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23cm antenna?


#41

Brilliant transverter


#42

Nice - what is the damage to the wallet?

Matt
VK1MA


#43

Look’s good Matt, you’ll have to give it a try on the 3rd Tuesday of the month in the RSGB UKAC from 2000-2230 Local time.

73

Matt G8XYJ


#44

Matt (VK1MA), I’m interested. Perhaps we could arrange to share the postage cost?

Andrew VK1AD


#45

Hi,

Back to 23 cm antennas, which was the original topic.

I’ve just built a double quad for this weekend and set it primarily for vertical pol as the other station will be HH. Easy to rotate 90 degrees if required.

I adjusted the spacing between the quads and the reflector for minimum SWR, otherwise it seems pretty insensitive to dimensional variations. I used 1.2 mm dia enam Cu wire for the elements and LMR400 to solder them to at the feed. Some 20 mm electrical conduit provides mechanical support and some construction adhesive holds it all together and makes it shower proof.

Tomorrow I’ll cut off most of the LMR400 and make up a foam core RG58 type coax lead - the flexibility and packability of the thinner coax overcomes the 11/2 dB loss. The antenna does seem to have about 10 dB gain. It outperforms a Chinese 10 ele yagi cut for 1200 MHz as measured by the signal from a repeater. Lower SWR too.

I might make up a one with brazing rod quad elements - better able to stand knocks, but only after I finish my 160 m vertical. Yes I can straighten the copper wire if (when) it gets bent, but if it doesn’t bend in the first place that’s better…

In terms of Bang for Buck it’s competitive with Kent Britian’s Cheap Yagis design when considering SOTA.

I’ve previously only used a dish or yagi’s on this band so it’s a bit of a novelty, but one that works and once you figure out suitable mechanics for it it’s easy and quick to build. I did borrow one from another uW amateur and gleaned a few ideas from his.

If I don’t get a few contacts this weekend this post will be my last on the topic. Pudding and eating and all that.

73
Ron
VK3AFW


#46

I’ll be interested in seeing the finished product. there seem do be a number of yagi calculators around.

Matt M0IAW


#47

156 Euro plus postage.


#48

Bargain!


#49

Matt (IAW),

I’ll be down from GM and active somewhere in G/NP on Sun March 19th and again in the G/NP,G/SP,G/LD part of the world for the Blackpool Rally on Sat 8th April. I’ll be returning to GM on Mon 10th. If you want to arrange some 23cms skeds then I will be happy to bring the 23cms gear with me and also to adjust my plans so I can be on summits which stand a greater chance of success with you.

If we can persuade a few people to be QRV too you may be able to get some QSOs that are long enough to let you claim a Microwave Award and also qualify an activation on 23cms alone.


#50

I too have gone for the 817 & SG labs xverter.
Just waiting for antenna to arrive from Wimo and could possibly be on air soon.
My plan is to try some of the local summits during the UKAC’s this summer.

Stuart. G1ZAR


#51

I could be persuaded to take 23cm out some where during Rally weekend.


#52

I couldn’t resist the SG Labs transverter, so I duly ordered one. It arrived within a week, complete with power plug to fit, 3.5 mm jack plug for control lead, and a 2 element PCB antenna.

Today being perfect for an outing, I took it up onto the Longmynd G/WB-005 to see if I could hear any beacons.

Just using the supplied antenna, I could hear:

GB3USK 1296.870 IO81VC (near Bristol)
G8MBU 1296.800 IO90IR (Isle of Wight)
And, of course, the Stoke repeater / beacon GB3SE 1297.075

Oh, yes, and the ziz from the big golf ball on Titterstone Clee :o)

Not a practical system yet, except for easy summits like this in nice weather, but very encouraging.
I’d like to find a lighter tripod, and perhaps mount the transverter in a weather resistant box - and make / acquire a better antenna. I also need to work out how best to handle talk back, given that the FT817 is connected to the transverter. (Though a 2m handie could be used as prime mover for 23cm FM)

I put up a spot for 1296.2 ssb. No takers on this occasion, but I had to try! I also called on 1297.5 with similar result.

