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23cm antenna?


#1

Having picked up a 23cm handheld (Icom ic-12e) I’m looking for a possible activation antenna. Being F3E I assumed vertical polarisation but this does not always seem to be the case. How about this? http://www.ebay.co.uk/itm/Antenna-collinear-great-gain-1296Mhz-23cm-radio-amateur-ham-/302212204607?hash=item465d40483f:g:jQEAAOSwd0BV7Ykx .What are other activators choices? Matt M0IAW


#2

For several years I used a Quadruple Quad. There are references to the design on this reflector and I believe Matt G8XYJ posted a photo of his version. The advantage of having a hand held antenna is that you can change polarisation very quickly. On 23cm quite a few people use horizonal polarisation even on FM. Unfortunately where I now activate up in GM there is next to no activity so I have not been on the band for a couple of years.

73 Gerald G4OIG


#3

That antenna is the last kind of thing you want Matt.

You have very little power and a huge free space loss compared to other bands so you want to ensure every little bit of signal goes in the direction of the chaser, an omni is wasteful. Random 23cms QSOs are possible but the vast majority will be prearranged. i.e. you were working people on 2m or 70cms first and you know where they are. So you need a directional antenna.

You can make (or buy) small Yagis that are just tracks on PCB. I have a 3 ele Yagi that is a little bigger than a credit card than knocks spots off the rubber duck, you can point it at the other station and easily swap polarisation. You can make a lightweight full size 20ele Yagi that collapses. Or you can build antennas like the Quadruple Quad or a Double Quad (Bowtie) antenna. These can be made out of twin&earth heavy cable and PCB materials easily using hand tools whereas making a Yagi is harder due to needing precision in drilling and cutting.

Finally don’t skimp on the cable to connect your antenna. Loss in coax at 1.3GHz can be vast in some cables. You can normally find scrap microwave cables in the junk boxes at rallies. Just dig down into the stuff under the tables. You can buy new but your eyes will water at the price.

Roger, MW0IDX, has the design for a quad quad on is webpages. His is for 70cms so make yours 1/3rd scale for 23cms. http://mw0idx.co.uk/quadruplequad.html

There is a design for a 23cms double quad here: http://www.w6pql.com/23cm_double_quad.htm

Finally, if you want SOTA QSOs, make it known in the alert you will be QRV on 23cms. You need to stir the stumps of other activators and chasers to ensure they will find their gear and get it on the air.


#4

There are quite a number of very well equipped 23cm stations in GM (come on Gerald G4OIG,let me know when you want to play :slight_smile:) and you can expect some contacts if you spot in advance. I believe one of my local hills was qualified on 23cm and it was the activator’s first foray onto 23cm - he was end stopping with me just running his transverter.

But, as Andy says, don’t waste erp by using an omnidirectional antenna - it is relatively easy to knock up something with directional gain that remains small and handheld. One qso over 50km and you are in the realm of the SOTA Microwave Award too!


#5

Having just had a big move around in the shack - have now found the PCB big wheel and 3 ele yagi purchased from Sam Jewell G4DDK about 200 years ago!

Andy - Are you mounting your 3ele directly to the radio with an SMA coupler?

73’s

Tim

G4YTD


#6

I had a piece of UT-141 semi-rigid coax that had an SMA male on one end and microwave “thing” on the other end. I bought it just for the cable/plug combo for £2 ISTR. I removed the “thing” and bent the cable through 90deg and soldered the Yagi to the cable. It’s so light I can attach it to the 23cms handy and it doesn’t strain the SMA socket.

I’m sure I have posted a picture of the result but I cannot find it. I’ll post it again tonight.


#7

Thanks Andy
Pretty sure I have something in the junk box that I could codge something together with.
Saves the cost of a second SMA socket and plug.


#8

I have sucessfully used one of these for SOTA activations.
http://www.wa5vjb.com/products2.html


#9

That is the one I have also - not used it yet.
How do you connect to your radio?
Do you have a picture you could post please?
Trying to find the easiest option :slight_smile:

73’s

Tim


#10

Hi Matt, two questions,

Where are you located in the country?

