Quote:
Originally Posted by Julesomega
You can now connect the three windings in series, with taps at 3 and 9 turns
|
My mistake, should have said "at 10 and 20 turns"
I had to try one so I bought from a UK seller and it arrived quickly. The original 66cm loop is 1.1mm dia stainless and the sensitivity was poor though it shows sharp nulls. I increased the loop to 1m dia using 6mm thick wire, like CT100 outer, and the sensitivity increased disproportionately. Now even the local noise background is S9 on MW and I'm hearing audio or carriers on most of the UK channels. The main limitation may be the internal noise (noise factor) but it is extremely good for local signals including anything you can hear weakly on a transistor portable. I was expecting signs of intermod everywhere but I can find none, even around local powerhouse Moorside Edge (400+50+50kW).
The sensitivity remains good at HF, though I've not done any critical tests above 5MHz. The most wonderful feature is that it has fabulous immunity to local mains noise. The loop and amplifier are balanced with a transformer output to feed the receiver via 10m of co-ax. Reception is unaffected by appliances in the house with the loop 10m from the house. This without any chokes or braid breaks on the cable. Hooray!