1. In celebration of the launch of the new redesigned site, we just gave away a FREE antenna! Click Here to See Who Won!

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:
    7,989
    Likes Received:
    946
    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:
    2,039
    Likes Received:
    577
    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