Drake 1-A, 2-A and 2-B

Reference pages:
b32 TR-4, TR-4C
b33 R-4C

Differences between 1st and 2nd version of Drake 1-A

6s) Development of passband tuning from Drake 1-A to 2-B.
Late version of 2-A is more or less like the 2-B in many respects





6r) Differences between first and second version of Drake 1-A receivers. I can't see any improvement in
the second version, but perhaps somebody would tell me why the AGC line is clamped? In Drake 2-B the
AGC level for an S9 signal is around -9V, and the AGC never goes higher than 15V, but it is important that
the receiver is blocked during transmission, so I don't see it as an advantage to avoid full blocking. Instead
of this strange connection I would have modified a 1-A receiver to include AM, and it seems not
difficult to find the signal rectifier diode.....

Fig.2

Fig 3