[R-390] Tube sheilds

[Roger Ruszkowski]

Robert,

Back in the 1960's a directive come out to remove most of the 
tube shields.

Leave the RF amp, mixers and oscillator shields on.
Remove every thing else.

It was understood that the stock tube shields held in more heat
and did nothing to reduce spurious radiation from tube stages that
had no inherent spurious radiation.

The better shields were known of but the military was not going
to pop the bucks for them. Never did. 

In my day 1968 - 1975 the receivers were run with only the minimum
set of shields on the RF deck, BFO and VFO. they were all
shinny and had no conductive inserts.

Back in the R390 archives are whole seasons of threads on
tube shields and test being conducted. Tube shields are
not all equal and if you feel the need to have them,
then by all means collect some good ones and use them.

Roger.