70cms Homebrew 6 Element Yagi-Uda Beam

Hi all,

Hope you're all keeping well and enjoying your radio.  


Can't help myself, enjoy this radio malarkey so much that I keep building things. (Makes for brilliant learning experiences if nothing else! )

The latest 'homebrew' creation is after an opportunity presented itself in the shape of some discarded TV antennas.


Actually, they were 'discarded' in my own attic! Left over from when we had to upgrade our antennas for the TV analogue service switch off to go digital. They call it progress.....now I have more channels than I can shake the proverbial stick at with far less things worth watching!?! (Repeats of repeats and each channel labelling them as 'New' but only new to their network or channel not to the unfortunate viewer!)

Wouldn't mind but the new antennas are monsters yet don't seem to reliably pick up signals from a huge TV transmission tower I can actually see on the horizon from the upstairs bedrooms!
(Sandy Heath.)


Anyway, whilst stripping apart the old antennas I began a bit of reading on Yagi-Uda beam antennas.
"Uda What?".....Mr Yagi was the front man and most forget about poor old Mr. Uda.

So after a bit of reading, researching, more reading, (some people really like their maths and numbers ), I came across the following site :-

ON6MU - Home Made UHF Yagi Antennas

Ah, here we go, some actual sort of plans without all the 'fap-fap' numbers, charts, diagrams thing going on.


The basic measurements helped, except the boom I had was a different size.....and the directors/reflectors were flat, not tubes....and a different size.....and in fact nothing I had matched the materials list whatsoever!

Hmmmm.....let's go for it anyway!


I broke the aluminium pipe that was the old TV folded dipole trying to straighten it, (Doh!), but luckily I had some 8mm soft copper pipe left over from my 2m Halo Antenna project a while back. That'll make a new dipole and should fit one of the TV antenna mounts, (a bit of drilling to enlarge the holes from 6mm to 8mm helped).

When you make this dipole cut it longer than specified on the ON6MU site.....go on, ask me how I know that.
(Yeah, cut it flipping twice!) I made the reflectors & directors pretty much the same size as specified luckily just needing to trim the old TV aluminium struts down to size.

I didn't have another spare piece of aluminium to make the 'bazooka choke' mentioned on the site but a ferrite tube cut from an old PC VGA monitor lead should slip over the coax and do a similar job.  

Then I marked the boom with a pencil with where everything should be placed but did NOT screw everything down yet......


I carefully balanced the dipole, reflector and directors on the TV boom, (15mm x 15mm), where the measurements/markings were made. Then tentatively hooked it up to my Zetagi SWR meter.....yep, CB SWR meter and as long as you have low power going into it, (My Baofeng was set to 'L'), it's quite useable at these frequencies. I then slowly moved everything back and forth until I got the lowest SWR reading, (1.8 ), and then finally trimmed down the dipole until the SWR improved even more, (1.2).

I still did NOT screw everything down yet.

With the aid of a field strength meter, (I didn't have one but a couple of pin diodes and an old analogue meter later I built one!), I then slowly moved everything back and forth again until I gained the highest readings on the field strength meter. It was at that point that I drilled the boom for all the fittings and finally screwed everything down.


So with a big 'Ta-Dah!' we landed up with this -




None too shabby eh?


It would have all been a little easier had my antenna analyser gone to 70cms, (MFJ-259B), or if I indeed had a NanoVNA....but I don't, so I managed with what I've got.


So how does it perform? (The real crux of the quest.)

Well, with my little Baofeng and the nearest repeater being some 15-16 miles away, (GB3OV), my 70cm activity has been a little lacklustre.
(I can only hit GB3OV if I hang out of the bedroom window!)

......Now I can hit SEVEN repeaters!!!!

All a clear radio 5 just by pointing this monstrosity towards the target repeater whilst sat in my chair, in my radio room. (Yep, haven't even mounted it yet!)


Think that'll do nicely.  

I can even chat to my old Ham friend who is only 20 miles from here but is separated from me by a rather large hill(!). He opens GB3TU, (Tring), and I point my beam South accessing it thereby circumventing said hill.


Gain? - Hopefully whatever the ON6MU site says or as near as dammit.

Charts? - Yeah, not my thing



Anyway, thanks if you got through another instalment of my waffle. Been a while.

Don't be afraid to make an antenna out of what you've got laying around and if the maths and charts puts you off...simply ignore them.


Right, I have an old cordless drill lying around somewhere.....and a broken telescope equatorial mount....

Should make a nice antenna rotator!



All the best,
Victor

nice job Victor.love diy projects.have good experiences with diy antennas, made a lot of them.this is my for pmr:

Thanks Aleksandar.

Nice job there yourself with the PMR Yagi.


A NanoVNA like you have would have made the job so much easier! Not bad for my first ever UHF beam though.
(Now that I've built one I'll have a lot more confidence in building others.)


