If filter question

[Se7en]

Tho i am sure Google can answer this question, but i want an answer from hams who use them unlike eham script kiddies.

What is: IF Shift, IF Notch ? what do they do? what is there purpose?

Yes i sold a radio with built in everything did i learn how to use 2% of filtering heck no!:bdh: so i am starting over with a radio i should have started with from day one

 

[fodendaf]

im not a ham but i'll try explain. they are both for minimizing receiver interference from other stations using usb/lsb mode. as you know with a single side band when tuning off frequency the station can sound higher or lower audio pitched.

anyway when you turn the if shift to the right the lower audio pitched part of the rf signal is cut off and you get more higher pitched audio if the transmitting station is running a wider transmit than you are. say they are running 2.3 khz rf wide and you are running 1.8 on your receiver.

likewise when you turn the if shift to the left the high audio pitched portion of the received rf signal is cut off and you get more low pitched signal to replace it.

because of this compromise between gaining one frequency response and losing another there are better designs with separate knobs for high cut and low cut or sometimes it may be called width.

If notch takes a slice of rf out of the receiver rf signal so you don't have to listen to it. it could be around 200hertz wide and is mostly used to cut am carriers out of the audio. it has a knob to control what part of the receive rf you would like to disappear.

sometimes you can use if notch on am when listening to wideband broadcast stations. In this case the am filters often let a little carrier through and engaging the notch while it is set at 12 o clock with the receiver on the exact same frequency will remove the carrier.

there are also other types of notch like auto notch on the modern computerized rigs that perform automatically so you do not need to chase the interfering signal with your notch knob.

there is a cheaper type of audio notch on some rigs and on which is operated the same which is not as highly regarded as the rf notch.

also there is a beat cancel on some rigs which is an auto audio notch specifically for removing stable carriers.