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6m beacon K8MMM off frequency?

Discussion in 'VHF/UHF - 50Mhz and Beyond' started by KE8OKM, Apr 3, 2021.

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  1. KE8OKM

    KE8OKM Ham Member QRZ Page

    I’ve been exploring 6m with my FT818/antennas getting ready for 6m/VHF season! The K8MMM beacon is 20ish miles from my QTH. The beacon transmits on 50.010.00. My FT818 is picking up the signal centered on 50.009.10 is the radio out of alignment or something else going on?

    Thanks in advance!
  2. W2SGM

    W2SGM XML Subscriber QRZ Page

    Assuming you have no test equipment, try this method to find out if your radio's frequency adjustment is truly 900 Hz off: Set it to USB and tune to 4.999.000, or 1000 Hz down from any of the other time signals (the highest one you can hear is best). You should have a 1000 Hz tone. Compare it to what you hear from a tone generator:

    You are limited in accuracy with this method because you don't know the accuracy of the computer's oscillator/clock that was used to generate the tone from that website. But since 900 Hz is significant, this method should get you close enough to find out if it's you or the beacon. If it's you, see the service manual for the FT-818 to find the reference frequency adjustment menu. If it's the beacon, I would try to confirm with others who can also hear that beacon before reporting it as a defect to the beacon operator.
    Last edited: Apr 3, 2021
  3. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I know Tom, we used to work on 6m SSB 50 years ago!

    Switch your FT818 to "CW" and do not use "SSB" (USB or LSB) and it's probably on frequency.
  4. KE8OKM

    KE8OKM Ham Member QRZ Page

    Ok awesome quick info thanks

    I was using SSB when listening to K8MMM. I don’t have time tonight but will try on CW in morning!

    * I looked into the beacon’s history and thought that It was a super cool way to remember a SK!


  5. W2SGM

    W2SGM XML Subscriber QRZ Page

    Switching to CW for listening to a beacon is good advice, and I think doing so will allow you to set the VFO to 50.010.000 and hear it.

    But I don't think there is an actual problem here: If the CW is being transmitted on 50.010.000, and your VFO is tuned to that in SSB, you will hear nothing (the CW tone would effectively be 0 Hz). Tune to 50.009.100, however, and the CW tone will be 900 Hz-- the offset between your VFO and the actual signal being transmitted 900 Hz away (on what the radio is treating as the carrier frequency for SSB).

    The manual says this about the CW pitch option:

    Last edited: Apr 3, 2021
    KE8OKM likes this.
  6. KA2RRK

    KA2RRK Platinum Subscriber Platinum Subscriber QRZ Page

    This android toy will measure the frequency of an audio tone
    Of any fixed carrier offset tone.

    Is my sidetone really 500hz or 800hz? This will display it.

    KE8OKM likes this.
  7. KE8OKM

    KE8OKM Ham Member QRZ Page

    I realized I never reported back. Changing the mode to CW was the trick! The beacon is where it should be on frequency.

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