Hi,
I am new to ham radio. Well I found lots of QRP receiver circuit on
web, I tried to build some. Everything going to be OK, except making
coil inductors. I don't know how to calculate them, with type I need
(air core or slug tuned), what a difference between coil and RF choke.
Let's assume I need a 100uH coil. How to star making it. I looked for
factory made coil at my radio shack store, but I only found bobbin for
coil.

If you know any interesting link on this topic, please let me know.
I'll appreciate any comment or help.

Thanks in advice,
Edgar
73

Inductors have several different and important properties besides
inductance -- loss (Q), stray capacitance, and temperature sensativity
among them. If the coil is wound on a magnetic core and DC is passed
through it, core saturation can be an important consideration. Which
properties are important depends on the application. So you'll very
often get badly reduced performance, or a non-working circuit, if you
substitute one type of inductor for another without knowing much about
them. Consequently, a decently written article should include details
about how each inductor is made. If that information isn't provided, I
suggest contacting the author of the article to find out what he used.
That's just about the only way of insuring that you'll get the same
performance the author did.

If you're interested in building QRP receivers, there are a number of
sources where you can find good circuits which include the necessary
information to build them. The very best, although perhaps a bit
expensive for a beginner, is _Experimental Methods in RF Design_,
available from the ARRL and other dealers. Less expensive, and a
tremendous bargain, is a CD containing the contents of 109 issues of
_Sprat_, the magazine of the G-QRP club. For only $25 + $4 shipping ($15
+ $4 for G-QRP club members), you get an amazing amount and variety of
information. It's available in the U.S. from Kanga US, contact Bill
Kelsey at . To order from other contries, go to
http://www.gqrp.com and click the "Club Sales" link.

Roy Lewallen, W7EL

Qas wrote:
Hi,
I am new to ham radio. Well I found lots of QRP receiver circuit on
web, I tried to build some. Everything going to be OK, except making
coil inductors. I don't know how to calculate them, with type I need
(air core or slug tuned), what a difference between coil and RF choke.
Let's assume I need a 100uH coil. How to star making it. I looked for
factory made coil at my radio shack store, but I only found bobbin for
coil.

If you know any interesting link on this topic, please let me know.
I'll appreciate any comment or help.

Thanks in advice,
Edgar
73

Inductors have several different and important properties besides
inductance -- loss (Q), stray capacitance, and temperature sensativity
among them. If the coil is wound on a magnetic core and DC is passed
through it, core saturation can be an important consideration. Which
properties are important depends on the application. So you'll very
often get badly reduced performance, or a non-working circuit, if you
substitute one type of inductor for another without knowing much about
them. Consequently, a decently written article should include details
about how each inductor is made. If that information isn't provided, I
suggest contacting the author of the article to find out what he used.
That's just about the only way of insuring that you'll get the same
performance the author did.

If you're interested in building QRP receivers, there are a number of
sources where you can find good circuits which include the necessary
information to build them. The very best, although perhaps a bit
expensive for a beginner, is _Experimental Methods in RF Design_,
available from the ARRL and other dealers. Less expensive, and a
tremendous bargain, is a CD containing the contents of 109 issues of
_Sprat_, the magazine of the G-QRP club. For only $25 + $4 shipping ($15
+ $4 for G-QRP club members), you get an amazing amount and variety of
information. It's available in the U.S. from Kanga US, contact Bill
Kelsey at . To order from other contries, go to
http://www.gqrp.com and click the "Club Sales" link.

Roy Lewallen, W7EL

Qas wrote:
Hi,
I am new to ham radio. Well I found lots of QRP receiver circuit on
web, I tried to build some. Everything going to be OK, except making
coil inductors. I don't know how to calculate them, with type I need
(air core or slug tuned), what a difference between coil and RF choke.
Let's assume I need a 100uH coil. How to star making it. I looked for
factory made coil at my radio shack store, but I only found bobbin for
coil.

If you know any interesting link on this topic, please let me know.
I'll appreciate any comment or help.

Thanks in advice,
Edgar
73

"Qas" wrote in message
om...
Hi,
I am new to ham radio. Well I found lots of QRP receiver circuit on
web, I tried to build some. Everything going to be OK, except making
coil inductors. I don't know how to calculate them, with type I need
(air core or slug tuned), what a difference between coil and RF choke.
Let's assume I need a 100uH coil. How to star making it. I looked for
factory made coil at my radio shack store, but I only found bobbin for
coil.

If you know any interesting link on this topic, please let me know.
I'll appreciate any comment or help.

100 uH is quite a lot of inductance for a radio circuit, expecially at HF.
Inductors around 10 uH or less are very easy to make using toroidal cores.
For instance, a 5 uH inductor is about 32 turns on a T50-2 core. I use a
simple Excel spreadsheet for this sort of thing.

