[R-390] Racal wadley loop RX s

[Bernie Nicholson]

I have Repaired large numbers of these recievers the the commonest fault is open circ resistor 100k assosiated with the third mixer  6F33 or US versions 6AS6  also some sets have red disc ceramic caps that havnt stood the test of time , the 40 mhz band pass filter and the 37.5 mhz filter are easily alighned using a 141T systerm and 8444 tracking gen , there is a test point no 2 I think that you can put a vtvm or HF oscillascope on and you can see the 1mhz pips passing as you turn turn the MHZ dial which is the 40-70mhz VFO, another fault that is quiet common is in the 100khz I F the transformers are wound with LITZ wire and over the years some strands have given way at the termination effecting the Q of the transformers and not beihg able to atain the bandpass characteristics in the manual , I cure this prob by Resldering the conections inside the can and running solder into the multiple wires the varnish burns off after a few secs of heat, another thing I have found is that you can increase the signal to noise ratio by judicious selection of the first and second mixer tubes, my RA17 was made in the 9th month 1974 and they started making these RX s in 1954 so it was a long production run ,I also have the SSB converter for this radio which turns it into an ISB system, they are a nice Rx and very reliable over long periods of time and very simple mechanically compared to the 390A , I also have the solid state model RA1217 ,only 3 inches high . regards to everyone Bernie N