Yes, another build.
(You too can post your 'homebrew' builds on here you know, whether wiring up a new mic, soldering that pesky PL259 or a new desk for your latest rig it's all good.
It doesn't have to be all that 'technical', just something you're proud of achieving.)
Recently I managed to sweet talk my better half to get back up in the loft/attic for me, (suitably floored with ladder access), to string up yet another antenna or rather extension to the previous for me. She's a wonderful woman putting up with my crippled nonsense but we ain't spring chicks and I have her hips to think about so won't ask her again!
We'd found a reel of mains wiring left over from some years back hidden in the back of one of the sheds during a spring clear up. I was elated...she sighed and said "Keeping this are we?" so I set about stripping it apart to get at that lovely copper wire thinking all the time what antenna design I could come up with. Having success up to now with a 'doublet' made from an electric lawnmower lead plus keeping in mind the age old Ham suggestion of "as much copper as you can as high as you can" a longer doublet was on the cards.
Squeezing it all in would be a right old job and I knew I would have to come up with simple instructions my 'willing assistant' could follow. She did a grand task of unstringing the last 88 foot doublet and adding all this extra wire to it before stringing it all back up to give me a 135 foot doublet. Wish I could do some graphics to show but it essentially runs across the roof apex either way for a bit before zig-zagging across the rafters either side of the roof space giving a sort of end loaded affair that only just about fits. A zig-zag antenna? Yep, you can just about get away with it too and how the last one operated.
Would it be any good? We'll just have to see won't we.
I couldn't get a very good match on some bands with my
Pi Match ATU even though it had been
Modified and my
160m ATU no longer worked either being designed for the shorter antenna.....Bum! (Or words to that effect.) I did hang a temporary made coax fed sloper dipole for 10m from the front of my house (much to the annoyance of village neighbours!) so I could at least join in with the
10m Summer Challenge but wasn't having much luck with it.
Pulling apart the 160m ATU for the T200 inductor, ordering a FT140-43 toroid for a new 1:1 choke (You don't need the expensive FT240 if using less than 150 Watts or so) and some other choice bits I came up with this:-
Yeah, right old 'breadboard' mess but flip me it works and that's what counts!
The switch for the inductor was made from an old 1960's "Made In England" job I had in my parts bin, problem was it was a four pole three way switch so I had to pull it apart to convert it to a single pole twelve way. (Try doing that with a modern switch!) A couple of old radio variable tuning capacitors I bagged recently, a few bits of wire and suitably connected together to make a typical T-Network matcher/ATU. The damn thing tunes the new doublet from 160m to 10m without a problem. You really do need to know how to tune one of these though so that you don't get confused with a low SWR reading along with QRP power and actually be miles off....you won't half notice on your receive.
How does it do then?
Surprisingly at 10m the 135 foot doublet did better than the 'resonant' tuned 10m sloper dipole!?! A/B tests are hard to do accurately and maybe the obvious 'floral' pattern of the doublet was getting areas the sloper may have not but there was a massive difference of several S-points. Luckily the bodged together ATU was able to load the attic 'monster' on transmit with a good 1:1 SWR (or near as dammit) so looked like it was good to go.
I haven't had much luck with my meagre 10 Watts on 10m SSB yet, but got closer than the sloper did with a Turkish "Repeat please, M7 What? M7 Victor? M7 Victor something Charlie? Sorry, propagation no good. QRZ"........Aaarrgghh! So close!
But then I did get a nice surprise when I dropped down to FT8 later and bagged Chile for the first time ever......not once, but flipping twice!
Obviously elated and eager to try it out some more now. Just as well because I don't think my missus is ever getting up in the loft for me ever again!
Just need to box it all up now. As lovely as those bakelite knobs are I may have to build some more wooden ones.
You don't always need a big expensive antenna nor lots of Watts to have fun with radio, (although it certainly helps for DX activities), and might be amazed at what you can do with essentially 'junk' and an attic antenna. I know I am and after achieving almost 1mW per mile I've seriously got the QRP bug too.
Have fun, enjoy your radio interests with much passion and thanks for putting up with yet more of my (infamous?) waffle.
All the best,
Victor
Today at 9:23 am by Razz229
Subject: Yet Another ATU! (T Match this time - can't help myself!) 
