Multiple inline filters

[jaystein327]

Hello,

So after successfully installing an antenna on my roof I now have the opportunity to learn all about front end overload. Basically im dealing with 2 sources of interference, a local FM Radio station and TV channel 14. I was looking over at scanner master I noticed they have a filter for FM radio as well and a filter which can be tuned to just about any frequency I might have to worry about. Including the TV station in question. I still have a few questions that anyone who has ever dealt with filters before (I know there are a lot of you out there) will probably find to be quite simple.

First: Can I use multiple filters inline from my antenna to my scanner?

Second: If multiple inline filters can be used is there a preference as to placement priority?

TIA,

Jay

 

[boatbod]

Usually you can daisy-chain multiple filters, but be aware there will be insertion loss associated with the extra connectors and filters themselves.

 

[zz0468]

Usually you can daisy-chain multiple filters, but be aware there will be insertion loss associated with the extra connectors and filters themselves.

There may be some unexpected consequences from daisy chaining filters. A filter is designed to operate at a specific characteristic impedance, ie 50 or 75 ohms. But they can also present complex impedances, something other than what it's designed to work with. This can cause the filter to behave as if it's detuned, or add additional loss, or maybe less loss where it's supposed to be. I'm not saying it WILL be a problem, I'm saying it COULD be a problem.

Try it and see how it works. But if the daisy chained filters behave somewhat bizarrely together, try removing one or the other.

 

[jaystein327]

Thanks for the advice, Im not overly concerned about insertion loss but this is a good thing to know thanks boatbod. Im hoping that daisy chaining the 2 filters wont be a problem. Thanks for the heads up zz0468. Both the FM radio and TV Audio are a real problem where I live. Does anyone out there have a setup with filters daisy chained which works well?