User-friendly 'kitchen cupboard' pantry transmitter

[Phil G4SPZ]

I’ve recently restored a KB FB10, and it now has pride of place in our kitchen. I wanted to simplify the use of this set and make it a viable performer by feeding it with alternative signals from a pantry transmitter. This has been so successful that I hope you won’t mind my sharing it with you.

I try hard to integrate my enthusiasm for vintage radios with normal family life, and whilst my wife is very tolerant of finding vintage sets in most rooms, quite rightly she expects them to tone in with the decor and likes to listen to them, but she expects to find Radio 4 (the FM programme material) and Classic FM, neither of which are available on conventional two-band sets. I had a spare commercially-built AM03 AM modulator, so I installed it adjacent to the newly-restored radio in the kitchen. I tuned the modulator's output frequency, on medium wave, to be in the same position on the FB10's dial as Radio 4 long wave. In the case of this particular set, this is around 400 metres (750kHz) which fortunately doesn't clash with any strong MW signals in this area. So if the cricket or the Daily Service on long wave don’t appeal, all my wife has to do to choose another programme is switch to medium waves, without touching the set’s tuning.

The audio feed to the AM modulator comes from a Logik IR100 internet radio which I was given a while back, and is out of sight in a kitchen cupboard. This set picks up its signal from our home wi-fi and has five presets which I’ve tuned to our favourite stations, including the feeds for Radio 4 FM, Radio 4 Extra, Classic FM, and of course my own favourite, Radio Dismuke. The source receiver and modulator are powered from a single mains socket, so can be switched on and off easily as required.

The AM03 is no longer available, sadly, as it was very reasonably priced (probably too cheaply to be commercially viable), covers a wide frequency range and gives excellent audio quality. A fine alternative is the excellent MiniMod, designed by Ian Liston-Smith G4JQT and which features several times on this Forum. I’ve built two of these and they perform brilliantly. Both the AM03 and the MiniMod are very low power devices and have a range of just a few metres, so are most suitable for use in conjunction with a single vintage radio or as a portable source of AM transmissions, but on the positive side they are unlikely to bring the user to the notice of the authorities, as their output signals have such a short range.

[Bazz4CQJ]

I'm using one of the LineX devices that Paul Sherwin recommended and works very nicely. My own favourite internet station is a little more modern than yours Phil http://www.softclassicrock.com which I can thoroughly recommend to anyone who's formative years were in the period 68-76.

B

[Phil G4SPZ]

Hi Bazz,

I assume the LineX is the FM transmitter. I have a couple of small FM transmitters too, they are very good and licence exempt in the UK but in this case I'm sending signals to an AM medium wave radio, hence my references to the AM03 and MiniMod.

I'm aware of two commercially-available AM medium wave modulators, the Spitfire and the SSTRAN AMT3000, both of which are in the £70 price bracket and deliver 100mW output, which comply with the American FCC Part 15 licence-free regulations, but may be too high for comfort if used in the UK. The MiniMod is available in small quantities built to order for around £35 - check with Ian G4JQT.