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That Notorious Field-Strength Meter: the pictures at long last

L

Leon Heller

Jan 1, 1970
0
Paul said:
Yes, that's well and truly sunk in, now. Just wondering, though, if
there's any type of project where it's *not* a good idea to make up
boards in this way?

High-speed digital designs using multi-layer PCBs where well-defined
impedances are required.

Leon
 
J

James Meyer

Jan 1, 1970
0
Yes, that's well and truly sunk in, now. Just wondering, though, if
there's any type of project where it's *not* a good idea to make up
boards in this way?

Yes. But for mechanical reasons for the most part. One example would
be a large single-sided board that needed to be wave soldered. If not done very
carefully, they come out of the solderer twisted and curled like a potato chip
(crisp) due to differential thermal expansion of the base board material and the
copper.

Jim
 
J

Jim Thompson

Jan 1, 1970
0
Jim,

Vector makes them, and Digikey carries them. Digikey pn: V1056-ND or V1057-ND.
Vector pn: P138A or P138C


Lee

Thanks!

...Jim Thompson
 
Y

YD

Jan 1, 1970
0
Paul said:
Hello chaps,

[ snip ]
Follow these links and let me know what you think of my constructional
abilities...
http://freespace.virgin.net/orion.osiris/trace_side.gif
http://www.burridge8333.fsbusiness.co.uk/top_side.gif

The schematic to which this circuit relates can be found at this page:
http://www.burridge8333.fsbusiness.co.uk/fsm3.gif

Well, I've seen worse looking Korean pocket radio PCBs. But L1 and L2
are much too close and have parallel axis, good recipe for
oscillations due to the coupling.

- YD.
 
R

Roger Gt

Jan 1, 1970
0
John Woodgate said:
I read in sci.electronics.design that Jim Thompson
4ax.com>) about 'That Notorious Field-Strength Meter: the pictures at
long last', on Sat, 17 Jan 2004:


These cutters are known engineering tools, but are not widely used. A
GOOD engineering tool supplier should have them. If not, a local
engineering company can easily make them for you.
=========================================


Actually the PAD CUTTERS have been around for a long time, I have some that
are at least 40 years old and I still use them.

They can be obtained form Digikey, but these are not the POS described above
and they will last a long time. Good tools help to do good work!

They are Digikey number V1056-ND Mfg pn P138A with handle and V1057-ND mfg
pn P138C with steel shank. These are made by Vector.

The on with the handle allows you to cut a pad by hand, no power tool
needed, the other is used in a drill press, (not a MOTO-TOOL) and both cut a
clean pad with a .040 inch hole.

Good building!
 
R

Roger Gt

Jan 1, 1970
0
Gee, did you copy the data from my previous post?


----- Original Message -----
From: "Roger Gt" <[email protected]>
Newsgroups: sci.electronics.design
Sent: Saturday, January 17, 2004 3:33 PM
Subject: Re: That Notorious Field-Strength Meter: the pictures at long last

<snip>
Actually the PAD CUTTERS have been around for a long time, I have some that
are at least 40 years old and I still use them.

They can be obtained form Digikey, but these are not the POS described above
and they will last a long time. Good tools help to do good work!

They are Digikey number V1056-ND Mfg pn P138A with handle and V1057-ND mfg
pn P138C with steel shank. These are made by Vector.

The on with the handle allows you to cut a pad by hand, no power tool
needed, the other is used in a drill press, (not a MOTO-TOOL) and both cut a
clean pad with a .040 inch hole.

Good building!
 
P

Paul Burridge

Jan 1, 1970
0
=========================================


Actually the PAD CUTTERS have been around for a long time, I have some that
are at least 40 years old and I still use them.

They can be obtained form Digikey, but these are not the POS described above
and they will last a long time. Good tools help to do good work!

They are Digikey number V1056-ND Mfg pn P138A with handle and V1057-ND mfg
pn P138C with steel shank. These are made by Vector.

The on with the handle allows you to cut a pad by hand, no power tool
needed, the other is used in a drill press, (not a MOTO-TOOL) and both cut a
clean pad with a .040 inch hole.

Surely Dremell must make something equivalent to this which is
available through Focus, Wickes, Homebase and so forth?
 
