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The Great GM Microwave Extravaganza


Despite getting soaked, despite getting lashed by the wind, despite sitting with no shelter assembling the system, despite all that, that was fun.

WX forecast said light rain. It said dry yesterday. Clouds said heavy rain. Tinto was heaving with people. I did think of turning back as it was so wet and windy at one point on the ascent, but I kept going. I tuned up to find lots of locals nattering away on 2m, Robert GM4GUF with Alan GM0USI (both keen microwavers), Alan was off to do something and Rober was off to warm up his 13cms gear. As he lives a few miles from the foot of Tinto I didn’t expect a new world distance record. I had a chat with Jack and John as set up the system. GB3CSB was silly loud, so loud I think it was overloading the front end of the transverter.

John announced he was QRV and he called. A quick tweak of the bowtie and he was 59+ from East Lomond, a LOS path of 78km. He gave me 59+. I had my antenna just propped again the rucksack and during our overs it fell over so it was pointing at the sky. John dropped to 59 and he gain me 57. No matter how I pointed the antenna we were able to have an armchair copy conversation (wind and rain excepted). A few mins later Jack appeared and I had to point the bowtie at Jack but when I did he was 58. Looking at the map, I was down a few metres from the top because of the wind so the path to Jack was not LOS. The antenna was only 15cms above ground and so I was beaming into the top of Tinto. Finally Robert appeared of 13cms for a third QSO.

Iain had texted he was delayed but I was not able to stay longer. I was now shivering as I was fully exposed to the wind and rain so I bid them goodbye and hightailed down to the car. Jack had the benefit of his wee shelter so I think he was staying longer. John pulled the plug too. Sorry Iain.

The antenna took about 1hr to make out of old PCB material, some 2mm brass tube and an off cut of RG-402 which was terminated in an SMA female. I need to make it SOTA-ready as it is fragile. For today I have a container from a Chinese Takeway meal attached to the reflector with rubber bands. Ugly but functional.


Oh yes. That was fun. In spite of getting pretty well soaked - and on getting back to be told that it had been completely dry in Edinburgh (should have gone up Scald Law).

Andy’s summary of the weather forecast and the contacts pretty well says it all. It’s quite entertaining that Andy could squirt most of his RF vertically upwards and yet he was still 56 to 57. Jack GM4COX/P was equally strong, and at nearly 100km (96.97 or something), though LOS.

Sorry not to have heard Robert on 13cm - 2m was easy, but there’s clearly too much stuff in the way for 13cm. We didn’t have time to play around looking for reflections - the rain had really set in. Apologies to Iain as well - I was really very soggy by the time I went QRT.

GB3CSB was a bit fluttery - it’s behind a local horizon from East Lomond. I’ve never actually been on the summit itself before - it was interesting, there was a bunch of archaeologists doing a dig near the trig point (which is well below the summit, very strange), something iron age I think.

Here’s the antenna pointing south(ish) into the murk.

Looking forward to more 13cm fun in due course.



Hi Andy,

Apart from the WX that all sounds good!

Interested in the bowtie antenna. I’ve looked at several designs for these with differing attempts at a balun. Some originate from the WiFi DX fraternity, and I’m not convinced by some of their descriptions of what the RF is doing…

What is the arrangement with yours - have you added any kind of sleeve balun, and / or is the coax outer soldered to the back plane?

It is obviously working!



I got the dimensions from the net but looked at ham not Wifi pages. There are people who still believe a Pringles can makes a good antenna. Well it does for 9cms not 13cms and not Wifi!

I got the dimensions from Bert Modderman PE1RKI’s website. But don’t go there, you’ll spend all day drooling over the millings and PAs :slight_smile:

I used a Eurocard sized piece of PCB as that was bigger than the minumum. I’m now not sure if the cable is real RG-402 or not as it is very flexible for semi-rigid. All dimensions per PE1RKI site. The cable outer is solder to the reflector on both sides as I used double side board. Finally I fashioned a nice gentle bend on the rear and folded the cable back and tacked it with solder to the reverse of the reflector. In the picture the antenna is set for vertical.

On all the activations so far (both of them!) I have hand held the antenna. I’m still working out the best set up. John GM8OTI gets about 2W from his arrangement (all home brew) and the SG Lab probably gives about 1.5W when driven from a LiPo supply. What was amusing was that John was much louder on 13cms than 2m! I really had to stop and pinch myself when the antenna fell of the ruck sack and pointed at the sky and John’s signal barely changed.

The books say 9dBd for the bowtie and between 11 and 12dBd for the 12 ele Yagi.


