[Boatanchors] Viking II

[Glen Zook]

The 6146 tubes used in the Viking II are rated at a
MAXIMUM INPUT power of 67.5 watts on AM phone (per
RCA, the designer of the tube) and a MAXIMUM of 90
watts INPUT power on CW.  The Johnson manual specifies
that 135 watts is the maximum to be run when using the
Viking II on AM.  This is in line with the RCA
recommendations on the 6146 since there are two tubes
in the final amplifier.

At 135 watt input you will get around 85 to 90 watts
out on 80 meters with new tubes.  This will drop to
around 70 watts on 10 meters.  At 180 watts input the
should be around 110 to 120 watts on 80 meters and
drop to around 90 watts on 10 meters.  Again with new
tubes.

However, if you reduce the power input to around 100
watts INPUT on AM and around 150 watts INPUT on CW
your final tubes are going to last a lot longer and
the station on the other end won't know the
difference.

Also, keep the grid current around 5 mA for the pair. 
The grid in the 6146 is VERY fragile and running much
higher will greatly reduce the life of the 6146.  RCA
originally said 3.75 mA per tube (7.5 mA for a pair)
maximum.  Then that was reduced first to 3.5 mA and
then 3.25 mA.  However, the 6146 works very well at
even 1.75 mA per tube and the power output doesn't
vary much, if any, with the lower grid current.

For the article on the 6146 family of tubes that was
in Electric Radio a while back (and has been reprinted
in various other publications with permission) go to

http://k9sth.com/Page_2.html

The article is the first in the links under the
"Article" heading.

Glen, K9STH


--- telegrapher at att.net wrote:

What i'd like to know is what is the Ip for CW and
Phone for proper  operation of the Viking II?  If i
load it to 300 ma Ip i can get 135W out on CW.  I
thought 200 ma was the correct value (i get about 90W
out at that point) but a fellow i was talking to
yesterday said his CD showed 300 ma.  If that's the
case, what would it be for Phone operation?









Glen, K9STH

Website:  http://k9sth.com


 
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