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

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

You can do this with an MFJ or any other analyzer to resolve the sign ambiguity
of X. Switch in small known reactance, see which way X goes. Also, hooking a
computer interface to an MFJ would probably not be that much more difficult
than interfacing with the AD chip. So, no I don't think this would run rings
around an MFJ. However, if you do go this route, I would be very interested in
how it turns out.
73 Gary N4AST

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

You can do this with an MFJ or any other analyzer to resolve the sign ambiguity
of X. Switch in small known reactance, see which way X goes. Also, hooking a
computer interface to an MFJ would probably not be that much more difficult
than interfacing with the AD chip. So, no I don't think this would run rings
around an MFJ. However, if you do go this route, I would be very interested in
how it turns out.
73 Gary N4AST

In article ,
says...
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.


Who knows what he meant by that, but the idea of using a "line
stretching" hack to resolve the phase ambiguity sounds like a great one
to me. I'd definitely be up for building a VNA that has decent
frequency coverage and that's PC-driven. I'll take a gander at the
AD8302's specs first chance I get and see how it looks!

-- jm

------------------------------------------------------
http://www.qsl.net/ke5fx
Note: My E-mail address has been altered to avoid spam
------------------------------------------------------

In article ,
says...
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.


Who knows what he meant by that, but the idea of using a "line
stretching" hack to resolve the phase ambiguity sounds like a great one
to me. I'd definitely be up for building a VNA that has decent
frequency coverage and that's PC-driven. I'll take a gander at the
AD8302's specs first chance I get and see how it looks!

-- jm

------------------------------------------------------
http://www.qsl.net/ke5fx
Note: My E-mail address has been altered to avoid spam
------------------------------------------------------

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

I'm just brushing you off. I wrote to let you know of another avenue to do
the job you wish to do where someone else has invested a tremendous amount
of professional work in both the hardware and software. It will be available
on the Internet in a week or so. (Several of us have enjoyed the end product
as a Beta test group for something over a year.) I don't have any time or
interest in participating in a sincere dialog.

Regards

W4ZCB

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

I'm just brushing you off. I wrote to let you know of another avenue to do
the job you wish to do where someone else has invested a tremendous amount
of professional work in both the hardware and software. It will be available
on the Internet in a week or so. (Several of us have enjoyed the end product
as a Beta test group for something over a year.) I don't have any time or
interest in participating in a sincere dialog.

Regards

W4ZCB

Well, I guess that settles that.
The definitive work has been done and there's no room for improvement or any
sense in discussing it further.

Thanks for your help

Joe

"Harold E. Johnson" wrote in message
news:Ierab.505021$YN5.337471@sccrnsc01...


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

I'm just brushing you off. I wrote to let you know of another avenue to do
the job you wish to do where someone else has invested a tremendous amount
of professional work in both the hardware and software. It will be
available
on the Internet in a week or so. (Several of us have enjoyed the end
product
as a Beta test group for something over a year.) I don't have any time or
interest in participating in a sincere dialog.

Regards

W4ZCB

Well, I guess that settles that.
The definitive work has been done and there's no room for improvement or any
sense in discussing it further.

Thanks for your help

Joe

"Harold E. Johnson" wrote in message
news:Ierab.505021$YN5.337471@sccrnsc01...


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

I'm just brushing you off. I wrote to let you know of another avenue to do
the job you wish to do where someone else has invested a tremendous amount
of professional work in both the hardware and software. It will be
available
on the Internet in a week or so. (Several of us have enjoyed the end
product
as a Beta test group for something over a year.) I don't have any time or
interest in participating in a sincere dialog.

Regards

W4ZCB

I'm just brushing you off. I wrote to let you know of another avenue to do
the job you wish to do where someone else has invested a tremendous amount
of professional work in both the hardware and software. It will be available
on the Internet in a week or so. (Several of us have enjoyed the end product
as a Beta test group for something over a year.) I don't have any time or
interest in participating in a sincere dialog.

Regards

W4ZCB

Hi Harold,
I well recall Paul's wattmeter- well ( or even way) beyond what others had done-
the engineering and documentation was superb. Looking forward to his work on the
VNR.
I am not far from you- near Cashiers on Lake Glenville.

Dale W4OP