01-05-2023, 09:21 AM
(This post was last modified: 01-05-2023, 09:31 AM by Radio Fixer.)
Just type into Goggle: “australian vintage radio” and it will bring up several leads to societies and groups with meetings in major Australian cities. I had a quick browse of Etsy, an auction site, and most of the early radios were from the USA. A friend down in NZ, said when he started collecting, as a young man, he called it Atwater Kent land as there were so many to be had.
In an article by him (https://nzvrs.com/peter-lankshear-articles/) one of those on the Early Days, he repeats what I said about distances ‘down under’ being similar to those in the USA and multi valve sets sold and would perform better than the sets made in Britain and Europe. Here, in our country, the distance between transmitters and receivers was short and 4 or valve sets the norm (don’t forget the valve Tax). Even Europe was behind the USA in receiver design and as an example Philips didn’t make a Superhet until about 1934/35 .
The Zenith, we are talking about here, is from 1936 and is before the triode hexode was commonly in use. It was probably invented around this time but even in radios worked on by me, from 1939, isnt seen.
Even Philips British sets in my collection from that year dont have it. I am aware of a German version of one of mine, the D58 1938/9, that used used an ECH11 triode hexode. This valve type was, it has been said, cleared up many problems. As you have noted it isolated the aerial from the oscillator better.
Yes! Adding a tuned RF stage in front of a multi grid ‘mixer’ would do the same and I think on the sets that I have worked on improves sensitivity on MW and LW bands (I was too late into the hobby for there to be much to explore on SW). I read somewhere of gain up to X10 but maybe this is unlikely. It would be easy to be impressed by the presence of big multi valve sets to imagine sensitivity that isn’t really as much as thought and I have no means of measuring and comparing.
A read I shall do again, when I have the time, is the chapter on Frequency Changers (Page 88 on) in the book “70 Years of Radio Tubes and Valves” by John W. Stokes. This whole book could be downloaded on line at the time I wrote an article on restoring the Zenith.
Gary
In an article by him (https://nzvrs.com/peter-lankshear-articles/) one of those on the Early Days, he repeats what I said about distances ‘down under’ being similar to those in the USA and multi valve sets sold and would perform better than the sets made in Britain and Europe. Here, in our country, the distance between transmitters and receivers was short and 4 or valve sets the norm (don’t forget the valve Tax). Even Europe was behind the USA in receiver design and as an example Philips didn’t make a Superhet until about 1934/35 .
The Zenith, we are talking about here, is from 1936 and is before the triode hexode was commonly in use. It was probably invented around this time but even in radios worked on by me, from 1939, isnt seen.
Even Philips British sets in my collection from that year dont have it. I am aware of a German version of one of mine, the D58 1938/9, that used used an ECH11 triode hexode. This valve type was, it has been said, cleared up many problems. As you have noted it isolated the aerial from the oscillator better.
Yes! Adding a tuned RF stage in front of a multi grid ‘mixer’ would do the same and I think on the sets that I have worked on improves sensitivity on MW and LW bands (I was too late into the hobby for there to be much to explore on SW). I read somewhere of gain up to X10 but maybe this is unlikely. It would be easy to be impressed by the presence of big multi valve sets to imagine sensitivity that isn’t really as much as thought and I have no means of measuring and comparing.
A read I shall do again, when I have the time, is the chapter on Frequency Changers (Page 88 on) in the book “70 Years of Radio Tubes and Valves” by John W. Stokes. This whole book could be downloaded on line at the time I wrote an article on restoring the Zenith.
Gary
