Well, some years ago, I built my own stick-and-wire quads for 2m and 70cm, and to my absolute amazement, found it easy to work the SO-50 FM satellite with just a couple of Watts from a handheld.
Unfortunately, so far as I know, only SO-50 is available as an FM low earth orbit satellite at the moment, although any time now, AMSAT's
FOX 1 is due to hurtle into space.
Weather - and my XYL's poor parking - took its toll on my 2m quad, and a 109mph wind that threw it up in the air in February 2014 meant its life was over.
Since then, I've been inactive on satellites. So, not being minded to build another antenna for the time being, I opted to buy a Sandpiper dual-band Yagi. The current price is £88 including postage, which is not cheap, but not expensive, either.
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| The Sandpiper 2m/70cm Yagi. |
The parcel duly arrived in a couple of days. I did give advance notice to the seller that I'd be reviewing the antenna.
How does it fare?
Firstly, the impression of the packaging is a 6 out of 10. The half cardboard tube, half crushed cardboard box wasn't very neat, and compared to the kind of proprietary tube in which the likes of Geoff Brown, aka G-Whip send their equally-priced mobile antennas out, it was pretty amateurish, to be honest.
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| I've seen better instructions. More notes on matching would be useful... |
The instruction sheet is a single sheet, with little by way of a step-by-step. It's no problem at all for someone who's played with Yagis before, but it might be slightly daunting for a newcomer. I thought the instructions could be a lot clearer with minimal effort.
The materials used are to Sandpiper's credit. Just about everything is stainless steel, although grubscrews looked to be mild steel to me. Not a big deal if you put a small amount of grease on them, or if you keep the modestly sized antenna indoors or in the car. The 2m elements are very springy, which makes the antenna quiver a fair bit when held in the hand. But that's just nit-picking; it's a perfectly sturdy, reasonably lightweight antenna that can clearly take anything the weather can throw at it in a permanent installation.
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| Stainless elements pass through demountable, wing-nut secured bolts. Great for transporting. |
I had hoped the antenna would be much lighter than I found it to be in practice. Despite being marketed as "ideal [for] satellites", it has the usual problem of front-heaviness, so it quickly becomes tiring to hold. A homebrew addition of a timber extension to the boom so that my forearm stops the thing from pulling down too much has sorted most of that out. As it is, you can just about manage a 10 minute pass without your arm giving up entirely. In reality, there's little to suggest the practicality of hand holding this antenna for satellite work has been a consideration in its design. With suitable changes, this could make the antenna much more attractive.
What (pleasantly) surprised me was the single feed. The antenna comes with an SO-239 socket, which is not ideal at VHF/UHF, although the very short cable lengths used for handheld satellite work make this an academic issue. The matching is achieved
via a twin gamma match. With both sets of elements in the same plane and interacting somewhat, adjusting for lowest SWR was not a trivial exercise; it took about 30 minutes for me to tweak everything, including some pretty significant bending of the gamma rods; the suggested setting length for 145MHz just wasn't possible out the box, as it was about 5cm too short! Some sliding in and out of the elements might have helped here, which is mentioned rather unclearly in the instructions, and I'll try that out at some later point.
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| The single-feed, twin gamma match for 2m and 70cm, prior to fitting the shorting bars. It works, but was very twitchy to match, especially on 2m. |
Eventually, I managed to get both bands down to about 1:1.4, maybe 1:1.3. That's acceptable for a twin band antenna and handheld at low power. I'm pretty sure that, whilst it would make the antenna more difficult to pack in a car, it would nevertheless have better matching with elements at right angles. The single gamma match probably mitigates against that design, though.
Here is the plot from my SARK-110 analyser for the 2m part of the antenna, performed several months after I first tuned it, and taking a more relaxed approach: it's best to match the 2m for lowest SWR, and not worry too much about less-than-perfect matching on the 70cm part, because that's only used for listening when satellite working.
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| Very good matching on 2m for the Sandpiper, but getting both bands matched is tricky. |
For sure, tests on a 70cm repeater at 63km on the Isle of Man (line of sight sea path), showed the antenna to work very well, with a good front-to-back I'd estimate at about 20dB or more. I didn't try the 2m beam. Tests on SO-50 haven't yet yielded any results, as it was very late during a weekday, and the satellite passing extremely high to the north, with consequently no activity.
One thing I did find out through buying this antenna was the ability of the Baofeng UV-5RC to transmit on one band, and listen on another. That's very handy, because otherwise, my single-feed Yagi would have been useless with one handheld tcvr! This
useful video helped greatly over reading some Chinglish manual that anyway doesn't seem to tell you how to do it! It is much nicer, though, to listen to your own transmissions coming back, in which case the easiest and cheapest solution is two antennas (or two feeds) to two separate handhelds. Without this feedback, and especially early on in the pass, you don't know if you're hitting the satellite, or whether it needs the lower CTCSS code to open the timer. Those are bigger issues than you might expect. On the flip side, managing two handhelds or two separate antennas is very difficult, unless you have one antenna supported on a pole (which was my earlier arrangement.)
UPDATE:
I've now had a chance to test the antenna on a couple of SO-50 passes. The signal on receive is very good indeed, and lacks nothing. There's also no problem getting up into the satellite, as I managed several QSOs on a low-to-the-horizon pass just now. The service, including packaging from Sandpiper gets a 6/10, dragged down by not-very-enthusiastic responses from the seller, and poor packaging quality. The value for money gets a 7/10, and the quality of the antenna a 7/10, dragged down by the difficult matching and misleading claim that, once assembled, it can be disassembled solely by use of the wing nuts. The instructions are 6/10. Ease of matching isn't really something to score as such, but it isn't very easy, and bore little semblance to the suggested settings. A few minutes creating and posting an assembly and matching video online would probably help Sandpiper's customers and save them some time.
The antenna fits in the car quite easily, which makes it very useful for me, as I often find myself waiting for kids for hours on end, when a ham radio is very good company.
Would I buy it again? I don't think the price is too bad, and having used it in anger on SO-50, can say I'm not at all disappointed by it - except for its pretty poor performance when the satellite is low in the sky; it's a very, very long way short of my old 5-ele up, 7 ele down quads in that respect. I'm not wildly excited by its matching and physical imbalance. In fact, because of the need to adjust for Doppler shift and sometimes to transmit a timer-opening CTCSS tone that's different to the normal access tone, I was forced to get to grips with programming channels on my Baofeng UV-5RC. Adjusting all the factors in Frequency Mode is impossible with a single handheld. The single button press required to change channel and thus allow for the Doppler shift is, in fact, a much better arrangement than the earlier, direct-entry system I was using.
Whilst I was very annoyed at having to do so initially, now I have done it, it's actually much easier to skip up or down a few kHz with everything pre-programmed. Just press an up or down button, and the correct shift is there on both uplink and downlink. An additional channel stores the correct tone for opening the sat when it's gone into sleep mode!
So, it's fine if you want to save some time and get going quickly. It's also good for single handie use and ease of transport. It's not so good for grabbing trans-Atlantic LEO QSOs, I'm afraid. All the same, I'm hoping that, seeing a shiny antenna pointing skywards, folk outside the school or in the shopping car park will stop by, ask what the heck I'm doing, and leave amazed that a 'walkie talkie' is sending signals into space!
