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SOTA Antenna Advice

Wow! Thanks for the replies. They had the effect I figured they would. I’m leaning back towards the KX2. I tried to rationalize myself out of the buy-once-cry-once mentality, but the KX2 just has a lot more room for me to grow into. The lack of a built-in tuner was my one nagging issue with the FT-818. Definitely something that could be overcome though. I just didn’t like the idea of dragging two or three different antennas and having to swap them out. I like the idea and six of the MTR-3B, but I have yet to grasp CW so it’s primarily SSB for me for now. It’s good to hear that the KX2 is hardier than I thought. That’s part of the problem with the inter web - it’s hard to get a unified opinion. Regarding antennas, I didn’t mean to make anyone think that I had plans to just buy an antenna. My intention was to build one. I’m still fairly wet behind the ears and actually doing it myself is the only way I’ll really learn.

The linked antenna designer is going to extremely useful. I didn’t see that in all my SOTA scouring.

Thanks again for all the awesome advice!

  • Sean/W4BKR

I’ve been using a linked dipole almost exclusively since 2011.
Started out with just 20m and 80m. My current antenna is cut for 10, 12, 15, 20, 40 and 80m.
I also have a shorter antenna for 12, 20 and 40m.

http://vk3zpf.com/link-dipole

1 Like

As a slight variant on the quarter wave vertical, mine is actually a linked vertical. I inserted a link for 12m when we had the 12m challenge and also added more wire and another link to take it to 30m. I increased the radial length to suit 30m and while it still works ok on 20m with the 30m radials (7.5m instead of 5m) I recently bought some larger slide switches to use for retuning the radials for 20m. Ie. open the switch for 20m, close it for 30m. With 20m not returning many contacts at present I have not been too concerned about 20m and have used other antennas there.

The link connectors I use are auto electrical spade lugs. I would go for the bullet shape next time, spade lugs are probably good electrically but they are hard to connect and disconnect with stressing the wires.

Although the vertical with 3 radials is basically a single band antenna, what you get for the “inconvenience” is a very efficient antenna. I’ve worked lots of dx at 10watts with mine.

With QRP power levels, don’t waste limited power with substandard antennas. Loading is generally wasteful, a full size resonant wire is much more effective. IMHO…

73 Andrew VK1DA/VK2UH

As you can see Sean, ask a simple question and get lots of answers. There’s no right answer just people telling you what they use. You can read all the books on antenna design etc. and you can learn how they work and how to design them for the bands you are interested in. Then you need to take on board that SOTA operating adds a whole set of extra requirements to your antenna.

The first is deployability. Whatever you make you need to be able to deploy it on your own. In wind and rain and snow and more wind? Can you rig it up with gloves on? Can you connect it with gloves on?

The second is durability. The antenna will be setup and taken down at least once per trip and then coiled up. If you do several summits in a day then your antenna will be up and down all the time. All that will take its toll on connectors. So every connection needs to have some kind of strain relief or it will fail after repeated use. You need to use wires that will cope with this kind of abuse.

The third is weight. You have to carry it on your back. Up and down. So don’t make it out wire you could use to tie up a super-tanker. Whilst you can now run 100W for a good few hours without needing a team of sherpas to carry the batteries, 100W level is still relatively rare. 25-40W is not uncommon but the vast majority will be using 5W (817 class) 10-15W (Elecraft KX2/3) or less (Altoids radios). So you don’t need to use massive cables. But don’t overlook item 2!

As for the antenna, it will depend on your location and what you want to do. Most of the time “make SOTA contacts” is the requirement. Sometimes we have special activity sessions (EU<>VK or EU<>USA) and you may want to select different antennas and powers for those from normal “vanila” SOTA antennas.

For me in Scotland, I have few summits that have trees and so this makes a small telescopic fishing rod essential. That needs some method of fixing, either lash the pole to fence post or use a set of guys. I use 5m rods and the top section is generally unable to support much weight hence the feed point is around 4.5+m (about 15ft). An inverted dipole at that height for lower bands is a different beast to a horizontal dipole 1/2 wavelength above ground. It will be much more omni than you would expect and it wont be a DX antenna.

I mainly use a 60m/40/30m link dipole with a SOTArised clone of a Buddistick for 30m/20m/17m/15. The Buddistick clone works well and is quick to deploy but it is obviously down in performance compared against full sized 1/4w GP antennas. When the sun is very active, a wet noodle lets you work DX. But at the solar minimum, the lower performance stands out. I’ve just built a 17m/20m/30m dipole which in testing seemed a lot more lively.

EFHW (end fed half waves) are very popular because if you have trees on most summits, you can thrown one end of the wire up into the trees and let the antenna drop back to your radio or slope back. So you don’t need the fishing pole a lot of the time.

