [TekScopes] Re: Why is Mu Metal used?
On 2/20/2016 2:06 PM, Jack Mcmullen forjack842@... [hp_agilent_equipment] wrote:
You're comparing apples and oranges. 60hz Magnetic fields are what MU-metal are best at filtering out. Copper screen is best for shielding RF electric fields as radiated from antennae.
Jack KG6INX
Hello-- ...And Mew Metal shielding will keep cats out of transmitters....<g>. 73-- Brad AA1IP
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Re: [TekScopes] Re: Why is Mu Metal used?
I know they're different Jack, I'm asking how.
Cheers
You're comparing apples and oranges. 60hz Magnetic fields are what MU-metal are best at filtering out. Copper screen is best for shielding RF electric fields as radiated from antennae.
Jack KG6INX ?
-----Original Message-----
From: 'cheater00 .' cheater00@... [hp_agilent_equipment] <hp_agilent_equipment@...>
To: TekScopes <TekScopes@...>; hp_agilent_equipment <hp_agilent_equipment@...>
Sent: Sat, Feb 20, 2016 11:02 am
Subject: [hp_agilent_equipment] Re: [TekScopes] Re: Why is Mu Metal used?
?
I understand a changing magnetic field would induce a current in the
copper foil, and so the magnetic field would effectively be "used up"
by the copper foil, though. Why is copper shielding not effective
against 60 Hz? That's not DC after all.
Thanks a lot
I'm only learning about EM theory
On Sat, Feb 20, 2016 at 7:57 PM, snapdiode@... [TekScopes]
< TekScopes@...> wrote:
> grounded copper foil would do precisely zero against a dc field
>
> Mu-metal - Wikipedia, the free encyclopedia
>
>
>
>
>
>
>
> Mu-metal - Wikipedia, the free encyclopedia Mu-metal is a nickel–iron soft magnetic alloy with very high permeability suitable for shielding sensitive electronic equipment against static or low-frequen...
>
>
>
>
>
>
>
> View on en.wikipedi...
>
> Preview by Yahoo
>
>
>
>
>
>
>
>
>
> Permeability (electromagnetism) - Wikipedia, the free encyclopedia
>
>
>
>
>
>
>
> Permeability (electromagnetism) - Wikip... In electromagnetism, permeability is the measure of the ability of a material to support the formation of a magnetic field within itself. Hence, it is the degree of...
>
>
>
>
>
>
>
> View on en.wikipedi...
>
> Preview by Yahoo
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> ------------------------------------
> Posted by: snapdiode@...
> ------------------------------------
>
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> ------------------------------------
>
> Yahoo Groups Links
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Re: [TekScopes] Re: Why is Mu Metal used?
You're comparing apples and oranges. 60hz Magnetic fields are what MU-metal are best at filtering out. Copper screen is best for shielding RF electric fields as radiated from antennae.
Jack KG6INX ?
-----Original Message-----
From: 'cheater00 .' cheater00@... [hp_agilent_equipment]
To: TekScopes ; hp_agilent_equipment
Sent: Sat, Feb 20, 2016 11:02 am
Subject: [hp_agilent_equipment] Re: [TekScopes] Re: Why is Mu Metal used?
?
I understand a changing magnetic field would induce a current in the
copper foil, and so the magnetic field would effectively be "used up"
by the copper foil, though. Why is copper shielding not effective
against 60 Hz? That's not DC after all.
Thanks a lot
I'm only learning about EM theory
On Sat, Feb 20, 2016 at 7:57 PM, snapdiode@... [TekScopes]
< TekScopes@...> wrote:
> grounded copper foil would do precisely zero against a dc field
>
> Mu-metal - Wikipedia, the free encyclopedia
>
>
>
>
>
>
>
> Mu-metal - Wikipedia, the free encyclopedia Mu-metal is a nickel–iron soft magnetic alloy with very high permeability suitable for shielding sensitive electronic equipment against static or low-frequen...
>
>
>
>
>
>
>
> View on en.wikipedi...
>
> Preview by Yahoo
>
>
>
>
>
>
>
>
>
> Permeability (electromagnetism) - Wikipedia, the free encyclopedia
>
>
>
>
>
>
>
> Permeability (electromagnetism) - Wikip... In electromagnetism, permeability is the measure of the ability of a material to support the formation of a magnetic field within itself. Hence, it is the degree of...
>
>
>
>
>
>
>
> View on en.wikipedi...
>
> Preview by Yahoo
>
>
>
>
>
>
>
>
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>
>
>
> ------------------------------------
> Posted by: snapdiode@...
> ------------------------------------
>
>
> ------------------------------------
>
> Yahoo Groups Links
>
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>
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David Hess