Pineapple standards converter.

[Richard_FM]

I've been intrigued by the pre-Aurora & Hedgehog converters.

The other ones I've heard of are the Dinosaur & Domino, there might be a few more enthusiast made ones.

This mentions 2 semi-professional ones along with details of one made from Rediffusion teleboxes, https://www.bvws.org.uk/405alive/tech/modulator.html

[ppppenguin]

Lots of stuff about 405 converters in several articles on my website.

[Richard_FM]

Lots of stuff about 405 converters in several articles on my website.

Thanks they look very interesting.

[ppppenguin]

There are many ways to make a modulator. The modern method is software defined radio. I did a quick and dirty experiment with an FPGA and DAC . Just a 1kHz sine wave on a 15MHz carrier but it was proof of principle. Frank Cuffe has also done some experiments.

I don't know if anyone has used one of the commercially available SDRs to do 405.

One thing that should be possible with SDR is vestigial sideband. If taking DIY approach in FPGA the Weaver or 3rd method for making SSB can be adapted for VSB.

[Geordie McBoyne]

An early attempt to construct a "self build" standards converter. The attachments show such a converter. The project started in late 1984, stalled in January the following year, restarted in August and completed by October 1985.
The converter fell into disuse and was just about to be scrapped and the parts used for other projects. However, in 1990 a fellow vintage TV enthusiast spotted the remains of the converter and asked if if it could be reconstructed, which it was. It was in regular use until replaced by an Aurora SCRF405 converter.
Pictures were taken October last year.

Geordie McBoyne.