Identification of old valve radio
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Location: Adelaide, SA
Member since 27 February 2010
Member #: 630
Postcount: 398
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Hi Ian
To answer all your questions:
1. The DC resistance of the transformer sound to be about right. The reason the heater is so low is because it is only a couple of turns (Compared to the HT winding) of heavy cored wire. DC Measurements of a Transformer is completely different to AC resistance known as Impedance. For example an O/P transformer might be a 8kohm impedance but might measure about 1k ohm when checked with a multimeter. The only real thing a multimeter dc resistance check will show is if it is open or a dead short.
2. The valve filament resistances seem to be correct. Remember they are 6 volt valves. Most heaters don’t short they will go open or just not heat anymore. They are all probably fine. I am not sure on the 6U7G but I think that might be stuffed, Someone else here will have to comment on that one.
3. Fuses!
The ideal fusing to be done on this radio would be on the HT lines. The set would probably only drawer about 50mA when running so put a slightly higher value in to account for turn on surge current.
The heaters... if you are going to fuse them then there is only 4 valves plus the dial lamps running off this winding. The 5Y3GT will be (Should be) supplied by its own 5v winding.
I only usually put a fuse on the mains ACTIVE lead I/P to my sets. I don’t like modifying them more than necessary to get them operating as they should.
Hope this helps.
Daniel
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Valve radios, They just don't make them like they used to
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Location: Melbourne, VIC
Member since 5 October 2009
Member #: 555
Postcount: 468
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Dan, I am sure that the circuit diagram has a few errors or typos. Do you wish to know the details for your own reference?? Anyone else interested??
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Cheers,
Ian
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Location: Adelaide, SA
Member since 27 February 2010
Member #: 630
Postcount: 398
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Hi there
If you have updated the diagram then I am interested just in case I end up needing it.
There is plenty of examples of errors in the AORSMs especially leading upto including and just after the war. I think that some of them were rushed out.
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Valve radios, They just don't make them like they used to
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Location: Melbourne, VIC
Member since 5 October 2009
Member #: 555
Postcount: 468
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I recapped this old radio yesterday and now have it running on the broadcast band. No response on the other band as yet; and there are a few other problems with it eg. volume control introducing static, an unwound wire cap etc, which I will get to over the next few days, hopefully. Dan, I will alter the circuit diagram and send it through in a day or two.
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Cheers,
Ian
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Location: Adelaide, SA
Member since 27 February 2010
Member #: 630
Postcount: 398
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Hi Ian
No rush on the diagram. I haven't come across that particular model of radio yet. If you do update it send a good sized copy to Brad and get him to host it in this forum. Then it will be there for others to use!
The volume control should be easy to sort out. Use a contact cleaner sprayed into the back of the controls, if you cant quite get get it in there you have plenty of room to get the control out and carefully undo the tabs that hold the back on. Then spray in the cleaner. This usually fixes them up.
With the wire wound caps, I hate them with a passion. That may be because I don't know how to rewind them (It doesn't look that hard!) and have never got one to work as it should after trying to adjust them, now I leave them well alone.
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Valve radios, They just don't make them like they used to
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Location: Melbourne, VIC
Member since 5 October 2009
Member #: 555
Postcount: 468
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Hi Dan and Brad,
Some of my emails have been failing.
Did you guys get the circuit diagram I sent on 22nd January????
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Cheers,
Ian
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Location: Adelaide, SA
Member since 27 February 2010
Member #: 630
Postcount: 398
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Hi Ian
Yep got it mate. I will put it with the rest of my diagrams.
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Valve radios, They just don't make them like they used to
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