Hi John & Andy,

Thought I would copy my profiles from yesterday’s SS-120 Activation onto the Reflector for wider distribution - outwith our email list.

Great day out but - WET, COLD, CLAG DOWN and yuk!!! - BUT!!! - on 13cms with some interesting observations. (More to follow with Pics - when I get time - hi!)

Kit at SS-120 FT-817 - 1W 432.200 SSB into SG Labs 13cms Transverter ~ 1W @ 2320.200MHz into 4el SG Labs PCB Yagi.

Anyone wishing to join us?



PS: Will be active from GM/SS-049 tomorrow in the SHF Activity Contest - S2S’s?


Jack, I’ve tweaked your links to point to the real webpages not the old ones which will disappear soon(ish).


Sorry Jack, no S2S tomorrow from me, the 2320-2350MHz part of the UKAC is from 2030-2230 (UTC) and I don’t like stumbling downhill in the gloom. I’ll try to find somewhere near home with a good chance of a contact.



Ok Andy,

If you wish to email the new URL’s (presume the Summits Database for the above inclusions) I could alter any future links accordingly?

Wx looking pretty good for tonight.




Hi John,

Edinburgh itself is (if my memory serves me) in the shadow of the Pentlands from Culter Fell, so you have to go some to get a half decent signal, but then again?

Catch you tonight.



They look like this





Well that was fun! I couldn’t get out to play SOTA today but did know that some people would be about for the UK Microwave contest that was on. Jack GM4COX was going up Cairnpapple Hill SS-254 which is LOS to my QTH at 10km or so. The 13cms gear was manfully mauled up the stairs from the shack to the spare bedroom and set up looking out of the window. A quick check showed the beacon out at Kilsyth, GB3CSB was peaking S7 having climbed up to such an elevation compared to the shack :wink: So it looked good for Jack. Where was he? I tuned and listened but no sign of him. Oh no, all that climbing carrying gear and I couldn’t hear him. Then I remembered the alerts are UTC so I went and made a cup of tea as I was an hour early.

75mins later, Jack was calling CQ on 2320.200 and was 59++. We QSY’d up the band to get away from the centre of weak signal working and switched to FM and had a wonderfully relaxed natter. On the 817 Jack was completely full scale. Effortless comms. Yeah, a whole 10km LOS with 1.5W or so each end is hardly DX or an achievement. It wouldn’t be an achievement with 24GHz wideband FM. 230GHz and you’re talking. But it was fun and I’ve now completed my 1st summit on 2.3GHz.

I’ve done loads of 1.2GHz and higher contesting over the years but there is something about having such a tiny. lightweight bit of gear that just works that makes this real fun. It also requires a bit of liaison and teamwork to ensure you’ll get at least 1 QSO. But even 1 QSO is worth the effort and it’s one more QSO on a band under threat.

Whilst waiting for Jack I did some tests between the 4ele PCB Yagi and my double quad. It seems that beacon (which was varying strength) would peak at S7 on the 817’s S-meter using the double quad and I never saw better than S5 with the Yagi using the same feeder in both cases. I don’t believe it’s 12db better, but it is better by some amount. I’ve since learnt the shape of the elements doesn’t matter, they just need to be a wavelength long and so can be circular. Circular are much easier to make, you just need a mandrel with a radius of 299 792 458/2320200/2/pi cms or 2.06cm to form the wire elements.


So if you first cut each element to be a full wavelength (without end correction as there is no end) you can bend or shape it in any way you want. Sounds easy enough.


Well another great Sunday on 13cms with GM/SS-060 being activated by Jim MM0GLM and Andy MM0FMF actvating GM/ES-045. And for further info checkout the POSTING on GM13.

And was hoping to head out this coming Tuesday with an overnight camp to take part in the UKAC night from a high 4 pointer in the south of Scotland, but wx and the not-quite-complete 21el SOTA 13cms beam is keeping me back. But ABW July UKAC?

Now next weekend for more 13cms fun?




I managed a new DXCC on 13cms this weekend. I was down at my club’s VHF contest site near Gatehouse of Fleet in SW Scotland. My SOTA target to tick off was Bengray GM/SS238. I wasn’t planning any microwave activity as I was on duty at that contest site and had to sneak off. Anyway, John GI7UGV lives near GI/MM-017 and the path plot between there is good. We arranged to see if we could work something. Unbeknown to me Jack GM4COX decided to see if he could get a QSO to John from Lowther Hill.

