I used to see 2W carbon comp resistors change values drastically all the
time in TEK 520 and 520A vectorscopes. I believe it's heat-related.
(it also might depend on how much V drop across them)

They used to char the PCB even with a 1/2" standoff spacing and some even
dropped off the PCB.

Sounds as if they used a bunch of recycled SWTPC Tigersaurus power
amplifier PCBs to make those vectorscopes (or, possibly, a couple of
recycled SWTPC designers).

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
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