What is the maximum safe exhaust air temperature I should see off of a 3cx1500a7 in a AL-1500? This amp has tube stack mod to keep the band switch and tank circuit area cooler, plus the fan is on the high speed setting. Also running @ 4000 volts on the plate with the upgraded 10 capacitor filter board. Currently seeing up to 110°C after very long key downs on SSB. The tube specs say a max of 250°C at the seals.
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