[Drake] preselector

[DJED1 at aol.com]

I'm not sure if Drake was the first, but it's interesting how the  
preselector function came about.  Back before 1950, in the days of  Hammarlund and 
National, all the preselection circuits were gang-tuned with the  tuning dial of 
the radio.  My SP-600 has one knob tuning for all circuits,  for example.  So 
there was no separate preselector knob. Then, Collins went  to the separate 
linearly tuned oscillator, with a crystal controlled  downconversion (75A2,  75A4, 
etc).  Interestingly, these had  integrated tuning, so that the preselection 
circuits were driven by cams from  the tuning dial- still one-knob tuning.  
The ultimate example of integrated  one-knob tuning is the R-390A, with a 
stunningly complex set of gears and  cams to tune both the RF preselector and the 
variable IF stages. Collins  undoubtedly decided this was too expensive for 
consumers, because the 51S and  75S series were the first Collins designs to use a 
separate preselector  knob.  Similarly, in that time frame, Drake also used 
this approach.   It's obviously a cheaper solution, which comes at the expense 
of having  another knob to tweak.
Anyway, the answer to the question depends on when the 75S Collins rigs  came 
out versus the Drake 2 line.
Ed  WB2LHI