Question on Zero Beat and calibration TS-520s

Discussion in '"Boat Anchor" & Classic Equipment' started by KC0GXX, May 4, 2012.

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  1. KC0GXX

    KC0GXX Ham Member QRZ Page

    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)"


    "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. KO6WB

    KO6WB Premium Subscriber QRZ Page

    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
  3. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    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.:eek:
  4. KE3WD

    KE3WD Ham Member QRZ Page

    "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.

    KM4OUS likes this.
  5. WA7PRC

    WA7PRC Ham Member QRZ Page

    The best way to stay in the band is to play your instrument VERY well. Oh wait... not THAT kind of band! :eek:
  6. WA6TKD

    WA6TKD Ham Member QRZ Page

    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.
  7. K9TW

    K9TW Ham Member QRZ Page

    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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