Homebrew ATU for 160m with a way too short antenna!

Hi All,

I hope you're keeping well and most of all enjoying your radio.



Recently I'd made mention about some experiments I'd performed with my way too short 44 foot Doublet antenna.

Despite it's diminutive size I've managed to press it into service already for 80m using my Pi-Network homebrew ATU.
(Was extremely pleased at making my QRZ World Friendship Award for 80m despite this antenna's small size.)


This all came about after reading an article here :-

https://www.dj0ip.de/open-wire-fed-ant/short-antennas/short-160m-antenna/


It pricked my ears with interest and I set about to utilise what sits in my junkbox. (Pretty much the whole of my shack is a junkbox!)

One old broadcast valve radio variable capacitor later, (that's been pressed into service for various projects and now pushed for this), plus a fat T200-2 toroid later, (I didn't have the huge and expensive T520 toroid mentioned in the article), and we landed up with this monstrosity.....





Bit of a tangled mess isn't it? 

None of that matters, it's whether it works or not that's important.


A quick test with the NanoVNA I luckily have assured me that it should work and a test transmission showed that I could get a good 1.1:1 SWR. (Not going to claim a 1:1 or even get into the arguments of what that actually means.)

With my Foundation licence 10 Watt limit we had no RF feedback so no issues in the shack, the link coupling, (bit of RG58 wrapped around the toroid and windings), ensured the doublet antenna is both galvanically isolated and as balanced as it can be. Handy, because then I didn't need the ubiquitous 'earth'.
The toroid also didn't heat up in any appreciable or detectable way either.


So does it actually work?

Well I suppose that depends on your point of view....

It certainly works on 80m being pressed into some FT8 action and makes the short bit of lawnmower lead in the loft, (ahem - antenna), less noisy than with the old Pi ATU. Always a bonus to improve your signal to noise ratio. I can actually hear more SSB transmissions than the local webSDR does with it's full size G5RV!

So last night, (18/08/22), I pressed it into service dialling that VFO on my old Yaseu FT757gx to the 160m band.

Bit of a tweak to the ATU variable capacitor and greeted with some white noise soon to come across the old 1942 net boys. (1.942Mhz) They were booming through from S5 to S9 but all a good radio 5.

A bit further up at 1.895MHz and the W.A.B. (Worked All Britain), fellas were coming through with one station at S9 +30!!

Dialling down I came across a French speaking Net, a little noisier but still legible with S3-7 signals.

Finally down at 1.840MHz the FT8 frequency to be greeted with........absolute silence!?!

Where is all the FT8 whale-song that always seems to come through regardless of prop forecasts on the other bands?!


I stuck with it making CQ calls hoping to hear at least something or a PSKReporter site report come back to me. (There were all of 15 stations monitoring FT8 according to PSKReporter.....in the whole world!!) Soon there was a Dutch station also calling CQ but despite several attempts at contacting them I never got a response. Perhaps this isn't working as well as I expected?

A short time later and a UK 'G' station started calling CQ so rather than give up early I called them.......and I got a response!!





My very first 160m contact!

Very pleased with myself and the heap of junk I utilised to perform this.


Now, some of you might not be that impressed.....A 46 mile contact? The next 'square' over? On FT8? Bit pathetic isn't it?

Not so......especially with such diminutive equipment available to me.


I've always said "Never Say Never" and also "Any antenna is better than no antenna". I certainly wouldn't have a 160m contact in my log had I taken thoughts to the contrary. Amateur Radio can and should always be about pushing yourself, to experiment, to see what you can achieve and I think I managed that well.


What now?

Well, I'm going to rewind that toroid with some thicker wire now that I know I need fewer turns and house it up with appropriate switching just for 80m and 160m work. Some 4mm banana plugs on the lawnmower lead ladderline should enable me to switch the antenna over more easily. As the winter months come on and the higher bands die off a little I'll be able to plug up and check those lower bands for some action.

