Gang.

A three-section ganged variable condenser, the heart of the superheterodyne circuit that made radio practical and accessible to the public; before, one had to adjust the gain of each amplifier stage very precisely, and select the frequency. A signal amplifier will only deliver optimal gain across a narrow band of frequencies. The superheterodyne circuit combines the desired frequency (from the tuner) with an internally-generated variable frequency, so that the resulting intermediate frequency is perfect for the amplifiers; they don't need to be adjusted, as the input frequency is always the same. Basically, this allows you to tune your radio with one knob, instead of three or more. This particular variable condenser is located on my radio chassis, featured previously.
Camera: Canon AE-1 (35mm SLR)
Lens: Makinon compound-zoom 80-200mm, set at 200mm, 4.5x magnification.
Film: Ilford XP-2 monochrome (ASA 400)
Exposure: f11@2 seconds
Negative #BPDG-11
Enlarged, cleaned, and contrast-adjusted using Adobe PhotoShop.