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Post by triman on Sept 11, 2022 3:27:36 GMT 12
Hi everyone. This is my first post on the this forum. I was born in Wanganui but grew up in Australia. And for the last 20 years, I've been living in England. I have a reasonable collection of Ekco and Philips radios which I enjoy slowly restoring. My latest project is my Grandmother's NZ radio from Wanganui. It's been heavily modified and I would really like to restore it back to original. If someone has the circuit diagram I would be much appreciative. best regards Craig  |
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Post by Richard on Sept 11, 2022 11:40:51 GMT 12
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Post by triman on Sept 11, 2022 21:30:02 GMT 12
Hi Richard,
Thanks a million, that's very helpful.
Craig
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Post by Richard on Sept 12, 2022 7:14:36 GMT 12
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Post by triman on Sept 20, 2022 2:35:12 GMT 12
Hi Guys, I thought I would give a little background. It was obviously repaired by someone who knew what they were doing. I can just imagine my Grandmother asking for it to be repaired - no matter what. The rectifier valve was replaced with a few diodes and resistors. The audio output valve is a double diode pentode and was replaced with an audio pentode and a germanium diode. And the output transformer was replaced with a modern version. You can guess what probably happened. "That" capacitor went leaky and took out the output transformer, the output valve and the rectifier. Because of it's sentimental value to me I and to restore it back to original. I haven't worked out what to do with the output transformer, it would be good to have an original transformer back in there. I have plenty of options from that era which will look 100 times better, but no NZ transformers. I'm listening to it at the moment and wanted to share a picture. All the best Craig  Attachments:
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Post by Peter Walsham on Sept 20, 2022 9:02:18 GMT 12
Out of sheer curiosity, what had the previous 'serviceman' replace the output valve with? (I suspect a 7C5?). If so, then the 7C5 would have made the radio appear to be quite insensitive (lacking audio gain) & lacking power gain. The reason for this is that the EBL21 valve is a 'high mu' type - essentially meaning that it has a greater power gain for a given audio input signal. Did you replace it with a EBL21?
Peter
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Post by triman on Sept 23, 2022 5:47:17 GMT 12
Hi Peter, You are correct. It was indeed a 7C5 that was replaced (along with the germanium diode) and yes my intension is to put back the original EBL21 - but not yet implemented. But you raise an interesting point about sensitivity. Here in England (and I live in the Cambridge area which is quite a ways away from most of the transmitters) we are soooo lucky to still have several AM broadcasts available. The sad reality is though, that with time these are one by one being turned off. Sometimes I do wish I lived in America and I could chat about sensitivity and selectivity. On a related topic, there are dozens and dozens of AM transmitter projects available. You steam the audio from the internet and broadcast in the AM band (usually at 1MHz because it's a "nice" frequency). There are little to no projects which do the same for 2, 4 10 or even 20 stations at the same time and you can tune your dial into any of these stations across the AM band, I am currently working on such a project.  This is the unfortunate direction we are heading in. There are these stunningly beautiful radios out there and plenty of people (with the help of the internet) who can restore them to close to original functionality. But how can we use them? I would quite enjoy putting several of these streamed stations at 6/7kHz or 10kHz spacing and see how different radios selectivity works. .... Just some thoughts. Craig |
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