Re: 23cm pre amplifier


GM6VXB
 

I think I have it fixed now but too dark and windy to stand on the roof putting the preamp back into the box.
Thanks to Conrad (PA5Y) for pointing out that the PGA103 is actually the second device rather than the first (my brain
not in gear while checking), and also pointing me to a circuit diagram.
So the PGA103 had failed short circuit. From the circuit diagram R3 series supply resistor had become desoldered due to
the PGA getting 'very' hot. Further investigation earlier and I found a small gap in the input side of the PGA where C6
should be. More by luck I found capacitor C6 still inside the box desoldered due to heat. Really difficult to resolder it back with my poor eyesight
even with magnifiers but now when checked I hear noise, which is more than it did before.
No test gear above 1GHz, but listening to a third harmonic at 432MHz  off the Sig Gen it looks very hopeful
So will get it re-fitted tomorrow and hope it is working.

Thanks all for the assistance, at least IO97 will (could/should) be back on air if you have not worked GM4ZUK during
the monthly contest.

Martin, GM6VXB (IO97AQ (as far north on the East coast as you can go))


Martin, GM6VXB

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