Re: HT / filament transformers from Aliexpress
The original design (1940's) actually uses a 240V transformer, with a valve rectifier and then a voltage regulator tube to get down to 150V (the required anode voltage is only ~105V). I'll replace the regulator with zeners just to save space.
My 450MHz digital frequency counter (~£8 inc p&p) arrived from China a few days ago and the quick tests I've done so far are all good. Mostly, my budget-buy Chinese cheapies have been very satisfactory.
B
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