E-bay find of the month

I'm delighted that there's been a fair bit of interest in the cheap loop idea.

Perhaps the only real problem with loops is their extreme sensitivity to tuning - which of course is why they are also good for receiving, as they reject pretty much everything outside an incredibly narrow 'window', such as that depicted below:

 

Whilst a motorised tuning system is pretty easy to construct from cheap components, a manual system is more useful in the field, as there is no need for batteries.

But it can be tricky to hit the 'sweet spot' reliably, especially near the self-resonance point of a loop.  A drive reduction system is desirable, if not essential.

So, I was happy to find this pretty vintage 10:1 reducer last week for about £14, not much more than the new, but far more basic and coarser 6:1 units you can find also on E-bay.

 

If you are going to get a reducer, keep in mind that the body of the drive has to be secured somehow, otherwise it has nothing to turn against.  This is sometimes not so easy to arrange.  This unit has holes through which it can easily be secured to a panel or frame if needed, but I found that, with the help of a single turn of self-amalgamating tape, it would fit neatly into a 22mm PVC pipe clip.  Very simple, for once!