472-479kHz in Poland

See this email:

Hi All!

New band 630m in Poland, the official regulation:

http://download.pzk.org.pl/public/KTPC/Dz.U.03.02.2014_Poz.161_KTPC.pdf

472-479kHz, power 1W EIRP

73! Marcin SQ2BXI

The same document confirms the secondary allocation of part of the 4m band too. 

The 630m band is available in Poland from Feb 18th 2014.

472kHz earth-electrode WSPRing this evening

The 472kHz WSPR beacon has been running this evening using the 20m spaced earth electrode antenna described in my March 2013 RadCom article. A reminder that there is NOTHING in the air at all, just the wires along the grass to the earth rods.

Quite a few reports received and given already.

472kHz unique WSPR reports received so far tonight

The same earth electrode antenna will be used at the TX end of my VLF test with the mag-mount E-field probe RX tomorrow morning.

SMA version of the G3XBM 472kHz transverter

In an email,  John G4BAO tells me he has built an SMA version of my 472kHz transverter. At present, he is getting 5W RF out using standard SMA parts and a different FET.  If you wish to enquire about this version please contact John and NOT me!

G4BAO's SMA version of the G3XBM 472kHz transverter

New ERP calculations on 472kHz with earth-electrode antenna in 8cm snow

With several repeatable ground wave reports on 472kHz WSPR using the earth-electrode antenna, it is time for a recalculation of my ERP based on a formula (for 500kHz) supplied some years ago by M0BMU.  The assumption (from M0BMU, that I am not at all sure is right) is that the noise floor is around 3uV/m in a 2500Hz (WSPR) bandwidth. So, based on the WSPR S/N ratio the field strength when using the earth-electrodes can be calculated.

• G3ZJO at 79km gets me at around -19dB giving my field strength around 355nV/m. 
• G3XDV at 61km he gets me around -12dB S/N giving my field strength around 810nV/m.  
• M0BMU at 69km he gets me around -30dB S/N giving a field strength around 100nV/m

ERP Calculations

• ERP using G3ZJO's results = (E*d)^2 / 49; with E = 355nV, d = 79km   ERP = 16uW
• ERP using G3XDV's results = (E*d)^2 / 49; with E = 810nV, d = 61km  ERP  = 49uW
• ERP using M0BMU's results =  (E*d)^2 / 49; with E =100nV, d = 69km  ERP = 1uW

Now, to me these figures seem far too low, so perhaps the noise level is much higher than 3uV/m. Certainly that is the case here where I have an S4- S8 noise floor due to SMPSUs and other noise sources. I think these numbers can be doubled based on ground wave losses but, even so, the figures appear to be extremely low.  My Marconi antenna is some 8dB (average) better than the earth-electrode antenna and I am sure the ERP is well above 1mW using this antenna.

Conclusions

I am totally puzzled: measuring antenna current on the Marconi I get ERPs that are an order of magnitude higher yet measured results with the earth-electrode antenna average just 8dB down on the Marconi. This suggests ERPs for the earth-electrode antenna in the low mW region, which I find much more believable.

Any thoughts please?

Back on the earth-electrode antenna on 472kHz

The red dots show where the wire to my far earth rod goes - under the snow!

This afternoon I've installed a coax cable from my operating shack down to the back of the garage where I do my radio building and where I can connect to the earth-electrode antenna running down the back garden. Now I have my 472kHz transverter in the garage too so it can connect directly into the earth-electrode antenna without any matching. Even with 8cm of snow on the ground and nothing of the antenna visible above the snow line (!) this antenna is still radiating a decent signal with reports already this afternoon from G3ZJO (-22dB S/N) and G3XDV (-12dB S/N) at good range. I find it truly amazing this system works at all.

I am signing G3XBM/1 on the WSPR database to distinguish my signal from that transmitted using a Marconi where I use G3XBM.  I hope no-one minds me using this suffix for a short period, but it is very much in the interests of good research. The signal level with G3XDV at 61km is about 8dB weaker on the earth-electrode antenna than on the vertical Marconi.

