b72. Siemens Funk 745 E310 "Rainbow receiver"
Links to pages for similar
b 71 Lorenz 6P203 Communication receiver
b 73. Racal Ra 17 mods
Siemens 745 E310 receiver has 12AT7/ECC81 as detector/BFO, but it is useless for SSB reception.
It is relatively easy to modify it for proper SSB reception by some simple changes, it is some mechanical work, but no
real challenge.The first step is to reduce the input level to the product detector so it is not overloaded by a normal
IF level. You must open the IF can and remove 11C4 capacitor, mount 560 and 5600pF capcitors underneath and
connect the center to the screened cable going to the valve grid. A grid leak must also be added since the grid is no
longer grounded through the coil. Then 11W3 is changed and a .02µF capacitor is added between the cathodes. 11W9 is
changed to 22k. The screen grid voltage for IF output stage is stabilized for better AGC operation
IF-stage chassis details for Siemens Funk 745 E310 receiver, the drawing shows parts mentioned in the modifications