RF chokes are basically inductors, but specifically intended for stopping RF
from going somewhere unwanted. They are usually wound on ferrite cores, and
tend to have fairly high inductance values. They are used on their own,
usually, unlike coils, which tend to be used with capacitors. RF chokes have
a self-resonant frequency due to their self-capcitance - this needs to be
checked when using them and the self-resonant frequency avoided.

73, Leon
--
Leon Heller, G1HSM

http://www.geocities.com/leon_heller

"Qas" wrote in message
om...
Hi,
I am new to ham radio. Well I found lots of QRP receiver circuit on
web, I tried to build some. Everything going to be OK, except making
coil inductors. I don't know how to calculate them, with type I need
(air core or slug tuned), what a difference between coil and RF choke.
Let's assume I need a 100uH coil. How to star making it. I looked for
factory made coil at my radio shack store, but I only found bobbin for
coil.

If you know any interesting link on this topic, please let me know.
I'll appreciate any comment or help.

100 uH is quite a lot of inductance for a radio circuit, expecially at HF.
Inductors around 10 uH or less are very easy to make using toroidal cores.
For instance, a 5 uH inductor is about 32 turns on a T50-2 core. I use a
simple Excel spreadsheet for this sort of thing.

RF chokes are basically inductors, but specifically intended for stopping RF
from going somewhere unwanted. They are usually wound on ferrite cores, and
tend to have fairly high inductance values. They are used on their own,
usually, unlike coils, which tend to be used with capacitors. RF chokes have
a self-resonant frequency due to their self-capcitance - this needs to be
checked when using them and the self-resonant frequency avoided.

73, Leon
--
Leon Heller, G1HSM

http://www.geocities.com/leon_heller

Frank - your email address bounced:

Subject: Making inductors
Date: Monday, September 08, 2003 9:18 AM

Frank

I got mine from Kanga U.S., but I see Kanga U.K isn't selling anything, and
they only list one book. I also suspected G-QRP as a source, but they don't
show it on their web site. If there is a U.K. Source, George Dobbs, G3RJV,
would know. In fact, I think I saw it at George's booth at Dayton. Bill
Kelsey at Kanga U.S. is a nice guy and easy to deal with
(http://www.bright.net/~kanga/kanga) but I suspect there is a UK source
somewhere which could be a lot easier for you.

The book is $20 U.S. so it's probably going to be 20 pounds by the time you
get it across the pond.

Paul Harden does this wonderful artwork which makes the book a real joy.
It's such a dense collection of reference info that it really is a "must
have" for a builder. It may be a little more U.S. centric than you would
like. Although he does show drill sizes for various metric screws, his
transistor table pretty much sticks to the 2N and 2SC types. Still, it's
almost worth it for the wonderful capacitor section. And he does show all
the common toroid mixes, how to wind toroids, and he has some nice charts of
inductance and Q for the more common mixes.

72/73 de WB8RCR http://www.qsl.net/wb8rcr
didileydadidah QRP-L #1446 Code Warriors #35


----- Original Message -----
Sent: Friday, September 05, 2003 7:48 AM
Subject: Making inductors


As always, all the equations are in the handbook. Paul Harden's "Data
Book for Homebrewers and QRPers" has all the tables, without the
explanations, and it's a lot more compact (and cheaper besides).
========
Hi, Could you please provide me with a source where to obtain this book
..
I am in Scotland UK but can order in the USA Approx cost ?

TIA

Frank GM0CSZ / KN6WH

Frank - your email address bounced:

Subject: Making inductors
Date: Monday, September 08, 2003 9:18 AM

Frank

I got mine from Kanga U.S., but I see Kanga U.K isn't selling anything, and
they only list one book. I also suspected G-QRP as a source, but they don't
show it on their web site. If there is a U.K. Source, George Dobbs, G3RJV,
would know. In fact, I think I saw it at George's booth at Dayton. Bill
Kelsey at Kanga U.S. is a nice guy and easy to deal with
(http://www.bright.net/~kanga/kanga) but I suspect there is a UK source
somewhere which could be a lot easier for you.

The book is $20 U.S. so it's probably going to be 20 pounds by the time you
get it across the pond.

Paul Harden does this wonderful artwork which makes the book a real joy.
It's such a dense collection of reference info that it really is a "must
have" for a builder. It may be a little more U.S. centric than you would
like. Although he does show drill sizes for various metric screws, his
transistor table pretty much sticks to the 2N and 2SC types. Still, it's
almost worth it for the wonderful capacitor section. And he does show all
the common toroid mixes, how to wind toroids, and he has some nice charts of
inductance and Q for the more common mixes.

