It might be possible to find a donation, too, and of course that
wouldn't have to be new (but might be). My specific recommendations
would be biased so I'm going to avoid giving them. However, I think
you should make a wish-list of features, first, and perhaps your
students could help you come up with those. It would even be a chance
to engage them in a little research. I'd say you should have an
instrument that's easy to learn and use, and that introduces the
students to a good range of the capabilities of a good VNA. It would
be good if it introduces them to the importance of calibration, and
just _what_ should be calibrated on a VNA. It would be good if it can
make s-parameter measurements. The concept of having the ability to
make calibrated measurements at the end of a (possibly fairly long)
transmission line is very useful. In actual use, I'd look for ways to
illustrate that they (all of them) have limitations: there are
tradeoffs in the design of a VNA, made with an eye to the intended
application(s).

I know that HP published some nice application notes about VNA
applications and calibration and accuracy limits. Likely Rohde &
Schwarz and Anritsu and others have similar ap notes. If you have
trouble finding HP ones, I may be able to help, but they're likely on
the Agilent web (somewhere). Also look for articles in the HP
Journal...again, I can help if you can't find anything.

Cheers,
Tom

Bob Liesenfeld wrote in message ...
Hi gang,
I know there are several professional engineering types on the list,
so I thought I'd post this here. I teach at a technical college and it
is budget time. My boss asked me for a "wish list" and a vector network
analyzer came to mind. What I had in mind would be something we could
use to characterize small signal BJT and JFET circuits at say 3-30MHz.
VHF and UHF would be nice, but not required. I'd be looking for
something that could provide real and imaginary values, so as to be able
to develop s parameters for various circuits.
In order to qualify for consideration, the unit would have to be new,
and non-kit. I know HP and others make things like this. Any
recommendations?
BTW, I know something like this is going to run in the kilo or tens of
kilo buck range. Hey, it's their money and they asked.

Thanks for the input.

Bob WB0POQ

I just got through building up the VNA that Dale mentioned. Kit price is 250
dollars, plus 5 dollars shipping in the USA.
Right now, I am etching the power supply board, and I hope to have the unit
up and running later this afternoon.

Pete

"Tom Bruhns" wrote in message
m...
It might be possible to find a donation, too, and of course that
wouldn't have to be new (but might be). My specific recommendations
would be biased so I'm going to avoid giving them. However, I think
you should make a wish-list of features, first, and perhaps your
students could help you come up with those. It would even be a chance
to engage them in a little research. I'd say you should have an
instrument that's easy to learn and use, and that introduces the
students to a good range of the capabilities of a good VNA. It would
be good if it introduces them to the importance of calibration, and
just _what_ should be calibrated on a VNA. It would be good if it can
make s-parameter measurements. The concept of having the ability to
make calibrated measurements at the end of a (possibly fairly long)
transmission line is very useful. In actual use, I'd look for ways to
illustrate that they (all of them) have limitations: there are
tradeoffs in the design of a VNA, made with an eye to the intended
application(s).

I know that HP published some nice application notes about VNA
applications and calibration and accuracy limits. Likely Rohde &
Schwarz and Anritsu and others have similar ap notes. If you have
trouble finding HP ones, I may be able to help, but they're likely on
the Agilent web (somewhere). Also look for articles in the HP
Journal...again, I can help if you can't find anything.

Cheers,
Tom

Bob Liesenfeld wrote in message
...
Hi gang,
I know there are several professional engineering types on the list,
so I thought I'd post this here. I teach at a technical college and it
is budget time. My boss asked me for a "wish list" and a vector network
analyzer came to mind. What I had in mind would be something we could
use to characterize small signal BJT and JFET circuits at say 3-30MHz.
VHF and UHF would be nice, but not required. I'd be looking for
something that could provide real and imaginary values, so as to be able
to develop s parameters for various circuits.
In order to qualify for consideration, the unit would have to be new,
and non-kit. I know HP and others make things like this. Any
recommendations?
BTW, I know something like this is going to run in the kilo or tens of
kilo buck range. Hey, it's their money and they asked.

Thanks for the input.

Bob WB0POQ

On Wed, 11 Feb 2004 14:17:15 GMT, "Pete KE9OA"
wrote:

I just got through building up the VNA that Dale mentioned. Kit price is 250
dollars, plus 5 dollars shipping in the USA.
Right now, I am etching the power supply board, and I hope to have the unit
up and running later this afternoon.

Please let us know how you get on....
--

The BBC: Licensed at public expense to spread lies.

Hi Paul,
I just finished it this evening......................it is a
good piece of equipment, and worth the money. Tomorrow, I will do more
in-depth testing. It appears to have resolution to 6 digits, which is good.
It consists of a pair of 9851 DDS chips, with a 1496 being used as a direct
conversion detector. I think I am going to build another one, so I can use
one at home and one at work.

Pete

"Paul Burridge" wrote in message
...
On Wed, 11 Feb 2004 14:17:15 GMT, "Pete KE9OA"
wrote:

I just got through building up the VNA that Dale mentioned. Kit price is
250
dollars, plus 5 dollars shipping in the USA.
Right now, I am etching the power supply board, and I hope to have the
unit
up and running later this afternoon.

Please let us know how you get on....
--

The BBC: Licensed at public expense to spread lies.

