[Drake] Opinion on Drake recievers

[Garey Barrell]

fkamp at comcast.net wrote:

>I feel the 13 tube R4A is the better of the group as a do-all receiver. 
>It does have a crystal roofing filter at the first IF, but it is only a
>two pole.  I am not sure if the R4B has the crystal filter or not. I
>suspect it does. 
>
>  
>
All 4 Series up to the R-4B used the same crystal filter in the first IF. 

>I don't much care for the later model R4Bs.  Seems that Drake used them
>to 'learn' about solid state design and all but the FET PTO design
>performed poorer than the all tube R4A.  At least in my oppinion.  The
>stock solid state audio amp in the R4C is also a good example of poor
>solid state design.
>
>  
>
Most of the solid state conversions were in LO's and low level AF 
stages.  I think we'd be hard pressed to quantify poorer performance 
from a solid state crystal oscillator, AGC or low level Class A audio 
stage.  Some claim that the two diode product detector doesn't perform 
as well as the 6GX6 PD in the R-4 and early R-4A.  There are also those 
who claim the MC1496 in the Version 2 TR-7 PD sounds better than the 
Version 1 two diode PD.  I'm inclined to believe that the change in the 
TR-7 was made for cost reduction.  A single <$1 IC to replace half a 
dozen discrete components and a transformer.

I also think the AF output stage in the R-4C was not necessarily a poor 
design  _at the time_  it was made.  It is a Class A stage, that granted 
wasn't very efficient, but it is low distortion.  The frequency response 
was altered to make it more "communications quality", primarily by 
rolling off the lows, making it sound kind of "hissy".  The "C100" mod 
goes a long way to mitigate that situation.  Yeah, today we have AF IC's 
that are a lot more efficient, but are also more susceptible to 
crossover distortion, which some find more irritating to listen to.

Says something that these "nits" are the only ones we can find to pick 
in a 30-40 (!) year old design.  Yikes!  That 40 is a depressing 
number!  :-)

73, Garey K4OAH
Atlanta