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PE1RRR > TECH 08.08.23 08:16l 111 Lines 4192 Bytes #999 (0) @ WW
BID : 10492_PE1RRR
Read: GUEST
Subj: RFI & ELMER-GPT Advice
Path: IW8PGT<I3XTY<I0OJJ<N6RME<CX2SA<PE1RRR
Sent: 230808/0614Z 10492@PE1RRR.#NBW.NLD.EURO LinBPQ6.0.23
ELMER is available on VTYNOD / VE3VTY- If you have a link to RIJEN
the node is available 1 hop away.
I needed to do some research on RFI surpression, is the Elmer
getting it factually true?
PE1RRR-5: how does putting a ferrite toroid on a feedline not affect
the signal?
Elmer: Hello PE1RRR-5! That's a great question. When a
ferrite toroid is placed on a feedline, it can effectively suppress
or eliminate common-mode currents without significantly affecting
the signal passing through the feedline.
A common-mode current is a type of interference that flows in the
same direction through both conductors of a transmission line or
feedline. These currents can cause problems such as RF interference,
noise pickup, and unbalanced signal levels.
The ferrite toroid, which is made of a material with high magnetic
permeability, creates a magnetic field that helps to absorb the
common-mode currents. The magnetic properties of the ferrite
material reduce the ability of the common-mode currents to flow
through the toroid, effectively suppressing them.
At the same time, the ferrite toroid's impact on the desired signal
passing through the feedline is minimal. This is because the
toroid's magnetic field mainly affects the unwanted common-mode
currents and has little influence on the differential-mode (desired)
signals.
It's important to note that the effectiveness of a ferrite toroid in
reducing common-mode currents can depend on factors such as the
specific ferrite material, number of turns through the toroid, and
the impedance of the feedline. So, it's important to select the
right ferrite toroid for the application and follow recommended
installation practices for best results.
I hope this clarifies how a ferrite toroid on a feedline can
suppress common-mode currents while having minimal impact on the
desired signal. Let me know if you have any further questions!
PE1RRR-5: how many winds of a T43 torroid do I need for RG58 coax
Elmer: When using a T43 toroid with RG58 coax, the number of
windings will depend on the specific application and the desired
level of common-mode suppression. However, as a general guideline,
you can start with around 10 to 15 turns through the T43 toroid.
Keep in mind that this is just a starting point, and you may need to
experiment with different numbers of windings to achieve the desired
level of common-mode suppression. Additionally, the effectiveness
may also vary depending on the frequency range you are operating in.
It's recommended to refer to the manufacturer's datasheet or
application notes for more specific guidance on the number of
windings for the T43 toroid with RG58 coax in your particular
application.
If you have access to a network analyzer or an SWR meter, you can
also use those tools to measure the common-mode current and adjust
the number of windings accordingly.
I hope this helps, and let me know if you have any further questions!
PE1RRR-5: which end of a feedline should a T43 ferrite torroid go on
rg58 coax
Elmer: When placing a T43 ferrite toroid on an RG58 coax
feedline, it is generally recommended to install the toroid towards
the antenna end of the feedline.
By placing the ferrite toroid closer to the antenna, it helps to
suppress common-mode currents that may be picked up by the feedline.
This can help reduce RF interference and noise.
The specific placement of the ferrite toroid may vary depending on
the application and the specific setup. However, it is common
practice to install it as close as possible to the antenna, ideally
within a few inches or less.
Remember to make sure that the coaxial cable is properly threaded
through the toroid, ensuring that it passes through the center of
the toroid's hole or opening for optimum effectiveness.
If you are using multiple ferrite toroids, it may be beneficial to
distribute them along the feedline, with one closer to the antenna
and another closer to the radio equipment. This can help ensure even
suppression of common-mode currents throughout the entire feedline.
I hope this clarifies how to place the T43 ferrite toroid on an RG58
coax feedline.
73
Red
--
PE1RRR <pe1rrr@pe1rrr.#nbw.nld.euro>
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