Hopefully I'll be able to beat that so far personal best of a 46 mile contact.


I could give SSB a bit of go, especially as my 10 Watt Foundation limit isn't far off from the Intermediate and Full licence 32 Watt limit.

https://www.ofcom.org.uk/__data/assets/pdf_file/0027/62991/amateur-terms.pdf


Let's see what that 'short' antenna can really do.



More of my 'waffle' but I do enjoy writing about what I'm up to and hopefully it inspires someone else to give such things a go.

All the best,
Victor

Nice one Victor.
1 up on me i have 0 ft4/8 contacts on 160m.
Doesn't matter what it looks like as long as it does the job.
Will have to target 160m now lol don't normally bother with there or 80m on ft4/8 40m early in the morning but then that drops out for me after about 9am or even before.
Would send you the cable of our mower but it's battery and not got one.

Cheers Alan.

I'll probably never get a QRZ confirmation much like the rest of the contacts we get so will still need to work twice as hard.

It's been fun and hopefully will give me more fun putting it into regular use.
(Next challenge is boxing it up.)

I wax lyrical about the 'lawnmower' lead but it's just a length of copper wire after all.

Be careful with that lawnmower of yours...it may not have a lead but it's got a handy battery, motor, switches....

It's Linda's mower lol she don't like anybody else cutting her lawn.
My job is keeping the moss clover and that stuff away and feeding it twice a year.
Might have to get one of my external tuners out as the internal won't tune up on top band.
Might just do that now thinking about it ready for morning well if 40m and 80m is to go by i get more on there early 5am ish don't laugh i don't sleep well.

Edit
Brazil "bing" on 17m as i clicked send on this R-18 but got it.
Edit Edit
All set but noise band here.

mAT-30........I've got one of those, or at least the case for one after my old Ham friend burned it out!
(I think he was trying to work the lower bands as well with his end fed!)

My circuit posted is basically an L network matcher but I could never get one to work until I stumbled on the article mentioned with the link coupling. Thinking about doing the same with my upper HF ATU now to see if I can get any noise improvements up there. (Although the 1:1 Guanella is doing the job for now.)

I did get horrendous noise and 100Hz lines all over the waterfall especially if a neighbour started mowing their lawn with a mains electric mower. With this new circuit I don't get any of that at all.
Not that many are mowing at night when the band picks up!


The reason I like to experiment is put really well on Rick's (DJ0IP) website -

"It doesn't have to be perfect to be good enough."


That and not being able to afford to 'peruse' through the online catalogues for shiny goods that are essentially 'black boxes', as in you don't know what's in them or whether they can do the job until you've paid for the damn thing.

Like you Alan I get up early enough to kick the old 'cockerel' out of bed, but although I have the luxury of an indoor shack it's right next to the bedroom where the missus is and she would not be a happy bunny if I fired up the radios at that time!


Anyway mate, I wish you well with it, be good to see you 'experiment' and see if you can get on those other bands too.

I wish i had the brains and the patience to make something like you have done but you know me.
Let me know when you get the top band star in qrz i will do the same but not holding my breath on it lol.

It's just a coil and a capacitor after all Alan.


Well my FT8 on 'top band' tonight has been as lacklustre as this posting......lots of views but little in the way of replies. (Always appreciate your replies though.)

Reports coming in from all over Europe receiving me but no one answering?!?!?

Time to call it a night methinks.


All the best to you Alan.

Victor wrote:

It's just a coil and a capacitor after all Alan.

It might be. But you clearly know what to do with them Victor. Well done on building and making work the ATU, and for making your first 160m contact!

I've tried the lazy route a few times to get contacts on 80m and 160m, by just using the rig internal tuner, which does match up the 10m to 40m fan dipole on both those lower bands, but because of what it is matching up and the coax losses I am probably only effectively radiating milliwatts. I've managed half a contact on 80m (didn't get full callsign over) and nothing on 160m.

