Bush AC 81 Transformer 230v or 250v setting? - UK Vintage Radio Repair and Restoration Discussion Forum

BrianAllen · 8th Dec 2022, 4:57 pm

Should this transformer (also any other transformers) be set at 230v or 250v?

And what difference would it make to the radio set plugging in to either?

Thank you.

Brian

paulsherwin · 8th Dec 2022, 5:04 pm

Measure your normal mains voltage, and set it to that. 250V will normally be the correct setting in the UK.

If the mains voltage is significantly higher than the transformer tapping, then the valve heaters will be overrun, which will shorten their lives.

G6Tanuki · 8th Dec 2022, 5:09 pm

Would be worth trying it on both settings and seeing what the LT/HT voltages are.

Normal 6.3V valves are OK with a +/- 5% variation from 6.3V so pick the tapping that gets closest to delivering 6.3 then don't worry.

BrianAllen · 8th Dec 2022, 5:33 pm

Thank you gents.

If I hold my multimeter near a 13 amp socket I get about 230 volts. Interesting info regarding the valve heaters Paul.

Brian

paulsherwin · 8th Dec 2022, 7:21 pm

Supplies in rural areas can be on the low side, but measure again mid-morning or late at night when people haven't got their electric ovens on.

BrianAllen · 8th Dec 2022, 7:46 pm

Ok thank you, will do.

BrianAllen · 9th Dec 2022, 9:57 pm

Hello Paul, I did as you suggested and tested mains supply late at night; it fluctuated between 240v to 256v. So you were correct and I can leave the setting at 250.

Great help, thank you.

Brian

David G4EBT · 10th Dec 2022, 11:28 am

The mains Voltage here is 237V, but I always set the voltage on vintage radios to 250V to be kinder to the valves and other components. It makes no discernible difference to the performance. Out of curiosity, a couple of years ago, on a Bush DAC90A that I'd restored, I checked the voltages on both the 230V and 250V mains settings, and have attached the results.

Hope that's of interest.

BrianAllen · 10th Dec 2022, 8:03 pm

Thank you David, will print off and take a closer look.

Regards,

Brian

8th Dec 2022, 4:57 pm	#1
BrianAllen Heptode Join Date: Nov 2018 Location: Staffordshire Moorlands, UK. Posts: 595	Bush AC 81 Transformer 230v or 250v setting? Should this transformer (also any other transformers) be set at 230v or 250v? And what difference would it make to the radio set plugging in to either? Thank you. Brian Attached Thumbnails

8th Dec 2022, 5:04 pm	#2
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,927	Re: Bush AC 81 Transformer 230v or 250v setting? Measure your normal mains voltage, and set it to that. 250V will normally be the correct setting in the UK. If the mains voltage is significantly higher than the transformer tapping, then the valve heaters will be overrun, which will shorten their lives.

8th Dec 2022, 5:09 pm	#3
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,995	Re: Bush AC 81 Transformer 230v or 250v setting? Would be worth trying it on both settings and seeing what the LT/HT voltages are. Normal 6.3V valves are OK with a +/- 5% variation from 6.3V so pick the tapping that gets closest to delivering 6.3 then don't worry. __________________ I'm the Operator of my Pocket Calculator. -Kraftwerk.

8th Dec 2022, 5:33 pm	#4
BrianAllen Heptode Join Date: Nov 2018 Location: Staffordshire Moorlands, UK. Posts: 595	Re: Bush AC 81 Transformer 230v or 250v setting? Thank you gents. If I hold my multimeter near a 13 amp socket I get about 230 volts. Interesting info regarding the valve heaters Paul. Brian

8th Dec 2022, 7:21 pm	#5
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,927	Re: Bush AC 81 Transformer 230v or 250v setting? Supplies in rural areas can be on the low side, but measure again mid-morning or late at night when people haven't got their electric ovens on.

8th Dec 2022, 7:46 pm	#6
BrianAllen Heptode Join Date: Nov 2018 Location: Staffordshire Moorlands, UK. Posts: 595	Re: Bush AC 81 Transformer 230v or 250v setting? Ok thank you, will do.

9th Dec 2022, 9:57 pm	#7
BrianAllen Heptode Join Date: Nov 2018 Location: Staffordshire Moorlands, UK. Posts: 595	Re: Bush AC 81 Transformer 230v or 250v setting? Hello Paul, I did as you suggested and tested mains supply late at night; it fluctuated between 240v to 256v. So you were correct and I can leave the setting at 250. Great help, thank you. Brian

10th Dec 2022, 11:28 am	#8
David G4EBT Dekatron Join Date: Feb 2003 Location: Cottingham, East Yorkshire, UK. Posts: 5,760	Re: Bush AC 81 Transformer 230v or 250v setting? The mains Voltage here is 237V, but I always set the voltage on vintage radios to 250V to be kinder to the valves and other components. It makes no discernible difference to the performance. Out of curiosity, a couple of years ago, on a Bush DAC90A that I'd restored, I checked the voltages on both the 230V and 250V mains settings, and have attached the results. Hope that's of interest. Attached Thumbnails __________________ David. BVWS Member. G-QRP Club member 1339.

10th Dec 2022, 8:03 pm	#9
BrianAllen Heptode Join Date: Nov 2018 Location: Staffordshire Moorlands, UK. Posts: 595	Re: Bush AC 81 Transformer 230v or 250v setting? Thank you David, will print off and take a closer look. Regards, Brian