Fits in-line between the aerial and the receiver. The input connection is a BNC socket, output by BNC plug on a patch lead (supplied).

It features a neat and compact assembly in a black enamelled metal box, and can be powered by an internal 9 volt (PP3) battery (not supplied), or an external supply.

Box dimensions are 70 x 30 x 45mm

The minimum gain is 15dB over the range 118 – 137MHz which should make those weak signals fully readable. Another advantage of this preamplifier is the rejection of out-of-band signals which will further improve the quality of the in-band signals. The 0dB points are typically 108MHz and 150MHz, which means potentially troublesome strong signals from Band II broadcast and PMR stations are attenuated.

The external power supply should be in the range 9 to 15 volts, but a regulated supply must be used. Note that unregulated supplies may pass mains-borne interference and there is a risk that their output voltage may be too high under the low load drawn by the preamp. We can supply a suitable mains adaptor type MA-300 at GBP 8.50.

The price of the AP-3 is GBP 29.95