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Can someone explain this for me....

  • 08-05-2007 10:59pm
    #1
    Heathen
    Registered Users, Registered Users 2 Posts: 1,459 ✭✭✭


    ... ok i found this a few years ago and wrote if on a freq sheet i had.. will i found it today and remembered it... dont ask me how i found it out, i just remember finding it out a few years ago

    when i tune to 27.0750 fm and transmitt, i can pick it up crystal clear on 162.4500 fm on my vhf transceiver

    havent explored much more on other freq's but i just find it weird that i am getting a full crystal signal.. its one way by the way.. if you tx on 162.4500 you recieve nothing on 27.0750.. lol

    anyone?


Comments

  • #2
    PauloMN
    Moderators, Technology & Internet Moderators, Regional North East Moderators Posts: 10,878 Mod ✭✭✭✭PauloMN


    It's a harmonic. Myself and a mate used to use it to our advantage when we were young lads... I had a set of 49MHz walkie talkies and could hear them perfectly on just under 100MHz on any FM radio. It was our "local radio station"... :D

    If you divide 162.45 by 27.075 you will see the result is exactly 6.

    Cheaper equipment - like many CBs - are more prone to emitting harmonic radiation. A good low pass filter will help, especially of it is causing problems to neighbouring equipment.

    Another common problem was around 54MHz - right where NTL/Cablelink/RTE Relays etc. used to transmit Channel 4 on cable. If a CB station was causing interference, it was always on C4 as 54MHz is the first harmonic of 27MHz.


  • #3
    Heathen
    Registered Users, Registered Users 2 Posts: 1,459 ✭✭✭Heathen


    ahh brilliant cheers for clearing that up for me :D


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