[Milsurplus] Oscillator part of BC-684 or BC-604 schematic?

[Mike Morrow]

I wrote:

> Both the 1619 and 1624 have directly heated cathodes.  See the 1938 RCA
> data sheet at
http://www.mif.pg.gda.pl/homepages/frank/sheets/049/1/1619.pdf .


I thought this statement might bring comment.  Some data sources show the
1619 as having an *indirectly* heated cathode.  For example, the repair
manual TM 11-4037 for the BC-684-(*), and the NJ7P tube data base show
indirectly heated cathodes on the 1619, while most ofther SCR-508/608
manuals and RCA data sheets show directly heated 1619 cathodes on the
schematics for the same circuits.  I don't know why this is.  I can't find
my RCA transmiting tube data book right this moment to see if it would
explain anything.  The 1619 is a metal tube, so one can't visually look and
see what the actual construction is.

It's good to hear of others interested in the SCR-508.  It's always been a
white elephant on the ham market, since it is wide band FM in the 20 to 28
mc range, and it's big and heavy and ugly.  But historically and
technically, it would be hard to identify a more significant radio set from
any era.  Considering the frequency range, there must have been some amazing
and unexpected long range contacts made with it during solar cycle peaks
such as occurred in the late 1940s.

Mike / KK5F