I’ve used the Slim G 3/4 wave antenna from Spectrum Communications on three activations now, it was originally recommended to me by Ben GW4BML.
It fits perfectly on a 4M Caperlan fibreglass fishing pole which are sold by Decathlon. The most noticeable thing is how so much stronger received signals are.
This antenna was a replacement for a Hawkins Viper (2M) 7/8 wave flower pot which I thought I had lost, it turned up last night in an inconspicuous box during a search for a data cable for my DStar radio!
I am wondering how the Viper is going to perform on a summit as the theory says, the signal will not be heading towards the horizon, I do also have two Hawkins Thunderbolt 5/8 wave antennas for 10M and 6M which work brilliantly during Sporadic E season. Not sure why I ended up with Viper as I would have preferred the 2M Thunderbolt.
I know of one activator that uses the Hawkins 2M Thunderbolt, is there anyone else? Also any recommendations for a 70cm antenna?
I used the Hawkins viper 2m antenna for a good few months, always struggled to receive signals a friend of mine was receiving! So, I was informed of the antennas my friend used and I’ve never looked back! I even give my 2m Viper antenna away for free to a newly licensed SOTA operator, then bought another slim-g as a spare from spectrum communications.
Both tried and tested side by side for at least 3 activations - slim-g won hands down!
The slim-g also works well for me on 70cms using my Yaesu FT-65e on 5w.
They’re just pieces of coax or ribbon cable cut to the correct length. Variations on the J-pole, G2BCX (Fred Judd sk) Slim Jim or a sleeve dipole. Possibly with a choke balun in the feed line. They’re not anything complex and at 2m the dimensions are not that critical either. So unless you are suffering from failing eyesight or dexterity issues then you should be able to measure, cut and attach a plug to a piece of wire. Whilst you can, you should make your own antennas especially simple things like this. Making a 7ele mono-band Yagi for 40m is a different story!
I looked up one of these antennas that are being sold and I’m still laughing at the claimed 0-degree radiation angle. Not in the real world sunshine. About 10m of RG58, an SO-239 and some PVC conduit and heat shrink, let’s be very generous and say £8 for all those components. Retails for £65. So that’s a £55 markup and once you’ve made a few and have templates for the lengths to use known, you can make one in 15mins. Or a possible £220/hr rate.
Come on, buy some cable and make them yourself. And if they don’t work, find out what you did wrong so the next one you make does work.
@MM0FMF Andy, I have made my own… I have purchased different ones to test in the field… I have also tried a few friends home made designs BUT, I have not yet made, found or come across one side-by-side that achieves as good as results on transmit and receive to what the slim-g does! Spectrum communication has a special magic white cylinder which does all the hard work! Tried and tested on many many summits it’s also got me out of the poop a few times, hahaa
Go on be honest you don’t like the Smurf or is it SNP blue colour of the Hawkins antennas?
As I said the Thunderbolts work for me during the SpE season, this particular antenna has a matching stub and I have no interest in cutting coax just to reinvent the wheel. The other thing is I don’t have any real space where I can do some serious home brewing of either antennas or radio gear.
But you talk about the cost, a crimp tool for Anderson power poles costs £27, and that crimper may only get 30 mins of use in my lifetime, is that a good investment of £27 or do I buy ready-made power cables?
The reason I bought it (Slim G) was despite being lucky enough to get an S2S from Moelfre, GW/NW-041 on using an HT with MRW210 whip (about 114 miles), it failed miserably with an S2S on Cadair Idris which is a similar distance, that could have been down to the other station. but it was disappointing to lose it. The same set up got me Shining Tor to Cleeve Hill but at the back of mind was can I do better, like I said not regretted getting the Slin G
Hi Ben, I have to admit that I haven’t used the antenna from a local summit as yet only sat on the top of my DMR HT into the local 2m repeater. On receive it really has a narrow beamwidth (off the end of the loop). Miles better than the rubber-ducky but a lot more fragile.
