Russian GS-31B Internal Pictures
by W4EMF, 9/13/2008
These pictures were taken by W4EMF. This tube was one of four purchased several years ago that were all soft when they were powered up. The discoloration on the grid ring and on the anode may give us a hint as to why they they were bad. The pictures were taken right after breaking the tube open so the appearance of contamination on the anode and grid ring are not because the tube parts sat open any length of time before the picture was taken.
This is the anode. The small dings around the edge of the anode occurred when the tube was broken open. The rainbow colors on the upper face all make us feel that the tube was contaminated or badly used when it was received. Note that you can actually see what appears to be an impression of the grid on the anode!
This shot of the grid and cathode does not show any signs of an arc from the cathode through the grid. Lawson said that the tube had never arced but had been very soft, starting off with good power output and dropping to less than half of that. Note the discoloration of the support ring for the grid. The cathode appears to be slightly out of concentricity with the grid but Lawson feels that it likely happened when he broke the tube open.