Stone Soup


At last, my µBITX is configured and I can use it for local contacts on 80 m, together with a Pi-filter antenna matcher and a G5RV antenna. The band is quiet at 09.00 local time and I am not likely to annoy anybody with spurious emissions.

The discussions about filters and spurious emissions go right over my head, since I do not have access to a lot of expensive lab gear. This can be left to those who have access to equipment and better knowledge than I have.

I bought a Wehrmacht receiver about 20 years ago. Although it was then about 50 years old, its calibration was still spot-on. It was quite simple, electrically, but was ruggedized and field-serviceable. Many of the components were located in individual diecast aluminium enclosures. Thinking about the discussion about µBITX filters, I realised that it would be reasonable to assume that the cross-talk etc. that people complain about could be cured or reduced by putting each filter unit in its own metal box.

So I offer the challenge to those who know better than I do - please install metal shields round each individual filter and tell us what happens.

While you are at it, you could also test rigs like the HW-7 or HW-8 and tell us about their spurious emissions.

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