Thursday, 16 May 2019

How Low Can They Go!

courtesy: Roger, G3XBM



For the past few years several amateurs in Europe and along the east coast of North America have been experimenting on the ‘dreamers band’, 8.7 - 9.1 kHz.








Some rather surprising distances have been covered on these frequencies in spite of the dreadfully poor efficiencies realized with backyard antenna systems.

Previous 'earth-mode' backyard experiments on VLF by Roger, G3XBM, are well documented on his website along with details on his simple homebrew gear used to send signals across town using the earth. Following Roger's steady progression via his previous blog spots makes for fascinating reading ... there is some really great stuff here making it difficult to not jump in and take the plunge yourself.

This experimental field presents the ideal opportunity for a couple (or several) local amateurs to work together at exchanging signals on these low frequencies with simple home built equipment.

A major contributor to the present state of the ‘VLF / ULF amateur art’ is Stefan, DK7FC and a posting this week to the old RSGB's (blacksheep) LF reflector makes some of his earlier work pale by comparison as he announced the reception of his 270Hz signal (the 1110km band!) at a distance of  177 km!

Just a note from a recent experiment at 270.1 Hz.

On Sunday morning, 2019-05-12_10:34,+150m, I've done a carrier transmission on my ground loop antenna again. I did not expect more than, hopefully, a detectable spectrum peak in 57.6 km distance, i.e. at my tree site. The tree receiver site was listening and recording data using vlf-rx tools.
One E field antenna and two orthogonal loops were listening. The loops have been improved recently! They consist out of a single circular turn of 1.2 m diameter using 10mm diameter copper tube (about 25 mm^2). It is a closed loop, non-resonated, with an impedance matching transformer. This transformer previously had 1:100 turns. Now it (they) has 2:240 turns, i.e. two turns primary (out of 14mm^2, AWG6). This improved the sensitivity below 2 kHz significantly ( abt. 4...5 dB).
Furthermore the TX antenna length and angle has been improved, resulting in about +3 dB more signal strength on the RX site!

In a previous experiment at 270.1 Hz, some month ago, there was no result at all, not the weakest trace, despite excessive tweaking of all parameters. So the question was, will the improvements result in a detectable signal now?

Several things went wrong in that experiment. I forgot a bag containing important equipment such as the power supply for the netbook that generates the carrier signal. Also the output power was not as high as planned, just about 380 W, giving 2.2 A antenna current (I measured 64.7 V at 1 A DC). Anyway i managed to improvise so the experiment was started, but with some hours of delay which meant i higher QRN background level. Then, on the WLAN link to the tree, there were several interruptions of the stream (i'll move to 5 GHz very soon!). I even got some QRM from my battery charger for some short time periods (forgot to disable the charger remotely). So there were several factors that could have been improved or avoided. And the middle of May is not the ideal time anyway.

Well, 270.1 Hz, that's the 1110 km band! The far field begins at 177 km distance, i.e. i am clearly in the near field here. Thus, from a 'magnetic' TX antenna, we would expect that the signal is mainly detectable on the H field, i.e. the loop antennas.
The first interesting results is that this expectation is actually confirmed. There is nothing detectable on the E field but the carrier S/N in the H fields is close to 10 dB in the first run. Mixing the H fields and tweaking the filters rises the carrier S/N to 10.7 dB, see attachment.

So far not really an undoubtedly detection but it is a candidate for optimism! With a few less problems during the experiment there is a chance for 14 dB SNR. Also, there is quite much sideband QRM around 300 Hz which makes 270 Hz a bit harder to work on.

73, Stefan

Saturday, 4 May 2019

More 'Hydroponic' RF

courtesy: ARRL

Today's blog is a repost from August, 2015.

I see that the ARRL has filed three more formal complaints to the FCC concerning the bone-crushing HF emissions being produced by off-the-shelf grow light ballasts. The complaint also includes detailed lab data collected on all three devices and it is not pretty. One wonders why it is necessary at all that the ARRL be the industry watchdog instead of the FCC ... why aren't they being more diligent in filtering out these products before they hit the market? If importers and dealers are simply bypassing regulations for the sake of a quick-buck, then heavy fines must be imposed until someone 'gets the message'.

Some of the test products were ordered and purchased through Amazon and through Sears ... the ARRL's thorough report makes it obvious that rules are being ignored and amateurs are paying the price.

