Please help need some co-ax instructions...

Mike wrote:

Please help need some co-ax instructions...


Specificity is clearly not your long suite...

Try again,

Jeff

--
Jeff Wisnia (W1BSV + Brass Rat '57 EE)

"My luck is so bad that if I bought a cemetery, people would stop dying."

Mike wrote:

Please help need some co-ax instructions...

You've got to describe the problem a little more.
Maybe this'll get you started:
Keep the middle in the middle and the outside on the outside.

If the lack of a comma is intentional, I can't help.
I have no idea how to help you need co-ax instructions.

Hmm.. I guess I'm in a picky mood.
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Mike wrote:
Please help need some co-ax instructions...



Guessing that you have one of these knock-offs of the Blake Co-Ax indicator,
and need to know how to use it.

You need a rod that screws into the side of the body to keep it from
rotating.

As your run the spindle at dead slow speeds (ie less than 60 RPM)
a feeler wipes around the ID of the bore you are trying to center over.
If the bore is not very smooth and round, you will find it very difficult
to make the indicator work.

Assuming a round bore, the dial will wobble back and forth. By watching
the dial and the feeler at the same time (making the spindle run even
slower, maybe 25 RPM helps) figure out where the "high spot" is, and
move the table to pull that high spot away from the spindle. When you
get that axis right, the dial will read the same when the feeler is
touching points in line with that axis. Now, adjust the other axis
in the same way. When you get close, the pointer will only wobble a
few thousandths each way. Make very small movements in each axis to
minimize the pointer movement. At some point, you may not be able to
reduce pointer movement below some small amount. This is due to
a bore that is out of round, or possibly a bore that is not parallel
to the spindle rotation. But, the spindle should be as close to
coaxial to the bore as you are going to get.

Jon

I though maybe he had a piece of 50 ohm transmission line.

Bob Swinney
"Jon Elson" wrote in message
...


Mike wrote:
Please help need some co-ax instructions...



Guessing that you have one of these knock-offs of the Blake Co-Ax
indicator,
and need to know how to use it.

You need a rod that screws into the side of the body to keep it from
rotating.

As your run the spindle at dead slow speeds (ie less than 60 RPM)
a feeler wipes around the ID of the bore you are trying to center over.
If the bore is not very smooth and round, you will find it very difficult
to make the indicator work.

Assuming a round bore, the dial will wobble back and forth. By watching
the dial and the feeler at the same time (making the spindle run even
slower, maybe 25 RPM helps) figure out where the "high spot" is, and
move the table to pull that high spot away from the spindle. When you
get that axis right, the dial will read the same when the feeler is
touching points in line with that axis. Now, adjust the other axis
in the same way. When you get close, the pointer will only wobble a
few thousandths each way. Make very small movements in each axis to
minimize the pointer movement. At some point, you may not be able to
reduce pointer movement below some small amount. This is due to
a bore that is out of round, or possibly a bore that is not parallel
to the spindle rotation. But, the spindle should be as close to
coaxial to the bore as you are going to get.

Jon

In article , Bob Swinney says...

I though maybe he had a piece of 50 ohm transmission line.

They do make those in other resistances besides 50....

g

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

Impedance; not resistance. Just to be impudent.

--
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Dewey Clark http://www.historictimekeepers.com
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http://cgi6.ebay.com/aw-cgi/eBayISAP...ems&userid=dsc
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Makers of Historic Timekeepers Ultrasonic Clock Cleaning Solution

"

In article , ??? says...

Impedance; not resistance. Just to be impudent.

Well it says 50 "ohms." What's that but a resistance?
My problem is we just bought a big roll of cable, and
the darn stuff is all defective.

The simpson meter says it's a *lot* bigger than
50 ohms!!

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

On 18 Mar 2004 12:35:09 -0800, the renowned jim rozen
wrote:

In article , ??? says...

Impedance; not resistance. Just to be impudent.

Well it says 50 "ohms." What's that but a resistance?
My problem is we just bought a big roll of cable, and
the darn stuff is all defective.

The simpson meter says it's a *lot* bigger than
50 ohms!!

Jim

You got it set on the AC-ohms range?

Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

use lightning suppressors as directed

Mike wrote:

Please help need some co-ax instructions...

In article , Spehro Pefhany says...

The simpson meter says it's a *lot* bigger than
50 ohms!!

You got it set on the AC-ohms range?

It's sure set on *something*!

:^)

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

Naw! I was thinking 50 ohms; like you get when you measure with an
ohmmeter from center to shield

Bob Swinneyh
"jim rozen" wrote in message
...
In article , Bob Swinney says...

I though maybe he had a piece of 50 ohm transmission line.

They do make those in other resistances besides 50....

g

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

Impedance? Is it not expressed in ohms, as well?
"???" wrote in message
...
Impedance; not resistance. Just to be impudent.

--
Regards,
Dewey Clark http://www.historictimekeepers.com
Ebay Sales:
http://cgi6.ebay.com/aw-cgi/eBayISAP...ems&userid=dsc
Restorations, Parts for Hamilton M21s, Products for Craftsmen
Makers of Historic Timekeepers Ultrasonic Clock Cleaning Solution

"

Errr, welll, OK Jim, I'll help you troll - how much bigger than 50?