It was very blustery on Bengray. John and I started of on 2.1GHz (3g text message) then tried 145.400FM. Handy to handy John was 54 and a good signal. Jack popped up at 57. A quick test and John was 59 on 13cms, he used the 4ele PCB and I used the bowtie. In fact copy was effortless on 13cms and was much better than 2m! John tried his Vivaldi wideband antenna and was 1S point down on before which makes sense.

When John and Jack beam at each other they were 45degs off me but pointing my antenna so it was equally off on Jack and John, they were still 51 signals. I listened as they tried for a contact. Jack was suffering from strong to severe winds and driving rain. I’d had that the day before during the contest.

So for me, that is DXCC #2, 98 to go on 13 :grin: and it was John’s first 13cms QSO.

I’ve now had 13cms QSOs as a chaser or activator with GM4COX,GM4TOE, GM4GUF, GM8OTI, MM0GLM, GM3UAG & GI7UGV. 3 of my contest group are QRV 13 and waiting till activations are possible to their QTH’s in Edinburgh. Talking about this it turns out another contest group member has the gear and is giving it a fettling so that he can chase from his QTH out Dunfermline way.

I was expecting a success rate of about 10% with anything better be a bonus. To be sat at 100% success now after 5 activations and 1 chase is way beyond my wildest dreams. This idea is working because we have a small group pushing along activity and it seems to be encouraging non-SOTA people to dig out old and infrequently used gear to use from home as their is a greater chance of a QSO from a domestic location. Not everyone lives in the ideal location for microwave activity but if you can persuade SOTA-loonies to take their microwave gear up hills, a lot more relatively rubbish domestic environments become viable.

What would be wonderful is if some stations in GW and G would consider getting going on the band. There are easy paths possible from the bigger SS summits to bigger Snowdonia peaks and to the bigger Northern LD fells. These are the guaranteed to work paths. Lots, lots more is possible including bouncing signals of mountains when no direct path exists. My contest group regularly bounce our 13cms signal off Black Combe so we can work GD0EMG on the Isle of Man as Snaefell directly in the path.

I have been impressed enough with the SG Labs 13cms transverter that I’m likely to get the 23cms unit. HF is so rubbish at present that if we can get a few more out on 13cms and 23cms, I can ditch all the HF antennas and just have 2m, 23cms and 13cms with me with sufficient confidence to activate the summit and revert to HF when I know there is less chance of activating on 23/13.

So please consider giving this a try, the transverter is plug and play and antennas can be built with simple hand tools with materials bought from the local DIY store. The last time I was this excited about amateur radio was when I got good enough to have CW contacts after 19 years of just SSB and data modes. This has added a whole new layer of fun on top of getting out in the countryside and have radio fun.


Downunder in VK1 we now have four activators on 23cm SSB plus two regular chasers. Three of the four activators are using SG-Labs 23cm transverter. Interestingly the supplied HB9CV antenna is an excellent choice for summits around Canberra.

I’m trying a homebrew 12el yagi for stations beyond 50 km out to 300 km. Doing my darn best to work Compton VK2HRX in Sydney, I think we need an A380 in the sweet spot en route flying over Canberra and Sydney.

We do expect further growth in 23cm with at least two more VK1s keen to get on board.

73, Andrew VK1AD


That’s excellent to hear. The availability of cheap and effective transverters make these once “difficult” bands easily available. I know there’s a few guys in W6 or W7 doing 23cms FM SOTA activations and having some success. I need to scan the NASOTA emails to see who it was. So I hope you can get a few more hooked onto the SHF bands either with the SG Lab unit or using 23cms FM handhelds which are still eminently usable with a good antenna.

A 12ele should be somewhere about 12dBd gain. The double bowtie version of the single bowtie I made is 11dBd or so. It maybe worth knocking one together to compare against the Yagi. Ease of construction vs 1dB more gain!


My plan for this year was to “get going” on 23 & 13 cms. having got all the 23 cm bits together, my 817 driver failed. Finally got that sorted out on sunday, so will be giving the SG-Labs 23cms a spin in the next UKAC (as it’s the only time I can guarantee to be free).
Unfortunately, my local SOTA (G-CE004 Bardon Hill) is just a mere pimple compared to those summits up north, but plenty of locals will be on during the contest.
If it is sucessful, then the 13 cms one will be ordered straight away.


Hi Stuart,

Interesting as to your thoughts and aspirations as to 23 & 13cms. Good luck.

And, you might like to check out GM13 as to how things are progressing in GM from a SOTA/13cms point of view, with some interesting observations on the SG kit.




You might like to complete that URL please Jack…


EDIT: When I posted this, the software told me Jack had posted this link already but looking at his message “something” has been along and tidied it up and ruined the link. Damn software writers are too clever for their own good. :grin: