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

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

The inductance, length, diameter, wire size, number of turns, and much more
information on single-layer coils of any proportions, long and thin, short
and fat, can be accurately calculated using program SOLNOID3.

Q, self capacitance, self resonant frequency, tuning capacitance for a
particular frequency, temperature-rise for given applied RF volts, etc. can
all be calculated. Covers mini-coils in UHF receivers to high-power
transmitter tank coils, antenna tuners and traps.

You will never need another solenoid calculator. Beats them all!

Download in a few seconds directly to an icon on your desktop, small
self-contained, user friendly program SOLNOID3 from website below. No
unzipping inconvenience. Run immediately. No training course needed.

Go to the "Download from here" page and browse through a list of other
programs written to professional standards available.
----
=======================
Regards from Reg, G4FGQ
For Free Radio Design Software
go to http://www.g4fgq.com
=======================

The inductance, length, diameter, wire size, number of turns, and much more
information on single-layer coils of any proportions, long and thin, short
and fat, can be accurately calculated using program SOLNOID3.

Q, self capacitance, self resonant frequency, tuning capacitance for a
particular frequency, temperature-rise for given applied RF volts, etc. can
all be calculated. Covers mini-coils in UHF receivers to high-power
transmitter tank coils, antenna tuners and traps.

You will never need another solenoid calculator. Beats them all!

Download in a few seconds directly to an icon on your desktop, small
self-contained, user friendly program SOLNOID3 from website below. No
unzipping inconvenience. Run immediately. No training course needed.

Go to the "Download from here" page and browse through a list of other
programs written to professional standards available.
----
=======================
Regards from Reg, G4FGQ
For Free Radio Design Software
go to http://www.g4fgq.com
=======================

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