Iceland get the new MF band

Icelandic radio amateurs have been granted access to 472-479 kHz and temporary permits for 1850-1900kHz, 5.260-5.410 MHz 70.000-70.200 MHz have been extended.

472kHz update

With nearly 2 weeks of operation on the new band with very low EIRP levels (varying from typically 5-10mW with 100mW on just one occasion) perhaps it is time to summarise how things have been going. A check of the WSPR database shows almost 70 unique reports across Europe of my signals from just a few km away to 1736km. I have still not managed to be copied by TF3HZ in Iceland at just over 2000km and this is my next target. To achieve this will need me to re-erect and better optimise my Marconi vertical. With some optimisation it should just about be possible achieve 200mW EIRP.

Unique WSPR spots in the last 2 weeks on 472kHz

On CW I have received a report from over 160km away when I was calling CQ. A JT9-1 QSO with G3ZJO at 79km is still my best 2-way QSO, although I believe it should be possible to work much further with this mode (I worked OR7T in Belgium with it on 500kHz).

So, pretty satisfying results so far. This has been helped by the huge number of stations currently monitoring WSPR on the new band - frequently over 40 people at any one time. Right now there are 59 stations monitoring!

On 136kHz the challenge with small antennas and low power is considerably harder on WSPR as there are too few stations monitoring: even if the signal was getting several hundred km, one can only tell if someone is at the far end and reporting it.

Earth electrode antenna conclusions (472kHz)

With some further tests today I am now able to arrive at some conclusions from my experiments with an earth electrode antenna at 472kHz. Many people including Jim M0BMU and Rik OR7T have been particularly helpful in analysing the data.

My current 472kHz earth electrode "antenna" - can you see it in the grass?

These are my conclusions:

1. The earth-electrode antenna at 472kHz (2 earth rods in the soil 15-20m apart fed from the TX output) behaves like an H-field loop transmitting antenna.
2. It has directivity, with strongest signals in the line of the loop and weakest signals at right angles to it.
3. It works as an effective RX antenna too.
4. In my environment the loop looks like about 50-60 ohms resistive, so a good match to my transverter directly without matching.
5. The structure works because much of the return current flows deep within the soil and rock beneath the earth-electrode antenna. In my case Rik OR7T calculated that the loop area in the ground is effectively 290m sq with a radiation resistance of 0.017 ohm and a loss resistance of 66 ohms.This is a BIG loop!
6. Performance compared with my 9m high top loaded Marconi antenna averages only around 8dB down, not a bad figure at all, even with the connecting wire on the ground and not elevated at all.
7. Where no other antenna option is available, the earth-electrode antenna is well worth trying both on 472kHz and on 136kHz both for RX and TX. Although it works well here, your geology may be different and results not the same.

These last few days have been most interesting and, with the help of many people - listeners giving me WSPR reports, advice from others on the Internet forums, suggestions by email - I have been able to do some quite useful science. Thank you one and all.

472kHz RX and TX with Marconi antenna last night

Overnight I was using a 9m high top loaded Marconi antenna on TX and RX WSPR on 472kHz. I have since taken this down so it doesn't interfere withe the latest earth electrode antenna tests.

The performance of this larger,"in the air" antenna was certainly better than the earth electrode antenna, although not by a huge amount (2-14dB). As you can see, I managed my first transatlantic amateur reception on the new band WE6XGR at 5640km amongst the 27 unique RX spots.

472kHz RX spots on Marconi antenna

On TX with the same antenna, results were equally satisfying with 34 unique station reports.

472kHz TX spots on Marconi antenna

472kHz earth electrode antenna: nothing in the air

Today, I took my experiments with an earth electrode TX antenna for 472kHz to new levels by placing the connecting wires on the grass i.e. not elevated at all.  The theory developing is that the earth electrode antenna works by forming a buried loop in the ground with the earth return path being in the soil and rock beneath the structure. If this is so, then even with the wire sitting on the grass there should still be a loop within the ground, so some radiation from it. Results this afternoon prove this is indeed the case. The following are the results with a 20m baseline between the far earth rod and the copper pipe ground at the home end and with the connecting wire just laying on the grass lawn.

