NBFM Xtal VHF Receiver.

This Narrow VHF FM receiver will Tune between 70MHz and 170MHz and drive an 16ohm speaker with 200mW AF power. Inductor L1 should be 22WSG and 7 turns on 7mm air former for 70MHz, 100MHz 6turns, 115MHz 5turns. 135MHHz 4turns and 145 3.5turns. The gain of the receiver drops of considerably after 150MHz. The XTAL X1 is a 3rd overtone Xtal-455KHz IF, hense for 145.750MHZ it will be 48.3MHz. C1 is a 12pF variable for precission frequency tuning. T1 is the IF mixer BF981. The 455KHz IF is applied to a ready made 455KHz filter, then FM Discriminated (the diodes are 1n60's) and the audio fed to the Audio Output IC.

Forrás: AJP circuits