Where do you plan to activate?

I ask this as if you’re planning to activate around NE Wales and the NW of England you could probably get away with an omni directional antenna. If like me, you go to Mid Wales and South Wales alot, then you need directional antennas.

I activated Moel Gyw (NE Wales) once and had 7 randomly generated QSOs from calling CQ all into Greater Manchester and NE Wales.

If I am in range of the Black Country then I know there are 3 FM 23cm users there.

If I am in range of Cheltenham then you have about 5-6 FM users there.

I mainly use a small 11 ele beam made by sandpiper, but the quadruple quad that Gerald mentioned is pretty good and lightweight. I also have the PCB antenna, do not rate it if i am honest, the wheel is not much better.

If you’re ever in the Welsh Borders, I can fire 8-10 watts at you with either a horizontal beam or a vertical beam. I have no permanent antennas up for the band, but can be QRV within about 3 minutes and can change the polarity very quickly. I have LOS to G/WB 002, 3, 4, 5, 6, 7, 12, 14, 15, 18, 23 and GW/MW-002, 9 and 13.

Surely the below photos show the crudest set up for 23cm ever! An 11 element attached to the handle of a glass lifting sucker. The word “Amateur” certainly comes to mind - normally fed with westflex 103 (the thin coax was for testing purposes, RG 223 I think?). The house windows are facing North (front of house) and South (rear of house), so by opening and shutting the window through 90°, I can beam a full 180° (depending on which window I attach it to - No wonder the Neighbours think I am odd!

Matt, I wish you all the best and hope to have a QSO with you soon.

73 Matt G8XYJ


#11

Like it :grinning:


#12

Some excellent ideas! Matt we met up not so long ago, my QTH is Walsall. i dont think 1w from my home location (471 feet) will be up to much so will be activating only.Matt M0IAW


#13

I don’t have 23cm, But thanks for a very interesting read Gents. Very informative to someone who knows nothing of this band, Thanks… I know that John GW4ZPL runs 23cm from home in North Wales & I know that Jim EI9GLB Wexford is always looking for contacts. Both chasers.

Don GW0PLP.


#14

Of course Matt!

Good to see you’re planning to be active on the band!

73 Matt G8XYJ


#15

Unfortunately sandpiper will not manufacturer a beam, however having no test equipment does leave a dilemma. This seems a good choice and as I enjoy building aerials simple enough. http://www.marwynandjohn.org.uk/GM8OTI/proj23cm15eleyagi/proj23cm15eleyagi.html

Matt M0IAW


#16

A DIY Bobtail is another option. I made one for 70cm and it’s quite compact, so a 23cm model would be very portable. They are easy to construct and are a good 50 ohm match with very minimal twiddling. Not as fiercely directional as a 9 element yagi, but still a major improvement. I wonder if a fold-up “measuring tape” version would be possible…

http://www.hamuniverse.com/2meterbobtailbeam.html

73,
Bruce - WB8OGK


#17

The reason why quad quads and double quads are recommended for home 23cms construction is they are very tolerant of measurement errors that can affect things like Yagis a lot more.

John @GM8OTI will no doubt tell you how straightforward it was to make his antenna.


#18

My PCB Yagi plus second hand piece of UT-141 cable/SMA attached to an Alinco DJ-G7.


#19

23cm in GM, well I am up for it Barry if you are. I only have 0.4W FM to the quadruple quad, but there is virtually no loss between the two… rig in one hand, antenna in the other. I have tried 70cm SSB and FM from various GM summits, but gave it up as a bad job. Sometimes it can be difficult to qualify a hill on 2m!

The next outing is back up around Biggar and Moffat. If you think you can get down to that area, then drop me a PM and I will take the kit.

73, Gerald G4OIG


#20

Here is how I do it.
[URL=http://s1019.photobucket.com/user/Comptonallen/media/SOTA%2023cm%20yagi_opt.jpg.html][/URL]