Do I need a cw filter?

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

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  1. KF4ZGZ

    KF4ZGZ Ham Member QRZ Page

    Learn to properly zero beat and you can live without one.
    That said, in crowded conditions, filters are nice.
    My main rig is a Yaesu FT-101ZD ..... 40 year old technology ....
    It does have filters ..... but like I said .... 40 yrs ....
    A good option is a stand alone DSP unit. At a hamfest, one can be had in the $50.00 range. My MFJ-784B works well.
    $40 at a hamfest .... the CW narrow filter I put in y Icom IC-702 MKII was about 3-4 times that.

    My first rig was an ancient Yaesu FT 1-1EE with standard filters ( 500 cw) made hundreds of CW contacts on it just like it was.

  2. WB5YUZ

    WB5YUZ Ham Member QRZ Page

    But not the DSP in the '718.

    I wish I had noticed this thread earlier. As a long-time CW op who has used a number of rigs over the years, I would strongly urge anyone even casually interested in CW who is buying a '718 to get the CW filter.

    I usually leave mine turned off; the other day I heard D2EB starting up, quite a bit off from my frequency; I politely excused myself from the ragchew I was involved in, moved off, and worked him before the pile-up got out of hand. If I had the filter on, I wouldn't have heard him. (Only after he was in the log did I realize I was on the wrong antenna!)

    Even so, at least once a month I am involved in a QSO that I would have had trouble completing without switching in the filter. Being able to use the "reverse" mode to flip the product detector helps lots of times, and is more useful than the '718's DSP for CW work; but even then it is occasionally necessary to use the filter to finish the contact.

    The DSP on the '718 is mostly useful in SSB or AM modes. It really doesn't do too much even on those modes, and I never use mine. About all it's good for is suppressing QRN.
  3. US7IGN

    US7IGN Ham Member QRZ Page

    DSP on 718 is UT-106 which works on AF not IF. And it does only ANF Automatic Notch Filter and NR Noise Reduction. UT-106 don't narrow passband. All external filters are AF too. In modern radios DSP works on IF and much more effective. And they are narrow passband too.
    So narrow CW IF filter is quite effective on old Icoms. I bought used FL-232 for my IC-706mk2g for 50$. The difference was significant. And I must to say the money was not wasted. With IF shift it well receive even in contests.
  4. WB5YUZ

    WB5YUZ Ham Member QRZ Page

    Yes. In my experience, the notch filter is ok on SSB (and of course does not work in CW mode), but the noise blanker can work quite well on pulse type noises across modes, especially on electric fence pulses, ignition noise from trucks and tractors, and even some kinds of data transmissions/OTHR or whatever, but rarely if ever on power-line noise.
  5. KB4MNG

    KB4MNG Ham Member QRZ Page

    I operate cw 90 % of the time. I just bought the new ft 891, it has awesome filtering in the software and this is the first radio I do not have a filter in. New technology is amazing. If its and older rig with a cw filter slot to fill, you need to put one in it. You can try all the aftermarket audio filter you want. Yes, much better than nothing but you cannot compare the performance to a real if filter.

    i recently puchased an icom 706. the very first thing I did was order a cw filter. Very hard to work cw without one....
  6. KA0USE

    KA0USE Ham Member QRZ Page

    hey, hold on!! the adjusting knob on the mag loop IS the tuner.
    save yourself some money. just put an inexpensive swr meter between the radio and the antenna. set the frequency you want and turn the antenna knob until you get minimum swr.
    make sure the meter is rated for your power level- don't get one rated for 5w if you're gonna run higher than that.
  7. KD8ZM

    KD8ZM Ham Member QRZ Page

    Agree! I have been working cw on the drive to/from the office for several months on the ft891. I can almost always filter out anything using the ISO, WDH, or ATT functions. Amazing rig for $575.
  8. WA9CFK

    WA9CFK Ham Member QRZ Page

    I work qrp with a home brew receiver. With direct conversation you get two signals. So I built an active audio CW filter. Most of the time it is not necessary but when it is, it is very handy.
  9. N8TGQ

    N8TGQ Ham Member QRZ Page

    I've never had a filter in my rigs
    Never thought it neccesary but may not know what I"m missing. Never found the bands that crowded on CW.
    Watch your power levels with that indoor loop! The burns really hurt. Don't ask me how I know.
    KD8ZM likes this.
  10. KM1H

    KM1H Ham Member QRZ Page

    If the 718 uses the same very common crystal filters that are used in other models then a used one is about half the cost and many of those are on Fleabay and elsewhere.

    All my gear is Kenwood and Ive never bought a new filter nor received a bad one. With KW the filters were the same but some were solder in and others a direct plug in or on a small PC board. Same filter adaptable over ~30 years of models.

    For most work the 500 Hz is fine for me and the 250 only gets used for serious digging in pileups and 160 noise. The SSB filter is often best for drifters.


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