zero beating?

Discussion in 'Ham Radio Discussions' started by W8RNO, Nov 19, 2011.

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  1. W8RNO

    W8RNO Ham Member QRZ Page

    i've really been practicing my code and i think i'm almost ready to start making contacts. I'm getting pretty good at copying slow cw down on 40m. I'm a little confused about this "zero beating" thing. from all the research i've done, i think ive got it figured out.

    i find a person calling cq, and then i turn the vfo down untill the sound disappears. then i turn on my rit and tune back up untill i hear the tone again at the frequency i want to hear.

    is this correct? i figured i had better get this worked out before i start answering cq's. what do i do if i want to call cq? whats the procedures on that? I have a Kenwood TS-930 and a kenwood TS-130S (the 130 changes frequency automatically when i flip to send? does this mean no zero beating?)


    Thanks,
    Chris
     
  2. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    There are several ways to get properly centered on another stations' signal. One way is 'zero beating'.

    Zero beating is matching the other signal with the 'side tone' of your transceiver. A few radios actually have a special zero button which creates the tone without transmitting. For those without, the other way to close your key, while having the radio VOX feature turned OFF so you don't transmit. At the same time adjust the tuning knob until your sidetone and the other fellows signal match. Musicians are familiar with this procedure for tuning.

    Another way is to turn on your Narrow CW Filter, if you have one, and tune until you hear the other station clearly and with some resonance.

    With experience you can become familiar with the approximate correct tone, and you can hear the station peak in strength and resonate, without any filters.

    The side tone offset is adjustable on most modern radios. Typical default ranges may be 500Hz - 700 Hz. This is a matter of personal taste and I've seen people mention using 300Hz and 1200Hz.

    For calling CQ just pick a frequency and transmit. It is up to the other guy to get centered on you.

    When operating CW, ensure that you have CW Mode selected since you may find the frequency shifted if you are listening in SSB and then change to CW.

    Don't wait to get on the air. You won't bruise it! :)

    73, Bill
     
  3. K9STH

    K9STH Platinum Subscriber Volunteer Moderator Platinum Subscriber QRZ Page

    To properly "zero beat", you have to tune the desired signal to where there is no tone at all from the receiver BFO. Then, you tune your transmitter so that there is no tone at all. As you approach the exact zero beat the "S" meter, if the AGC/AVC is turned on, will start to waver, going from side to side at a rate equal to the difference in the frequency when compared with the BFO frequency. The slower this motion the closer you are to true "zero beat".

    Unfortunately, most "modern" transceivers do not have separate variable frequency determining components for the transmitter and receiver and therefore you must try to match the side-tone frequency with the tone of the received signal. Some people can do this accurately. But, way too many people have problems getting the received tone exactly the same as the received tone. As such, many operators are not that close to the real "zero beat". When the "other" station is using a narrow filter, the transmitted signal frequency may be outside of the bandwidth of the filter. Especially when working DX and in contests, when the band is crowded, you will not work the desired station and even may be called by another station operating on a close frequency because your signal is actually closer to "zero beat" of that station.

    When narrow bandwidth filters are use, i.e. in contests, it is very common for stations to be operating within 200 Hz of each other and, because of the filter bandwidth, those stations present no problems to the others. But, when you try to "zero beat" just by listening to the side-tone frequency, often your transmitted signal is much closer to another station's frequency and that station is much more likely to answer you. However, since you are listening to the original station you often will not even notice that you are being answered by a different station.

    I have filters in my various receivers that allow me to go as narrow as 200 Hz. That means when the desired signal is in the middle of the band-pass that a signal 100 Hz away is going to be 6 dB down and a signal that is 200 Hz is going to be much further down and a signal 400 Hz away is going to be at least 60 dB down. Frankly, if you are much over 100 Hz from my frequency I am not even going to be able to copy you! In contests, because of the high level of activity, even 100 Hz away is going to be problematic because of QRM from other stations.

