[Hallicrafters] SR-400A PA cathode resistors

[Glen Zook]

There are similar problems with the Collins S-Line and the Heath SB-Line.  The S-Line uses 12 ohm resistors and the Heath SB-Line uses 10 ohm resistors, both 1/2 watt.  I have yet to work on equipment from both series that have not had the cathode resistors change.  The "fix" is to double the wattage.  That is, on that equipment I replace the 1/2 watt resistors with 1 watt resistors.  The "new" resistors are about the same size as the original 1/2 watt versions.

Glen, K9STH

Website:  http://k9sth.com


--- On Fri, 8/14/09, rbethman <rbethman at comcast.net> wrote:

While I've never owned or operated an SR-400A, my $0.002 worth, is my gut telling me that you nee3d not only to replace them again, BUT to replace them with a HIGHER wattage version.
 
They are apparently dissipating at a higher wattage level than what has been in there.
 
It could be a design flaw - OR - the preceeding owner replaced them with a lower dissipation set.