[HCARC] Low Pass Filter

[SARA SANDSTROM]

Gary, 

That is a low pass filter used to reduce the harmonics from a transmitter so they won't interfere with VHF TV.  The 1000 Watts is the maximum transmitter power and it provides 80 dB of attenuation to signals above 41 MHz.  The 41 MHz was selected so that the 41 - 45 MHz TV IF frequency is also protected.  As long as your transmitter operates below 30 MHz, you won't even know it is there.  It is designed to be placed between the transmitter and antenna in na 50 Ohm line.  

People don't seem to use low pass filters anymore.  I think its mainly because so few people watch TV off the air now.  Its usua lly from a satellite or a cable system.  You can't use it on 6 meters because it has at least 80 dB of attenuation at that frequency since it is above 41 MHz.  I'm not familiar with Bell Industries.  Low pass filters I've seen have been made by Drake, E F Johnson, Collins and B & W.  I think MFJ has made one also and I'm sure others.  I have an old Drake LPF that I don't use at the moment although I have in the p ast.  You might see how many club members on HF use one.  That should give you a good idea whether you need one or not.  If you were running a vintage vacuum tube transmitter and/or amplifier, you probably need one.  I f you are operating modern equipment and don't operate from a condo or apartment building, you probably don't.    

Kerry