Dear List,
I am looking for your wisdom and lore regarding uses for some of the
more exotic capacitors found in my junque-box. I have been a ham for a
whole sunspot cycle now. I know what an NP0/C0G capacitor is and when
to use it, I know electrolytics, tantalum, and about the use of
Temperature Compensating capacitors. I have checked the usual places
(books, ARRL TIS, the archives of this list, etc) and none of these
resources tell me several important things: what they look like and
where would I use them in ham homebrew circuits. Here is my list:

UNKNOWN TYPE AND APPLICATION:
1. Blue, really shiny, flat, and small like a disc ceramic.

2. Orange and shiny- definitely not electrolytic or tantalum. Both
bulgy and flattish.

3. Green and shiny- both bulgy and flattish. (I've heard these are
either mylar or polyester film. How do I tell them apart?)

4. Dark orange (maybe brownish?) and bulgy.

5. Yellow rectangular blocks.

KNOWN TYPE, UNKNOWN APPLICATION
6. Labeled "monolithic dip"- what do I use these for?

7. "Mallory DC Film" (250V)- what do I use these for?

8. What's the difference between the following three types of mica
capacitors?
* Dipped silver mica
* Old-style micas (colored dots and physically large rectangular
blocks)
* Modern, not dipped-silver micas

Thank you VERY much for any input on this matter.

73,
Ross, NS7F

Howdy,


Without seeing the parts I can only take a WAG at what the
capacitors in question might be. This web site might help.
http://www.faradnet.com/

UNKNOWN TYPE AND APPLICATION:
1. Blue, really shiny, flat, and small like a disc ceramic.

Possibly Murata (or others) ceramic capacitors designed for
use in AC line filters.

2. Orange and shiny- definitely not electrolytic or tantalum. Both
bulgy and flattish.

Possibly Sprage Orange drop polypropylene film capacitors. There are
various types in this product family. Generally good for high dV/dT
or pulse current applications like snubbers. Could be metallized film
or film and foil.

3. Green and shiny- both bulgy and flattish. (I've heard these are
either mylar or polyester film. How do I tell them apart?)

I think this is a good guess. Mylar is a polyester film.

4. Dark orange (maybe brownish?) and bulgy.

Another film capacitor. If brown possibly Panasonic polyester.

5. Yellow rectangular blocks.

It's a film capacitor, Possibly Wima. I can't remember what the
material is. Could be Philips polyester too.


KNOWN TYPE, UNKNOWN APPLICATION
6. Labeled "monolithic dip"- what do I use these for?

General low energy use, coupling, by pass and filtering.

7. "Mallory DC Film" (250V)- what do I use these for?

Polypropylene, bypass or noise suppression.

8. What's the difference between the following three types of mica
capacitors?

* Dipped silver mica
* Old-style micas (colored dots and physically large rectangular
blocks)
* Modern, not dipped-silver micas


Dipped mica is still made and good for RF coupling and snubbers. I use
these in antenna tuners.

The box type with dots are similar construction but with metal plates
instead of metalization. They're good for RF coupling and high current
like tank circuits.

The non-dipped I'm guessing Unelco metal clad which are more like the
box style without the box. Less series inductance so better high frequency
performance. I've used these in solid state linears up into the VHF range.


The film capacitors vary in the material, polyester (mylar) polyproylene,
polycarbonate, polystyrene and more exotic films like polysulphone...each
has its strong and weak points. Some use mixed dielectrics. The
construction can be metalized film, metal foil, double layer (self healing)
or stacked film. The method for attachment of the lead wires may vary too
with high current capacitors having thicker termination or schouping (sp?)
metal sprayed onto the ends of the foil or film. The Farad Net site
documents some of the types and applications.


As always YMMV. I'm just guessing.


73,
Grumpy

Grumpy The Mule wrote:
Howdy,


Without seeing the parts I can only take a WAG at what the
capacitors in question might be. This web site might help.
http://www.faradnet.com/

UNKNOWN TYPE AND APPLICATION:
1. Blue, really shiny, flat, and small like a disc ceramic.

Possibly Murata (or others) ceramic capacitors designed for
use in AC line filters.

I'll add my cents worth.
A few years ago I bought some high-voltage disc ceramics like you are
describing. 6kv rating in 'rf' values like "681" (680pf). About 10mm
in diameter and 5cm thick. The 1kv ones are about half that size.

I used them in the output pi-network loading of a Galaxy 5 and they were
up to the task although they are plain Z5U types.