All the best to you,
Victor

put a stronger lithium polymer battery(more mAh) and little diy on SMA to SO-239 adapters on my nano.yes, made the job so much easier.

I did notice on the pictures there Aleksander. Looks like it makes the NanoVNA much easier to use.

Hi Victor

What a good bit of recycling and antenna building.

On the South Coast PMR net, antennas are often a topic on conversation and I say that if you see an old 406 tv antenna in a skip grab it. It is an easy/cheap way of building your first beam antenna.

Now what happens if another free tv antenna becomes available?
Will you adding more elements and doing a comparison?

Good luck & all the best

Ray

Hi Ray,

Thanks, did enjoy building it.  

I'll bet you have some great topics of discussion on the South Coast net and a shame I'm not a bit closer to join in on the fun. Well done tempting people into constructing their own antennas from whatever is available, I learned a lot, saved putting it in the bin and best of all it didn't cost me a penny!


Another antenna?
Who knows, but in the mean time I'm going to have fun with this one as I now have several more repeaters to explore.


All the best to you, well done with the nets & send my 73's to all involved.

Victor

Hiya Tony,

Much appreciated mate.  


No need to apologise about being away from the forum. Life, health, family, etc. will always come first.......Charlie Tango does come a close second though!

Sorry to hear you haven't been too well and I hope you are feeling much better. Please do take care of yourself.


All the best,
Victor

Well done Victor. It looks a very tidy little beam and pleased it's working well for you. Kirstie Allsopp would be proud.. if you don't know what she's into other than selling houses I am sure you'll come across her in a repeat of a reduce, reuse, recycle type TV program on one of the many digital channels at some point in the future.

I made an antenna out of what I had laying around yesterday too which was just up in the garden for the day. No photos.. they wouldn't be very interesting, it was just a sloping random wire for 10m - 20m. Mostly listened whilst doing other things, but had a few contacts on some of the bands in between from N Ireland to Russia. Surprising what just a bit of random wire can do when conditions are right.

I've yet to play on vhf/uhf. Have made note of your project for when I do as I believe the closest, or at least the most used repeater from me is about the same distance as the one to you.

Hi Neal,

Cheers mate, was fun building it and also having fun using it.

You can't beat a good old 'Sloper' for simplicity and radio reward on HF so well done on that.  

Kirstie who?  
(Never really been a big fan of TV but my missus brought me up to date.)


Yeah, get yourself on VHF/UHF Neal. Doesn't have to all be serious SSB competition stuff, the repeaters are great for getting to know Hams in your locality and I often listen to them in the background whilst doing stuff.

My nearest 2m repeater must be close as I can hit it with a Baofeng and the rubber-duck even indoors but there's never much traffic on there. (Can actually hear and open it on my old Yaesu FT227r hooked up to a dummy load!!)

The GB3OV repeater I mentioned can even open on low power on the Baofeng, (1W), with this homebrew beam! 

I'm looking forward to exploring more and even digging through old publications for further antenna ideas. Corner & Trough reflectors looked interesting but then I came across.......Bi-Quad Reflectors. Seems like that conversation we had a while back about the 'Duga' woodpecker array may make a scaled down appearance in my loft space after all.


Did tempt me into looking at modern VHF/UHF rigs but I don't like the fashion for 'closed systems' on repeaters today with Fusion switchover and the like. Amateur Radio should be open for all to enjoy so if I can do it all with a Baofeng and some scraps of metal then it makes it much easier for others to replicate. Between that and fitting CTCSS circuits in my old gear it doesn't have to cost the earth either. 

.....besides, most of the 'kerchunkers' and random 'hub-net' dial ups on the repeaters seem to be other 'bored' Hams anyway.


All the best,
Victor

Just to say a big Thanks to all of you that,

a) Read my waffle and

b) Commented and Liked  


Much appreciated and made this old fart smile!



Also a big thanks to the true king of monster antennas  Andy591/P  to which examples such as his 4 Element Quad I can only aspire to.

Another HUGE thank you to another certain Charlie Tango member that saw fit to gift me something to help me along my antenna quests and fun......more on that another time, for now he shall remain anonymous.


All my very best to all of you out there in Charlie Tango land. You're a very fine bunch indeed!

Victor

Victor.
I've got a Yaesu FT65E hand held and am going to have a go at building an antenna maybe like the on you've done here for VHF 2m and UHF , Yagi or J pole . I notice you mentioned you got away with the CB swr meter .  The handy is only 5w output . You reckon I could just use the CB one to start with ?

For future I was looking at  something like a Sharmans AV 600 meter which covers 1.5 to 500+ MHz at about £75 , Do you know if they are OK ? I know there will be better but not got the budget for the higher end yet.

Hi Richard,

I used the old Zetagi meter as it's what I had to hand and does the job in a pinch. As I mentioned they are more sensitive further up the frequency range so need less power pushed into them for indication. They do perform a relative measurement anyway so as long as you can adjust the 'set' for FSD, (Full Scale Deflection), the readings will be in the ball park.

