Hi all,

I need a couple of accessories to enable me to make some phase
measurements with my HP network analyzer. I'd thought I could pick
these up on ebay easily enough, but note the lack of availably with
surprise and dismay.
I need to therefore contrive two precision parts:

Firstly, 50 ohm load that's essentially non-reactive up to 1.3Ghz.
Power handling only need be a few tens of miliwatts. N-type
connection.

Secondly, a 50 ohm power splitter (one feed-in; three outputs) N-type
connections, again flat up to 1.3Ghz. No switching needed, thankfully.

If I can't source these parts elsewhere, how feasible is it to make
them up and can anyone point me to any designs on the web that might
fit the bill?

I'm aware that the introduction of any stray reactances into the
devices will render all subsequent measurements invalid so I need to
get these parts right. At least 1.3Ghz capability should be achievable
for a hobbyist with care.

Thanks,
P.
--

"What is now proved was once only imagin'd" - William Blake

http://www.vistarf.com/pdf/vlc-040105.pdf

www.minicircuits.com can supply some of your needs as well.

In article ,
says...
Hi all,

I need a couple of accessories to enable me to make some phase
measurements with my HP network analyzer. I'd thought I could pick
these up on ebay easily enough, but note the lack of availably with
surprise and dismay.
I need to therefore contrive two precision parts:

Firstly, 50 ohm load that's essentially non-reactive up to 1.3Ghz.
Power handling only need be a few tens of miliwatts. N-type
connection.

Secondly, a 50 ohm power splitter (one feed-in; three outputs) N-type
connections, again flat up to 1.3Ghz. No switching needed, thankfully.

If I can't source these parts elsewhere, how feasible is it to make
them up and can anyone point me to any designs on the web that might
fit the bill?

I'm aware that the introduction of any stray reactances into the
devices will render all subsequent measurements invalid so I need to
get these parts right. At least 1.3Ghz capability should be achievable
for a hobbyist with care.

Thanks,
P.


Hi Paul,

Take a look at Mini-circuits (www.mini-circuits.com). They seem to stock
what you are after.

http://www.minicircuits.com/

Have a range of splitters and loads.

Paul Burridge wrote:
Hi all,

I need a couple of accessories to enable me to make some phase
measurements with my HP network analyzer. I'd thought I could pick
these up on ebay easily enough, but note the lack of availably with
surprise and dismay.
I need to therefore contrive two precision parts:

Firstly, 50 ohm load that's essentially non-reactive up to 1.3Ghz.
Power handling only need be a few tens of miliwatts. N-type
connection.

Secondly, a 50 ohm power splitter (one feed-in; three outputs) N-type
connections, again flat up to 1.3Ghz. No switching needed, thankfully.

If I can't source these parts elsewhere, how feasible is it to make
them up and can anyone point me to any designs on the web that might
fit the bill?

I'm aware that the introduction of any stray reactances into the
devices will render all subsequent measurements invalid so I need to
get these parts right. At least 1.3Ghz capability should be achievable
for a hobbyist with care.

Thanks,
P.

--

Kind Regards

David Huisman
General Manager
-----------------------------------------------------------------------
ORBIT COMMUNICATIONS Pty Ltd - Wireless Solutions that Work
(Telemetry, Control, Monitoring, Security, HVAC ...)
A.C.N. 107 441 869


Website : http://www.orbitcoms.com
PO Box 4474 Lakehaven
NSW 2263, AUSTRALIA
Phone: 61-2-4393-3627
Fax : 61-2-4393-3685
Mobile: 61-413-715-986

Paul Burridge wrote:

Hi all,

I need a couple of accessories to enable me to make some phase
measurements with my HP network analyzer. I'd thought I could pick
these up on ebay easily enough, but note the lack of availably with
surprise and dismay.
I need to therefore contrive two precision parts:

Firstly, 50 ohm load that's essentially non-reactive up to 1.3Ghz.
Power handling only need be a few tens of miliwatts. N-type
connection.

Secondly, a 50 ohm power splitter (one feed-in; three outputs) N-type
connections, again flat up to 1.3Ghz. No switching needed, thankfully.

If I can't source these parts elsewhere, how feasible is it to make
them up and can anyone point me to any designs on the web that might
fit the bill?

