Hi Kevin,
The choke folks are correct. This choke is used to stop/reduce the amount
of RF on the shield of the coax traveling down the coax into the shack.
Some folks will put a choke at the antenna and the shack end.
Do a Google search on common mode chokes, you'll get plenty to read.
GL.
Stay safe, wear a mask.
John
VE7KKQ
On Thu, Dec 24, 2020 at 5:22 AM AllassoPraise <allassopraise@...>
wrote:
I have seen desktop antenna/coax assemblies (such as for an SDR) that
take the (thin) coax cable and wrap it around a small toroid about 3
or 4 times, close to the antenna. I understand this is to keep the
shield of the coax from radiating.
I have tried to find information on the construction of these, but not
much comes up that is specific, making it seem like this isn't an
exact science, just "wrap a few turns around a toroid." Also, I have
heard them referred to as chokes and baluns, although others say they
do not function as a balun, only a choke.
Can anyone fill me in on this? And are there considerations to be
taken into account regarding the size of the toroid and the number of
wraps?
Also can this principle be used effectively for larger outdoor
antennas with larger coax, such as RG58 size?
Kevin