For a dipole, you need a length of coax that runs up your fishing pole plus a few metres to reach to where you are sitting. This will have some loss for the very lightweight cables. Less loss means more weight. An EFHW can be attached without any real feeder and so saves on this weight and loss. But you need a matching unit which is simple to make but can be lossy. Horses for courses!

As a newbie, I’d make a link dipole to begin with. Not because I think it’s the best but it’s the easiest to make and get working with limited experience and tools. Have a play with that. Likewise 1/4wave GP is a great antenna but needs a bigger pole quickly as it will be 1/4w + 1/8w in height. Also do try an EFHW. Making the matching unit is not hard and there are loads of designs to follow as well as kits of components available.

When you have all the kit ready, pack your bag and go and setup in a local park. Then you can make a list of everything you used and everything you forgot. That will help you pack the kit you definitely need along with stuff that may be useful but wasn’t needed. You don’t want to find out you forgot some essential gizmo when you’ve driven for 2hrs and walked for 3hrs. In miserable weather!

Above all, go out and have fun.

3 Likes

Two comments:

  1. if your summits are packed in with trees (as they often are in the northeast USA), an EFHW (single ended) will be easier to deploy than a doublet (double ended).

  2. I’m not a fan of linked antennas - they make band changes too cumbersome/slow especially if the weather is very cold or I’m trying to chase an S2S on another band. I prefer either trapped multi-band antennas or non-resonant antennas using my KX2’s ATU.

73 Barry N1EU

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Sean

As stated earlier, EFHW are popular in the US and I like others have been very happy with the LNR Precision Trail Friendly.

I think you are based in VA and if your activations are generally in that area maybe 20m and 40m will do you just fine.

For what its worth I support my end fed with a carbon fibre fishing mast that works fine and never use trees even if they are around.

And also for what its worth, the Elecraft KX2 is fabulous radio which has worked for me for many activation. I like that fact that the battery is internal and sufficient to run 5-10w for 2+ hours.

Paul

1 Like

At the moment, due to the solar cycle, the vast majority of my contacts are on 40m. With this in mind, you could try a monoband end-fed for 40m from SOTABEAMS:

It will work well with an FT-818 if you decide to go down that route, and would be about the lightest option possible. You could buy the Laserbeam filter for your 818 at the same time:

There is also a speech compressor available. Then again, if you’re going to shell out for so many accessories, mabye you would be better off with a KX2. I love mine.
de OE6FEG / M0FEU
Matt

2 Likes

Hi Sean,

It’s normal for me to try a different antenna each month looking for a better compromise or just wanting to do a field test of an idea that has been buzzing around in my head. The gold standard for me is the SOTABEAMS 80/40/30/20 linked dipole. It is a bit slow to change bands but there is no ATU to carry and no toroid match required. Inevitably some signal is lost in the ATU or the toroid but the convenience in band changing might be seen as worth the loss.

Last Friday I used a tuned feeder to a 30 m half wave with an ATU on one summit and the SOTABEAMS linked dipole on the second summit. I had the same number of contacts on each.

I use an FT817 for backpacking trips - owned it before the KX2 or KX3 were around.

As Andy said there is a diversity of opinions and some hold to their favorites like a much loved child. Whatever you decide on you have made a start and should not be afraid to experiment and make changes later.

Don’t wait hoping for perfection, get out and enjoy the activity.

73
Ron
VK3AFW

MM0FMF has nailed it for me with the antennas and trialing in your local recreation area or field.

I’ve owned both and both are great for their respective price points and it the age old adage of you pays yours money…

I have a KX3 and it’s head and shoulders above the Yeasu, as I would expect for something nearly twice the money. But Is it worth it - I’d buy mine again and wish I hadn’t wasted money by buying the FT817 first, so a cautionary tale here. There are so many happy users and stalwarts of the Yeasu out there so they can’t all be wrong. No one can tell you how to spend your money it depends on how serious you want to be. My KX3 would double as a base rig - it’s that good. Good luck :wink:

It does indeed :slight_smile:
I use mine to chase at home; no amp - the noise is so bad that the weak link is hearing the incoming signal.

73,
Rod

Do you use it in conjunction with HDSDR?

http://www.hdsdr.de/

I have found it makes a big difference when the KX3 is used as an SDR. I am able to resolve signals so weak that they would never hear me if I didn’t turn on the linear, and some of the noise where I live is pretty bad.

I asked the same question a year or two ago. And I still use the linked SOTA dipoles.

It isn’t much of a fag changing bands. Its not as though you’re centre support is an immovable object.

No tuner, less to go wrong and less to carry / pack.

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I love the FT817 as I do a lot of VHF Activations…a big deal out here in the mountain west…nothing like VHF form a tall mountain. Obviously works well on HF also. Over 12000 contact from summits on it for me.

It is a very versatile radio…virtually all modes and all bands, and drop proof.

You will not be disappointed.

