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The weekend CLE event described in an earlier blogpost provided the first real opportunity to put my new LF loop to the test. Actually, it has already passed the most important test...surviving a large 60+ mph windstorm, while I was away on a short vacation. Unfortunately, a 60' Douglas Fir, just a few feet from the loop, blew completely down...thankfully, over the bank, in the other direction. Cleaning it up will take a few weeks but should provide some good firewood as well as exercise.


Before leaving, I tied the end arms of the loop down just in case it might get windy, but it seems that the light PVC frame does not produce the same windage as my large wooden 10' loop frame.

Beacons logged over the three-night event:

VR-266 Vancouver Int'l (50W) - heard as far east as NC

How time flies...once again it's time for the monthly Co-ordinted Listening Event (CLE) for NDB hunters....the 187th event. These always interesting and popular affairs take place over three nights, with this one starting on Friday, October 24th at local noon and running until Monday, October 27th, local noon.

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

This time, it's a two-part activity, should you decide to chase normal DX beacons as well as those from your own country or state/province. Here are the details. 

Days: Friday 24th October - Monday 27th October
Times: Midday on Friday to Midday on Monday, your LOCAL time
QRG: Normal LF/MF frequencies (190 - 1740 kHz)
NDBs: Normal DX and 'HOME' ones (not DGPS, Navtex or Amateur)

DX:
Please try to log NDBs that are over 2,000 km / 1,250 miles from you.
If you have a wall map in your shack, you could draw a circle on it.
It will be accurate if it is a great circle map centred on your location.
(There are other easy and very good ways to find which NDBs qualify
for you - I will describe them in the Final Details email)

HOME:
Please also try to log NDBs in YOUR OWN radio country. For listeners
in AUS, CAN and USA, that means your State or Province.
It will be trivial for a few of us in tiny radio countries, very challenging
for a listener in, e.g., RUS (Eu). Most of us should have a fair list to
try for.
If we also mention any of our home regulars NOT heard, it will help
others to know about NDBs that are not currently active.

If you report on both parts, DX and HOME, I suggest you put them in
separate parts of your log. As usual, any UNIDs that you come across
will also be of interest - in a third part of your log.


Final details can be found at the NDB List website, and worldwide results, for every participant, will be posted here a few days after the event.

The very active Yahoo ndblist 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.

If you are contemplating getting started on 630m, listening for NDBs  is an excellent way to test out your receive capabilities as there are several NDBs located near this part of the spectrum.


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

Reports may be sent to the ndblist or e-mailed to either myself or CLE co- ordinator, Brian Keyte (G3SIA). It was very exciting to see two new reporters to last month's event after reading about the CLE right here. Hopefully there will be more first-time reporters for upcoming CLE187.

Please...don't be shy and do 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.

ZVR - 368 Vancouver -  Middle Marker Rnwy 08R - reported as far as California

Now that CLE186 has come and gone, worldwide results will soon be posted by e-mail (to all those submitting reports) as well as to the CLE website. CLE organizer and data-cruncher Brian Keyte (G3SIA), indicates that 50 logs (and over 2,000 reports) have been submitted, including two first-timers - Graham (VE3GTC) near Ottawa, ON and Hans (BX2ABT) in Taiwan. It's always great to see new activity, especially on LF!

As is usually the case with CLE's, propagation conditions begin to deteriorate shortly after the announcement of the upcoming event. By the weekend's arrival, conditions are usually much worse than earlier in the week and such was the case once again! In North America, lightning activity and mediocre propagation dominated the three-night event, with the consensus of opinion giving the nod to Saturday night and early Sunday morning as being the best period.

Courtesy: http://www.lightningmaps.org/

Here on Mayne Island, Friday night was pretty much a wash and only the stronger signals made it through the din and into the log. A twilight check on Saturday evening indicated improving propagation and less lightning, renewing optimism that the entire weekend would not be a wipeout.


Since purchasing the Perseus SDR earlier this year, I have been using it exclusively for the past few CLE's. I have been exploiting one of it's main features....the ability to record the entire band overnight and then tune through the band the next day, as in real time. I no longer had to prop my eyelids open until 0100 or later, or to leave a sound sleep to journey out to a cold shack to hunt the pre-sunrise band for anything new....yes, Perseus has made it possible to DX while I sleep!

