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.