“The level of conducted emissions from [these devices] is so high that, as a practical matter, one RF ballast operated in a residential environment would create preclusive interference to Amateur radio HF communications throughout entire neighborhoods,” ARRL General Counsel Chris Imlay, W3KD, wrote in each complaint. The devices exceeded conducted emission limits under all test conditions, “sometimes by extreme margins, throughout most of the HF range ...”


In a similar vein as its recent complaint about marketing of certain RF lighting devices by The Home Depot, the ARRL pointed out that there were no FCC labels on two of the devices mentioned nor any FCC compliance information “anywhere in the documentation, or in or on the box, or on the device itself,” in violation of FCC Part 18 rules.

The League asked the FCC to require removal of all such illegal “grow light” devices from retail sale and marketing and the recall of those devices already sold or available for retail sale, and it said the device importers should be subject to a forfeiture proceeding.

With the proliferation of both legal and illegal 'hydroponic' operations, this kind of QRN is probably just the tip of the iceberg. It's good to see the ARRL slowly pounding away at the rule-breakers on behalf of American amateurs.

I see these same devices being sold on E-Bay, where presumably, they could be purchased worldwide and installed anywhere. As well, several of the U.S. online dealers state "We ship to Canada" ... just great.

Hopefully Industry Canada and RAC are gearing-up for the fight.

Wednesday, 24 April 2019

Hunting For NDBs In CLE243

YPM - 274 courtesy: VE3GOP



This coming weekend will see another monthly CLE challenge. This time the hunting grounds will be 270.0 - 319.9 kHz.

 





For those unfamiliar with this monthly activity, a 'CLE' is a 'Co-ordinated Listening Event', as NDB DXers around the world focus their listening time on one small slice of the NDB spectrum.

If you've been meaning to participate in  CLE, then maybe this weekend is a fine time to try!

A nice challenge in this one is to hear YPM - 274, located in northwest Ontario near Pikangikum.

'YPM' runs just 25W into a 100' vertical but is well-heard throughout North America. Listen for its upper-sideband CW identifier (with your receiver in the CW mode) on 274.368 kHz.

Summer lightning storms may provide additional listening challenges but maybe we will get lucky.

When tuning for NDBs, put your receiver in the CW mode and listen for the NDB's CW identifier, repeated every few seconds. Listen for U.S. NDB identifiers approximately 1 kHz higher or lower than the published transmitted frequency since these beacons are modulated with a 1020 Hz tone approximately.

For example, 'AA' near Fargo, ND, transmits on 365 kHz and its upper sideband CW identifier is tuned at 366.025 kHz while its lower sideband CW ident can be tuned at 363.946 kHz. Its USB tone is actually 1025 Hz while its LSB tone is 1054 Hz.

Often, one sideband will be much stronger than the other so if you don't hear the first one, try listening on the other sideband.

Canadian NDBs normally have an USB tone only, usually very close to 400 Hz. They also have a long dash (keydown) following the CW identifier.

All NDBs heard in North America will be listed in the RNA database (updated daily) while those heard in Europe may be found in the REU database. Beacons heard outside of these regions will be found in the RWW database.

From CLE organizer Brian Keyte, G3SIA, comes the details:

 Hello all

Our 243rd co-ordinated listening event is this weekend, covering a 50 kHz
frequency range - about three times wider than usual. 

    Days:     Friday 26 April - Monday 29 April
    Times:   Start and end at midday, your LOCAL time
    Range:   270.0 - 319.9 kHz  (NDB signals only)

In part of the frequency range it might be quite a challenge to tease out
the NDB signals from among the DGPS ones.
Any first-time CLE logs will be very welcome, as always.

Please log the normal NDBs you can identify that are listed in the range
(it includes 270 kHz but not 320 kHz).

Please send your CLE log to NDB List, if possible as a plain text email
and not in an attachment, with 'CLE243 FINAL' at the start of its title.

Show on EVERY line of your log:
  #   The Date  e.g. '2019-04-26', etc.  (or just '26')
  #   UTC  (the day changes at 00:00 UTC).
  #   kHz  - the beacon's nominal published frequency if you know it.
  #   The Call Ident.

Those main items can be in any order within themselves, but BEFORE any
other optional details (Location, Distance, etc.) later in the same line.

As always, give details in your log of your own location and the receiver,
aerial(s), etc. that you were using.
If you send any interim logs, be sure to send a FINAL (complete) one.

You can find anything else to help you, including CLE seeklists for your
part of the World, from the CLE page, http://www.ndblist.info/cle.htm

Please look out for our 'Any More Logs?' email at about 17:00 UTC on
Tuesday so that you can check that your CLE log has been found OK.

