zero beating?

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

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  1. N5PVL

    N5PVL Ham Member QRZ Page

    I dug around and found the poster.

    Zero beating is not specifically spelled out, but the intent is clear.

    [​IMG]
     
  2. WA4OTD

    WA4OTD Ham Member QRZ Page

    I have a hard time telling pitch so I use the narrow filter method. At FD I worked around 900 on CW, all running and it was really rare I had to tune my receiver.

    Of course the method I use ~50% of the time is tuning from spots so I trust the other guy and most DX stations tune to the khz which makes tuning easier.

    Yes the TS130 is automatic in that it puts a 800hz offset in for you. You will see that when you transmit. I have a TS130 also.
     
  3. K9STH

    K9STH Platinum Subscriber Volunteer Moderator Platinum Subscriber QRZ Page

    1F:

    If one station is using USB for receiving and the frequency offset for CW transmitting (which most, but not all, units in use these days do), and the other station is using LSB for receiving and/or the frequency is offset for CW on LSB (which a few units do use), if the desired frequency is not "zero beated" VERY close, then the signal being sent can be twice the actual difference between the desired frequency and the actual frequency of the sent signal. The farther the tone difference is, the worse the problem.


    WIK:

    It has been my experience that, especially when a higher frequency side-tone is used, quite a number of people cannot determine the frequency difference that accurately. I have seen, on a number of occasions, that the actual frequency determined by the person trying to "zero beat" is definitely more than 200 Hz away, and sometimes considerably more. For the relatively few persons who have "perfect pitch", getting the correct match between the tones is no problem. However, most people do not have "perfect pitch" and getting the tones accurately matched requires some effort.

    On a week night, when the bands are not that crowded, and when a narrower CW filter is not used, then being "off" of the desired frequency does not usually present a problem unless the frequency difference is extreme. But, when narrower filters are used, like during contests, then any noticeable difference in the "zero beating" can, and will, cause problems.

    Glen, K9STH
     
  4. N5PVL

    N5PVL Ham Member QRZ Page

    There was a ham I had a schedule with for a while, who owned an older radio that drifted radically. I would literally have to have one hand on the VFO knob while the other wrote down what he was sending. It was one of those "walk and chew gum" situations where being ambidextrous actually comes in handy.

    After he finished sending, I would zip back to the proper frequency to reply. While I sent slow code, his rig would cool down so that we could start off at the proper frequency again for the next chase across the dial.

    I am certain that there were brief periods of time there when we were in zero beat, our signals perfectly aligned. Kind of like the broken clock that's right twice a day. We were all over the place, so no doubt we were in proper alignment every once in a while, too.
     
    Last edited: Nov 20, 2011
  5. KT1F

    KT1F Ham Member QRZ Page

    I really don't know what you're talking about.

    If I tune in a CW station on receive and reply, then my transmit will be off frequency by the difference between the audio tone I tuned in and the "magic" tone frequency that the radio was designed or setup for. Lets say my transceiver is setup for CW to be 700Hz. If I tune in another station so I hear 700Hz then my transmit will be on the same frequency. If I happen to tune to 800Hz then my transmit will be 100Hz off. Whether it's high or low depends on my receiver. If I receive CW the same way as I receive USB then I'll be transmitting 100Hz lower. If I receive CW the same was as LSB then 800Hz audio will mean that I'll be transmitting 100Hz high.

    Nothing changes at my end if he changes his method of generating the signal. I have no way of even knowing how he generates the signal.

    I agree with those that say it's usually a non-issue, especially when answering a CQ in normal non-contest operation. Just tune in and reply. If you're a little off then it's no big deal. The other guy shouldn't be calling CQ with a very narrow filter.

    Tuning so that the received tone is the same as the sidetone on transmit is the correct thing to do but of course the circuitry or firmware in the radio is what makes it correct. The sidetone is just an audio oscillator and has nothing directly to do with the RF side of things.
     
  6. N3HQN

    N3HQN Ham Member QRZ Page


    Well said! Just get on the air. You'll muddle through a few dozen QSOs till it all becomes second nature. I know, I know easier said than done.....Try not to turn it into a science project. That can come later on. gud luck. 73
     
  7. WA8UEG

    WA8UEG XML Subscriber QRZ Page

    How do you zero beat a Eico 753? :confused:
     
  8. AC0H

    AC0H Ham Member QRZ Page

    The poke and hope method.
     
  9. WA4OTD

    WA4OTD Ham Member QRZ Page

    The way they drift it will be right at some point in a QSO. That rig has so much character!

     
  10. N3HQN

    N3HQN Ham Member QRZ Page

    Hahaa! But that's only fer the big'ns
     
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