Do I need a cw filter?

Discussion in 'QRP Corner' started by KE9RJM, Dec 22, 2017.

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  1. KE9RJM

    KE9RJM Ham Member QRZ Page

    New general ticket ham...I will be running an Icom IC-718 with DSP, LDG z-100Plus tuner and an indoor Mag Loop antenna as a startup (learning) rig.

    Since the antenna is indoors I am thinking about using QRP levels for both phone and (as soon as i learn) CW .

    My question is, for general rag chewing - not contests, do I really need a CW filter? I hate to spend an additional $170 or so unless it really makes things that much easier...I appreciate any input.


    Bob McCann
  2. KM4DYX

    KM4DYX Ham Member QRZ Page

    Welcome aboard, Bob. I'm new at CW myself, but I think that is safe to say that yes, you need a CW filter. There are times when you're just not going to be able to copy the station you're in a QSO with unless you can block out the other traffic near your frequency.

    Good luck learning CW; if an old dog like me can learn, anybody can. Hope to catch you on the air soon.

    WN1MB, KU3X and KB2SMS like this.
  3. NN4RH

    NN4RH Premium Subscriber QRZ Page

    Having a narrow IF filter, 300 to 500 Hz, available for CW can certainly help if there's other strong stations near the frequency you're trying to work someone on. An audio filter can be useful too but not as effective as an IF filter.

    Having said that, though, I had plenty of contacts without a narrow filter for several years. You can get used to listening to certain CW pitch or tone and you can kind of train yourself to ignore other signals than the one you're listening for ... sort of filter it in your head. That doesn't help if the interfering signals are strong enough to overwhelm the AGC, but you can get by just fine most of the time. Helps if you operate times and bands that are not real crowded.

    The optional IF filters for the IC-718 are kind of expensive, and I believe ICOM discontinued those a few years ago. You may have to find it on eBay. There may be a substitute filter available but I am not that familiar with Icom.

    Suggest you simply operate without it for awhile and see how you do. Maybe you won't feel you'll need the filter for the kinds of operating you do.
  4. K6GB

    K6GB XML Subscriber QRZ Page

    A filter helps, but can be pricy, you might check out the easy to build tuned speakers made out of pvc pipe, also available in kit form.
  5. NN4RH

    NN4RH Premium Subscriber QRZ Page

    I saw an article in QST earlier this year, Feb 2017 page 43, "A Resonant Speaker for CW". I haven't built it but it looks interesting.
  6. N2SUB

    N2SUB Premium Subscriber QRZ Page

    Bob - The answer is maybe. :) I agree with others who have said to try without one first. Everyone's ears (and equipment) are different. I've never liked a 500Hz filter. I usually use 800Hz and feather the RF Gain once I zero-beat the station I want to work. You'l get the knack, and eventually you can decide for yourself. Although it's not really the same thing, you can try to play with the narrow filters on just to hear what a filter would sound like.

    Best of luck and welcome to the hobby.
    K3XR likes this.
  7. KA9JLM

    KA9JLM Ham Member QRZ Page

    Normally if you need a better filter for CW you need to change frequency. o_O
  8. N1OOQ

    N1OOQ Ham Member QRZ Page

    I don't know the ic718, but you might be able to use the dsp to close the audio down around the signal you're working. An adequate, but not perfect compromise until you get an IF filter.
  9. KA9JLM

    KA9JLM Ham Member QRZ Page

    IF is the key here. :rolleyes:
  10. VA3VF

    VA3VF Guest

    I have an IC-718, no, you do not need an IF filter at $170 for general rag chewing. Mine does not have the DSP module, so no idea how effective it is, it may be more than enough for now.

    If you ever change your mind about contests, instead of buying an IF filter, upgrade to an IC-7200 (I'm trying to keep costs down, but feel free to go high end, if you can afford), because the IC-718 without a good CW filter in a contest, is an 'assault' on ones hearing.

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