[Boatanchors] Need suggestions and question on antenna for DX-100

[Glen Zook]

The RCA manual output ratings are under laboratory
conditions and do not generally take into
consideration things like losses in the tuned
circuits, etc.  In the "real world" you seldom see
much more than 60% to 65% efficiency in amateur radio
equipment.  Occasionaly on 80 meters with new tubes
you may see as much as 70% or a little more (but not
that often).  But, as the frequency increases and the
tubes get some "age" on them the efficiency goes down
pretty fast.

I have seen "tube manual ratings" showing over 90%
efficiency on tubes.  But, again, these are under
laboratory conditions and in the "real world" are
generally considerably less.

As for the 6L6:  I have known amateur radio operators
who were using the 6L6 in the 1930s and even into the
1950s who said that they definitely had to send CW
fast.  A "short" dah tuned the plates red and a "long"
dah melted them!

Glen, K9STH


--- Garey Barrell <k4oah at mindspring.com> wrote:

I think you may be overlooking the fact that the
DX-100 final is operating Class C, which typically
shows 75%  _TUBE_ efficiency.
 
The RCA Tube Manual shows ICAS ratings of 67.5W max
Plate input with an "approximately" 52W output, which
is a _TUBE_ efficiency of 77%.
 
Of course this is at a MAX DC Plate voltage of 600 VDC
for Class C AM operation, but that's another story!
 
So it looks like Heath merely used RCAs specs, and
even allowed 3% loss for the Pi-Net!  :-)   100W
output carrier is probably a little over optimistic,
but not all that bad for ICAS service. 










Glen, K9STH

Website:  http://k9sth.com


 
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