On Thu, 12 Feb 2004 01:51:41 GMT, "Pete KE9OA"
wrote:

Hi Paul,
I just finished it this evening......................it is a
good piece of equipment, and worth the money. Tomorrow, I will do more
in-depth testing. It appears to have resolution to 6 digits, which is good.
It consists of a pair of 9851 DDS chips, with a 1496 being used as a direct
conversion detector. I think I am going to build another one, so I can use
one at home and one at work.

Thanks, Pete. Resolution is one thing, accuracy is another. Do you
have a proprietory instrument within calibration to compare it
against? I want to believe in this kit. If it works as advertised then
it's a significant breakthrough for those of us who feel reluctant to
part with 20,000 quid for a piece of relatively infrequently-needed
test equipment! Please report back here when you've had the chance to
check it out properly and let us know how it performs...
--

The BBC: Licensed at public expense to spread lies.

Thanks, Pete. Resolution is one thing, accuracy is another. Do you
have a proprietory instrument within calibration to compare it
against? I want to believe in this kit. If it works as advertised then
it's a significant breakthrough for those of us who feel reluctant to
part with 20,000 quid for a piece of relatively infrequently-needed
test equipment! Please report back here when you've had the chance to
check it out properly and let us know how it performs...

Paul, what part of the comparison between my Boonton and the N2PK VNA do you
have a difficult time with? Or for that matter, the comparisons with Chip
Owens HP 5783C? The accuracy is primarily limited by the quality of the OSL
standards used in setup, and the experience of the user in establishing
his/her reference plane.

W4ZCB

Agreed.....................a super good unit.

Pete

"Harold E. Johnson" wrote in message
news:bJRWb.300189$na.451700@attbi_s04...


Thanks, Pete. Resolution is one thing, accuracy is another. Do you
have a proprietory instrument within calibration to compare it
against? I want to believe in this kit. If it works as advertised then
it's a significant breakthrough for those of us who feel reluctant to
part with 20,000 quid for a piece of relatively infrequently-needed
test equipment! Please report back here when you've had the chance to
check it out properly and let us know how it performs...

Paul, what part of the comparison between my Boonton and the N2PK VNA do
you
have a difficult time with? Or for that matter, the comparisons with Chip
Owens HP 5783C? The accuracy is primarily limited by the quality of the
OSL
standards used in setup, and the experience of the user in establishing
his/her reference plane.

W4ZCB

Agreed.....................a super good unit.

Pete

"Harold E. Johnson" wrote in message
news:bJRWb.300189$na.451700@attbi_s04...


Thanks, Pete. Resolution is one thing, accuracy is another. Do you
have a proprietory instrument within calibration to compare it
against? I want to believe in this kit. If it works as advertised then
it's a significant breakthrough for those of us who feel reluctant to
part with 20,000 quid for a piece of relatively infrequently-needed
test equipment! Please report back here when you've had the chance to
check it out properly and let us know how it performs...

Paul, what part of the comparison between my Boonton and the N2PK VNA do
you
have a difficult time with? Or for that matter, the comparisons with Chip
Owens HP 5783C? The accuracy is primarily limited by the quality of the
OSL
standards used in setup, and the experience of the user in establishing
his/her reference plane.

W4ZCB

Paul Burridge wrote:
On Thu, 12 Feb 2004 01:51:41 GMT, "Pete KE9OA"
wrote:

Hi Paul,
I just finished it this evening......................it is a
good piece of equipment, and worth the money. Tomorrow, I will do more
in-depth testing. It appears to have resolution to 6 digits, which is good.
It consists of a pair of 9851 DDS chips, with a 1496 being used as a direct
conversion detector. I think I am going to build another one, so I can use
one at home and one at work.

Thanks, Pete. Resolution is one thing, accuracy is another. Do you
have a proprietory instrument within calibration to compare it
against? I want to believe in this kit.

N2PK's website (www.qsl.net/n2pk) gives exhaustive information about
measurement accuracy, standards and comparisons with professional VNAs.

When used correctly (a necessity for any VNA), N2PK's instrument is so
accurate that he had to go to extreme lengths to find any real
differences from commercial equipment. For example, the measured signal
magnitude tracks a 'standard' step attenuator to better than 0.1dB over
a 90dB range... but which is in error, the VNA or the attenuator? At
those levels of performance, it's almost impossible to tell.

Bottom line: you'll hardly ever need to worry about accuracy as such,
only about using the instrument correctly.

The only minor drawbacks are a small amount of thermal drift (because
this is a DC-coupled system) and the possibilities of responding to DDS
harmonics and spurs; all of these are very thoroughly documented.

If it works as advertised then
it's a significant breakthrough for those of us who feel reluctant to
part with 20,000 quid for a piece of relatively infrequently-needed
test equipment! Please report back here when you've had the chance to
check it out properly and let us know how it performs...

Having had one running for about six months, I can confirm it's
excellent. Far from being infrequently-needed, it has become one of
those instruments I couldn't possibly manage without!

Read the documentation and you'll see exactly why.


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)

http://www.ifwtech.co.uk/g3sek

On Thu, 12 Feb 2004 19:52:26 +0000, "Ian White, G3SEK"
wrote:

Having had one running for about six months, I can confirm it's
excellent. Far from being infrequently-needed, it has become one of
those instruments I couldn't possibly manage without!

Read the documentation and you'll see exactly why.

I shall. And thanks for the info!
I didn't realise you'd bought the kit. Did you have to have it shipped
over from the States? I assume there's no outlet for them here, as yet
at any rate. What's the UK price inc.shipping? (Just in case I can't
find those details on the site).

--

The BBC: Licensed at public expense to spread lies.