A quad of Mullard EL 34, labeled as Rogers.Mullard XF2 model with welded plates and double O getter. Date codes are B4K3 , meaning these were produced at the Blackburn UK plant in November of 1964. All tubes have identical construction and labeling and test very strong at 102 to 104 on my B&K tube tester , the minimum acceptable rating is 65 for an EL34 on this tester.
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