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Thread: Question on Zero Beat and calibration TS-520s

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  1. #1

    Default Question on Zero Beat and calibration TS-520s

    Just got my Kenwood TS-520s

    I have so many questions!

    For normal xceiver calibration, the instructions read:

    "Turn the FUNCTION switch to CAL-25kHZ to activate xtal calibration. (blah blah blah)"

    Then:

    "LSB.......Set the MODE switch to LSB and tune the main tuning knob to zero beat one of the marker signals."

    Question: Does that mean I turn until the tone generated is "zero" or "gone"

    and then ...

    "If the dial scale reading under the left hand LSB dial pointer is not an even 25kHz marking, hold the blah blah blah..until the dial scale shows the correct reading."

    So, I turn the generator on, "zero" the tone (until its gone) then make sure the tuning dial is matched on the 25kHz setting.

    Is this correct?

  2. #2
    Join Date
    Feb 2004
    Location
    Bakersfield, CA
    Posts
    4,442

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    Sort of. You would find the tone from the 25Khz marker. Then tune the VFO on the TS-520S for a tone that goes lower in pitch. When you have it exactly zero beat you will not hear the tone as before. You could mistakely tune for a higher pitch and the tone would still disappear at one point. That would be wrong.
    After you have taken the pitch lower in tone until it disappears then you can set the dial to the nearest 25Khz mark on the VFO.
    Hope this helps
    73
    Gary

  3. #3

    Default

    Yeah. But who cares? Knowing exactly what frequency you're on only matters if you're right at the edge of the band and don't want to be outside it.

    I never look at my frequency, other than for that. I try to stay inside the band.
    A government which robs Peter to pay Paul can always depend on the support of Paul.

    -- George Bernard Shaw

  4. #4

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    "Beating" describes what happens when two audio pitches are close, but not quite exactly on, the same frequency.

    It is the same phenomenon as used with the heterodyne (and superheterodyne) radio receivers, where the combining of two frequencies yields the sum and also the difference of the two frequencies. Only it is not done at radio frequencies for this purpose, you use the audio tones generated inside the rig and match them, or, like when tuning a guitar, you move one until it is exactly on the same pitch as the other.

    When the two get close, you can actually hear the "beating" of the two signals get slower and slower as you gradually tune towards the other one, until it stops. That's a zero beat. If you go too far, you will go past that point and as you move away, the beating will start again.

    ex: 700Hz and 705Hz will produce a Beat tone of 1405Hz (sum) and 5Hz (difference). It is the difference frequency that creates the "beat" and in this case, it would be 5 beats per second. That will sound like one tone, but it will be varying in amplitude (apparent loudness) 5 times per second, which is where the cancellations of the two frequencies take place. Tune closer until that annoying pulsation ceases and you should be right at zero beat.


    73

  5. #5

    Default

    Quote Originally Posted by WB2WIK View Post
    I try to stay inside the band.
    The best way to stay in the band is to play your instrument VERY well. Oh wait... not THAT kind of band!

  6. #6
    Join Date
    Jun 2009
    Location
    Hercules, Calif
    Posts
    1,611

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    Is this correct?
    Yes, that will do it. Keep in mind that will only calibrate the VFO knob for the band you are presently on as each band uses a different HFO mixer crystal.
    Reality is that which, when you stop believing in it, doesn’t go away.
    WA6TKD, Larry

  7. #7
    Join Date
    Aug 2010
    Location
    Edwardsburg, Mi
    Posts
    360

    Default

    Staying within the band ends is of course required. Also, good idea to operate within the phone and cw allocations of your license. Helps to know what frequency you are on if you are trying to make a sked or perhaps taking a turn at Net Control station.

    Many old timers on here remember 5khz analog VFO days and how we all wished we owned 1khz rigs and when we attained that we were in heaven and then digital readout arrived. Nothing wrong at all about wanting to know with reasonable assurance what freq you are on. No different than any other parameter that we measure with test gear of probable accuracy. All depends on the purpose.

    Here is something else you can do:
    1. Rig in SSB
    2. Marker on
    3. AGC to Fast
    4. Slowly turn VFO and watch the S-meter. As you approach Zero Beat the S-meter needle will begin to quiver. If your Carrier Osc trimmer caps are adjusted properly the quiver will be around S3 to S4.
    5. Now must have very lite touch on the VFO. As you move the dial the needle quiver will slow down and as you get a very slow rythmic motion you should hear a slow "woosh"- "woosh" sound from the speaker.
    6. This is about as close to Zero Beat as you can get.

    It is hard for some of us who have been doing this for 50 years to realize there was a time we did not know what Zero Beat meant. I kind of miss those days. Have fun. Terry K9TW

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