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Old 30th Jul 2021, 5:59 pm   #28
John Caswell
Hexode
 
Join Date: Jul 2009
Location: Wokingham, Berkshire, UK.
Posts: 437
Default Re: DIY FM tuner with 6CW4 nuvistor and ECC85

I have been reading this with a great deal of interest. Back in the early 60s I came across an article in the American Magazine "Radio Electronics April 1953" for a Long Distance FM tuner. having nothing better to do I decided to have a go at building this (fools rush in etc..what did I know about FM radio construction) My boss at the time, Bob, reckoned that we could do it together. It took about 6 months as we had to import a couple of valves from the US.
After much faffing about getting it stable (lotta gain built in) we finally had it running very satisfactorily. Its performance was quite startling, no good for FM stereo as IF bandwidth was quite narrow, but with the proverbial piece of wet string as an aerial, any signal passing was sucked in. When connected to a serious 8 element FM aerial long distance continental FM was eminently possible especially with Sporadic E conditions. I, in particular, learnt a great deal about RF earthing, component, positioning, screens across valve bases which has stood me in good stead in my later life, especially as I am now getting quite good at repairing/aligning Quad FM tuners.
A bit of a preamble for "regenfreaks" comment re an IF strip etc. I would think that a Quad valve FM IF strip would fit his purpose very well as it is complete strip with the mixer IFT mounted on it ready. It should be possible to find a valve FMT to butcher, and I think I may have one somewhere, will have a look and post back here If I find it.
Next thought I am pretty sure that the article will be in the American Radio Magazine website.

John

Last edited by John Caswell; 30th Jul 2021 at 6:07 pm.
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