[R-390] A vs non A

[Roy Morgan]

On Oct 13, 2012, at 10:51 PM, wli wrote:

> Stagger-tuned IF's are an interesting subject.

Does anyone know which R-39x manual(s) tells of stagger tuning the iF  
(Sorry I cannot dig out my manuals to look for myself.)  Note that the  
MIT Radiation Laboratory series book on Radar Systems (I think) tells  
about the factors involved in designing 30 mc radar IF amplifiers:  
some of the factors are center frequency, desired bandwidth, coupling  
between tuned circuits, circuit Q, and gain per stage.  No doubt the  
R-390/URR designers understood all that.  Maybe the Radiotron  
Designers Handbook, 4th ed. covers the topic as well.

I do remember reading that at the Marantz factory, the legendary  
Marantz 10b FM receiver (the one with the little scope for tuning) was  
aligned with a complicated and built-to-purpose test setup.  The whole  
IF strip was heated to normal operating temperature, and then, I  
suspect, aligned on a sweep system.

The design, implementation, and care in alignment produced the  
astounding sound the thing is known for, and it all makes them worth  
very big amounts of money nowadays.  There are two listed on the e- 
place for $2550 and $4000 and a contemporary 8B amplifier is offered  
at $2000+.  (My fantasy is to find a tuner at a garage sale for $20.)

Roy

Roy Morgan
k1lky at earthlink.net
K1LKY Since 1958 - Keep 'em Glowing!