Been reading through some of the Intermediate manual over weekend. I reckon you'd breeze certain sections of it that my brain is struggling to take in with your hands-on experience of caps and coils.

Cheers Neal,

(BTW, liking your new profile pic.)

Like you I tried the route of simply 'matching' an antenna and quickly found coax to be the issue and hence why I moved to ladder line as well as losses that can occur through a matching or ATU system. The article mentioned gave me a path to explore with other options and I'm glad I was able to knock something together from the junk I have laying around in my shack.

I'm still loving getting a 160m log entry from such a setup though.  


Yeah, should have thought about what I was saying before I said it as in the capacitor/coil remark......
It can be as complicated as you like getting involved with all the mathematics if that's your thing or as simple as throwing some windings together and an old capacitor, (which is pretty much what I did!)

OK, some "maths" was involved but nothing extraordinary.


I have been inkling with the Direct To Full path but we shall see. At the moment I'm having too much fun building stuff and QRP.

Cheers again Neal and I wish you the best in everything you do.

Well, it's been a month and I've since added an extra 22 foot to my antenna.
(11 foot either side with some speaker wire attached to the lawnmower lead! )

Made a huge difference on the bands and surprisingly much better on the higher part of HF. (???)

About time I beat my measly 46 mile distance......

Poland - SP7TF - 160m - FT8 - 10W

That'll be 875 miles then.


Still not great but better than expected and although I'm being reported back on PSK reporter I don't seem to be getting a lot of replies? Go figure.

Don't know how to improve on this all now as I've gone from 44 foot which just about fit into the loft to 66 foot which is a tight squeeze, (and clever folding!) I'd have to scrounge some more wire from somewhere too.....my wife has already told me to keep my eyes off the Henry vacuum mains lead!!


It's all fun and after all isn't that what radio should be all about.

All the best,
Victor

Nice one Victor.
Not had much on it 160 that is the last couple of days.
Not sure but i don't think that many people use that band on ft8 but could be wrong.
Don't look on the sdr ?? sites or whatever should give it a go but thought that many times and never did.
Not sure on my longest contact but it is not far but things will get better.
80 isn't up to much this morning as well but just had my third contact in 45 minutes lol.
Of to try 40 then 30 now see what is going on.

Very well done victor. I don't know what to suggest to make further improvements to the antenna for a small space, I'm still a 160m tx virgin so no experience. With you managing a QSO of that distance I am sure you'll get some more good ones in using it.

Thought about making a very compromised antenna for the band to tx, but I can hear quite well with all the wire in the loft attached and on phone modes all I've heard is the 1933, 1942 etc type groups that I'm not really interested joining in with even if they let me.

Hi Lads,

Appreciate your posts and quite pleased with what I've achieved with relatively little. I do like to give things a go!


Alan,
You're quite right, when you look at how many active FT8 stations are on the air on 160m it's very lacklustre, but perhaps most think you need a massive antenna and don't bother with the band.(?) Then again I lit up the USA on 17m last night with reports but do you think I could get a contact from any of them!?! Always worth trying even just for the fun of it despite not yet gaining a QRZ 'star' on 160m.......yet.


Neal,
Yes, very easy to receive on the 160m band but totally different kettle of fish trying to transmit there as I've found out. (At least I'm a bit beyond limited NVIS now.) Never let the 'clique' groups put you off though, (seems the 42 boys don't need call signs?  ) There are a few more open and welcoming transmissions down there which I've received before with the odd CQ and the WAB lads doing their thing. Just hoping I get to catch some of that action now I can transmit more successfully on the band.  


I'm going to keep plugging on with it all as it has been fun and a great learning experience. 
Plans are afoot for a different ATU with either a dirty big air coil on a balanced circuit or maybe even a much bigger toroid choke.... that and seeing if I can scrounge up some more 'unneeded' wire.


