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New program - Coax Choke

R

Reg Edwards

Jan 1, 1970
0
New program SELFRES2.exe
--------------------------------------
Input data :

Length and diameter of solenoid.
Number of turns.
Conductor diameter
Length of line in which the coil is inserted.
Testing frequency.

Output data :

Coil self-capacitance.
Coil self-resonant frequency.
Choke impedance vs frequency.
Insertion loss of choke in dB.

Performance is based on a choke wound with coaxial cable of the same type as
the transmission transmission line in which it is inserted. Conductor
diameter is that of the coax outer. It behaves a single wire. Coax inner
diameter is of no consequence.

Choke insertion loss is a measure of the reduction in power radiated from
the feedline. But, despite the attention it attracts, actual power radiated
from the feedline WITH the choke will never be known because the power
radiated WITHOUT the choke is indeterminate.

SELFRES2 is 51 K-bytes. Download from website below in a few seconds. It is
not zipped-up and will run immediately.
----
............................................................
Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
............................................................
 
R

Robert Baer

Jan 1, 1970
0
Reg said:
New program SELFRES2.exe
--------------------------------------
Input data :

Length and diameter of solenoid.
Number of turns.
Conductor diameter
Length of line in which the coil is inserted.
Testing frequency.

Output data :

Coil self-capacitance.
Coil self-resonant frequency.
Choke impedance vs frequency.
Insertion loss of choke in dB.

Performance is based on a choke wound with coaxial cable of the same type as
the transmission transmission line in which it is inserted. Conductor
diameter is that of the coax outer. It behaves a single wire. Coax inner
diameter is of no consequence.

Choke insertion loss is a measure of the reduction in power radiated from
the feedline. But, despite the attention it attracts, actual power radiated
from the feedline WITH the choke will never be known because the power
radiated WITHOUT the choke is indeterminate.

SELFRES2 is 51 K-bytes. Download from website below in a few seconds. It is
not zipped-up and will run immediately.
----
...........................................................
Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
...........................................................

Incomplete.
No core specifications and/or no way to change core specs.
I dare say, that with a given totoid size, that one would see
differences uing wood, air, plastic, iron, pyrolytic graphite, between
the various ferrites (over frequency), etc.
Then change the dimensions for more fun and games (big as a pea or
small as a truck?).
 
L

Leon Heller

Jan 1, 1970
0
Robert Baer said:
Incomplete.
No core specifications and/or no way to change core specs.
I dare say, that with a given totoid size, that one would see
differences uing wood, air, plastic, iron, pyrolytic graphite, between
the various ferrites (over frequency), etc.
Then change the dimensions for more fun and games (big as a pea or
small as a truck?).

A coax choke doesn't have a core! It's just coax cable wound into a coil
shape. Very convenient, as one can often just coil up the coax feeder where
it connects to the antenna.

Leon
 
R

Reg Edwards

Jan 1, 1970
0
On the suggestion of Ian White, G3SEK, program SELFRES2 has been modified by
the addition of an extra operating facility.

The terminating impedance at the other end of the line from the coaxial
choke, which was fixed at 20 ohms, can now be varied between 1ohm and 1000
ohms from the keyboard.

The name has been changed to SELFRES3 and is now available from website
below. If you have already downloaded the earlier version which is no longer
available, overwrite it with SELFRES3.
----
...........................................................
Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
............................................................
 
R

Robert Baer

Jan 1, 1970
0
Leon said:
A coax choke doesn't have a core! It's just coax cable wound into a coil
shape. Very convenient, as one can often just coil up the coax feeder where
it connects to the antenna.

Leon

I am used to seeing coax cable being used to make RF and pulse
transformers; the coax is wound on a ferrite core (which is necessary)
and the shield is the primary and the center conductor is the secondary
(or vice-versa depending on the needs). And turn ratios are not limited
to 1:1 either.
Now these chokes, using coax cables, are they 2-terminal or
4-terminal?
If 2-teminal, then the use of coax cable is a rather expensive
proposition.
And in both cases, the inclusion of a core material, whether the coil
has a solenoid structure or a toroidial structure, would make a large
difference in inductance and could add useful loss factors above certain
frequencies.
Even with air core (no, not the flyboys), the dimensions make a big
difference.

Sounds like the drawing board needs to be used some more.
 
L

Leon Heller

Jan 1, 1970
0
Robert Baer said:
I am used to seeing coax cable being used to make RF and pulse
transformers; the coax is wound on a ferrite core (which is necessary)
and the shield is the primary and the center conductor is the secondary
(or vice-versa depending on the needs). And turn ratios are not limited
to 1:1 either.
Now these chokes, using coax cables, are they 2-terminal or
4-terminal?
If 2-teminal, then the use of coax cable is a rather expensive
proposition.
And in both cases, the inclusion of a core material, whether the coil
has a solenoid structure or a toroidial structure, would make a large
difference in inductance and could add useful loss factors above certain
frequencies.
Even with air core (no, not the flyboys), the dimensions make a big
difference.

Sounds like the drawing board needs to be used some more.

They are often used by radio amateurs, and work very well. Often the feeder
isn't even wound into a solenoid, it's just coiled up for a few turns -
simple and cheap.

Leon
 
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