HF Manpack Success!

I like the convenience of operating from home, where I have a modest, 'kitchen-top' station.

But, using one's home as a radio sation can be intrusive on other members of the family.  It can also be far too much like putting all your eggs in one basket if EMC issues develop in the neighbourhood.

So, I've always kept my hand in simple, rapid deployment of HF radio away from the home, so that, whatever comes to blight me there can be avoided simply by getting in the car and visiting a hill or beach.

My most recent incentive to go portable in earnest came a couple of weeks ago, when a neighbour installed an electric fence right up to my boundary.  Whilst noise blanking gets rid of the ticking almost all the time, and the fence is not that noisy anyway, it does show how easily and quickly neighbour EMC problems can come to influence and possibly spoil your home station.  (Update: three years later, the electric fence was such a maintenance headache that they gave up on it - hurrah!)

So, I took some inspiration from a few images under a Google search for 'HF manpack'. These were all much the same, copper tube constructions that contain all the equipment and are either backpacks in their own right, or otherwise slip into a fabric rucksack.

WSPRlite testing of the copper tube manpack.

I was interested to see whether I could reach any sort of workable match of the tube frame when I mounted a 20m mobile whip on top of it, using a gutter mount, but no ATU.  A quick connection to my SARK-110 antenna analyser showed that, indeed, a perfect and relatively broad match could be achieved quite easily, simply by adjusting the whip length as normal.

Armed with quite a positive first indication from the analyser, I set the frame out in the garden and hooked-up my WSPRlite QRP transmitter, running 200mW.

I left the unit running all day whilst I was out, but conditions were so poor in an R2 blackout that I had no spots at all!  That changed the following day, when conditions relented somewhat, and good distances out to Finland during the day were being achieved.  Later, a few spots out to Russia and the US were reported.

I can tell the bakcpack is working well because, thanks to DXPlorer, the software that comes with WSPRlite, I can compare with known, efficient stations elsewhere in the UK and see that it is as good as, for example, a full wave horizontal loop.  More time is needed for a full assessment.

Clearly, this frame is a workable and efficient solution to not only going mobile but backpack (or pedestrian) mobile, all at very little cost.  Those who operate /PM from the beaches of the UK on a regular basis know how they can manage QRP contacts with VK and ZL very easily, whilst folks at home can't even hear the antipodes!

I'm looking forward to grabbing an FT857 or similar rig, and enjoying morning and evening sessions down the beaches.  Imagine, no noisy solar PV, plasma screens, LCD lights or electric fences anywhere in sight!

UPDATE!

Here are some results from WSPRlite testing.

First, a comparison with a horizontal, large loop antenna:

Next, a comparison with a doublet:

And, finally, against a trapped dipole:

Update 2:

I've now assembled my TS-480 and a 12Ah battery onto the frame.  It's comfortably backpackable, having bought some shoulder straps for it.  The overall experience of using the system on SSB is pretty much identical to operating from a car with a magmount, so I'm pretty happy with that.

The battery is small, but provides enough duration to enable me to cover plenty of overs during the 20-30 minutes of peak long path propagation.  On about 15-20W peak output, I've managed Russia and the mid-west US so far, as well as the usual lot of easy EU stations.  Overall, it is working as well as such a system can be expected to.

An obvious improvement in terms of power duration and ease of transport would be to install the system around a decent, large-wheeled all-terrain pushchair.  Sadly, I sold ours years ago, and that model, which was perfect, is either difficult to find and/or very expensive now.If you go down this route, avoid, at all costs, those buggies with front wheels that swivel, and wheels that are either too narrow, too small, or both!  Wheels needs to be at least 12" in diameter to cope with sand and rough surfaces well.

RadCom asks - me? - to help them out!

Last month, RadCom ran a second article about earthing an amateur radio station.

None of the following constitutes advice.  It is for you to engage qualified people to examine and install your system.

In this latest contribution, there was text, supported by a graphic, that showed, in essence, each piece of radio equipment attached to an earthing bus, connected to a stake/rod stuck in the ground outside.

Now, all amateurs are meant to have passed an examination which should mean they understand earthing to a reasonable level.  But, visit many shacks or listen to on-air QSOs, and you will quickly realise there are an awful lot of people who have absolutely no idea why they are earthing their equipment, or how to do it properly (i.e. safely.)

Unfortunately for RadCom and its author, who seem not to have thought an awful lot before publishing, they failed to include instructions on how to properly earth a shack that is served by what is actually a pretty common system in the UK - Protective Multiple Earth (PME).

The PME earthing layout, very common in the UK.

Setting up a shack with a ground rod attached to equipment in a PME-served household is potentially extremely dangerous.  The earth wire at the incoming mains is not a separate connection back to some remote earthing point, but one that is completed via a connection to the neutral wire.  If the neutral breaks during a storm or other failure, you could end up with a whole neighbourhood's supply trying to use your equipment and its questionable earthing to complete a ciruit.  Fire is the most likely outcome.