72/73 de WB8RCR http://www.qsl.net/wb8rcr
didileydadidah QRP-L #1446 Code Warriors #35


----- Original Message -----
Sent: Friday, September 05, 2003 7:48 AM
Subject: Making inductors


As always, all the equations are in the handbook. Paul Harden's "Data
Book for Homebrewers and QRPers" has all the tables, without the
explanations, and it's a lot more compact (and cheaper besides).
========
Hi, Could you please provide me with a source where to obtain this book
..
I am in Scotland UK but can order in the USA Approx cost ?

TIA

Frank GM0CSZ / KN6WH

Tnx for the info re Paul Harden's book .
My email address is OK but using a spam remover prog ,I might have
'accidentically 'bounced your message ,sorry for that.
I am a G-QRP Club member and shall check with George , G3RJV re
availability.
Perhaps you can give me the book's ISBN number ,such that I can order in the
US if necessary and get it sent to my son who lives in California.

TIA for your advice

Best wishes Frank , GM0CSZ / KN6WH

I got mine from Kanga U.S., but I see Kanga U.K isn't selling anything,
and
they only list one book. I also suspected G-QRP as a source, but they
don't
show it on their web site. If there is a U.K. Source, George Dobbs,
G3RJV,
would know. In fact, I think I saw it at George's booth at Dayton. Bill
Kelsey at Kanga U.S. is a nice guy and easy to deal with
(http://www.bright.net/~kanga/kanga) but I suspect there is a UK source
somewhere which could be a lot easier for you.

The book is $20 U.S. so it's probably going to be 20 pounds by the time
you
get it across the pond.

Paul Harden does this wonderful artwork which makes the book a real joy.
It's such a dense collection of reference info that it really is a "must
have" for a builder. It may be a little more U.S. centric than you would
like. Although he does show drill sizes for various metric screws, his
transistor table pretty much sticks to the 2N and 2SC types. Still, it's
almost worth it for the wonderful capacitor section. And he does show all
the common toroid mixes, how to wind toroids, and he has some nice charts
of
inductance and Q for the more common mixes.

72/73 de WB8RCR http://www.qsl.net/wb8rcr
didileydadidah QRP-L #1446 Code Warriors #35

Tnx for the info re Paul Harden's book .
My email address is OK but using a spam remover prog ,I might have
'accidentically 'bounced your message ,sorry for that.
I am a G-QRP Club member and shall check with George , G3RJV re
availability.
Perhaps you can give me the book's ISBN number ,such that I can order in the
US if necessary and get it sent to my son who lives in California.

TIA for your advice

Best wishes Frank , GM0CSZ / KN6WH

I got mine from Kanga U.S., but I see Kanga U.K isn't selling anything,
and
they only list one book. I also suspected G-QRP as a source, but they
don't
show it on their web site. If there is a U.K. Source, George Dobbs,
G3RJV,
would know. In fact, I think I saw it at George's booth at Dayton. Bill
Kelsey at Kanga U.S. is a nice guy and easy to deal with
(http://www.bright.net/~kanga/kanga) but I suspect there is a UK source
somewhere which could be a lot easier for you.

The book is $20 U.S. so it's probably going to be 20 pounds by the time
you
get it across the pond.

Paul Harden does this wonderful artwork which makes the book a real joy.
It's such a dense collection of reference info that it really is a "must
have" for a builder. It may be a little more U.S. centric than you would
like. Although he does show drill sizes for various metric screws, his
transistor table pretty much sticks to the 2N and 2SC types. Still, it's
almost worth it for the wonderful capacitor section. And he does show all
the common toroid mixes, how to wind toroids, and he has some nice charts
of
inductance and Q for the more common mixes.

72/73 de WB8RCR http://www.qsl.net/wb8rcr
didileydadidah QRP-L #1446 Code Warriors #35

On 4 Sep 2003 08:50:24 -0700, (Qas) wrote:

Hi,
I am new to ham radio. Well I found lots of QRP receiver circuit on
web, I tried to build some. Everything going to be OK, except making
coil inductors. I don't know how to calculate them, with type I need
(air core or slug tuned), what a difference between coil and RF choke.
Let's assume I need a 100uH coil. How to star making it. I looked for
factory made coil at my radio shack store, but I only found bobbin for
coil.

If you know any interesting link on this topic, please let me know.
I'll appreciate any comment or help.

Thanks in advice,
Edgar
73


Check out this website, its quite useful and has many different java
calculators for finding the inductance values of both toroid and air
form coils. I used the calculator to create a 3uh coil and it came out
pretty darn close to what I intended. (never bridge measured it
though)

http://eweb.chemeng.ed.ac.uk/jack/radio/projsoft.html

mike