Do make sure that your log has arrived at the very latest by 08:00 UTC
next Wednesday, 1st May.
We are hoping to make all the combined results within a day or two.

Enjoy your listening
Brian and Joachim

-----------------------------------------------------------------
From:      Brian Keyte G3SIA      ndbcle'at'gmail.com
Location:  Surrey,  SE England    (CLE coordinator)
-----------------------------------------------------------------

(Reminder:  You could use any one remote receiver for your loggings,
stating its location and owner - with their permission if required.
A remote listener may NOT also use another receiver, whether local
or remote, to obtain further loggings for the same CLE).

These listening events serve several purposes. They:
  • determine, worldwide, which beacons are actually in service and on-the-air so the online database can be kept up-to-date
  • determine, worldwide, which beacons are out-of-service or have gone silent since the last CLE covering this range
  • will indicate the state of propagation conditions at the various participant locations
  • will give you an indication of how well your LF/MF receiving system is working
  • give participants a fun yet challenging activity to keep their listening skills honed

The NDB List Group is a great place to learn more about the 'Art of NDB DXing' or to meet other listeners in your region. There is a lot of good information available there and new members are always very welcome. As well, you can follow the results of other CLE participants from night to night as propagation is always an active topic of discussion.

You need not be an NDB List member to participate in the CLEs and all reports, no matter how small, are of much value to the organizers. 

Remember - 'First-time' logs are always VERY welcome!

Reports may be sent to the NDB List Group or e-mailed to CLE co-ordinator, Brian Keyte (G3SIA), whose address appears above. If you are a member of the group, all final results will also be e-mailed and posted there.

Please ... give the CLE a try ... then let us know what NDB's can be heard from your location! Your report can then be added to the worldwide database to help keep it up-to-date.

Have fun and good hunting!

Sunday, 21 April 2019

An Old Friend Returns + A Heads-Up For CLE243!



Over the years, one of the ‘most heard’ NDB signals from Alaska was the decades-old beacon located near the western tip of the Aleutian Islands at Adak.

'ADK' had been around in one form or another since WWII but it suddenly vanished from the air in 2012. Like numerous other NDBs in Alaska, as well as in the lower 48 and Canada, once officially NOTAM’d (Notice To Airmen) as shut down for ‘maintenance’, they often never return.

Such was the case assumed by all NDB DXers with regard to ADK, especially following the cryptic 2015 NOTAM announcing a permanent closure. It was hard to believe that this early-morning regular was now gone for good.

Transmitting on the lower edge of the AM broadcast band (530kHz), ADK was often stumbled upon by wayward BCB DXers or sought-out as a good propagation indicator for the pre-sunrise Asia-North America path on the BCB. I’m sure that some even heard it on their analog car radios back in the day when many of them would tune down as low as 520kHz!

All that changed this weekend when Dan, VE7DES, a regular weekend-contributor to the RNA database, found ADK had risen from the dead after all these years and was putting a nice signal into the southern west coast of Canada!

It seems that ADK’s antenna had been blown down in the summer of 2012 which explains its sudden demise. An FCC employee in Alaska has indicated to me that in recent months there had been much interest in reviving ADK which would apparently allow more airlines access to the field than had previously been the case ... whatever the reason, NDB DXers are delighted to hear their long-lost friend once again!

Hopefully it stays around for many more years yet, but just in case, why not give a pre-dawn listen for its CW identifier on 531.034kHz, with your receiver in the CW mode. Long haul propagation can often be excellent in this part of the spectrum in the early morning and ADK has been logged from Hawaii to Illinois.

Here’s how ADK's 25 watts sounded here this morning at around 0530 local time.

***************************

Heads up for CLE243 this coming weekend ... final details coming mid-week:

For our 243rd Co-ordinated Listening Event, coming in a few days, we can expect a bit of a challenge.
   
    Days:     Friday 26 April - Monday 29 April
    Times:   Start and end at midday, your LOCAL time
    Range:   270.0 - 319.9 kHz  

Yes, it does include most of the DGPS beacons - and 50 kHz wide is about three times more than usual, but we shall only be listening for the 'NORMAL' NDBs.

We last searched for NDBs on these frequencies in February 2018 when a record 59 of us took part in CLE229.

We shall all have at least one end of the range for some easy listening, but the main challenge will be to find the Morse signals among those DGPS noises.  

REU and RNA show that, in the last 18 months, about 310 and 200 normal NDBs have been heard in this range by listeners in Europe and North America respectively.

There are also several to be heard by members away from Europe and North America, as you can see in the map from RWW, below.

