The chip you're looking at does have a 180 degree ambiguity unresolved.
Makes it tough to do the job you're asking of it. Wait a couple weeks and
look on Google for N2PK. You'll find a real vector network analyzer good
from 50 KHz to 60 MHz with narrow band application to 2 meters and 432 MHz.

W4ZCB

Harold,

The chip's phase measurement transer function has a positive slope for phase
angles less than 0deg and a negative slope for phase angles greater than
0deg. So it seems to me that resolving the 180 deg ambiguity is just a
matter of knowing which slope you're on. This might be done by switching in
a small known reactive component and observing which direction the phase
output changes. Once you know which slope you're on, I think you're home
free...no??

Joe
W3JDR
"Harold E. Johnson" wrote in message
news:Yhiab.496033$Ho3.84151@sccrnsc03...
The chip you're looking at does have a 180 degree ambiguity unresolved.
Makes it tough to do the job you're asking of it. Wait a couple weeks and
look on Google for N2PK. You'll find a real vector network analyzer good
from 50 KHz to 60 MHz with narrow band application to 2 meters and 432
MHz.

W4ZCB

Harold,

The chip's phase measurement transer function has a positive slope for phase
angles less than 0deg and a negative slope for phase angles greater than
0deg. So it seems to me that resolving the 180 deg ambiguity is just a
matter of knowing which slope you're on. This might be done by switching in
a small known reactive component and observing which direction the phase
output changes. Once you know which slope you're on, I think you're home
free...no??

Joe
W3JDR
"Harold E. Johnson" wrote in message
news:Yhiab.496033$Ho3.84151@sccrnsc03...
The chip you're looking at does have a 180 degree ambiguity unresolved.
Makes it tough to do the job you're asking of it. Wait a couple weeks and
look on Google for N2PK. You'll find a real vector network analyzer good
from 50 KHz to 60 MHz with narrow band application to 2 meters and 432
MHz.

W4ZCB

The chip's phase measurement transer function has a positive slope for
phase
angles less than 0deg and a negative slope for phase angles greater than
0deg. So it seems to me that resolving the 180 deg ambiguity is just a
matter of knowing which slope you're on. This might be done by switching
in
a small known reactive component and observing which direction the phase
output changes. Once you know which slope you're on, I think you're home
free...no??

Do it the way you want to.

W4ZCB

The chip's phase measurement transer function has a positive slope for
phase
angles less than 0deg and a negative slope for phase angles greater than
0deg. So it seems to me that resolving the 180 deg ambiguity is just a
matter of knowing which slope you're on. This might be done by switching
in
a small known reactive component and observing which direction the phase
output changes. Once you know which slope you're on, I think you're home
free...no??

Do it the way you want to.

W4ZCB

Do it the way you want to.

Harold,
I'm puzzled by your reply. Does it mean that you agree, or that you
disagree, or that you're just brushing me off? If it's the latter, I can
accept that too...I'm just looking for a sincere dialog about an idea.

Joe
W3JDR

Do it the way you want to.

Harold,
I'm puzzled by your reply. Does it mean that you agree, or that you
disagree, or that you're just brushing me off? If it's the latter, I can
accept that too...I'm just looking for a sincere dialog about an idea.

Joe
W3JDR

All the analyzers I have considered have always been to inaccurate. They
sure may work on the DC bands below 30MHz where people think an
antenna is good if the SWR is below 3.

This IC seem promising. Together with a small MCU and AD and some flash
memory you might be able to build a really good instrument that could
beat everything on the market.

Does anyone know a source for these chipts whithin the EU? I have some
directional couplers without detectors that could easily be combined
with this chip.

Your Idea to use a PC to control the radio as a source seem interesting.
The only drawback would be the size of all the stuff you need to bring
into the garden when measuring.

Perhaps a modular design.
a) Optional RF-circuit (directional couplers) different for different
bands to increase accuracy.
b) Detector device (AD-chip, small controller with calibration data)
c) Optional display for computerless operation
d) Optional signal source for rig-less operation.

/Leif

All the analyzers I have considered have always been to inaccurate. They
sure may work on the DC bands below 30MHz where people think an
antenna is good if the SWR is below 3.

This IC seem promising. Together with a small MCU and AD and some flash
memory you might be able to build a really good instrument that could
beat everything on the market.

Does anyone know a source for these chipts whithin the EU? I have some
directional couplers without detectors that could easily be combined
with this chip.

Your Idea to use a PC to control the radio as a source seem interesting.
The only drawback would be the size of all the stuff you need to bring
into the garden when measuring.

Perhaps a modular design.
a) Optional RF-circuit (directional couplers) different for different
bands to increase accuracy.
b) Detector device (AD-chip, small controller with calibration data)
c) Optional display for computerless operation
d) Optional signal source for rig-less operation.

/Leif

Leif,

Does anyone know a source for these chipts whithin the EU?
I believe you can purchase them from the Analog Devices Web site. Don't know
if that works outside the US though.

I have some directional couplers without detectors that could easily be
combined with this chip.
Do you really need a directional coupler? How about just driving the load
through a known resistor
and measuring the voltage & phase shift across the unknown?

Your idea to use a PC to control the radio as a source seem interesting.
The only drawback would be the size
of all the stuff you need to bring into the garden when measuring.


I suggested the station rig as a source because it already has a
programmable frequency generator for any frequency the ham is likely
to need to measure...why reinvent it? On the other hand, it's easy these
days to build a DDS frequency source that works into the VHF range.
Used laptop PC's are plentiful and cheap, and have great computational and
display facilities. I was thinking of a small module that works
with the station PC or a laptop.

Joe
W3JDR