Pete
WA7JTM

Wow. I’m eternally grateful for all the responses. I’m still in the soaking-up-information stage. In a sheer fit of irony and at the strong suggestion from a few folks, I was able to get a great deal on a barely used KX2 that FedEx is in the process of rushing to me. Hopefully, by this time next week, I’ll be on the air…not SOTA, but on the air. I want to get to know the radio where I can fiddle with creature comforts before I head into the hills. I’m planning on going with a 35.5 ft random wire and 16 ft counterpoise since the KX2 I’m getting has the internal tuner.

Thankfully, except for a few knobs, most of the ‘peaks’ around here are wooded. I’m still trying to finger out how I want to go for a portable mast. I had a 20 ft collapsible fishing pole, but it really only collapses down to 47”/1.2m and weighs a heavy 22 oz/620g. It’s not the best thing for backpacking.

1 Like

I had a 20 ft collapsible fishing pole, but it really only collapses down to 47”/1.2m and weighs a heavy 22 oz/620g. It’s not the best thing for backpacking.

I used such a pole for two years and know several SOTA activators who still do. Strap it to the ouside of your backpack and go out and play. :wink:

Ahoi
Pom

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@OE6FEG A filter that can automatically select either SSB or CW mode? That’s what I’ve been looking for! :smiley_cat: Everything I’ve seen for the FT-817 is one or the other requiring two filters to be purchased and manually swapping them when desired. Maybe it just helps Yaesu collect more money by selling two.

Going a bit off topic here, but I have fitted the filter module for a friend and it is a relatively straightforward job. However, I would recommend a magnifying glass and a fine tipped soldering iron as there is one very fiddly bit of soldering to do. Believe me, this filter makes a big difference, well worth the money. It should also be remembered that end fed half waves fed via a tuned circuit, like the one from Sotabeams, also provide excellent out of band rejection for what is a very wide front end on the 817/818. The Fuchskries from QRPproject is a multi band EFHW tuner that works from 80-10m.

It is very popular here in Austria and Germany, and in conjunction with the SWR meter on the 817/818, it is very easy to tune the antenna safely. I made another thread on the construction of this kit here:

If you need an English instruction manual then send me a PM and I can let you have a link.
de OE6FEG / M0FEU
Matt

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Hi Sean

Welcome to SOTA. Like you I have had these debates in my mind over the years. I started out with an FT817 a long time ago and my first contact was VK6LC on SSB (no less). However, I built a K2 in 2012 and a KX3 shortly after. My KX3 has survived many trips overseas while I operated as ON/NY4G (Belgium), TA3/NY4G (Turkey), NY4G/VY2 (Prince Edward Island) and even a solo DXpedition to Saint Pierre and Miquelon as FP/NY4G and my KX3 is robust enough even after 11 SOTA activations. I activated Wine Spring Bald in a pouring rain. I did take precautions to protect the rig but the rig did get wet. The rig survived and worked in the next activation of Lickstone Bald with 1440 feet of elevation gain in the hike of 2 miles. I would prefer a KX2 for SOTA if I had the extra funds to have both a KX3 and a KX2 but all I do now is strengthen my legs for the extra 6 ounces of weight. As for antennas, I prefer EFHW because it is easier to deploy. The linked dipole is perhaps more efficient but the efficiency improvement is marginal - and considering the ease of deployment - the EFHW still edges the linked dipole out. My EFTF 40-20-10 is resonant is my goto antenna as it is shorter than the 40-30-20 MTR and even tunes 30m with the internal tuner in the KX3 and have made dozens of contacts on 30m with it.

Let us all know what you decide and look forward to chasing you.

Ariel NY4G

Actually the 817/818 only allows for one optional filter. However it is an IF filter, meaning that once filtered out, nearby interference does not affect the gain of the receiver. Whereas audio filters are outside the AGC loop so a strong nearby signal can “pump” the AGC, confusing the audio you hear through the audio filter, but only in the case of really strong QRM. The ssb filter is a “nice to have” option, but the cw filter is a must if you are a regular cw user operating on a crowded band. If you are not a frequent cw user, you possibly don’t need the cw filter because you can still use the rig on cw with the ssb bandwidth. This is why those narrower filters are both optional, but as stated, there is only one socket for an optional filter.

But - there is a way of fitting both filters. W4RT offers (or offered) an option to allow both optional filters to be fitted to your radio. The mod required is a little more surgical and requires the stock ceramic filter to be lifted out of the board, a new board added to carry the two filters and so on. That option depends on the availability of the Collins mechanical filters which are no longer in production. Possibly obtainable on the second hand market.

For that reason, the practical option is probably that neat dual bandwidth internal switchable filter from sotabeams. or another the many audio filter options which are nearly all external filters, further complicating your portable station. At that point you may well ask, why didn’t I get a kx2?

Or… (this discussion can go forever) … Andrew VK1DA/VK2UH

They show up regularly on the world’s most popular tat bazaar. Second hand ones now offered for the same price as they were when new. Dealers may still have stock too.