Several requests have been made to put pictures of the internals of the 20C online - and I've sent the occasional picture or description in email. Now it's time to actually put pictures of what one looks like on this page.
Keep in mind that this is for the 7570 - and your model
a bit different. It is also likely that even for the same
slight changes in layout/construction/components were made, so
The Model 20C, removed from its case.
Note the brass tube socket collars
typical of the 7570.
A close-up view of the 1st RF stage.
The antenna connections are
on either side of the tube
The 2nd RF stage (right of center) and the
detector (left edge.) The 250 pf
capacitor is under the coil, on the
back of the tuning capacitor.
Right-to-left, the detector, 1st and
2nd RF stages.
Underneath the 1st and 2nd RF
stages. Note the 600 ohms wire-
wound resistors on the back of
the tuning capacitors.
Top view of the AF and detector stages.
Underneath the Detector and AF
stages. The white cylinder on the
right edge is the "2-4 Meg" grid-leak
resistor. The 0.002 uf capacitor is
to the left of this resistor.
A top view looking down upon the
2nd RF tube socket. The 0.3uf bypass
capacitor is the gray box in front of the
socket, between the 2nd and 3rd stage
A closeup of the "Antenna Tap"
A view from above the AF/Detector
strip showing the audio transformers
and the power switch. The open-frame
transformer (which was on the radio
when I got it) is a vintage replacement:
It's a "DeForest" brand!
Close-up view of the power switch.
Close-up view of the 600ohm resistor on the
back of the 2nd tuning capacitor
A few comments:
for a redrawn schematic of this radio.
AC-Operated power supply for the Atwater Kent Model 20
Go back to the
the AK20 main
Go back to KA7OEI's main
Any comments or questions? Send an email!
This page copyright 2001-2012 and is maintained by Clint Turner, KA7OEI. It was last updated on 20121101