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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only. |
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25th Feb 2023, 11:57 am | #1 |
Pentode
Join Date: Aug 2005
Location: Ashford, Kent, UK.
Posts: 204
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Krone “standard broadcast”
Hi, I have recently been given a small Krone valve radio. There doesn’t seem to be a lot of information out there on this model It looks like it was “kit built” although from memory it says made in Japan on the case ? A limited circuit diagram and a 2 pin mains plug suggests the whole circuitry is at mains potential. It looks like it has got hot at some time. Does anyone have any comments or observations ? Many Thanks.
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25th Feb 2023, 12:09 pm | #2 |
Moderator
Join Date: Jun 2003
Location: Oxford, UK
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Re: Krone “standard broadcast”
It certainly looks Japanese. A lot of cheap Japanese radios of that era had pretty hairy mains arrangements - maybe the low mains voltage used in Japan encouraged a casual attitude.
It does seem to have melted at some stage. |
25th Feb 2023, 1:28 pm | #3 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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Re: Krone “standard broadcast”
Also branded as Viscount.
Lawrence. |
26th Feb 2023, 10:27 am | #4 |
Pentode
Join Date: Aug 2005
Location: Ashford, Kent, UK.
Posts: 204
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Re: Krone “standard broadcast”
Thanks for your replies. Considering the mains voltage in Japan is 100volts, it’s probably not a good idea to plug it in ? The previous owner claimed to have used it in The Netherlands . The 2 pin plug is not a European type.
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26th Feb 2023, 10:37 am | #5 |
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Re: Krone “standard broadcast”
You should certainly check the mains voltage before trying to power it up, which should be easy to do by looking at the heater arrangements. It may well have been built for export to Europe rather than being a Japanese domestic set. I think Japan uses NEMA plugs (2 flat pins).
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26th Feb 2023, 11:27 am | #6 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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Re: Krone “standard broadcast”
Some of those Japanese radios made for export for 220-240V mains used a capacitor dropper for the heaters (in part) and the heaters themselves to drop the AC voltage to the rectifier, the dropper capacitor was connected in parallel across the rectifier and the DC load circuit which was then connected in series with the heaters.
Lawrence. |
27th Feb 2023, 5:43 pm | #7 |
Pentode
Join Date: Aug 2005
Location: Ashford, Kent, UK.
Posts: 204
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Re: Krone “standard broadcast”
Hello again,
Here's a picture of the back of the radio. The legend shows 220V on the input and also the mains plug has 220V enscribed on it. I belive ms660 has hit the nail on the head with his power supply description. I was going to carry out some cold DC tests before powering up. Does anyone have some additional suggestions ? Many Thanks in adavance. |
27th Feb 2023, 5:51 pm | #8 |
Heptode
Join Date: Feb 2007
Location: West London, UK.
Posts: 867
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Re: Krone “standard broadcast”
It looks as if the valves in series add up to 121 volts, so should not be connected to our 240v mains direct.
I have on of these radios and when I got it it had been fitted with a line cord to drop the voltage. (Resistive mains lead) I removed that and fitted a US type mains plug and if I use the set I run it from a transformer. You could make up a capacitive dropper. John |
27th Feb 2023, 5:52 pm | #9 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
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Re: Krone “standard broadcast”
There's no capacitor dropper shown in that schematic.
With the schematic as shown I can't see how it can work. EDIT: Post crossed. Lawrence. |
27th Feb 2023, 6:21 pm | #10 |
Dekatron
Join Date: Apr 2012
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Re: Krone “standard broadcast”
The circuit looks all-but identical to what I would expect in a classic 40s/50s "All American Five" receiver.
See https://en.wikipedia.org/wiki/All_American_Five And yes the heater voltages don't add up to 220/240V so proceed with caution!
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22nd Mar 2023, 2:40 pm | #11 |
Pentode
Join Date: Aug 2005
Location: Ashford, Kent, UK.
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Re: Krone “standard broadcast”
Thanks for all your comments, I will have access to a variac next weekend so after a few DC checks, I will try and power it up gently and report back. Thanks again.
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23rd Mar 2023, 10:39 am | #12 |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
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Re: Krone “standard broadcast”
The "220V" stamped on the circuit looks like an official afterthought. It might be worth a close look at the actual set to see whether there is a likely looking extra capacitor there!
Powering up from 100-120V on a variac and checking a random heater voltage would give a strong hint though......
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23rd Mar 2023, 8:15 pm | #13 | |
Heptode
Join Date: Mar 2017
Location: Cedar Grove, Wisconsin, USA.
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Re: Krone “standard broadcast”
Quote:
Many of them were sold as kits. Dave, USradcoll1 |
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