I mostly deal with sets from the Depression Era but recently I received a 1925 Apex Super Five. It's got three tuning dials, a "Detector" dial and a "Radio Frequency" dial.
I'm used to the "two knobs and a speaker" sets. How do you even BEGIN to find a station with this thing?

I checked on Antique Radio Forum. This one is supposed to be similar to a Stewart Warner 300, for which schematics are available on Nostalgia Air.
What's the 3rd dial?
I would start by using the Detector dial until I could hear a station, then adjust the RF to increase the signal.
What's your antenna?

Rich

:I mostly deal with sets from the Depression Era but recently I received a 1925 Apex Super Five. It's got three tuning dials, a "Detector" dial and a "Radio Frequency" dial.
:I'm used to the "two knobs and a speaker" sets. How do you even BEGIN to find a station with this thing?
:

There is a picture of it at Radio Museum: http://www.radiomuseum.org/r/apex_super_5.html

Hard to see the dial labels.

What's your antenna?

Most TRF enthusiasts kept a log of dial settings.
http://www.antiqueradios.com/gallery/v/temp/AK+3+dial+w+taps.jpg.html

Rich

:There is a picture of it at Radio Museum: http://www.radiomuseum.org/r/apex_super_5.html
:

:I mostly deal with sets from the Depression Era but recently I received a 1925 Apex Super Five. It's got three tuning dials, a "Detector" dial and a "Radio Frequency" dial.
:I'm used to the "two knobs and a speaker" sets. How do you even BEGIN to find a station with this thing?
:
= = = = = = =

The two small knobs probably set the DC voltage to the tube filaments. My guess is that there are two separate rheostats, one for the RF tubes and one for the audio tubes. These knobs essentially set the gain for these stages.

The three larger dials are the RF stage reactor adjustments. Later TRF sets had all the tuning reactors (usually capacitors) ganged together, so "one knob" tuning was possible. However, several engineering advancements in tubes had to take place before this was feasible- the older sets such as yours had too much variability between stages (mostly due to the tubes) to make "ganging" possible.

Having said that, the three tuning dials should ROUGHLY track. To tune a station, you basically set all three dials to the same numerical reading, then rocked the last dial (last stage before the detector) until you got a station. Then you go back and twiddle the other two dials until you get maximum volume.

Radio hobbyists of the '20's usually kept small logbooks by their receivers, so that when they found a station, they could record the three dial settings to find it later without a lot of noodling around.

Improved tubes and circuit designs led to the obsolescence of the multi-dial TRF set, moving radio out of the realm of radio geeks and into the hands of the general public.