P

Paul Burridge

Jan 1, 1970
0
Well, I've seen worse looking Korean pocket radio PCBs. But L1 and L2
are much too close and have parallel axis, good recipe for
oscillations due to the coupling.

Okay. I can see now I'm going to have to make up a new board to an
entirely different design and implement all the advice I've recieved
on this subject. It should be interesting to see if it does indeed
cure the problems I've been having.
So the coils require further separation. Are there any other
components that might similarly benefit from being moved away for one
another? Are plate ceramics okay stacked-up next to each other,
touching, for example? Is the use of plastic-cased transistors to be
deprecated in this application?
I'd always thought one only had to worry about adequate screening when
dealing with RF power amplifiers. Am I to take it it's important in
small signal reciever circuits as well??
 
R

Roger GT

Jan 1, 1970
0
"Paul Burridge" <[email protected]>
wrote in message
Surely Dremell must make something equivalent to this which is
available through Focus, Wickes, Homebase and so
forth?

There are none listed on their website, and I have
never seen any advertised.
It would be hard to beat Victor quality.
I have seen some small hollow dowel or plug
drills, but they were also low speed and rather
large, 1/4", 3/8", and 1/2".
 
L

Leon Heller

Jan 1, 1970
0
Paul said:
Surely Dremell must make something equivalent to this which is
available through Focus, Wickes, Homebase and so forth?

Farnell stocks them - look for 'isolated pad cutter'. I've got one.

Leon
 
L

Leon Heller

Jan 1, 1970
0
Paul said:
Okay. I can see now I'm going to have to make up a new board to an
entirely different design and implement all the advice I've recieved
on this subject. It should be interesting to see if it does indeed
cure the problems I've been having.
So the coils require further separation.

Try using toroids. Most of the field is contained so there is very
little coupling between them. You can also mount them at right angles to
each other to further minimise it.


Are there any other
components that might similarly benefit from being moved away for one
another? Are plate ceramics okay stacked-up next to each other,
touching, for example? Is the use of plastic-cased transistors to be
deprecated in this application?
I'd always thought one only had to worry about adequate screening when
dealing with RF power amplifiers. Am I to take it it's important in
small signal reciever circuits as well??

It basically applies to any RF circuit, especially receivers, because of
the high gain required.

Leon
 
R

Roger GT

Jan 1, 1970
0
Roger GT said:
"Paul Burridge" <[email protected]>
wrote in message
a
long time, I have some that pad
by hand, no power tool to
this which is so
forth?

There are none listed on their website, and I have
never seen any advertised.
It would be hard to beat Victor quality.
I have seen some small hollow dowel or plug
drills, but they were also low speed and rather
large, 1/4", 3/8", and 1/2".
http://www.vectorelect.com/Catpdf/Page 71.pdf

Check it out!
 
John Woodgate wrote:

Possibly, the thing to do is to simulate a pad on a board with a Dremel
drill and router and take that to show what you want to do.

Here's a poor man's "Dremel technique" for pads that I use.
Using a Dremel drill press, I place a 2" square double sided
pc board on the drill press table against a square which is
held against the edge of the press table. I lower the drill to
cut the copper, and slide the board, using the square as an
edge guide. I do this repeatedly, moving the square between
cuts. Then I pivot the board 90 degrees, and do it all over
again. The result is a grid of pads. The 2" square board can
be mounted on a larger board with as many other 2" boards
as are needed. All wiring is done on the top of the board,
except for vias for ground to the underside. The dremel can
be used to groove the underside, the via wire can be bent into
the groove, and soldered, then filed & sanded to keep it as
flat as possible. It gives decent, not great results, but
certainly acceptable. 'Course the cutter would be sooo much
better!
 
Y

YD

Jan 1, 1970
0
Okay. I can see now I'm going to have to make up a new board to an
entirely different design and implement all the advice I've recieved
on this subject. It should be interesting to see if it does indeed
cure the problems I've been having.
So the coils require further separation. Are there any other
components that might similarly benefit from being moved away for one
another? Are plate ceramics okay stacked-up next to each other,
touching, for example? Is the use of plastic-cased transistors to be
deprecated in this application?
I'd always thought one only had to worry about adequate screening when
dealing with RF power amplifiers. Am I to take it it's important in
small signal reciever circuits as well??