I'm aware that the introduction of any stray reactances into the
devices will render all subsequent measurements invalid so I need to
get these parts right. At least 1.3Ghz capability should be achievable
for a hobbyist with care.

Thanks,
P.

You can make a pretty good 50 Ohm termination with a PCB-mounting SMA
connector. Cut off the centre pin of the PCB-end of the connector leaving
0.5mm or less protruding (careful of your eyes, the pin can go shooting off
pretty fast, it's hard metal), and then solder two 0.1% 100 Ohm 0603
resistors between the centre pin and the outer (ground) part of the
connector. The resistors should be diametrically opposite.

I made one with 1% resistors and got the following:
s11 -30dB up to 6GHx and
s11 -47dB up to 500MHz

It helps to tweak how flat you lie the resistors on the teflon at the back
of the connector, but without a working VNA you just have to accept what
you get.

If you want a termination with a N connector, then you could use a really
good adapter with the SMA termination I mentioned above, or work out
something similar with a N connector however I have never tried that since
I mostly use SMA anyway.

I think a very accurate / flat power divider would be fairly hard to make
well unless you can get boards made with microwave substrates. If you can
work out your measurement setup such that the flatness etc of the divider
is not so important, then that would help.

There's a guy in the UK selling a one input two output type power divider
with N connectors and a 50 Ohm N termination on e-bay at the moment if that
helps you.

Chris

Chris Jones wrote in
:

Paul Burridge wrote:

Hi all,

I need a couple of accessories to enable me to make some phase
measurements with my HP network analyzer. I'd thought I could pick
these up on ebay easily enough, but note the lack of availably with
surprise and dismay.
I need to therefore contrive two precision parts:

Firstly, 50 ohm load that's essentially non-reactive up to 1.3Ghz.
Power handling only need be a few tens of miliwatts. N-type
connection.

Secondly, a 50 ohm power splitter (one feed-in; three outputs) N-type
connections, again flat up to 1.3Ghz. No switching needed,
thankfully.

If I can't source these parts elsewhere, how feasible is it to make
them up and can anyone point me to any designs on the web that might
fit the bill?

I'm aware that the introduction of any stray reactances into the
devices will render all subsequent measurements invalid so I need to
get these parts right. At least 1.3Ghz capability should be
achievable for a hobbyist with care.

Thanks,
P.

You can make a pretty good 50 Ohm termination with a PCB-mounting SMA
connector. Cut off the centre pin of the PCB-end of the connector
leaving 0.5mm or less protruding (careful of your eyes, the pin can go
shooting off pretty fast, it's hard metal), and then solder two 0.1%
100 Ohm 0603 resistors between the centre pin and the outer (ground)
part of the connector. The resistors should be diametrically
opposite.

I made one with 1% resistors and got the following:
s11 -30dB up to 6GHx and
s11 -47dB up to 500MHz

It helps to tweak how flat you lie the resistors on the teflon at the
back of the connector, but without a working VNA you just have to
accept what you get.

If you want a termination with a N connector, then you could use a
really good adapter with the SMA termination I mentioned above, or
work out something similar with a N connector however I have never
tried that since I mostly use SMA anyway.

I think a very accurate / flat power divider would be fairly hard to
make well unless you can get boards made with microwave substrates.
If you can work out your measurement setup such that the flatness etc
of the divider is not so important, then that would help.

There's a guy in the UK selling a one input two output type power
divider with N connectors and a 50 Ohm N termination on e-bay at the
moment if that helps you.

Chris

A two-output splitter,IIRC,uses 3 25 ohm resistors in a Y config.
Use a double-sided PCB for the ground plane between the three N connectors.

--
Jim Yanik
jyanik
at
kua.net

Chris Jones wrote:
Paul Burridge wrote:

Hi all,

I need a couple of accessories to enable me to make some phase
measurements with my HP network analyzer. I'd thought I could pick
these up on ebay easily enough, but note the lack of availably with
surprise and dismay.
I need to therefore contrive two precision parts:

Firstly, 50 ohm load that's essentially non-reactive up to 1.3Ghz.
Power handling only need be a few tens of miliwatts. N-type
connection.