They are marked, btw, no mystery as to their rating. You don't normally
look at something this small and think 6kv!

-Bill

On Dec 1, 11:27*pm, "Ross, NS7F" wrote:
Dear List,
I am looking for your wisdom and lore regarding uses for some of the
more exotic capacitors found in my junque-box. I have been a ham for a
whole sunspot cycle now. I know what an NP0/C0G capacitor is and when
to use it, I know electrolytics, tantalum, and about the use of
Temperature Compensating capacitors. I have checked the usual places
(books, ARRL TIS, the archives of this list, etc) and none of these
resources tell me several important things: what they look like and
where would I use them in ham homebrew circuits. Here is my list:

UNKNOWN TYPE AND APPLICATION:
1. Blue, really shiny, flat, and small like a disc ceramic.

Probably is a disc ceramic :-). Some makers use blue on their higher-
voltage disk ceramics. Labeling will probably tell voltage and
capacitance.

2. Orange and shiny- definitely not electrolytic or tantalum. Both
bulgy and flattish.

3. Green and shiny- both bulgy and flattish. (I've heard these are
either mylar or polyester film. How do I tell them apart?)

4. Dark orange (maybe brownish?) and bulgy.

5. Yellow rectangular blocks.

All of the above are probably film capacitors of some kind or another.
Color doesn't mean much except maybe to an audiofile.

KNOWN TYPE, UNKNOWN APPLICATION
6. Labeled "monolithic dip"- what do I use these for?

Widely used ceramic capacitors. Small values are good for RF, larger
for bypass. Depending on the dielectric may not be worthwhile for
audio.

7. "Mallory DC Film" (250V)- what do I use these for?

These are higher voltage film polypropylene capacitors.

8. What's the difference between the following three types of mica
capacitors?
* Dipped silver mica
* Old-style micas (colored dots and physically large rectangular
blocks)
* Modern, not dipped-silver micas

All are potentially useful where you need a low-dissipation capacitor.
The old-style micas less so. Sometimes even if it's a rectangular
package with colored dots, they are just ceramic and not micas.

For many modern purposes, modern C0G ceramics will be superior (better
lower tempco) to the long-recommended silver micas.

Tim N3QE

exray wrote:
Grumpy The Mule wrote:
Howdy,


Without seeing the parts I can only take a WAG at what the
capacitors in question might be. This web site might help.
http://www.faradnet.com/

UNKNOWN TYPE AND APPLICATION:
1. Blue, really shiny, flat, and small like a disc ceramic.

Possibly Murata (or others) ceramic capacitors designed for
use in AC line filters.

I'll add my cents worth.
A few years ago I bought some high-voltage disc ceramics like you are
describing. 6kv rating in 'rf' values like "681" (680pf). About 10mm
in diameter and 5cm thick. The 1kv ones are about half that size.

I used them in the output pi-network loading of a Galaxy 5 and they were
up to the task although they are plain Z5U types.

They are marked, btw, no mystery as to their rating. You don't normally
look at something this small and think 6kv.
=======================================
They might be OK capacity and voltage wise ,but are possibly not
suitable to handle RF current ,so when using them in HV RF circuits it
might be better to use a few in parallel.

Frank KN6WH

highlandham wrote:

They might be OK capacity and voltage wise ,but are possibly not
suitable to handle RF current ,so when using them in HV RF circuits it
might be better to use a few in parallel.

Frank KN6WH

That may well be true but thats also why I stated a case of a 200-watt
output rig where they DID work.

-Bill

On Mon, 1 Dec 2008, Ross, NS7F wrote:

Date: Mon, 1 Dec 2008 20:27:52 -0800 (PST)
From: "Ross, NS7F"
Newsgroups: rec.radio.amateur.homebrew
Subject: uses for exotic capacitor types?

Dear List,
I am looking for your wisdom and lore regarding uses for some of the
more exotic capacitors found in my junque-box. I have been a ham for a
whole sunspot cycle now. I know what an NP0/C0G capacitor is and when
to use it, I know electrolytics, tantalum, and about the use of
Temperature Compensating capacitors. I have checked the usual places
(books, ARRL TIS, the archives of this list, etc) and none of these
resources tell me several important things: what they look like and
where would I use them in ham homebrew circuits. Here is my list:

UNKNOWN TYPE AND APPLICATION:
1. Blue, really shiny, flat, and small like a disc ceramic.

