Jerry Martes wrote:
I have a HP8405A Vector Voltmeter I'll give you and even pay the shipping
if that is of any help with the measurements.

Wow, thanks for the offer. That would certainly be more
accurate than eyeballing an o'scope. Do you think the
use of such would prove me right or wrong? Does the
VV compare two signals and report the phase difference?
Are the probes differential or coaxial? I've never used
a VV.
--
73, Cecil http://www.qsl.net/w5dxp

"Cecil Moore" wrote in message
. com...
Jerry Martes wrote:
I have a HP8405A Vector Voltmeter I'll give you and even pay the shipping
if that is of any help with the measurements.

Wow, thanks for the offer. That would certainly be more
accurate than eyeballing an o'scope. Do you think the
use of such would prove me right or wrong? Does the
VV compare two signals and report the phase difference?
Are the probes differential or coaxial? I've never used
a VV.
--
73, Cecil http://www.qsl.net/w5dxp

Hi Cecil

I dont know how to use a VV either. I got a couple of them from Pacific
Missile Range surplus. One has a probe sheared off. I figured I could
build a "pair of probes" to make that one work for myself. You are welcome
to have the other. That one looks complete.
It sure would be worth the effort to ship it to you if you'd like to have
it.
I cant guarentee that the 8405A works but I do know they are repairable.
If you are willing to check it out, its yours.
I downloaded a manual for the unit. E-mail me your address. Maybe you
can tell me something about the unit after you figure it out.

I have such a high respect for Roy and Wes that it is not possible for me
to think they'd both be wrong while in agreement. And, I like to read your
discussions on this group so much that I'd offer anything I can to assist
your 'getting some measurements made'. I am absolutely sure all you guys
will agree on this stuff after you make some measurements. You are all too
bright to have such severe differences in understanding on this subject.

Jerry

Jerry Martes wrote:
It sure would be worth the effort to ship it to you if you'd like to have
it.

I hate to accept it for free. Maybe I could just borrow it
for awhile?

I have such a high respect for Roy and Wes that it is not possible for me
to think they'd both be wrong while in agreement.

So why are you offering a free VV to someone they both hate? :-)
--
73, Cecil http://www.qsl.net/w5dxp

On Fri, 10 Mar 2006 05:10:24 GMT, Cecil Moore wrote:

Jerry Martes wrote:
It sure would be worth the effort to ship it to you if you'd like to have
it.

I hate to accept it for free. Maybe I could just borrow it
for awhile?

I have such a high respect for Roy and Wes that it is not possible for me
to think they'd both be wrong while in agreement.

So why are you offering a free VV to someone they both hate? :-)

I don't hate you. While I shook your hand at Flagstaff once, I don't
know you well enough personally to get all worked about you one way or
another.

This is Usenet, not the real world. No sense taking it too seriously.

Wes Stewart wrote:
Cecil Moore wrote:
So why are you offering a free VV to someone they both hate? :-)

I don't hate you. While I shook your hand at Flagstaff once, I don't
know you well enough personally to get all worked about you one way or
another. This is Usenet, not the real world. No sense taking it too
seriously.

I wasn't serious, Wes. That's why the smiley face.
I apologize if my humor irritates anyone.
--
73, Cecil http://www.qsl.net/w5dxp

"Cecil Moore" wrote in message
om...
Jerry Martes wrote:
It sure would be worth the effort to ship it to you if you'd like to have
it.

I hate to accept it for free. Maybe I could just borrow it
for awhile?

I have such a high respect for Roy and Wes that it is not possible for me
to think they'd both be wrong while in agreement.

So why are you offering a free VV to someone they both hate? :-)
--
73, Cecil http://www.qsl.net/w5dxp

Hi Cecil

There is no reason to ever return any of the stuff I send out. I
actually enjoy knowing that someone appreciates this stuff. I dont pay $$
for it. It gets surplused by the government. My buddy buys it in bulk.
I am able to refurbish alot of the surplus he buys, like 100 KW gen-sets, so
he can re-sell the units back to them. Since I enjoy learning how to fix
the broken stuff, I dont charge for my time. So, he lets me sort thru his
"scrap piles". Everyone wins. But, I dont get to watch much TV because
I keep too busy learning how to fix the stuff.

Send me your shipping address. The HP 8405A will be in the mail within a
day after I get the address.

