Tube list:
12BE6 - AM Pentagrid Converter (RF amplifier, local oscillator, mixer)
12DT8 - Dual Triode - FM RF amplifier, local oscillator and mixer
12BA6 #1 - remote cutoff pentode - 1st AM/FM IF amp
12BA6 #2 - remote cutoff pentode - 2nd FM IF amp (Not used for AM)
14GT8 - FM Detector (uses two diodes for a FM ratio discriminator) and
1st stage audio preamplifier (triode in tube - used for both AM and FM)
50C5 (or 35C5) - audio power amplifier (gets quite hot!)
Semiconductors:
A silicon diode rectifies AC to DC for its power supply
A silicon diode is used as the AM Detector
A varactor diode is used for Automatic Frequency Control (AFC) for FM
This radio seems to have pretty good sensitivity and fairly good selectivity
due to the superheterodyne design. Its output stage and wooden cabinet makes
a very nice sounding bass with little to no chassis vibration making it one
of the better sounding radios I own. The AM sounds somewhat similar to the
Heathkit AR-3 radio, though the speaker is virtually in a
sealed box and uses a different tube.
Controls and connectors:
Oddly enough, there is no backlight like many AA5's, but this is clearly
not an AA5. The volume control with power on/off sits on the left.
The tuner knob towards the right is string connected to the ganged capacitors
and frequency indicator along the right side.
A three position DP3T sits between that selects between AM, FM, or
AFC FM (to help lock into stations.) It looks like AFC feeds back part of the
audio signal to adjust the center frequency used for the local oscillator.
On the back is the "cheater" cord that forces disconnection of the power when
opened ("cheater" since it was removed from the back panel), and the external
antenna connector.