Now the very concept of this horrifies many of the 'purists' and I myself held-out for several years before venturing over to the darkside...but...embracing new technology along with its associated new learning is what is important. If I get to sleep-in because of it, even better!

So....that's the way it is supposed to work, but due to operator error, Perseus failed to launch on Saturday night, and the best conditions of the CLE were missed altogether. Having seen the error in my ways, the perils of Perseus will, hopefully, not strike again!

Conditions on Sunday night were noisy once again, although not as bad as Friday, and the following log was gathered after parsing through my overnight recordings.


I have, over the years, logged all of these beacons before, except for one..."OKT" in Yoakum, Texas...new catches are always nice and are harder to find  it seems. The Google Map's 'street view' shows what appears to be a nice top-loaded "T" antenna at OKT:

Courtesy: https://www.google.ca/maps/

My CLE186 beacons - Courtesy: https://www.google.ca/maps/

It was nice to salvage Sunday night but I'm still a little bummed about missing the best night of the weekend...at least I had a good night's sleep.

The Mini-Whip at University of Twente's (Netherlands) Remote Receiver

I think many hams believe that they need big antennas and lots of space to operate on 630m or even to listen on the band. I can assure you that big antennas are definitely not needed to listen or for that matter, even to transmit effectively.

You might be surprised at just how well you can hear on 630m using one of your low band antennas, such as an 80m or 40m dipole. Best results will be had with the coaxial feed's shield lifted from ground and connected to the center pin. This, in effect, allows your dipole to act as a top-loaded 'T', with the coaxial feedline now acting as the vertical element and the dipole section as a capacitive tophat. With a few ground radials, such an antenna can even be used for transmitting, if suitably resonated, but that's another topic altogether. Even untuned, this system will allow you to receive suitably on 630m providing your location is not inundated with high noise levels. High noise levels can often be overcome by using loops, either resonated or broadband. Loops can be very effective at nulling noise, particularly if it is coming from one direction, and vastly improving LF receive-capabilities.

Another popular solution and one that can be quite effective at lowering noise levels and improving overall signal-to-noise is the use of a short active (amplified) whip antenna. One very popular and proven design is that of Roeloff Bakker, PAØRDT. His simple-to-build active whip has been employed around the world and is being used by many LF'rs for dependable reception on the NDB band as well as on 630m. Roeloff himself operates from a noisy urban area yet manages to hear amazingly well on LF and MF with this simple antenna. Unlike a much larger wire antenna or large loop, the small active whip can be easily positioned in the quietest part of your backyard or rooftop. Often just moving such an antenna a few feet one way or the other can make a huge change in the noise level if you are operating from a typical city or suburb location....the PAØRDT whip may be all that you really need for long-term, reliable LF reception.

Courtesy: PAØRDT

Common practice is to mount the PCB inside a small weather-sealed PVC pipe and erect it atop a mast, after taking the time to "sniff-out" the quietest location for its placement.

Courtesy: http://www.leeszuba.com/projects/

With very few parts needed, the whip can be built for just a few dollars...even less with a good junkbox and the needed transistors.

Courtesy: http://www.leeszuba.com/

You can read Roeloff's own information on construction of the active whip here, with additional information here.

I even see the parts and PCB available on e-bay. As well, Roeloff himself, can provide finished units ready to mount in the air.

Courtesy: http://countingradios.blogspot.ca/2014_01_01_archive.html

There are plenty of informative Mini Whip articles and construction stories on the web should you wish to learn more:

• Fundamentals of the Mini Whip  by PA3FWM

• A Compact Active Wide-Band Receiving Antenna  by G3GRO

•  PAØRDT Mini Whip - Commercial & Homebrew Versions Tested  by GØKYA

• The PAØRDT Mini Whip  by DL1DBC 

• The Mini Whip Antenna  by Lee Szuba

If you're stuck with limited space for an LF-receive antenna, this may be just the answer!

