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Thread: Schematic for valve stereo FM Transmitter needed

  1. #1

    Join Date
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    Default Schematic for valve stereo FM Transmitter needed

    Hello one and all,

    This is my first post here so I thought I'd kick off with a doozy.

    A local radio station that I volunteer with has just been awarded an FM Community Radio Licence (we're currently broadcasting on DAB+ and the interweb). The application has been in for some time now and we're over the moon to be getting back on the FM airwaves after two very sucessful RSL broadcasts.

    Now, I'd like to look in to potentially building a 25w stereo FM Transmitter but after some, albeit superficial, searches on Google I can't seem to locate a suitable schematic to help point me in the right direction. I did, however, find this site so thought I'd try and pick the brains of those more knowledgable than I.

    Can anyone help me on my quest?

    Thanks in advance,

    Rich

  2. #2
    Super Moderator 5B4AJB's Avatar
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    You mean a valve linear amplifier? pretty simple circuit for a monobander...

    A full valve stereo transmitter is going to be huge - get over to ebay and check out some of the cheap stereo transmitter there, it will save you a lot of headaches...

  3. #3

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    Quote Originally Posted by 5B4AJB View Post
    You mean a valve linear amplifier? pretty simple circuit for a monobander...

    A full valve stereo transmitter is going to be huge - get over to ebay and check out some of the cheap stereo transmitter there, it will save you a lot of headaches...
    Many thanks. Didn't think of fLeabay. I'll check that out.

  4. #4
    dtrewren's Avatar
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    I have not looked in detail at these offerings but lots of FM power amplifiers available here ......

    https://www.ebay.co.uk/sch/i.html?_s...ifier&_sacat=0

  5. #5

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    Well - not wishing to put the mockers on this, but the standards OFCOM insist on for broadcaster of all sizes make it quite unlikely you could build one that met their standards for much less than the price of buying one.

    I assume you've read the technical standards requirements - https://www.ofcom.org.uk/__data/asse...3/code2013.pdf

    Some of this is quite rigid in engineering terms, and probably why RSL equipment hire fees are 100-300 a week! You can buy a cheap on for around 600 that meets the EU spec. I'm sure you can build one - maybe from a kit, if you aren't that advanced - but you'll need to get access to some decent test kit to align it and prove to the man from OFCOM who comes to commission and test it, that it is suitable. For the sake of 600, I'd buy one that would be guaranteed to comply. It's a nice project - but looking at the kits available, it's very unclear if they meet the specification OFCOM insist on. Looking at the Ebay products, I doubt hardly any would comply - and the people selling them mention ham radio, so they have no clue either!

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