Having acquired a FT405D from my good mate Steve over at Mullard Magic I experimented last night with a loft dipole – my aim is to make up a fan dipole for 40 thru 6 metres (for 40m it will be a zig zag). So, having measured the coax distance from the proposed centre point to the radio I made up a choke round a bit of 7″ PVC and hung it from a wire dipole centre supported by string.
Ok so far. As 6m is the shortest wire I decided to make that one up and see how it looked on the VNA.
So, two bits of PVC coated wire with crimp connectors for the dipole centre went up in a more-or-less inverted-vee stapled to the rafters. The SWR was 3-ish, not bad for a first go. Then the cable went loose but the SWR dropped – one end pulled out of its crimp! Huh. Eventually, after a bit of a fiddle I got to 2-and-a-bit SWR, fine for now. Coax pushed thru the hole in the ceiling to the little bedroom and into the radio, after merrily knocking everything over. Coax into radio, and the internal tuner is happy. But absolutely no signals! Hmmm. Well, it transmits, I can pick it up on the IC-R2. But no idea if it transmits more than 6 foot…
I tried the local repeater, no joy. Mind you, I’ve never even heard signals from that so maybe it’s just too much to ask.
Of course having made one continual length (17 metres of Westflex WF103 in all) of coax I cannot now use the VNA in the loft! So I need to cut it and add a couple of plugs so adjustments can be made up there… probably a good time to wrap the choke in tape too as I can imagine it trying to unwind itself given the chance.