Here are a couple of photos:

Looking forward to the first QSO :smile:

73
G4AZS


#53

Next band up…

How do you ensure you qualify the summit? Get your fellow GM SOTA ops to invest!


VHF/UHF is alive and well
#54

Most people stack antennas, but I suppose stacking rigs is another way of gaining contacts :wink:


#55

They only arrived the other day. 1 for me and 4 are going to SOTA ops and 2 to local microwavers. I need to do a bit of antenna brewing, probably a pair of double quads. That should give a theoretical 13db of gain whcih would give about 40W ERP. I have one for 23cms and a small PCB yagi similar to yours. The double quad is better than the PCB yagi and both knock spots off the rubber duck my 23cms handy came with.

There are microwave awards to claim. For S2S microwave contacts, the DB can work out the distance. For other contacts you enter the chaser’s locator or lat& long using the following formula in the comment field:

%QRA%IO87FB%

or

%QTH%53.1234,-3.654%

The DB will do the rest when it spots those in the comments you are were QRV on 23cms or higher.


#56

Yes Andy looking forward to our 13cms SOTA S2S’s and experiments Vertical & Horizontal.

As mentioned I have a design for tape/coaxial collinear and of course my 50mm pipe yagi - both horizontal/vertical design.

By the way was taking to David GM6BIG and he mentioned that the 13cms beacon is back on from the old CS site at the Tak-ma-Doon road, in preparation for our 13cm activity - horizontal - not sure the beamwidth - but certainly south. Maybe you’ll be able to hear it from your QTH? Not a problem for me - I look at it - hi!

73

Jack(;>J

PS: One of the down sides to vertical polarisation was in the use of a metal vertical support which could effect the beam pattern to varying degrees. Robin GM7PKT and myself will carrying out some experiments hopefully this year, going some way to answer the question if there is any significant difference between V/H on 2 metre - on distant summit paths.


#57

Hi Adrian,

I’m looking to fit 13cms SG Labs beastie in padded (waterproof?) laptop case. With a suitable clip this can hang on the rigid section of mast with a short coax feed to the aerial.

Nice pics :slight_smile:

73

Jack(;>J


#58

Yes! Certainly on distant paths.
For S2S then both ends should be able to arrange their polarisation to match but other stations may not be as flexible.
It is very unlikely that homebound Chasers will have a vertical with any gain/directivity on these higher bands and, as I have found when chasing Robin, his signal can go from “workable” when horizontal to “is he actually transmitting” when vertical and cross polarised.

I am sure there is an antenna guru out there who can explain the theory about “ground gain” and similar esoteric subjects which come into play with antenna polarisation.


#59

Hi Barry,

Exactly. And ideally if I could be bothered I would re-erect my 10 XY along with rotator on the tower and switch polarisation accordingly. But there are certain downsides nowadays to this so I have come up with a new set-up which I started building in 2015. But had to set-aside whilst I built new shack last year.

It consists of a high gain commercial collinear (used for paging at 140MHz I have moved it up to 145) which works without radials. I have introduced radials in the form of a homebrew heavy duty 6M (3 x 3/4 on 2M) horizontal dipole which I have ‘coupled’ into the collinear. Mounted below the collinear is a ABS box in which the 6M dipole is terminated along with a head amp and RF switching relays. When used in the Vertical mode the 6M is grounded. When used in the Horizontal mode the short is removed from the dipole which can be used on either 2 or 6M. The 6M dipole will be mounted E/W with the main lobes of course N/S (where the mountains are from this QTH).

So as you know, Activators prefer to ‘hunker down’ to get out the weather (certainly in GM land), rather than faffing about rotating a beam. And this is where vertical really scores. Put up your vertical hunker down and let the Chasers chase you vertically - FM,SSB, CW.

We will be trying this on 13cms and see how works out.

73

Jack(:>J


#60

One watt Alinco HT into 16 element Comet 23 cm Yagi, Entire package obtained for 246 USD. Sufficient for award certificate number one in the SOTA Microwave Award program…Elliott, K6EL

Mt Davidson, the only SOTA peak in San Francisco