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turretslug · 13th Feb 2021, 11:48 am

The BC453B here has a yellow-base 12K8 in it, which struck me as curious with a valve that isn't expected to perform beyond 635kHz! (The metal "bottles" are all RCA-brand with similar font, so possibly original). Maybe it was specified for the HF versions and it was simply easier to load all receiver versions with one stock type.

There was a suggested "upgrade" for the AR88 series that involved replacing the 6SA7 mixer with a 6SB7Y, but I suspect that this was another one of the slightly straw-clutching attempts to make old-timer thermionic sets seem more attractive and "with it" as transistors inexorably muscled in as the '60s progressed.

13th Feb 2021, 11:48 am	#9
turretslug Dekatron Join Date: Nov 2011 Location: Surrey, UK. Posts: 4,396	Re: 6SK7 and 6SK7W The BC453B here has a yellow-base 12K8 in it, which struck me as curious with a valve that isn't expected to perform beyond 635kHz! (The metal "bottles" are all RCA-brand with similar font, so possibly original). Maybe it was specified for the HF versions and it was simply easier to load all receiver versions with one stock type. There was a suggested "upgrade" for the AR88 series that involved replacing the 6SA7 mixer with a 6SB7Y, but I suspect that this was another one of the slightly straw-clutching attempts to make old-timer thermionic sets seem more attractive and "with it" as transistors inexorably muscled in as the '60s progressed.