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I would be interest in any observations that you have about the pro's and con's of using a 250hz vs a 400hz narrow CW filter. I am trying to decide which one to get for an ICOM 718 tranceiver.

I have a S8 to S9 noise level on 40 mtrs. That is one of the bands I would specifically like to use the filter on. But observations for other bands would be appreciated.

John Pierce

Hello John,

Icom offers CW filters in either 500 Hz or 250 Hz, I didn't see anything about a 400 Hz CW filter although that could have been a typo if you were in a hurry.

Since it appears that you haven't had experience with a narrow CW filter of 250 Hz or 500 Hz, it would be difficult to make a concise recommendation on which one to purchase. I personally like a 500 Hz filter and since the Icom - 718 isn't a top of the line H.F. transceiver there are some things beyond your control like the lack of an AGC selector switch. But all is relative when your dealing with high noise levels. The IC - 718 has a feature called "IF Shift" and working in conjuntion with a 500 Hz CW filter it's possible to narrow the 500 Hz filter even less than that bandwidth, knocking down the unwanted noise level.

I also went out on the Internet looking for information on the purpose of the "IF Shift" and here's the web link, which better describes the feature:

http://www.astrosurf.com/luxorion/qsl-transceiver.htm

73,

Dan
WA9WVX