Solving this problem is not difficult.  You do the same as RadCom published - i.e. connect each equipment to a ground stake, but also add a separate wire that is connected directly to the stake, and runs back on its little own to the consumer unit. The wire needs to be a minimum of 10 square mm to handle the potentially high current that might try to use it, down to your earth stake.

Even then, the job may not be good enough.  I found that the very short earth wire between the incoming mains and the consumer unit was very thin - probably way below what modern regulations stipulate.  That was installed by the supply company about 40 years ago, so it's entirely their fault.  If your wire is similarly inadequate, you will need to ask the supply company to inspect and change the wire, hopefully without charge because it doesn't conform to their own regulations.

I pointed all this out to RadCom and the author of the article.  After a month, I received a sheepish e-mail from the editor of the magazine that said many people had been in touch about this issue, and would I consider writing an article to set the record straight?  I politely declined the offer, saying that they had better get someone with current electrical engineering qualifications to do so, and maybe pay more attention to proof reading and quality control in future.

So, if you have PME, do consult the document that RadCom and its author seemingly didn't, freely available here:  http://rsgb.org/main/files/2012/06/emc-leaflet-07.pdf

None of the foregoing constitutes advice.  It is for you to engage qualified people to examine and install your system.

RSGB Expenses Hike Prompts Departure

It's that time of year again when the finer details of the RSGB's accounts are slowly sinking in.


I'm always interested in the non-remuneration of the board members which, the Articles of the company say, is to cover legitimate expenses.  It is not, therefore, pay.

So, let's look at this latest accounting period.

In 2015, eight board members collectively claimed £15,000.  That's the equivalent of £1875 each.

In 2016, seven board members - one less than in 2015 - claimed £17,000.  A new equivalent of £2428 each.  Note that some members may have claimed more than others.  That's why I use the term "equivalent".

Now, these are not huge sums, and there is no suggestion that the claims are not legitimate and properly due.

What is surprising is that, despite the number of board members claiming dropping by 12.5%, the total claimed has nevertheless gone up by 13%.  Inflation is essentially flatlining, so that doesn't explain much of anything.

I find myself again questioning why I have joined the RSGB when, in practice, all I get is a magazine that I don't actually ever enjoy reading.  This is very different from the experience of being a member of the ARRL, where everything in QST and beyond is so much more practical and approachable, albeit with no influence in the UK.

I think the basic problem I have with the RSGB is (a) that it is a limited company where the directors each shoulder the non-responsibility of a £1 liability if it all goes belly-up.  That doesn't foster a sense of ownership and responsibility, as this event, or this one have fairly recently proven.  I think an alternative structure like a not-for-profit or community benefit organsiation might better match what we actually expect a hobby society to be.

And, (b) there is a very strange culture surrounding the RSGB.  I found this out with some amazement a few years ago when Len Paget, still an RSGB bigwig, decided to send his views of me (based on exchanging a couple of emails about planning matters) to 11 members of a non-radio organisation, questioning my suitability to be a representative of that organisation.  He used his personal e-mail address to do so, but was in practice representing the RSGB, because that was the only route through which I had ever approached him, via the 'haveyoursay@RSGB... address', and the RSGB (and ICO) accepted the breach was their responsibility, not a personal matter between myself and Paget. Paget was very lucky he didn't end up with a libel writ.  Sadly for him, I wasn't even a member of the society he contacted.  The ICO carpeted the RSGB for its poor data control.

With many of the same old people in charge, it's hardly surprising that I find the RSGB hasn't really changed very much with some new faces over the  past three or four years.  I can't even say I've been very impressed by the quality of advice offered by those volunteers I've approached for help; I could have done as well or better under my own steam.

For example, the RSGB continues to claim that a member using its planning advice service is more likely to gain planning approval than someone who doesn't use those services.  This is a big claim.  It's also a claim that, without a very extensive, expensive and, so far as I know, not actually undertaken exercise, one the RSGB is not in a position to make.

So, for the second time in about six years, I've decided this is not a society that represents my values, wishes and interests.

I thought I was clever in joining the GQRP Club, until I received a very unwelcoming email from someone there, who clearly showed this was not the place for me.  I demanded a refund - and was as relieved to receive it as they were to issue it. 

WSPRLite Test - Magloop on 40m

Having run very successful week-long transmissions on 20 and 30m using 200mW WSPR recently, I turned by attention earlier this week to the final test for now - on 40m.

The approach of a particularly severe storm - 'Doris,' meant the 40m test had to be curtailed after only two and a half days.

The results are extremely favourable in comparison with an OCFD atop a clear hill:

Magloop (blue) vs. OCFD (red)

The advantage of the magloop is that, for the most part, it keeps up with the OCFD most of the time, and is somewhat superior to it during the night time.

Now, a comparison with a doublet, which returns an even better result:

Magloop (blue) vs. Doublet (red)

And finally, the magloop loses out significantly to a 'skywire' type horizontal loop, which has much better night time performance:

Magloop (blue) vs. Skywire loop (red)

As always, take the results in context.  Overall, and considering the antenna is just 1.2m across and covers down to 5MHz, the achievement of the loop is really quite outstanding.  Certainly, those people who keep bleating on that a small loop is nothing more than a dummy load are once again definitively proven wrong, even on 40m, where a small loop of this size is starting to lose efficiency.

