Tech-Master NIB TV Kit #5516

[dieseljeep]

Originally Posted by old_coot88

Compliments once again on your outstanding workmanship sir. But offhand, it seems a minimalist, low-B+ design chassis trying to drive a large CRT is not going to deliver optimum performance, particularly with only 11KV on the anode (if your HV meter is correct).

Try this for a moment.. short out the resistor feeding G2 (screen grid) of the 25CD6 to raise G2 voltage a bit. See if this improves HV, width and focus at all. If it does, it suggests that a higher B+ supply voltage on the H output/damper circuit would improve performance. If it doesn't, then maybe a smaller CRT would work better with this chassis.

All good points!
I would only halve the G2 resistor, another one in parallel.
All the low B+ larger screen sets I worked on, seemed to use a 25DN6 instead of a 25CD6. IIRC, Sylvania designed the tube for that purpose. It looks like the tube in your set is the old style 25CD6G. After the resistor trick, the first thing I would try is a 25DN6.