472kHz WSPR reports with earth electrode antenna with wire on the lawn

Just one slot of WSPR - 15 reports on 472kHz!

Reports in just one 2 minute WSPR time slot with 100mW ERP on 472kHz

With the improved performance from a 9m long Marconi antenna on 472kHz, these were the reports I just got in one single time slot just now. 15 unique stations reported me! It is too easy, even with just 100mW ERP.

Even more fascinating 472kHz experiment

Following on from yesterday's tests, today I started a further test using an earth electrode "antenna" on 472kHz WSPR.

This time I used 2 ground rods in the soil separated by 15m of wire (fed directly from the transverter output at 50 ohms) and powered entirely from a battery supply - PC, FT817, transverter, SignaLink interface - so that there was no connection whatsoever to the house mains earth or copper pipes in the house. The power out would have been slightly lower (lower supply voltage) and the baseline 25% shorter.

472kHz earth electrode "antenna" system in garden

So far, results are almost identical to those obtained yesterday when one side of the earth electrode system was connected to the copper pipes in the home on one end.

My best DX WSPR report this evening with 10W RF out from the transverter into the 15m separated electrodes is G0KTN at 210km. ERP is in the low mW region at best. On RX DJ8WX has been copied at 643km.

Although a large Marconi antenna will be far better, this set-up certainly works and gives highly credible results. Considering just how simple this is I hope others experiment with the earth electrode "non antenna" and see how they get on.

UPDATE: Best DX report of my few mW ERP signal with 15m spaced earth electrodes was from DL-SWL at 701km. I am copying lots of signals including SM6DHZ and DK7FC even after breakfast time. Amazing.

Half century reached on 472kHz with 10mW ERP

After less than a week on the 472kHz band, I see that my tiny QRP signal has now been copied by 50 unique reporters in 8 countries so far with the best DX over 1000km.

If anyone thinks they have no chance on this new MF band then please note my antenna has just 6m outside the house which is vertical - the other 6-8m is in the loft against copper pipes and wires. This wire is just the coax to my 10m halo taped to the aluminium pole and my ground just my central heating copper.  ERP is around 10mW from my transverter producing around 10W (i.e. about 30dB antenna efficiency loss because of the short size and compromised feed). The ATU is still just a ferrite rod coil on my desktop! I tune the antenna for maximum current and do not have an SWR meter for this band ( when matched the PA runs cool and the antenna current is highest).

My apologies for the small type size below, but I had to reduce the browser size to get all the reports on a page I could screen capture. Getting a signal out on MF is honestly not difficult at all.

50 unique reports on 472kHz WSPR so far with 10mW ERP

In the next few days I want to try my earth antenna (20m spaced earth electrodes connected by a wire only 1.5m above ground) used on VLF earth-mode TX to see how reports compare. Tests on 500kHz suggested reports were around 8dB down on my loop used at that time, but I have not yet compared results against my compromised 1/100 wavelength high vertical. It will be intriguing to see how I get on.

First JT9-1 QSO on 472kHz

This afternoon I had my first digital 2-way QSO on the new 472kHz band using JT9-1 mode created by K1JT. The contact was with G3ZJO in IO92. Solid -15dB S/N reports were exchanged. I am still getting to grips with the JT mode procedure.

QRP JT9-1 QSO with G3ZJO today on the 472kHz band

 I also tried to work G3KEV on CW but he was unable to hear my QRP signal. I will try for more JT9-1 QSOs over the weekend.

First CW QSO on 472kHz

Although my local noise level is a little lower on 472kHz than on 500kHz it is still not low, so working stations with the current TX antenna (using it on RX and TX) is not the best of set-ups. Nonetheless, this evening I had my first 2-way QSO (on any band) of 2013 and this was on 472.5kHz CW with G3XIZ in Biggleswade. We exchanged 579 reports, although I was rather generous with my report really because of the local SMPSU noise. Also heard was G3YXM who was rather weaker than Chris.

