Re: Feedline "Chokes": Yes or No?
I agree with the genera sentiment - use a choke. I've tried several versions lately, and have mixed results that seem to be band dependent.
One type that is easily obtainable and holds a lot of promise is the ferrite core harvested from an old color TV deflection yoke. The core is a two peace unit - held together with spring loaded clips. Once you get the old wire off, treat the unit like a large toroid - loop the coax through it multiple times. From what I can see, the more turns you create, the more effective it is at lower frequencies.
My initial effort used RG-8X - one continuous length from radio to tuner. Recently, I've switched to RG-213 and received considerably better results. My current configuration is a 100 foot length, 50 feet of it is simply coiled up on the grount, and so far this has given the best results.
I believe it is always best to stop unwanted RF energy - at its source, so it would seem logical to place the choke very close to the tuner. Secondary measures probably won't hurt either
Finally, I think that it is prudent to try to improve the ground system. Keep in mind, this tuner is trying to make up for the fact that your antenna and ground system, is not really appropriate for the frequency that you are trying to operate on. A better ground not only make for a more efficient system, it will make life much easier for your tuner, and consequently you'll have less RF coming back into your shack.
Again - take care of the problem where it starts.
73s - Steve KG4LJB
- I want to thanks the hams who responded to my question regarding the use of a feedline choke. I plans to install two: one at the station end and one just ahead of my SG-237. What I really need is about 25 more radials!
73 de K6SBA
David in Santa Barbara CA