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Old 13th Oct 2019, 1:52 pm   #102
Croozer
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Join Date: Jul 2016
Location: Edinburgh, Scotland, UK.
Posts: 110
Default Re: Philips BX281U20 valve radio

Quote:
Originally Posted by cdm1christopher View Post
Well another check again ew.
although visually and measuring wise seem perfectly fine.
It may be worth noting that from your measurements to date, the valves are bring significantly overrun.

One of the frequency changer valves has 26V across the heaters instead of 20V - more than a 25 per cent too high. Like wise the output valve has 10 V more than it should across its heater and the rectifier appears high by 5V .

This is only measurement of the heater circuit, but over running old valves by this much will not do them any favours, especially if thry are subjected to prolonged running .We have yet to understand or measure the HT circuit voltages but it would be reasonable to expect these to be high as well owing to the set's design voltage being lower than your mains voltage.

It would perhaps be worth getting the heater voltages right before exposing replacement valves to the same treatment.
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