Fredbox schematic

Fredbox 2m AM transceiver

The Fredbox was my design for a 10mW AM transceiver for 2m use back in the 1970s. It was rebuilt a few years ago and a 6m version was spun off. The same basic approach would work on 10m and 4m too, but I have not completed versions for these bands.

Even 2m 10mW AM was enough to work across the English Channel handheld on 2m and the 2m Fredbox made several 60 mile handheld QSOs . For quite a while it was used to natter across town in Cambridge. The Fredbox was named in honour of local Fred G8BWI back in the 1970s.

The Fredbox and Sixbox have appeared in G-QRP SPRAT and in Practical Wireless mags. The schematics also appeared in several foreign language magazines too. The circuits are basic and certainly capable of being improved.

See https://sites.google.com/site/g3xbmqrp3/vuhf/fredbox.
See https://sites.google.com/site/g3xbmqrp3/vuhf/sixbox .
 

Roger Lapthorn, G3XBM, is a regular contributor to AmateurRadio.com and writes from Cambridge, England.

One Response to “Fredbox schematic”

  • Dave K1THP:

    Hi Roger,
    If you ever come up with a pc-layout for the Six-Box keep me in mind, althouigh nI may try it this winter using the old Manhattan stye of island construction used by many simple QRP designs. I had forgotton about how good super regens worked back in the early sixties. The Heathkit Sixer and Twoer rigs were examples of rigs that brought vhf operating to many new hams on a school boys budget.
    73,
    Dave K1THP

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