[Laser] first time, simple system, but problem

[KB1LQD]

hey all, KB1LQD here, built the simple RX'er out of a 741 op amp, and a 386
amp with a photodiode. It works, but there is a terrible occilation when the
10k pot is at a volume point of anything decent, also, it seems like a
signal is there or not there at all, (No background noise), any tips? the
only long leads are the leads to the photo diode in the PVC pipe with a
lens. Also, any tips on making an aiming system for the RX and TX, Also, how
do I make sure the lens is perfectly in posistion with the photo diode?

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73's