New Laptop, New RFI.

After six trusty years of heavy daily use, my Samsung netbook has finally given up the ghost.

Enter a brand-new HP14-AN001NA E2 laptop, a pretty good bargain offering from Tesco here in the UK, selling for just £239.

Having hooked everything from the station up to the HP, there was no immediately-evident RFI.  I was quite pleased.  Pleased, that is, until I switched to 24MHz, a band that remains surprisingly active, despite the lack of solar excitement and the belief amongst many ops that it is a dead band.

Whilst the RFI was narrow, rather than broad band, it was quite strong at 24.917 - slap-bang in the middle of the JT65A window. 

Rather despairing of the sheer number of RFI-generating consumer goods now overwhelming the hobby, I took to adding a wire of about 2m length to the chassis of the laptop, via the shell of the HDMI socket, using a small crocodile clip.

Voila!  The chassis is detuned such that the RFI vanishes at ham frequenices.  No further action necessary!

More WSPRlite Testing: Single vs. Triple Magnetic Loop

G3JKF runs probably the definitive magnetic loop on WSPR across many bands.  He and I have exchanged thoughts many times, and continue to do so.

I encouraged Ken to buy a WSPRlite last week, and we had a brief meeting on 30m where his triple loop array could run against my single loop.  Ken's construction is very careful and considered, as he has a long career in electronics enginnering.

This is how the loops, running 200mW, compared.  My single turn, 28mm copper pipe loop is in blue, Ken's triple, 15mm pipe loop in red:

In terms of the average distance achieved, the two loops were identical, coming in on that day at 6.6% of the maximum possible (antipodan) distance.  Ken's loop managed a greater distance periodically.

Overall, there isn't an awful lot to choose between the two loops, but it's clearly worth adding a bit more metal if you can manage it.

The question of whether a loop is any good and can keep up with full-sized antennas is one that is dominated by each antenna's environment.

For example, here's the week-long loop run against a doublet end fed wire run by the WSPRlite maker:

Clearly, the loop does better than this particular doublet by all measures during the whole run.  Notably, the loop keeps going through the night, whereas the doublet EF wire drops out for long periods.

Here's a comparison with an inverted-L, tuned at the base:

The loop is not quite as good as the inverted-L, but it does very well, nevertheless, especially when one considers the difference in physical size and the simplicity with which a loop can be installed.

And, finally, few people have anything bad to say about a loft dipole.  Yet, many criticise magnetic loops as just 'dummy loads'.  Here's why that view is utterly misguided:

Again, and whilst the loft dipole wasn't running some of the time, the magnetic loop does better at all points.

So the message is always the same: a well-made magnetic loop in a good, clear environment can do as well as or better than full-sized wire antennas in many cases.

Homebrew Magloop vs. Butternut Vertical, and Others.

Thanks to a rare spell of cold, fairly calm and, above all, dry winter weather this week, I've had a chance to stick my magloop out in the garden attached to my WSPRlite unit at 200mW out.

I'm amazed that the WSPRlite is able to handle the sub-zero temperatures, all without a hint of drift.  That said, someone from Norway is running his at -17 degrees Celsius, so it's clearly a very robust unit!

On initial assessment, it looked as though my magloop wasn't doing terribly well, because the reach of the signal was only really as far as the Canary Islands.  But I then started comparing my results against other stations, using the very useful DXplorer webware.  This showed that it wasn't the antenna, but poor propagation conditions that was the cause of the short reach.

This comparison revealed, again and again, a magloop that was doing almost as well as, and sometimes better than, full-sized antennas like the Butternut vertical operated by G0MJW, a plot for which is given below.  The only time it does poorly is during the later evening, apparently a result of having a low elevation pattern (not detecting high angle, short skip signals).

The only thing to do now is build-up the data and see how things pan out over time.

For sure, those who say that magloops are of no use are definitely wrong!  Also nice to remember that my magloop,even with new 28mm copper tube, cost only about £40, when the Butternut is several hundred pounds!

UPDATE.

Encouraged by the surprisingly good performance of my loop, I set things up for 30m the following day, where propagation was considerably better.

I compared my loop with known antennas - G3CWI running a doublet, and G7TSX running an inverted-L.

Again, the results were excellent.  Indeed, over the 1-day run, which I accept needs lengthening (the run is still ongoing), the magloop in this environment beats the socks off the doublet in its environment on both mean and maximum distances spotted.  For the inverted-L, my loop is essentially the same on the mean distance, and very slightly behind on maximum distance.  Remember my loop is just 1.5m off the ground, and only 1.2m per side!

My loop (blue) vs. a doublet (red)

My loop vs. an inverted-L.

I've no doubt that, if I were to run a doublet and/or inverted-L in the same location as my loop, it would be a little behind in comparison.  But there's the rub - from the right location, a magloop can indeed be as good as and even better than a full-sized wire antenna in a somewhat less ideal location.

So, the main message is: don't take what others say about any particular antenna as Gospel, because they know nothing about your environment, and are probably ignoring or underestimating the effect of theirs!