RA117 serial number N0489 (/cont)

The second mixer brings together the outputs of the 40MHz and 37.5MHz band-pass filters. The layout is very similar to that in the RA17L etc. However, note the 4-pin power connector on the far left … this carries the HT and heater supplies up to the 1.7MHz/third-IF module. When aligning the second mixer, it is important that the trimmer capacitor is 50% meshed as a starting point. Then simply adjust the inductor for maximum deflection on the front panel meter. The go back to the capacitor and move it either clock-wise or anti-clock-wise slightly (a few degrees). Then readjust the inductor core. The idea is to find a setting on the capacitor that corresponds to a maximum reading when the inductor is adjusted.

Second mixer before

Second mixer after

These are the HT and heater filters for the 1MHz Osc. And harmonic amplifiers (top) and the first VFO/Front-End unit. The latter differs from the that in the RA17L in that the 220nF capacitor is a new addition and the 68K resistor in the AVC line has been replaced with a 100K resistor and is now located elsewhere.