Is there a need to create an rf choke with coiled coax near the connection to ladder line?

[KJ4ZFJ 2]

Would there be a need to create an rf choke with coiled coax at the connection to the ladder line?

[K3MRI 56]

29 minutes ago, KJ4ZFJ said:

Would there be a need to create an rf choke with coiled coax at the connection to the ladder line?

Hi Tim. Moved the question to a new thread. Will reply shortly.

[K3MRI 56]

So, that's also a really good question and one which other Elmers might answer better, but I'll give it a shot.

First of all, a coiled choke has a purpose, to reduce common-mode current that may bring RF into the shack. As such, in all cases, you would rather have the choke nearer to the tuner than to the connection. Secondly, I will point you to an interesting, albeit technical paper on chokes: 

I will add that you should only use a choke if you experience noise - generally speaking. One reason is a loss of power through heat. When he common mode signal hits the choke and creates a magnetic flux inside, lots of energy is lost (hysteresis and perhaps other effects) as heat. You're reducing energy.

Another thing to consider is whether or not there is a likelihood of common mode noise in your environment. Bad full-bridge power inverters can be one source. Grounding issues are another.

If I were you, I would avoid the choke initially, you can always wind the coax later.

Let's see how many disagree with me? 😎