Comparing antennas on RX

I have three HF antennas - and three rigs: The trusty 817, and a couple of shack rigs. I've been "testing" the setup on RX by running three copies of WSPR 2.0 in parallel, on the same band, one connected to each radio (I use SignaLink boxes as interfaces)

The antennas are a couple of long wires, running similar but not identical routes, and an inductively loaded vertical I bought many years ago from sandpiper aerials - it's been lying behind the garage where it was placed when we moved house a few years ago, and everything is seized. I set it up on a fence at the bottom of the garden. It has now grown its own earth stake. I can't tune it for resonance because of the corrosion so the setup I made when it was new is stuck in place. Two or three of the bands - 12,15 and 17 metres - tune reasonably well directly. 40m is a complete no-go, and the others needed tuning.

A few months ago the winner, on most bands, was a LW/earth stake, tuned through an SGC Mac-200 to my Icom 756 ProIII.

Now, things are very different. I have spent the day with this trio, moving down the bands. So far, I've played with 21MHz,14 MHz, 17MHz and 10MHz. The 817 / LW appears to be deaf. It's generally around 12dB down on the winner. The Winner is the corroded Sandpiper which is, as I write, capturing some Stateside stuff on 30m which neither of the others sniff at. The 756 is pretty effective on the LW, generally turning in about 3-6dB down on the vertical

So what has changed? I'm guessing saturated ground probably has a fair bit to do with it. The earth on the vertical must be pretty effective at the moment, since the ground is sodden.

I'm trying to work out why I now find the 817 deaf. I'm sure I remember being pleasantly surprised by it....

I hope to move down to 3.5 and 1.8 this evening. I am confidently predicting that the vertical, with an immense loading coil on it, will not out-perform a long wire. And, of course, on 160m there is no choice.

[Later]

The situation on 80m is surprisingly even. All three systems perform around the same level - in each case, one is a few dB up or down on the others, and all three have good and bad moments. I'm surprised the Sandpiper does so well. Or, maybe, to put it another way, are the long wires doing badly?

the next step is to rotate the antennas around the rigs

30m

It's easy to forget 30m. It's neither to long, nor too short, not too wide, and it's one of those suspicious WARC bands. For me, yesterday, it was the Goldilocks band. I couldn't get much out of 10m, and I didn't want to spend the day on 160m (I tend to drop down there at dusk), so 30m it was.

This is the whole day - from about 9AM until about 9PM 21st December. Operating at 2.5W. Most of the DX heard me, but I didn't hear them (usual poor antenna problems at M0DEV)- but I am perpetually surprised at how well I get out.

I'm running on 30m again today, but this time with 500mW. Clearly, a direct comparison doesn't mean a great deal, but it will be interesting. KK5MR has already spotted me from what appears from his station notes to be a relatively modest setup.

Antennas- properly.

There's an object lesson for you. Do it properly.

I spent an hour this morning re-arranging a long wire antenna - it's now insulated, is not (now) lying on anything, and I connected the other side to an earth stake instead of a flimsy counterpoise ending on the (admittedly metal) washing line post.

The signals I'm seeing on 80m WSPR now are awesome, even though I am still only up about 4m. G8JNJ/A (I assume it was him) came in at +9, and in the last 10 mins of operation I haven't seen a negative dB

TX seems better too - I'm using my usual 500mW, and DK4XI is hearing me.

I'd better re-fettle the "main" LW at M0DEV, methinks. It's got the good earth, but the route runs through trees, in a zig-zag. There must be points where some RF escapes to earth...

Log Analysis

What to do on a quiet day, but look at your logs. I have been meaning to do this for some time. I extracted the last 1000 or so QSOs from my log (kept in HRD) and I've analysed distance, by band. I was convinced that I was getting the "best" results out of my kit on 17 metres. It appears that this may not be the case!

The graphic isn't very clear (click on it) but I poured the exported data into "R"(a stats package) and got it to process it for me. The distance is in km. It's worth saying that virtually none of these contacts are SSB or FM - I am almost exclusively digital or CW

20m appears to have provided me with my best DX(a ZL), so it retains its label as a DX workhorse of the bands. followed by 10m, 15m and then 17m. I'd say 12m was underperforming - probably my antenna. I don't spend much time on 30m. I find 40m crowded. I don't stay on 80 or 160m long enough in the evening to pick up real DX.

What is interesting is that the median distance - half the contacts are above, half below - (indicated by the bold line in the middle) on 20m is way down on the median distance on 17m - I think this is caused by heavy local (i.e. European) QRM drowning out the DX, hence my impression that 17m at M0DEV is more DX-y. If you have a very high presence of european stations, then you won't hear the DX - even though it is there. Indeed, 17m at M0DEV has the highest Median. Of course, I am probably skewing this by going after DX contacts calling CQ, and ignoring the locals. The 20m distribution (and 15m and 40m) is classic positive skew, bunched up at the bottom end. The 17m distribution looks more "interesting".

It would be interesting to take this further, and try to tease out factors which are caused by my equipment, and factors which are really "there".

So what does it all add up to? Very litte!

20 metres WSPR

I left WSPR running on 20 metres whilst flitting in and out of the shack today. It's been on for about 6 hours, and this is a cumulative plot.

Running 2.5 watts out of the ft-817 to what is probably the world's worst antenna - a piece of wire running along some guttering about 2.5m up. With an earth, admittedly. The Elecraft T1 tunes it easily, but I am astonished at how well the 2.5W has got out. It turns out, i think, to be a better TX than RX antenna - a number of these stations can hear me, and only a few are heard by me but don't hear me.

By far the best DX here is RA0SX, who hears me but I can't hear him.

So why do we use such high power? I think there's an element of beat the competition. And, of course, nearly every mode will be much less efficient than WSPR.

QRP /P

I have an FT-817, which has seen hard use with SOTA, which I exhumed for a short break in Cornwall last week. I took a ZM-3 ATU - a manual Z match ATU, which I built a few years ago. And strung up a LW up the side of the house, with a counterpoise. The ZM tuned this quite happily, and it sounded especially perky on 30m. RX. TX was useless. Stations clearly couldn't hear me at all. Do I conclude that QRP operation running <=5W with a poor antenna is a waste of time? Or is it the ZM ATU? I use a LW at the home QTH quite successfully, and have worked VK and other DX easily with it. hmm... ZM-3 reviews
SOTA UK