I am now continuing with WSPR beaconing and will run the beacon (TX and RX) through the night for the first time on the new MF band. So far my best DX report is from Germany, but I would dearly love to be copied, if just once, by TF3HZ in Iceland. Haldor is monitoring and it is just about at (or just beyond) the limit of range with my 10-20mW ERP.  With QRP I have learned that nothing seems to be impossible with a bit of perseverance and good luck.

Hello 472kHz!

Today I did my first proper transmissions on 472-479kHz, although I did operate for a few hours before Christmas when there was some confusion over the NoV start date. Results today have been excellent with just ~10mW ERP from the short vertical antenna.

14 unique stations reporting my QRPp WSPR today on 474.2kHz

 Best DX is 990km, a very promising start on the new band. In addition, I appear to be suffering less noise on the new band than on 500kHz so I have been able to copy 6 unique WSPR stations so far.

In summary, a good few hours on the new band.

472kHz (quiet) RX preamp

When the grandchildren and family have all gone home next week, my first project will be to improve the RX antenna system for 472-479kHz receive. As mentioned before, I am suffering badly from SMPSU noise pick-up inside the house, so plan to install a magnetic loop and preamp somewhere towards the bottom of the garden in an attempt to minimise pick-up from my own home and from neighbours. With a loop there is also the ability to sharply tune the antenna and to null interference from the worse directions. The circuit I propose to use is a version of my 9kHz tuned preamp, which has been used to copy G, DL and OK amateur stations on 8.97kHz last year. The loop will simply be retuned to the new MF band.  Not sure whether series or parallel connection to the loop will be better as both should work depending on the FET stage configuration (common base or common source).

Proposed tuned preamp, but with values changed for 472-479kHz

472kHz WSPRing (now QRT)

It is now clear that the issue of my NoV for today's date was an error, either with OFCOM or the RSGB and that there was, sadly, no intention of releasing the band earlier than Jan 1st 2013. So, I have now gone QRT on the band again until the new year. I question why an NoV should be needed at all: why not just release the new band in the UK to all full licence holders and save the time wasting and paperwork chasing!

In the few hours of operation with my antenna very wet and lossy, so the ERP was around 10-20mW only at best, results achieved were very promising.

472kHz WSPR TX results today (10-20mW ERP)

Reports of my WSPR signal were received from 4 countries with the best DX being from Germany and the far NW of Eire.

I'm now back on 500kHz WSPR for the rest of the evening.

472-479kHz NoV received

Today I received my 472-479kHz NoV via the RSGB website. The NoV for 5W eirp (about 20dB more than I can run!) seems to indicate that the new band may be used by NoV holders immediately judging by the date of issue.

There is some confusion as the OFCOM website says:
"However, as a result of the World Radio Conference, under Agenda Item 1.23 amateur radio has been given an alternative allocation, on a secondary basis, of 472 479 kHz. We propose that Full Licensees should be able to to apply for an NoV to operate in this band from 1st January 2013. Application can be made online at http://www.rsgb.org/operating/novapp/nov-472-479-khz.php" 

My official OFCOM NoV says applicable from Dec 20th start date so I am allowed to operate from today unless told otherwise later by email or phone from OFCOM. This may be pedantic, but they should have checked before sending out the form.

My first WSPR reports have been received from PA3ABK/47 at around -24dB S/N with my ERP currently around 10mW only (too much wet on the antenna). Also received a report from G8HUH (250km) and PA3FNY (360km).

It now seems that the official 472kHz NoVs issued this afternoon (mine was this morning)  now state a Jan 1st 2013 start date.  So, am I legally operating I wonder? If the world ends tomorrow, at least I've got a few 472kHz reports in the log, HI.

472-479kHz NoV Applications

The RSGB now has a link on its website (although at this time it does not appear to be working, but it did earlier for some) for the form to apply for an NoV to operate in the UK on the new 472-479kHz band.

This is the link I have http://www.rsgb.org/operating/novapp/472-479-khz-nov.php

I have yet to succeed and get my NoV application through, but hope to do so before Jan 1st 2013 when the band will be available to full UK licence holders as long as they have the NoV.