Rap 'n Tap
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From: Philip Miller Tate
Date: 6/1/00
Time: 4:00:14 AM
Remote Name: 141.241.36.84
Rule of thumb: never ask what-if questions about aerials and their setting up, just try it out! All kinds of things work unexpectedly, especially at short wave. Short wave reception doesn't usually need an earth the way that lower frequencies do, so do try hooking up to that FM aerial - the downlead may work a treat. Try (i) one wire to aerial socket; (ii) the other lead to aerial socket; (iii) one to aerial, one to earth socket; (iv) the other way round. You'll not harm your set, because there's no significant current present (unless there's a thunderstorm going on!). I have seen a neat design for a shortwave regen. set using an 8-foot length of 300-ohm flat feeder, looped at one end, as both the aerial AND the tank inductor. With receive aerials at short wavelengths, life is full of surprises.
Re. variable capacitors, it depends on the sort of capacitor you intend to use. Cheapo transistor radio polyfilm variables are usually in two halves, 140pF + 140pF or 120pF + 120pF. One section would do. With air-spaced units, I have heard of folks carefully pulling some of the plates out, but that feels like vandalism to me!