These pictures show views of the Philips 2514 showing the
compactness of the design

Top view showing the coil pack with its wavechange switch
mounted on the centre metal screening plate dividing the grid
and anode coils. The left side contains the grid coil with its
tuning condenser. Just visible on the end panel is a tubular device
carrying three integral fixed condensers for allowing different
degees of selectivity/sensitivity to be selected via three aerial
sockets. On the left of centre, coloured black is a large high
Q aerial or grid tuning coil of the RF amplifier. On the right
are the anode and grid coils of the second stage with the tuning
condenser. Coupling between the valves is via the pair of vertically
mounted coils, the rear of which carries a variometer assembly
(a pick-up coil which may be moved mechanically to alter the degree
of coupling between two others) for setting the degree of feedback
or regeneration. This is one of several ways, in those days, of
implementing a reaction control. This inductive technique gives
a noise-free infinitely variable setting. The mechanical control
is via a rod passing through a hole drilled through the centre
of the tuning condenser spindle. Setting of both the large tuning
condensers is via slow motion drives which are integral to the
design of the condensers and offset a few inches from the spindle
carrying the condenser vanes. The tuning scales are fixed to rear
projections of the condenser spindles and are calibrated with
the usual 0-180.
The end plates are made of black bakelite but that on the
right is plated on the inside with metal to minimise hand capacity
which would affect stability.
The small pegs around the end plates are used for accommodating
the case screws.

Rotating the chassis through 90 degrees reveals the valve
bases, two of which, those for the detector and output valves
are integated within a black bakelite assembly. The rectifier
base on the left, is integral to its own detachable assembly.

This view shows the screened grid RF amplifier on the left,
next to the power rectifier. On the right are the detector valve
and the output valve. The output transformer is on the extreme
right next to the power output valve. It was important to keep
the two sets of tuning coils well away from each other to prevent
instability through unwanted positive feedback.

This view shows the mains transformer on the bottom right
next to a decoupling condenser block. The device at the centre
of the lower edge is a safety switch socket which is used to disconnect
the mains transformer primary feed. The lower part of the case
covers the valves and most of the exposed connections carrying
high voltages and incorporates an isolated metal tongue which
inserts into the safety socket. When the panel is removed the
HT supply is disconnected from the set's wiring. The centre metal
plate to the left of the rectifier screens the RF amplifier valve
from the detector valve.
See more>>