How to know your low pass filter is working

[Big Kahuna]

Just a funny story -

Last week I picked up a cool old drake TV-1000 low pass filter and dropped it inline (not my video) -

Then I was testing out a new radio yesterday and got to the part where I wanted to test out the WX channels but I wasn't picking up anything on any of the WX channels. I was like what the heck? Spent 5 minutes trying to mess with it before....

...I looked over and remembered I had the low pass filter inline.

 

[Shockwave]

They will also prevent a VHF radio from blowing up the front end of an HF (or CB) receiver, in cases where it's not possible to separate the antennas enough to accomplish this.

 

[Shadetree Mechanic]

I run an RF Limited DF 3000 on the coax going to my antenna. I thought about putting a small one between the radio and the amp too.

 

[Shockwave]

Unless you live in an area where a VHF television station is still using RF channel 2 or 5, they really have little ability to do anything. Let's face it, they did very little many years ago when everyone had a TV antenna and they never did anything for any type of RFI interference that wasn't directly related to the harmonics that land on TV channel 2 or 5.

Unless the device you are interfering with, operates on a multiple of the frequency you are transmitting on, NEVER expect a TVI filter to make any difference whatsoever. Much more can be done at the antenna in terms of decoupling the coax and mast for RFI reduction. Ferrite beads work on the end receiving the interference, when other efforts fail.

 

[Captain Kilowatt]

Many years ago I could not understand why I could not key up the local 6m repeater. I do not usually use it so I tried swinging the six element yagi around a bit and reversing the offset in case I had forgotten something. Nope nothing. Then I noticed the SWR was REALLY high and started following my coax cable. Yup you guessed it. I had the Barker & Williamson FL1500 inline. No hope in hell of keying it up or hearing it with over 72 dB of attenuation. LOL

 

[Big Kahuna]

The build quality on some of these older filters is really nice workmanship, not surprised they have lasted a long time in such good condition.