I have a pair of Denco Maxi-Q Type “C” TRF Coils, the ‘improved’ version, from the 1950s or 1960s. They originally came with an information sheet showing the connections and a suggested circuit…so far I have been unable to find a copy of the sheet, and wondered if anyone else could help; I’ll then share it with others too.
But, before you jump in, I know that there is half a page on them in the Denco Technical Bulletin DTB4, which is freely available on the internet…but it doesn’t include the content on the sheet. I also know there is a receiver design by SW Amos using EF50 valves in the February 1950 edition of Wireless World…but that uses the original version of the Type “C” coils. Denco DTB4 suggests the use of the ‘improved’ coils will improve the performance of SW Amos’ receiver. Again, it doesn’t contain the content I’m after.
These are also NOT the same as the little nine pin (B9A) coils and older Octal coils, which people used in projects fifty or more years ago…so the information sheets for those are no good either.
The Type “C” TRF coils are chassis mounted with a screw, and have no adjustable dust core. They measure about one inch in diameter across the base, and are dual range coils for medium and long wave.
The photo above will show you my coils, but I’m hoping someone else has a copy of the original information sheet squirreled away somewhere, that they could do a good scan of for me.
Can you help?
I have another set of identical coils, except the green coil has no tickler winding…I’m assuming it is for a true TRF receiver, rather than a regenerative receiver. Can anyone help with that too?
I actually have two sets of these.