2. Orange and shiny- definitely not electrolytic or tantalum. Both
bulgy and flattish.

3. Green and shiny- both bulgy and flattish. (I've heard these are
either mylar or polyester film. How do I tell them apart?)

4. Dark orange (maybe brownish?) and bulgy.

5. Yellow rectangular blocks.

KNOWN TYPE, UNKNOWN APPLICATION
6. Labeled "monolithic dip"- what do I use these for?

7. "Mallory DC Film" (250V)- what do I use these for?

8. What's the difference between the following three types of mica
capacitors?
* Dipped silver mica

Capacitance should be more stable with temperature change.

* Old-style micas (colored dots and physically large rectangular
blocks)

Cheaper than silver mica.

* Modern, not dipped-silver micas

Should be larger (?) and more for higher currents (RF) and maybe
voltages.

Micas should be very resistant to the kind of ageing in paper dielectric
caps (leakage, change in value, short, open). And, also, some capacitors,
such as electrolytics have capacitance changes as a function of voltage
applied, and thus are very non-linear.

Thank you VERY much for any input on this matter.

If this is important to you, then it would have been more helpful to us if
you gave some specific dimensions of an example or two, and described any
writing or other markings (such as bands, "+", "=" ), and voltage and
capacitance numbers or even code numbers. Many new caps don't have
specific characteristics on them any more, just code numbers and you have
to guess or know what they mean.

Another possiblity would be to obtain catalogs, even current catalogs,
from parts suppliers. Often they have pictures or line drawings that can
give you hints.

I don't know about the newest ARRL handbooks, but many of the old ones
have typical pictures of examples and you can go by that.

Be aware that some of the newer caps do not have forms or colors that are
as standardized as they once were and the external appearance might not
give you a good clue as to what you have.

Capacitor color codes (six dots) on the old caps are also "decoded" in
some of the older handbooks.

73,
Ross, NS7F

On Dec 1, 11:27*pm, "Ross, NS7F" wrote:
Dear List,
I am looking for your wisdom and lore regarding uses for some of the
more exotic capacitors found in my junque-box. I have been a ham for a
whole sunspot cycle now. I know what an NP0/C0G capacitor is and when
to use it, I know electrolytics, tantalum, and about the use of
Temperature Compensating capacitors. I have checked the usual places
(books, ARRL TIS, the archives of this list, etc) and none of these
resources tell me several important things: what they look like and
where would I use them in ham homebrew circuits. Here is my list:

UNKNOWN TYPE AND APPLICATION:
1. Blue, really shiny, flat, and small like a disc ceramic.

2. Orange and shiny- definitely not electrolytic or tantalum. Both
bulgy and flattish.

3. Green and shiny- both bulgy and flattish. (I've heard these are
either mylar or polyester film. How do I tell them apart?)

4. Dark orange (maybe brownish?) and bulgy.

5. Yellow rectangular blocks.

KNOWN TYPE, UNKNOWN APPLICATION
6. Labeled "monolithic dip"- what do I use these for?

7. "Mallory DC Film" (250V)- what do I use these for?

8. What's the difference between the following three types of mica
capacitors?
* Dipped silver mica
* Old-style micas (colored dots and physically large rectangular
blocks)
* Modern, not dipped-silver micas

Thank you VERY much for any input on this matter.

73,
Ross, NS7F


Hey OM

I hate to inform you but not one of those is an exotic capacitor. They
are all garden variety.
Now maybe a Russian made 1 farad 28WVDC capacitor the size of an
overnight bag that would be exotic.
Since yoiu been a ham for a sunspot cycle maybe you can find sum sun
spots in that junque box for me eh? I could use sum sun spots.

73 OM
n8zu

"exray" wrote in message
...
highlandham wrote:

They might be OK capacity and voltage wise ,but are possibly not suitable
to handle RF current ,so when using them in HV RF circuits it might be
better to use a few in parallel.

Frank KN6WH

That may well be true but thats also why I stated a case of a 200-watt
output rig where they DID work.

-Bill

A year or so ago I toasted a cap in my SDG tuner. I don't recall the value
but it was one of a few in that tuner with ratings between 7.5 and 15 kV.
They looked just like you described. I order a replacement, plus
replacements for all the other HV caps in that tuner just in case. The
parts from Digikey looked just like the parts in the tuner, blue, shaped
kind of like an overweight disc ceramic.

Only a 100 watt rig, but if you hit the feedline with enough SWR you sure
can get the volts right up there.

...