Cut yourself 1.3 meters of rg174 coax and fit to one end a plug to suit the radio you intend to use the antenna on. In my case a VX8, DJ-VX50 or FT817 so its a crimp on bnc with sma adaptor. Once the plug is fitted with heat shrink on, measure up 35cm and start a coil wound on 13mm irrigation drip tube. I drilled a small hole to poke coax through from the inside edge of the drip tube. Wind 8 full turns on the drip tube then drill another hole at the other end of the coil and poke it to the inside of the tube to finish the coil. It might pay to wrap the coil in tape just to secure your windings for now, My piece of drip tube is 4cm plenty to fit the windings. Where the coax continues out of the topside end of the coil measure the coax to 56 cm and cut it to that length. Now cut the outer covering of the coax about 2cm down and expose the braid but leave 2cm on inner conductor sticking out. Trim off exposed braid back to the top of the outer casing. Then trim the inner dielectric covering off the wire so some extra wire can be soldered to the inner conductor. This point becomes your dipole centre as such so make sure coax braid and inner conductor are clearly insulate of each other. Nearly there. I started with 50cm of SOTA beams yellow wire as the other half of the antenna. I tuned it straight on top of a vna to get a good vswr with the antenna not me hanging in a tree out in clear space. The Yellow wire ended up in my case 46 cm long as the top section of my vertical dipole or Flowerpot antenna. Gently tin both pieces of wire before you join them at the inner of the coax to make sure you don’t apply too much heat to the job and melt the inner dielectic of the coax. Cover joint with some more heat shrink and there you have a Flowerpot antenna nice and light and fits in any small compartment of you SOTA bag. I have a short piece of string on top to tie to to either a tree branch or mostly use the hand strap on my walking pole up in a bush or if nothing on the summit I hold the pole above my head and talk into the radio with the other hand. I have made simplex 2m contacts from summit well over 100km to chasers many times. Make something for yourself that works is a learning experience and all part of this craft of amateur radio.
Ian vk5cz …
I have used a simple 1/2 wave flowerpot made from RG/174 for most of my 2m activations. Needs to be tuned fairly accurately - I did that using a VNA. The choke part is 9 turns on a 22mm pipe. Including 60cm of coax below the choke and terminated in a BNC, it weighs in at 50g.
I don’t use RG/174 up the 6m pole though … that needs something better so I have used M&P Hyperflex 5
It has never broken or given any trouble and I will use it till it breaks and make another the same for about £1.
A man after my own heart. I find the 5D-FB cable that I use to be briliiant for 2m and 70cm… and it’s far easier to handle in sub-zero temperatures than any RG-58 or 174. I prefer yagis to simple antennas as I work both SSB and FM, but the flowerpot antenna I built to the dimensions given to me by David G0EVV works a treat. Somehow I can’t bring myself to buy an antenna when I can make one myself for a fraction of the cost. Maybe I’ve activated too many GM summits.
Me - I did the opposite to you. I made my yagi but bought a slim-G, basically because I lost patience with trying to get a home made one to resonate anywhere near the 2m band, and for £22, what’s not to like?
I have one of this Portable magnetic loop but, at least mine, it’s really difficult to trim and very very sensible to nearby objects. The tuning range is really little and the resonance dip very sharp.
This was my reason too! I love making antenna’s to find out they work well on summit. I just didn’t have the magic hands to make a working 2m/70cm antenna equivalent to the slim-g. So, £22 was a bargain and it fits every bill!
You are correct Paolo, in fact, all loop-fed magnetic loop antennas are high-Q and hence narrow band and have to be precisely tuned. On HF I have one that is fed by a gamma match and that is somewhat broader.
I tune the 2m one using my nano-VNA and then mount it on the HT.
Just to know, do you tune it directly on the field during the activation, or at home on a probable frequency?
I’m wondering to use it on the aprs frequency atop my backpack, but unfortunately the polarization and radiation pattern is non good.