1. Marconi is the winner of the December WDX CB Club DX Contest! Please Congratulate him here!

Cobra 148 gtl Philipi

Discussion in 'CB Radio Modifications' started by flash1van, Jan 23, 2012.

  1. flash1van

    flash1van Member

    Joined:
    Dec 18, 2011
    Messages:
    2
    Likes Received:
    0
    I am trying to mod my 148 for 10 meter operation. I got the crystal but can only get it to key up at 28.245 but no higher. I was hoping to use a switch and keep 11 as well but don't realy care. Any ideas?


     
    #1

  2. Robb

    Robb Yup

    Joined:
    Dec 18, 2008
    Messages:
    8,287
    Likes Received:
    1,056
    Sounds like you picked the wrong crystal for 10m - to me.

    Using a DPST switch, stock/and 10m crystals, small piece of breadboard, and two variable caps, it might be possible to run both. Two parallel circuits and a switch between them - basically. Never done it myself; but in theory it might work. All you would need to do is wire both crystals/variable caps on a board and then wire them to the main board where you took the stock crystal from. Only one problem that I see, is that the VCO voltage might not be right for both bands and might unlock the PLL on one band or the other. Even that can have a workaround.

    The OTHER consideration is to open the clarifier and use a 'super diode' (diode/choke) so that it will slide ~6kc's.
    Re-aligning the VCO, 1st osc, and 2nd osc will be necessary too.

    Will it work?
    Maybe; maybe not . . .
     
    #2
  3. RatsoW8

    RatsoW8 Supporting Member

    Joined:
    Nov 3, 2009
    Messages:
    2,205
    Likes Received:
    642
    What frequency crystal did you install?
     
    #3
  4. flash1van

    flash1van Member

    Joined:
    Dec 18, 2011
    Messages:
    2
    Likes Received:
    0
    Used an 11.730 crystal, got it to work up to 28.240 even after adjusting the vco. As for the slider, got 16 kc down and 6 up...
     
    #4

Share This Page