All the very best to you both,
Victor

Victor
I bought a roll of this yesterday post and vat kill it somewhat but at the price i can play for a while.
30m is working well for me this morning.
Clicked on it and started looking at emails then got the Bing turned to look and it was a station from Australia called me.
Wire link   https://cpc.farnell.com/unbranded/6011713/cable-6491b-1-50mm-grey-100m/dp/CB19154?st=6491b

Hi Alan,

Cheers for the link and glad you're having fun with it all. (Antennas - the most fun you can have with bits of wire!! )

30m can be pretty active at times and pleased you're enjoying the fruits of your labours. I did manage Monaco last night on 30m but as of yet no confirmation....not holding my breath though despite the fact a confirmation is just a mouse click away.

I'm enjoying the "didn't cost one farthing guv'nor" attitude I've taken with my radio exploits scrounging around for bits I need where I can. I think it makes it all that much more fun!


You keep enjoying yourself Alan mate and post up any successes, (or failures as they're a learning experience), where you can. I enjoy making my postings but I don't half enjoy reading what everyone else is up to.


All the best,
Victor

Well done Victor. I always used to enjoy listening to top band and 80m when I was a teenager, but that was over 50 years ago when we didn't have all the QRM. I can't here anything on 160 now except about f6 of noise. I have a long wire the full length of the garden (about 60 feet). It's good for 80m to 20m but I miss top band.

Hi Michael,

Much appreciated.

Sounds like you're 200 foot short on your antenna too!
That's the problem I have in that my property is plonked right in the middle with the front and back garden both the same length and rather short. No room for an impressive antenna hence experimenting with short ones. (Plus keeping it away from prying village eyes by hiding it in the loft!)

I know what I'm doing is like tuning a paper clip up for 10m but I do seem to be getting at least somewhere with it all. (Hence the ATU build to handle the small impedances faced.)

Sounds like we had a similar story to tell with me listening on an old valve set tuned to the 'top band' above the medium wave broadcast band in my 'yoof'. 160m was totally alive back then with CW and of course loads still using AM or 'ancient modulation'. I'm afraid it's nowhere as busy nowadays but then many modern properties seem to have gone backward in time for hanging antennas with not many much bigger than the old two-up two-down terraces of old! (One of my daughters has a modern property, nice sized house but naff all garden.) I used to love listening to the old ship-to-shore telephony transmissions back in the day too but alas also gone.

Glad you're at least enjoying 80m and up though and believe you me 80 is a much busier band than 160m has been for a long time.

Oh, I had 6+ of noise when I first started out but moving to a doublet dramatically reduced that down to typical atmospheric noises. The only QRM now is when the washing machine is on or the neighbour is mowing her garden.


All the best to you,
Victor

Hi Victor. You have reminded me of the ship to shore. That used to be an interesting listen. I put f6 should have been s6. Either a typo or an age thing.

In them days I had an ex MOD R1155 and a Lafayette HE40. My Ariel was the metal window frame in my bedroom and it worked well. Both great radios and nowadays fetching silly money to buy if you can find one.

I'm getting s5 to 6 QRM on CB with my silver rod. I fitted it with a ground rod but all that did was raise the SWR so I took it off again.  

73s, Mick

Nice radios you used to have there Mick which increased in value and collectability unlike those that used to own such wonderful stuff!

I had a Codar CR70A which was my pride and joy for a while but most of my old SWL days was spent modifying discarded sets as well as making BFO's to resolve CW/SSB. I have a defunct 1950's Jubilee II and have been inkling with making a 12 volt operated valve regenerative receiver from the innards.....just for the nostalgia trip more than anything.

(Weren't those howls and whistles wonderful on some of those old sets!)

Metal framed windows, (single pane glass and Jack Frost in the winter!), they made for great antennas for a bit of SWL. I used to use the metal frame of my old bed before I started annoying everyone with lengths of wire hanging from everywhere.

Ha!
Better not start or we'd be here all day reminiscing.

Great to chat there Mick. Take care, enjoy your radio and I'll catch you soon.

73's
Victor