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Cobra 148 gtl Philipi

flash1van

Member
Dec 18, 2011
2
0
11
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?
 

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 . . .
 
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...
 

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