When M0XDK first asked my opinion on the PA0RDT mini whip design I told him I had no idea how it could possibly work. I think “snake oil” may well have figured in my reply. I didn’t put him off and he put one together from junk box parts. There were probably too many substitutions as it showed more promise as a jammer than an antenna being very unstable and oscillating at the slightest provocation. He bought a kit of parts from an eBay seller and was impressed with the result. Naturally when I looked the seller had no more on offer but I was able to find a kit of parts sold by WA3IAC Chuck Steer as eBay seller chuckwa3iac. Well after building mine and doing some initial testing which has unfortunately been brought to a premature end by a mishap with my FT817ND power connector which I won’t be able to fix till I get back home I still have no real idea how this design works but it certainly does. From the WSPR trials I did manage to do it was between 2dB and 7dB down on the 20m loaded whip I’m using for WSPR here at my holiday caravan on 20m and a few other bands using an LDG Z 817 QRP auto antenna tuner whose testing too will have to wait a while now. Now 7dB down on an antenna that is already down by no doubt a fair bit on a dipole isn’t world shattering until you consider it is less than 30cm total size and covers from MW to at least 30MHz and possibly more. I’ve been impressed enough to order another kit to mount at home.
Unfortunately the FET blew just before end of the caravan season so I’ve had to bring it home for repair. I’m not sure if this was just bad luck or is going to happen regularly – time will tell. If it does happen again then I may put a 1 meg resistor from gate to ground to bleed off any static that builds up. Testing will resume about April 2015 when we start using the van again. I have built the extra kit for use at home but haven’t got around to installing it yet – there are a number of outstanding antenna projects and it looks like I’ll need to drill yet another hole through the wall to accommodate the cables. I’ll take the opportunity to bring the weathercam feed in with RX antennas only as just the 120mW my WSPR beacon generates is producing some severe interference on it.