"LU" - 214kHz Abbotsford, B.C.  Has been heard from W1-KH6

Yes, it's once again time for the monthly Co-ordinted Listening Event (CLE) for NDB hunters....the 186th event. These always interesting and popular affairs take place over three nights, with this one starting on Friday, Sept 26th at local noon and running until Monday, Sept 29th, local noon. CLE186 covers the frequency range of 350.0 to 369.9kHz only.

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

Final details can be found at the NDB List website, and worldwide results, for every participant, will be posted here a few days after the event.

The very active Yahoo ndblist 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.

If you are contemplating getting started on 630m, listening for NDBs  is an excellent way to test out your receive capabilities as there are several NDBs located near this part of the spectrum.

Courtesy: http://www.classaxe.com/dx/ndb/rna/

You need not be an ndblist member to participate in the CLEs and all reports, no matter how small, are of much value to the organizers. Reports may be sent to the ndblist or e-mailed to either myself or CLE co- ordinator, Brian Keyte (G3SIA).

Please...don't be shy and do give CLE186 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.

It's often easier to achieve high power on 630m or LF by combining lower powered amplifiers than it is to build a single high-power rig. A simple Class D push-pull switching FET amplifier can readily produce 400-500W when operated in the 35V range. Combining two such amplifiers, both sharing a common oscillator / driver stage, would yield 800-1000W output...probably much more than needed on 630m.

The low parts-count of the amplifier stage in the GW3UEP Class-E transmitter should easily produce 150-200W when run at a slightly higher drain voltage and proper heatsinking. Combining two such modules would yield 300-400W output at very low cost.

Combining can be done with a Two-Way (3-port) Wilkinson Splitter / Combiner. Splitters and Combiners are one and the same, depending on which ends are used for input(s) / output(s). When used in the 'combine' mode, insertion losses are virtually zero and mainly due to the miniscule resistive losses of the coils.



Combiner component values can be calculated the old fashioned way or by using one of the numerous online calculators. This excellent online video by Sebastian (KF5OBS) explains exactly how to calculate component values for the truly dedicated amongst us:

Courtesy: https://www.youtube.com
He also has a new video showing how to calculate values for combiners having more than two outputs, should you want to combine three or more individual amplifier modules.

The first combiner I built was for my 2200m kW and combined the output of two 500W Class-D modules:


The air core coils are high-Q, cheap and easy to produce. If space is important, the inductors could just as easily be made using frequency-suitable powdered iron toroids, but at more expense. In actual operation, I have never been able to detect any heat from any of the combiner components, even when running a full kW at lengthy keydown periods of several minutes during QRSS transmissions, affirming the almost 'zero' insertion loss when used in the combining mode.

When I decided to use the same amplifier on 630m, a suitable circuit was designed and built for that band as well:


The terminating / balancing resistor (R) is used only as a safety device in case one of the two amplifiers fails during operation. It allows the still-working amplifier to safely dump some of its power into the load without destroying itself. Under normal operation, no current flows through this resistor so no power is wasted, assuming both inputs are equal. I have read of some schemes that will sense any current flow through 'R' and immediately shutdown the entire transmitter, thus allowing a resistor of lower dissipation to be used for 'R'.

Another benefit of the Wilkinson L-C Combiner is its filtering capability, as it works extremely well as a LPF. Neither my 2200m kW or 630m kW use any low-pass filtering other than that provided by the combiner's L-C network. It also seems to work well as a buffer of sorts, as both myself and VE7TIL noticed with our 2200m systems. We immediately stopped blowing FETs mysteriously when operating at full power. The amplifiers did not seem to react any longer to reactive components suddenly appearing in the antenna system or somewhere in the output network....everything was 100% more stable and reliable it seemed.

I can envision an exciting project consisting of a pair of GW3UEP finals feeding a toroid-based combiner, all in a very small footprint.

Should you choose to combine a pair of amplifiers for 630m, here are the values that were used in my own combiner:

I was finally able to put the finishing touches on the new GW3UEP Class-E transmitter by mounting the hardware on a small 19" panel.

Added to the panel were a 5A DC meter to monitor drain current, a keying jack and a key shorting-switch for keydown testing. This is the third version I have built using the design on Roger's page, with all three performing pretty much as advertised. It is an inexpensive, easily reproducible design.