Do you have any use for a HP 8660 signal generator main frame, *no*
plug-ins? That would sure be a nice generator to go with a Vector
Voltmeter. I have 5 main frames but I havent been able to win an eBay bid
for the plug-ins.

Jerry

On Fri, 10 Mar 2006 04:23:03 GMT, Cecil Moore wrote:

Jerry Martes wrote:
I have a HP8405A Vector Voltmeter I'll give you and even pay the shipping
if that is of any help with the measurements.

Wow, thanks for the offer. That would certainly be more
accurate than eyeballing an o'scope. Do you think the
use of such would prove me right or wrong? Does the
VV compare two signals and report the phase difference?
Are the probes differential or coaxial? I've never used

The VVM probes are comprised of a quad diode sampling bridge followed
by an FET amplifier. They are nominally coaxial, although without the
BNC adapters, they have an exposed pin (very delicate) and at lower
frequencies they can be used much as a high impedance scope probe is
used.

The instrument uses a phase-locked oscillator to drive the samplers
with the "A" probe being the reference. One meter can be switched to
display the amplitude of either channel and the second meter reads the
phase difference between them.

Wes Stewart wrote:
The VVM probes are comprised of a quad diode sampling bridge followed
by an FET amplifier. They are nominally coaxial, although without the
BNC adapters, they have an exposed pin (very delicate) and at lower
frequencies they can be used much as a high impedance scope probe is
used.

Thanks, Wes. When you say "lower frequencies", does that include
4 MHz?

The instrument uses a phase-locked oscillator to drive the samplers
with the "A" probe being the reference. One meter can be switched to
display the amplitude of either channel and the second meter reads the
phase difference between them.

I was planning to use toroidal pickups and a Lissajous figure
for the phase measurement. Did you know "Lissajous figure"
is described in my 1957 ARRL Handbook but not in my 2000
ARRL Handbook?

My main concern is how to ensure there are no reflections
present during the measurement. I need to put the 75m
bugcatcher coil in an RF loop where current is flowing
in only one direction. That's easy to draw on paper but
I'm concerned about it. How would you set it up?
--
73, Cecil http://www.qsl.net/w5dxp

On Fri, 10 Mar 2006 11:51:51 GMT, Cecil Moore wrote:

Wes Stewart wrote:
The VVM probes are comprised of a quad diode sampling bridge followed
by an FET amplifier. They are nominally coaxial, although without the
BNC adapters, they have an exposed pin (very delicate) and at lower
frequencies they can be used much as a high impedance scope probe is
used.

Thanks, Wes. When you say "lower frequencies", does that include
4 MHz?

When I wrote last, I was nursing a big toe that had just suffered the
trauma of having a 4' x 8' sheet of 3/4" plywood dropped on it edge
on. So I didn't want to hobble into the shack to search for the
manual.

Now I have it before me. The nominal impedance of the probes is 100
Kohm shunted by 2.5 pF. If this doesn't upset your measurement then
you're good to go.

I think that when I was remembering probing circuits with the bare
probes I was thinking of the HP Vector Impedance Meter more than the
VVM. It was a lower frequency instrument designed for that purpose.


The instrument uses a phase-locked oscillator to drive the samplers
with the "A" probe being the reference. One meter can be switched to
display the amplitude of either channel and the second meter reads the
phase difference between them.

I was planning to use toroidal pickups and a Lissajous figure
for the phase measurement. Did you know "Lissajous figure"
is described in my 1957 ARRL Handbook but not in my 2000
ARRL Handbook?

Well, they gotta leave something out so they can included the latest
PIC controlled-automatic-rig-to-computer-interface and coffeemaker
doodad.


My main concern is how to ensure there are no reflections
present during the measurement. I need to put the 75m
bugcatcher coil in an RF loop where current is flowing
in only one direction. That's easy to draw on paper but
I'm concerned about it. How would you set it up?

Can't help you.

Wes Stewart wrote:

Cecil wrote:
My main concern is how to ensure there are no reflections
present during the measurement. I need to put the 75m
bugcatcher coil in an RF loop where current is flowing
in only one direction. That's easy to draw on paper but
I'm concerned about it. How would you set it up?

Can't help you.

What Cecil needs to do is bias the coil with a DC bias current that
safely exceeds the peak RF current.

Then he would have RF current flowing in only one direction.

73 Tom