[BC] shielded strategy

[RLO2L@aol.com]

In a message dated 7/29/2005 4:23:00 A.M. Central Daylight Time,  
wa3vjb at yahoo.com writes:

So I'm  most of the way toward putting the 1948
Type-76C back on the air (this is  the RCA board I got
in June I told you about). Cleaned up, not yet  powered
up.

I've had to make some custom cables to the  remote
plate/filament supply, and have tried to replicate the
size and  style of wire as original. Can;t find that
old cloth covered neoprene  anymore, and doubt old
stuff would still pass 500V test, so I bought new  THHN
600V building wire as a substitute.

Question: Is a common  shield on separate bundles DC
and AC ok instead of individually shielded,  twisted
pairs?

I've made a bunch of runs of twisted pair  14ga
stranded  as the book specifies, but I've put the
eight total  pairs for the DC plate runs into two
bundles with an outer sheath of shield  braid (stripped
from some surplus coax line) on each  bundle.



Paul:
 
Seems to me that I recall mixing on some of those old Consoles with the BIG  
knobs at WSAL in Logansport, Indiana in the late 1950's! (:>)
 
The plate runs, being DC should not be much of a problem, but if the  
filaments are still AC powered, twisted pair will go a long way to cancelling  the 
resultant hum field. The braided shield will keep the retro look and as long  as 
it is grounded at a common point on the chassis should reduce any ground loop 
 problems.
 
Have fun.
 
 
 
Russel L.  O'Toole, P.C.
R&M Consulting

31 Ponderosa  Drive
Romeoville, Illinois 60446
815-372-1990 voice
815-886-9232  fax
KD5OAE General