No match for an 'ordinary' mystery set, this set has excellent performance as well as an unusual, unique appearance. The circuit is essentially the mystery Rev.2, but the coil is 1.5 times larger in diameter than the specified mystery coil. Note the ornate presswood coil form. The coil winding supports are made of bamboo barbeque skewers cut to length. These supports are very thin but quite rigid. The coil is wound with 620/46 litz wire, which is used for both the primary and secondary windings. Rather than provide terminals on the coil, I decided to leave the coil end wires long enough to terminate at their destination, reducing the number of solder connections required
The left side tunning capacitor tunes the antenna and the right one tunes the primary coil. Both tuning capacitors are 425 pf and sport ceramic insulators.
All the circuit wiring is the same litz wire as the coils with the exception of the ground, and a short piece of vintage cloth covered wire which connects the diode output to the headphone pin jack. The single ground bus consists #12 silver plated square copper wire. The tall rectangular porcelain standoffs provide a way of neatly routing and dressing the very limp litz for the circuit wiring.
The unusual aesthetics of the radio were inspired by the shape and physical contours of the two 1920's vernier tuning dials made by Pilot radio Corp. These verniers don't operate very smoothly any more but they still do the job.
The antenna position switch is home made with the exception of the two switch contacts. These are also authentic early 1920's radio hardware pieces.. The switch contacts are isolated from the wood front panel by antique hard rubber shoulder washers. The binding posts for the antenna, ground and detector are also vintage components.
The deep cherry finished base of the radio consists of several layered architectural moldings to provide the desired profile. The small legs on the corners of the base are solid brass. The chassis is a ¼" thick bakelite panel. The front panel is 1/8" hobby plywood and the front panel moldings are presswood architectural detail moldings. The face of the front panel is covered with a maroon coloured adhesive backed felt paper.
The sensitivity and selectivity of this radio are excellent when a shottkey barrier diode is used along with an impedance matching transformer. I regularily receive around 35 stations up to about 800 km distant. More distant stations are frequently received but this is dependant on reception conditions and the time of day. The Rola-Royale was fun to build by incorporating unique building materials, vintage componets and collective knowledge gained in the xtal set and ferrite core forums. Thanks go to my many WWW friends. Enjoy.
Dieter Billlinger (aka. Sky_Wave_ 99).