Secondly, a 50 ohm power splitter (one feed-in; three outputs) N-type
connections, again flat up to 1.3Ghz. No switching needed, thankfully.

If I can't source these parts elsewhere, how feasible is it to make
them up and can anyone point me to any designs on the web that might
fit the bill?

I'm aware that the introduction of any stray reactances into the
devices will render all subsequent measurements invalid so I need to
get these parts right. At least 1.3Ghz capability should be achievable
for a hobbyist with care.

Thanks,
P.

You can make a pretty good 50 Ohm termination with a PCB-mounting SMA
connector. Cut off the centre pin of the PCB-end of the connector leaving
0.5mm or less protruding (careful of your eyes, the pin can go shooting off
pretty fast, it's hard metal), and then solder two 0.1% 100 Ohm 0603
resistors between the centre pin and the outer (ground) part of the
connector. The resistors should be diametrically opposite.

I made one with 1% resistors and got the following:
s11 -30dB up to 6GHx and
s11 -47dB up to 500MHz

It helps to tweak how flat you lie the resistors on the teflon at the back
of the connector, but without a working VNA you just have to accept what
you get.

If you want a termination with a N connector, then you could use a really
good adapter with the SMA termination I mentioned above, or work out
something similar with a N connector however I have never tried that since
I mostly use SMA anyway.

I think a very accurate / flat power divider would be fairly hard to make
well unless you can get boards made with microwave substrates. If you can
work out your measurement setup such that the flatness etc of the divider
is not so important, then that would help.

Two SMD 100R resistors in parallel is good; six 300R resistors spread
symmetrically around the centre pin would be better (if you can fit
them in).

You can buy 50R terminating resistors on a circular alumina substrate
with a hole in the middle, where the conducting pat runs from the
(metalised) rim of the inner hole to the (metalised) circumference.
Finding them isn't easy, but they do offer the theoretical minimum of
inductance.

You should be able make a pretty accurate and flat power divider in a
metal box between two bulk-head-mounted coax sockets by stringing
together 0603 or 0805 0.1% SMD resistors with bits of 22swg wire in a
neat and symmetrical birds nest. A fiddly job, and you'd probably want
to use continuous solder seams to seal the box when you were finished
to avoid creating a slot antena or two.

The 0.1% SMD resistors are available off the shelf from Farnell - IIRR
you have buy them in multiples of five, but they aren't that expensive
and if want to built a low-inductance symmetrical structure you need to
put three or four resistors in parallel (six would be nicer, but you'd
need to be a Jim Williams level artist with the soldering iron to keep
it neat).

--
Bill Sloman, Nijmegen

On Fri, 06 Jan 2006 22:58:52 +0100, Paul Burridge
k wrote:

Hi all,

I need a couple of accessories to enable me to make some phase
measurements with my HP network analyzer. I'd thought I could pick
these up on ebay easily enough, but note the lack of availably with
surprise and dismay.
I need to therefore contrive two precision parts:

Firstly, 50 ohm load that's essentially non-reactive up to 1.3Ghz.
Power handling only need be a few tens of miliwatts. N-type
connection.

http://cgi.ebay.com/HP-909A-50-Ohm-C...QQcmdZViewItem

Secondly, a 50 ohm power splitter (one feed-in; three outputs) N-type
connections, again flat up to 1.3Ghz. No switching needed, thankfully.

I must ask, what is the purpose of this?

On Fri, 06 Jan 2006 19:40:27 -0700, Wes Stewart
wrote:


http://cgi.ebay.com/HP-909A-50-Ohm-C...QQcmdZViewItem

Thanks, Wes. I'll keep an eye on it.

Secondly, a 50 ohm power splitter (one feed-in; three outputs) N-type
connections, again flat up to 1.3Ghz. No switching needed, thankfully.

I must ask, what is the purpose of this?

The (thumping great) service manual that came with this VNA gives
various levels of tests that can be performed oneself prior sending
the thing away for calibration. The power splitter together with a few
other basic items enables the analyzer to 'check itself' for
fundamental operating fitness.
I'm eager to get measurin' stuff, but need to establish some basic,
satisfactory level of accuracy first. Being just a hobbyist, I don't
require any absolute standard, thankfully!!

--

"What is now proved was once only imagin'd" - William Blake