Please look out for the 'Final Details', which as usual will follow about two days before the start.
Happy Easter!
73
    Brian
-----------------------------------------------------------------
From:      Brian Keyte G3SIA      ndbcle'at'gmail.com
Location:  Surrey,  SE England    (CLE coordinator)

Friday, 5 April 2019

My End-Fed Half-Wave (EFHW)

The last few years have seen a resurgence of interest in the end fed half-wave wire EFHW antenna. A half-wave at the lowest band of interest will also work well on all harmonically-related bands which has become particularly attractive to those wanting a quick portable wire antenna.

It looked like an interesting antenna to try, as I was in need of a good 80m radiator and following several days of fine summer-like weather, I was able to get my new 80 / 40m wire vertical completed ... a half-wave on 80 and a full-wave on 40m. It’s built as an inverted-L, going up 80’ and the remaining 50’ being horizontal at the same height. It’s fed at the base through an impedance matching transformer and was pruned for the CW end of the band.

There's always a great sense of anticipation when first testing a new antenna and the experience only comes around once in a rare while ... it always brings back memories of my teenaged ham years, quickly scrambling off of my parent's steep three-story roof and tuning-up the DX-20 to see if the latest antenna was going to be something special. Yesterday was similar, except for the roof-top scrambling and the old DX-20.

By mid-afternoon everything was wired up ... but before waterproofing all the connections against the west coast rains, I went to the shack and warmed-up the FT-1000mp, setting it for exactly 10W out. Tuning across 40m, I immediately heard fellow NRR’r Howie, WB2AWQ down in Reno, calling CQ on 40m with one of his military transmitters. He came back immediately and we had a short chat, so at least I knew the new antenna worked!
 

 
Having  waterproofed all of the connections, I ventured to the shack once more, now just 45 minutes before sunset. I’ve always found that a quick way to gauge relative antenna performance is listening for my low-power signal via the vast KIWI online SDR network

With the power still set at 10W on 40m I listened on several east coast SDRs, from NH, PA, MD, NY, VA and immediately heard a surprisingly good signals on all of them. Even at 5 W, the signal was copyable. Several of them produced an audible copy when I reduced power to just 1W.

I then tried two SDRs in Brazil and immediately heard the 10W signal again! How about KH6 ... still late afternoon out there? Yes, easy copy in Hawaii as well. 

Dare I push my luck and try one more ... one of the SDRs in Iceland? 

I almost fell out of the chair when the 10W signal was good copy there as well ... still 15 minutes until sunset and with bright sky outside the shack window. 

One last thing to try was 80m although it was still very early here for 80 ... the SDR in MD returned a nice copy at 10W to complete my quick round of pre-sunset testing. 

From these early observations it would appear that the new antenna is working well but I had yet to do any A-B comparisons with my benchmark best performer, a 40m half-sloper which will be hard to beat. 

The 40m half-sloper has always outperformed any other antennas that I have tried. It's the same one that I completed my Tuna Tin 40m W.A.S. on, so its been well tested.

The following evening, I had a chance to A-B test the new antenna, listening on the Kiwi network once again with my power set at 10W.

N8DTT/6 (California)  EFW 1S unit better
NO2CW (Florida)   EFW slightly better
Jersey Shores, NJ    EFW slightly better
TF1VHF (Iceland)  EFW slightly better
ND7M (Nevada)     equal with slight edge to EFW
KA7EZO (Utah)      equal
RTM (Dominican Republic)   sloper ~ 1/2 S unit better
KP4CA (Puerto Rico)   equal
Paraguay   equal
PY2GN (Brazil)   EFW ~ 1/2 S unit better
AI6VN/KH6 (Hawaii)   equal
VE7HUN (BC)   equal  (groundwave)

Unlike 1/4 wave verticals that require a fairly robust counterpoise / radial system for effective operation, the counterpoise requirements for a half-wave are far less-demanding. Mine consists of about fifteen short turf-pinned radials and the first 50' of the coaxial feedline's shield. A common mode choke (CMC) is installed on the feeder at the 50' point, keeping any RF out of the shack and the rest of the feedline from radiating.

I was actually pretty surprised at these results but how they will relate to everyday operating is yet to be determined. My main goal was to get a good-performing 80m antenna and anything that works well on 40 would be a nice side benefit but not really required. Unfortunately I don't have another 80m antenna to run some A-B checks with but from what I can tell, performance on 80m seems to be good.

If you are on Facebook, there is a lot of good discussion and information available on the End Fed Half Wave Antennas group.