February 06, 2005

444.90 Lake Ann Rptr repaired


Today the wI0OK/r 444.90 repeater hosted by N7LMJ in Lake Ann was returned to service after a brief time offline (removed for repair late on 2/4). I am happy to report that the repeater is back up to 100% performance as far as can be measured.

The repeater had developed 'Mitrek Disease' sometime over the previous few months. Mitrek Disease is a loss of receiver sensitivity (dramatic in some cases) due to poor solder connections between the helical resonators of the receiver and their shielding. Over time the connections fail and the receiver 'front end' tuning changes. In this case, it looked as if a couple of the resonator sections had poor solder joints from the factory. The receiver tuning would change with the transceivers temperature-- yet never fully become optimum. The 449.9 receiver was noted to be anywhere from 20 to 40db less receptive than it should have been. A few minutes with a propane torch and some solder (and flux) was all it took to heal the receiver.

After the repair was made and the system returned to service the sensitivity was measured and found to be amazingly good. 0.06 microvolt into the duplexer antenna port would key up the repeater. By the time you got to .1 microvolt reception was near DFQ (this was with the ARR GasFet preamp in line).

Yee Haaa!