All,
Rambling through my junk box, I ran across a receive pre-amp I picked up many years ago (Don't remember where). It is a very simple circuit that I have tried to draw although I am sure it is not to engineering standards!
I did install it in a Cobra 29 many moons ago that was in my service truck. As I recall it worked well! Subsequently removed the pre-amp and sold/traded/misplaced the Cobra 29 (and the install instructions for the pre-amp). As I recall it installed between the first inductor coil (closest to the SO-239) and the first tuning can by removal of a small coupling capacitor (20pF or so) between the two. I'm sure it will work in most rigs the same way. (Experts please chime in!)
I do not know who made this and am not trying to infringe on anyone's copyrights just sharing a clever idea that you can build and experiment with. (If you know the origin of this, please share)
My NOT to Engineering standards of the circuit.
(But very good therapy for my partially paralyzed dominant hand!)
The actual board.
It can be used with a switch to put it "In" or "Out" of circuit but it might be best to use with a small relay to keep leads short. Using a relay you could also switch the small capacitor, removed to install this circuit board, back into the receive circuit and be "back to stock" receive. I used the RF gain on the Cobra 29 to reduce receive gain as needed.
73's
David
Rambling through my junk box, I ran across a receive pre-amp I picked up many years ago (Don't remember where). It is a very simple circuit that I have tried to draw although I am sure it is not to engineering standards!
I did install it in a Cobra 29 many moons ago that was in my service truck. As I recall it worked well! Subsequently removed the pre-amp and sold/traded/misplaced the Cobra 29 (and the install instructions for the pre-amp). As I recall it installed between the first inductor coil (closest to the SO-239) and the first tuning can by removal of a small coupling capacitor (20pF or so) between the two. I'm sure it will work in most rigs the same way. (Experts please chime in!)
I do not know who made this and am not trying to infringe on anyone's copyrights just sharing a clever idea that you can build and experiment with. (If you know the origin of this, please share)
My NOT to Engineering standards of the circuit.
(But very good therapy for my partially paralyzed dominant hand!)
The actual board.
It can be used with a switch to put it "In" or "Out" of circuit but it might be best to use with a small relay to keep leads short. Using a relay you could also switch the small capacitor, removed to install this circuit board, back into the receive circuit and be "back to stock" receive. I used the RF gain on the Cobra 29 to reduce receive gain as needed.
73's
David