Bob Swinney
"jim rozen" wrote in message
...
In article , ??? says...

Impedance; not resistance. Just to be impudent.

Well it says 50 "ohms." What's that but a resistance?
My problem is we just bought a big roll of cable, and
the darn stuff is all defective.

The simpson meter says it's a *lot* bigger than
50 ohms!!

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

Naw, Spehro - he read if off'n his megger. Sure was hard to crank too.

Bob Swinney
"Spehro Pefhany" wrote in message
...
On 18 Mar 2004 12:35:09 -0800, the renowned jim rozen
wrote:

In article , ??? says...

Impedance; not resistance. Just to be impudent.

Well it says 50 "ohms." What's that but a resistance?
My problem is we just bought a big roll of cable, and
the darn stuff is all defective.

The simpson meter says it's a *lot* bigger than
50 ohms!!

Jim

You got it set on the AC-ohms range?

Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers:
http://www.trexon.com
Embedded software/hardware/analog Info for designers:
http://www.speff.com

On Thu, 18 Mar 2004 18:19:27 -0600, "Bob Swinney"
wrote:

Naw! I was thinking 50 ohms; like you get when you measure with an
ohmmeter from center to shield


It the center conductor and the shield were made out of material that had
no resistance and if the dielectric in between the two was lossless and if
such coax was infinitely long than a DC ohmmeter would read 50 ohms if the
cable geometry was designed for it to be 50 ohms.

--

Boris Mohar

Bob Swinney wrote:

I though maybe he had a piece of 50 ohm transmission line.

Bob Swinney

My thought was " RG 8 or RG 11" :-)
...lew...

Mike wrote:

Please help need some co-ax instructions...

Work out a rhythm with the other ax person so you chop alternately.

Scary thought. gang chopping. everyone downrange of the others' heads. shudder
--


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"Clutter"? This is an object-rich environment.

Spehro Pefhany wrote:

On 18 Mar 2004 12:35:09 -0800, the renowned jim rozen
wrote:


In article , ??? says...

Impedance; not resistance. Just to be impudent.

Well it says 50 "ohms." What's that but a resistance?
My problem is we just bought a big roll of cable, and
the darn stuff is all defective.

The simpson meter says it's a *lot* bigger than
50 ohms!!

Jim


You got it set on the AC-ohms range?

Best regards,
Spehro Pefhany
Can't read the 'i' or 'j' on the number ? - that reactive imaginary stuff.

'i' for math, 'j' for physics - because 'i' was used.

Martin

--
Martin Eastburn, Barbara Eastburn
@ home at Lion's Lair with our computer
NRA LOH, NRA Life
NRA Second Amendment Task Force Charter Founder

On Thu, 18 Mar 2004 12:13:05 -0600, Jon Elson
wrote:



Mike wrote:
Please help need some co-ax instructions...



Guessing that you have one of these knock-offs of the Blake Co-Ax indicator,
and need to know how to use it.

You need a rod that screws into the side of the body to keep it from
rotating.

As your run the spindle at dead slow speeds (ie less than 60 RPM)
a feeler wipes around the ID of the bore you are trying to center over.
If the bore is not very smooth and round, you will find it very difficult
to make the indicator work.

Assuming a round bore, the dial will wobble back and forth. By watching
the dial and the feeler at the same time (making the spindle run even
slower, maybe 25 RPM helps) figure out where the "high spot" is, and
move the table to pull that high spot away from the spindle. When you
get that axis right, the dial will read the same when the feeler is
touching points in line with that axis. Now, adjust the other axis
in the same way. When you get close, the pointer will only wobble a
few thousandths each way. Make very small movements in each axis to
minimize the pointer movement. At some point, you may not be able to
reduce pointer movement below some small amount. This is due to
a bore that is out of round, or possibly a bore that is not parallel
to the spindle rotation. But, the spindle should be as close to
coaxial to the bore as you are going to get.

Jon
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

Hey Mike,


On the very basic side of things, you chuck the shiny part of the
shaft (1/2" ??) in a collet or drill chuck, and put on the anti-rotate
bar and something on the mill for it to rest against so the "body" of
Co-ax Indicator is in a position where you can see it easy. A
magnetic indicator-holder and rod, stuck on the side of the mill
head, or even on the work-piece or table, will do fine. Anything that
stops the Co-ax indicator from being able to turn when the spindle
turns. Then extend the quill down to just above what you want to
locate on, and rough center locate on the work-piece with the X & Y
hand-wheels.

Now just the same as on any DTI, you put on a useful contact tip to
reach the hole sides (or the boss) and "bend it" so that as you lower
the quill some more it will enter the hole (or touch the boss) and
will deflect the Co-ax needle all the way around the hole (or boss) as
you turn the spindle. If you didn't get the "rough centering by eye"
part close enough, the Co-ax indicator will peg out, but it won't hurt
it. Of course, it won't do it's job until you get centered to the
point where it can make a full rotation with-out "pegging".