Remember that SWR isn't everything, you can get a low SWR and have a terrible antenna, (think dummy load - beautiful SWR right across the frequency range but useless as an antenna! ). Equally a less than desirable higher SWR can be read from a fantastically performing antenna.

The meter you mention is more than good enough for the job, (some people seem to collect SWR meters and pay HUGE sums of money for them too???), but I was gifted something after all this from a very generous Charlie Tango member which has become invaluable......a NanoVNA.

If you're really wanting to play around with antenna experimentation and construction these instruments are a God send and a fraction of the price of similar instruments....

...but, you'll still eventually need a SWR meter if you want to check your power output and antenna on the fly.


Have fun with your FT65E Handy and antenna experiments - "You can do a lot, with not a lot".

(I've honestly had a lot of fun with VHF/UHF and actually have more gear for those frequencies than anything else! )


Oh, one last thing. Have a look around for SOTA, (Summits On The Air), and portable operations for antenna ideas as there is a lot of useful information that can be garnered from more than helpful Radio Amateurs. Above all, have fun!


All the very best,
Victor

A lot of useful info there Victor 
I got some basic kit to get used to transmitting  really .and yes I have myself become a little "distracted" by VHF at the first turn of the course .   Much as I was wanting to get right into HF and DX . Distance is relative , and using  a band that is  challenging to gain distance through line of sight 50 miles can be an achievement in it's self and if you can do it  with home made antennae even more so,  a bit like catching  trout on a home tied fly. You have of course got repeaters and satellites too . There also  seems to be a "community" type thing going on with vhf as it's more localised , yet via repeaters I can contact people 100 miles from me on a walkie talkie .
I've heard Vna mentioned before , I believe it's a network analyser (?)and something I can look into more and track down as required.
Richard

Good morning Richard,

Yes, Vector Network Analyser - useful bit of kit and the 'NanoVNA' is pretty cheap to purchase too.  

I agree, DX is pretty much in the eye of the beholder - I can't talk to my old Ham friend who lives all of 20 odd miles from me on any other frequency or mode but manage splendidly with a little Handheld and a homemade beam via a repeater! (Crossing three counties back and forth to do it! )

There's definitely a lot of opportunities on those higher frequencies. (Nearly wet me pants when I picked up the International Space Station for the first time even though I only decoded a partial Slow Scan TV Russian transmission!)


Well, I wish you the very best with your radio adventures and remember that there are a lot of helpful radio enthusiasts out there as well as here.

I'm still wanting to expand my VHF stuff with a 2m beam to play around with my old FT290 SSB set and maybe a bit of FT8 digital up there too. (Received the Netherlands direct last time I tried, none too shabby for VHF! )


Best Regards,
Victor

Yes  , 
When you think about it . In a situation such as if communications went down  getting the best out of V/UHF would be advantageous , you'd need to be in touch with people within a 20 mile radius  , after all it's used by all the emergency services and coast guard . 

I feel I'd have missed out on something  had I not bought the hand held almost on a whim due to it's low cost. and am now thinking perhaps a VHF with SSB might be interesting , also realising that getting a licence  in my late 50s there is so much in the world of radio that It's maybe a better idea to concentrate on getting the most from an area you are enjoying rather than attempting to have a finger in every pie and not giving each one the attention it needs. 
Back on subject are there any particular outlets or models of VNA to look out for?
Richard

First one i found but they are all similar unless you want to spend mega money.
Another thing you will be surprised how many of us getting our licences in our 60s.

Link as follows :-

Amazon UK NanoVNA

They look interesting and reasonably priced too Alan.

Cheers for that Alan.  


I've shortened the URL link you provided to be a bit more readable.

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They're great bits of kit Richard,

The obvious use being for tuning antennas but I've done so much more with mine after learning the functions - antenna duplexer design, low & high pass filter testing, crystal, capacitor and inductor testing, signal generation and more recently to tune-up the receiver sections in my old Yaesu FT757gx!

Thanks Victor.
Never looked just pasted it in and hit the send tab.

Alan Pilot wrote:

Thanks Victor.
Never looked just pasted it in and hit the send tab.

It worked any way !
Looks like an instrument which gives a lot info once you find your way round it. I've not seen them before . I'm assuming you connect it up in line as you would a meter and you can you can get the information you need from it's own screen , and the PC connection is for saving info or analytics . Would that be correct?

Best asking Victor as it did my head in so Victor got it lol.
I use a RigExpert pricy but i can use it.

Haa  I know what you mean . I may take the "challenge" I have found with a lot of these things I'm usually able to press the right buttons in the right order to get what I'm after . It's remembering what you did next time when the fun starts ! 

Exactly remembering what you did.
I couldn't lol.
So many things that they do i put it back in the box and forgot about it until Victor posted about his venture with the tv aerial lol.