Pretty much what Leon already said. You can keep the coils you already
have if you mount one vertically and the other horizontally with a bit
more separation, about 3 cm or more. A bit of shield between them
won't hurt.

Plate ceramics in themselves are OK, but keep them separated unless
you're sure any coupling between them won't destabilize the thing.
Decoupling caps should be mounted as close to the load as possible,
not lined up parallel in a nice little row all by themselves.

- YD.
 
F

Frithiof Andreas Jensen

Jan 1, 1970
0
Follow these links and let me know what you think of my constructional
abilities...

No ;-)

....But I will suggest that you get some litterature:
http://focus.ti.com/lit/ml/sloa089/sloa089.pdf and
http://focus.ti.com/lit/an/sdya011/sdya011.pdf should get you started on PCB
layouts....

....and use a PCB layout program ferricecakes: Eagle f.ex, is free for "home
use" i.e. small board with, I think, up to 4 layers!

It is *way* better than that dreaded felt-tipped pen I also used 25 years
ago. It allows you to experiment with many layouts quickly - and you can
assign rules to the tracks so that f.ex. the circuit tracks are "carved" out
from the "Ground Plane" thay you defined the copper of your single-layer
board to be.
 
M

Mark J.

Jan 1, 1970
0
In (Frithiof Andreas
Jensen):
No ;-)

...But I will suggest that you get some litterature:
http://focus.ti.com/lit/ml/sloa089/sloa089.pdf and
http://focus.ti.com/lit/an/sdya011/sdya011.pdf should get you started
on PCB layouts....

...and use a PCB layout program ferricecakes: Eagle f.ex, is free for
"home use" i.e. small board with, I think, up to 4 layers!

It is *way* better than that dreaded felt-tipped pen I also used 25
years ago. It allows you to experiment with many layouts quickly - and
you can assign rules to the tracks so that f.ex. the circuit tracks are
"carved" out from the "Ground Plane" thay you defined the copper of
your single-layer board to be.


A great place to get laser-printer transfer paper is:
http://www.allelectronics.com/cgi-bin/category.cgi?&item=TEK-5

Not that anyone would ever use it, but I've found that exporting board
graphics to a bitmap format (at a known DPI, 600+ is nice) and saving in
..DjVu image format maintains size exactly.
 
P

Paul Burridge

Jan 1, 1970
0
No ;-)

...But I will suggest that you get some litterature:
http://focus.ti.com/lit/ml/sloa089/sloa089.pdf and
http://focus.ti.com/lit/an/sdya011/sdya011.pdf should get you started on PCB
layouts....

...and use a PCB layout program ferricecakes: Eagle f.ex, is free for "home
use" i.e. small board with, I think, up to 4 layers!

It is *way* better than that dreaded felt-tipped pen I also used 25 years
ago. It allows you to experiment with many layouts quickly - and you can
assign rules to the tracks so that f.ex. the circuit tracks are "carved" out
from the "Ground Plane" thay you defined the copper of your single-layer
board to be.

Yeah, but it takes *time* to learn a new s/ware package and... oh,
bollocks. I guess there's no alternative. :-(
 
P

Paul Burridge

Jan 1, 1970
0
Pretty much what Leon already said. You can keep the coils you already
have if you mount one vertically and the other horizontally with a bit
more separation, about 3 cm or more. A bit of shield between them
won't hurt.

Yes, I like Leon's toriod idea but since it took me about two days to
get these coils made and tweaked to bang on value I think I'll stick
with 'em and just take the advice about seperation and orientation in
the next attempt...
Plate ceramics in themselves are OK, but keep them separated unless
you're sure any coupling between them won't destabilize the thing.
Decoupling caps should be mounted as close to the load as possible,
not lined up parallel in a nice little row all by themselves.

Noted.
 
L

Leon Heller

Jan 1, 1970
0
Paul said:
Yes, I like Leon's toriod idea but since it took me about two days to
get these coils made and tweaked to bang on value I think I'll stick
with 'em and just take the advice about seperation and orientation in
the next attempt...


15 turns on a T50-2 toroid gives about 1.1 uH. That's probably close
enough and will take you a couple of minutes to make.

Leon
 
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