    Also, you have to be very careful because your particular transceiver may be using the opposite sideband for CW than the other station's transceiver. In that case, your transmitted signal will be much farther away.

    This is not to try to discourage you from operating CW. However, it does take quite a bit of practice to accurately "zero beat" a station just by listening to the side-tone frequency.

    Glen, K9STH
     
  4. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Simply put: With modern transceivers you don't really need to do "anything." If your rig is set to the CW mode, when you tune a station in so he sounds like about the same frequency pitch as you hear when you send and hear your own sidetone in the headphones, you ARE zero beat with that station, and absolutely nothing else need be done. Unless you really have a "tin ear" and can't distinguish one pitch from another (rare condition), this will get you within 50-100 Hz of the other station's frequency every time, and that's definitely good enough 99% of the time.

    Your rig knows exactly where to transmit when you do this. No extra steps involved.

    I would never even think about tuning someone into a zero-beat and then using the RIT, etc. Complete waste of time, nobody does that.
     
  5. KT1F

    KT1F Ham Member QRZ Page

    That doesn't make sense.

    Sure, some transmitters might generate CW by effectively transmitting MCW on SSB but it makes no difference at the receiving end. It's not going to require you to do anything different or cause you to be "much farther away" than if the transmitter does it with USB, LSB or some other way such as direct "real" CW. It all comes out as the same on / off "continuous wave".
     
  6. N5PVL

    N5PVL Ham Member QRZ Page

    I operated CW for a year or so, every day and do not remember having any problem with tuning issues with my FT-101ZD or the TS-430 that followed. Both had narrow CW filters that I only used if I had to, as the audio distortion ( ringing, etc. ) was most annoying. If there was adjacent noise, the audio distortion was a lot easier to put up with, I discovered, so that's the only time I used the narrow filter.

    I had a daily morning schedule on 40m, then I would hang out in the novice section of 40 for some slow code QSOs. The "certificate" in this personal, non-magazine contest was earned by being there for a fellow amateur's very first CW QSO. - And since that was what I was looking for, I pretty regularly found them. I got a big kick out of that. My 25 years as an SWL prior to being a ham was an asset there, as I was patient and knew how to listen. I would jump on a lubberly or hesitant fist like a duck on a june-bug, and send slow, even, almost machine-like code for those guys, easy to read when nervous.

    I've used an RIT control a number of times but instead of zero beating, it was more a case of working around the deficiencies of one or both our radios in the QSO.

    It seems obvious to me that we should shoot for the best signal alignment and quality that we can, at all times. Waterfall displays are invaluable for that, when operating just about any mode. This is less of an issue than it used to be, as the quality of components improve and designs are tweaked for better performance.

    Kind of like the deal with cars, which used to have to have attention to the electrical system ( points 'n plugs ) every few dozen operating hours. Now you have no points and the plugs last longer than the tires.
     
    Last edited: Nov 20, 2011
  7. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    If you work CW a lot you'll find almost nobody is really off frequency. Every now and then, someone is because they're using a crystal controlled rig or don't know what they're doing.

    But I've made probably 150,000 or 200,000 CW contacts during contests over many years (almost five decades) and never had to do anything to tune any of them in. They're right there, where they're supposed to be. If they weren't, I wouldn't hear them.
     
  8. WA8UEG

    WA8UEG XML Subscriber QRZ Page

    If your G5RV will work 80 OK I would be happy to set up a sked with you to ease you in (I'm patient). I'm in The Pocono Mountains in far east PA. Any speed you comfortable with works for me.
     
  9. KC8VWM

    KC8VWM Ham Member QRZ Page

    Zero beating just means when the rig doesn't work right, you shouldn't hit the equipment with anything.
     
  10. KY5U

    KY5U Subscriber QRZ Page

    The "poster child" for zero beating is Rodney King. If you want to learn more, Google "OWS". :p
     
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