I don't use "power" to do the centering. Maybe because my J-head is a
step-pulley, and I'd have to fiddle around to get it in back-gear for
the slow RPM's, I've never spun mine under power. I just rotate the
spindle by hand to the four quad points and adjust the co-responding
axis at each. I try to get the centering as best as I can first with
these four point stops and gently moving the X or Y to see half the
deflection on the dial. When I think I have the four points set, I
try full and constant rotations and watch for "wobble". You are
looking for "zero" movement of the needle of course. Works for me.


Hey, .... Good Luck, and have fun. Neat to watch.

Take care.

Brian Lawson,
Bothwell, Ontario.

In article , Lewis Hartswick says...

My thought was " RG 8 or RG 11" :-)

Hmm. Probably "RG-50!"



Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

jim rozen wrote:
In article , Lewis Hartswick says...


My thought was " RG 8 or RG 11" :-)


Hmm. Probably "RG-50!"



Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

Nope - either CAT 6 or RG-20A since it is 30KV insulation. RG-8A is only 10kV :-)

Martin

--
Martin Eastburn, Barbara Eastburn
@ home at Lion's Lair with our computer
NRA LOH, NRA Life
NRA Second Amendment Task Force Charter Founder

On Thu, 18 Mar 2004 15:23:46 -0500, "???" wrote:
Impedance; not resistance. Just to be impudent.

Well, if it is properly terminated, or infinitely long, it'll be 50+j0,
in other words purely resistive 50 ohms.

If it is open or shorted, it'll be 0+jX or 0-jX with X being a function
of frequency and electrical length. In other words, purely reactive.

If it is mismatch terminated, it'll be R+jX or R-jX, with R and X
functions of frequency, mismatch magnitude and direction, and
electrical length. The one thing it won't be is 50 ohms. There is
no cable length which can transform a mismatch to the cable's
own characteristic impedance.

This assumes a lossless cable. Cable loss attenuates reflections,
so a long lossy cable can appear to be 50+j0 even when mismatched.

Gary

In article , Gary Coffman says...

This assumes a lossless cable.

Exactly! I was looking for the kind with
the 50 ohm loss.

Jim

==================================================
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JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

On 20 Mar 2004 13:51:53 -0800, jim rozen wrote:
In article , Gary Coffman says...

This assumes a lossless cable.

Exactly! I was looking for the kind with
the 50 ohm loss.

Try 100 feet of RG58 at 450 MHz.

Gary

In article , Gary Coffman says...

Exactly! I was looking for the kind with
the 50 ohm loss.

Try 100 feet of RG58 at 450 MHz.

Damn, that must be some fancy wire.
All my cable is rated in megacycles.
You guys are up on the latest stuff!

Jim

==================================================
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JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

jim rozen wrote:

Damn, that must be some fancy wire.
All my cable is rated in megacycles.
You guys are up on the latest stuff!

In case you're not joking: Your insulation gone brittle yet?

In article , Offbreed says...

In case you're not joking: Your insulation gone brittle yet?

I beg your pardon sir! I may be old, but my insulation
still has plenty of flex in it!



Jim

==================================================
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JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

In article ,
Offbreed wrote:
jim rozen wrote:

Damn, that must be some fancy wire.
All my cable is rated in megacycles.
You guys are up on the latest stuff!

In case you're not joking: Your insulation gone brittle yet?

I used to have (lost in a move) some RG-8 which had a braided
tarred cloth insulation (at least the outer jacket), so it would take a
lot to make it brittle. :-)

Enjoy,
DoN.

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In article ,
jim rozen wrote:
In article , Lewis Hartswick says...

My thought was " RG 8 or RG 11" :-)

Hmm. Probably "RG-50!"

How about "RG-365 A/U"? I saw a crate of 100 feet of it (2-1/2
turns total) out back of where I used to work. At first, I thought that
it was ventilation ducting. (Hmm ... perhaps that was 375 instead of
365? It has been a long time, and I'm too lazy (and too far behind in
the newsgroup) to bother digging up a catalog and checking. :-)

Enjoy,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
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DoN. Nichols wrote:

In article ,
jim rozen wrote:

In article , Lewis Hartswick says...


My thought was " RG 8 or RG 11" :-)

Hmm. Probably "RG-50!"


How about "RG-365 A/U"? I saw a crate of 100 feet of it (2-1/2
turns total) out back of where I used to work. At first, I thought that
it was ventilation ducting. (Hmm ... perhaps that was 375 instead of
365? It has been a long time, and I'm too lazy (and too far behind in
the newsgroup) to bother digging up a catalog and checking. :-)

Enjoy,
DoN.

Yep - some of that high power transmission cable is big! High voltage type.
The cores are typically tubes not solid since the skin current is only skin deep :-)

Martin

--
Martin Eastburn, Barbara Eastburn
@ home at Lion's Lair with our computer
NRA LOH, NRA Life
NRA Second Amendment Task Force Charter Founder