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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only. |
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22nd Sep 2021, 4:52 pm | #1 |
Heptode
Join Date: Jun 2005
Location: Sunderland, Tyne and Wear, UK.
Posts: 661
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Roberts BR added to my collection
Hi after getting a Roberts P4A radio discussed on another thread i have just bought a Roberts BA as David Boynes was telling me that the B7G Miniature valve sets are very good performers as well . It needs a power plug & on / off switch knob . I have downloaded from this site the 1123 Trader sheet that covers the CR mains and battery set as well as the BR battery only version but some of the component values are different to the BR on the Trader sheet here is some pictures of the set kind regards Bob
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Kind regards, Bob. |
22nd Sep 2021, 5:02 pm | #2 |
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Re: Roberts BR Have I Gone To The Dark Side ?
Why the dark side? I had one of these, worked well, now at the Chiltern Open Air Museum in pride of place in the grown ups bedroom of the "Amersham Prefab".
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22nd Sep 2021, 5:23 pm | #3 |
Heptode
Join Date: Jun 2005
Location: Sunderland, Tyne and Wear, UK.
Posts: 661
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Re: Roberts BR Have I Gone To The Dark Side ?
Hi Just a bit of fun never had a battery valve set till i got the P4D an did not know how really got they are kind regards Bob
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Kind regards, Bob. |
22nd Sep 2021, 8:54 pm | #4 |
Dekatron
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 7,444
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Re: Roberts BR Have I Gone To The Dark Side ?
Hi Bob,
Here's a picture of the internals of my Roberts model CR, the mains-battery version of your model BR. Note the different chassis metalwork employed in the two models. No holes on the chassis in the battery only version where the mains power supply components are fitted in the model CR. That's real quality. DFWB. |
22nd Sep 2021, 9:08 pm | #5 |
Heptode
Join Date: Jun 2005
Location: Sunderland, Tyne and Wear, UK.
Posts: 661
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Re: Roberts BR Have I Gone To The Dark Side ?
Yes David i agree the quality is really good the solder is great to work with no dry joints the components are easy to desolder no trying to pick out the wire that is wrapped round tag strips like other makes has any work been done on your set kind regards Bob
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Kind regards, Bob. |
22nd Sep 2021, 9:30 pm | #6 |
Dekatron
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 7,444
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Re: Roberts BR Have I Gone To The Dark Side ?
The set was restored last year as a lockdown project. The actual receiver didn't need much work but special care was taken with the mains power section, with particular attention to the low tension supply.
Performance is excellent, receives BBC R4 on the long waveband loud and clear. DFWB. |
22nd Sep 2021, 9:59 pm | #7 | |
Heptode
Join Date: Jun 2005
Location: Sunderland, Tyne and Wear, UK.
Posts: 661
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Re: Roberts BR Have I Gone To The Dark Side ?
Quote:
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Kind regards, Bob. |
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22nd Sep 2021, 10:20 pm | #8 |
Dekatron
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 7,444
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Re: Roberts BR Have I Gone To The Dark Side ?
"Hi David did you put regulator in the power supply ? as looking at the trader sheet the low tension side would vulnerable to voltage spikes kind regards Bob"
Hi Bob, I didn't use an LM317 for the filaments. Tomorrow I'll take the chassis out and show the methods I employed to repair the power supply. DFWB. |
22nd Sep 2021, 10:59 pm | #9 |
Heptode
Join Date: Jun 2005
Location: Sunderland, Tyne and Wear, UK.
Posts: 661
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Re: Roberts BR added to my collection
Thanks David that is a good idea if other forum members get the same set and it will save the valve filaments going OC if the low tension voltage gets high king regards Bob
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Kind regards, Bob. |
23rd Sep 2021, 10:20 am | #10 | |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
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Re: Roberts BR Have I Gone To The Dark Side ?
Quote:
A series string of suitable diodes across the LT supply could provide the braces for peace of mind....
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23rd Sep 2021, 6:18 pm | #11 | ||
Heptode
Join Date: Jun 2005
Location: Sunderland, Tyne and Wear, UK.
Posts: 661
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Re: Roberts BR Have I Gone To The Dark Side ?
Quote:
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Kind regards, Bob. |
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23rd Sep 2021, 6:32 pm | #12 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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Re: Roberts BR added to my collection
I can't remember for parallel connected but for series connected the trick originally was to run them at 1.3 Volts to help guard them against being over run due to voltage fluctuations.
Lawrence. |
23rd Sep 2021, 10:02 pm | #13 |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,536
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Re: Roberts BR added to my collection
The same 1.3V would apply for parallel filaments. The difference being that (4 valve set assumed) a series filament string would have a total LT of 6.5V (3*1.3V + 2.6V) whereas the parallel filaments would simply have the 1.3V.
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....__________ ....|____||__|__\_____ .=.| _---\__|__|_---_|. .........O..Chris....O |