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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:

going on over at QRP-L about portable antennas.  The catalyst for the "debate" is this article.

http://www.sotabeams.co.uk/blog/5-most-popular-hf-portable-antennas/

Lot's of good input by lots of people who know what they are talking about.  And as always, for portable operations (my emphasis), it seems to boil down to efficiency vs. ease of use.

Both Steve Weber KD1JV and Ron Polytika WB3AAL, who have done a lot of operating from the Appalachian trail, point out that while classic dipoles may be the most efficient antenna to use, there are practical logistical problems associated with them.  There may not always be trees available, and even when there are trees available, there may be so many and so close together, that hoisting up a dipole may not be practical.  I have to agree with Steve that hoisting a dipole or doublet in the classic sense, in a portable situation (especially when you are by yourself) can be an experiment in frustration.

Steve is a proponent of the End Fed Half Wave, while Ron likes a version of the portable vertical that he has designed and yields quite acceptable results for him.  I have used both and personally prefer the end fed wire for the ease of deployment. Don't get me wrong. I have verticals antennas and love them. My Butternut at home and my Buddistick on top of the Jeep have both done very well for me.  But as always, the ground plane is crucial.  Close to 60 radials at home and the Jeep's metal body acting as a ground plane for the Buddistick make all the difference in the world.

The thing that surprises me though, is that when speaking of dipoles or doublets, everyone always seems to think of them in the classic flat top or Inverted Vee configuration, which of course, requires three supports. I have used doublets, such as the NorCal doublet as a sloper and as a vertical dipole with a modicum of success.  My first Flight of the Bumblebees effort used the NorCal Doublet as a sloper and I was quite pleased with the results.

What it boils down to, of course, is that you have to try different things and see what works best for you. There is no single correct answer to the question of  "What is the best portable antenna?" What will work in one situation may be totally unsuitable for another.  No archer carries only one arrow in his quiver.  Hams who are adroit in portable operations always seem to be carry more than one antenna configuration into the field with them, as long as they meet the requirements for portability and ease of use. And I think all Hams who love portable operations are on a constant quest for the "Holy Grail", an antenna that is lightweight, quick and easy to deploy, and will work as many bands as possible.

72 de Larry W2LJ
QRP - When you care to send the very least!

Courtesy: http://www.picgifs.com

With the return of cooler weather and a few overnight rainy periods, the brown summer-lawn has suddenly turned green and is growing far too fast once again. I find this time of the year, as well as early spring, the best time to plant any new radials that I like to continuously add to my vertical antenna systems. My large inverted 'L' for 2200/630m as well as my half-slopers for 160, 80 and 40m, all have a common base, which lets all of the antennas benefit from the radials laying just beneath the lawn.


The procedure I follow is fairly easy but does take time and I usually just add four or five each year. Although I haven't kept an accurate count, I know the system now has fifty or more radials varying from 30' to 70',  fanning out in various directions from the base of my main tower.


The terminated end of the radial is first pinned-down using a U nail or a longer 3 1/2" galvanized finishing nail that has been bent over in the vise, with the height of the grass determining which one I use. Shorter grass lets you get away with the smaller U nails, which can be found in most building supply stores.


Once pinned, the grass is parted using a stick, knife or awl, to produce a shallow gap for the radial to sit in. I try and do a 3-foot section at a time before placing the wire into the opened-up area. Another way that is effective, especially if the grass is short and the soil dry, is to run the blade of a knife through the grass to actually slice a shallow slit which the wire can be pushed into. This allows the wire to be almost completely buried immediately. Both methods require pinning, with the nails, every few feet.

Once pinned in place, the grass can be quickly ruffled back into place, covering the radial. When done in the fall or in the spring, the grass will very quickly completely overgrow and incorporate the radial into the lawn, never to be seen again.


An interesting product that I have recently learned of may also be of interest - "Ground Staple Pins" by RossRadio. Details may be viewed at their website.

Courtesy: http://www.rossradio.net

It really is very little work for the immediate payback realized by lowering system ground losses and increasing your antenna efficiency and overall ERP, especially on LF.

With the winter DX season just around the corner and the pleasant fall weather, it couldn't be a better time to plant a new crop of radials in the backyard!

As Murphy would have it, and in spite of the low amount of solar activity, LF/MF propagation has been very poor since getting my new 10' x 20' loop in place. The few front-to-side nulling checks that I have done, have produced results varying from around 20db to 30db, depending upon the signal. I suspect the depth of null is also affected by the signal's arrival angle but there is still more to learn. The pattern seems to be very close to that of a typical circular loop...the classic figure-8 pattern illustrated below as shown on the Wellbrook data that came with my ALA100LN preamp.

Courtesy: http://www.wellbrook.uk.com

More typically, the null is around 21-22 db as shown on this test while listening to the ground wave carrier of the YZA ndb (236kHz) located in Ashcroft, B.C., about 150 miles to the NE. As expected, the null is fairly sharp and the front / rear lobe, fairly broad.


One short check at dusk, produced nice signals from  CJBC, the French-language station in Toronto. The past few nights it has been very strong but with a strong echo effect. I wonder if there is more than one CBC outlet here (860kHz), such as a low-power repeater, causing the echo.


At the same time, while still fairly light outside, WCCO in Minneapolis had a nice signal just before sunset.


No matter how poor conditions become, it seems that the Hinchinbrook (Alaska) ndb, 'ALJ' (233kHz), is always strong....looping north.

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

My apologies for the video quality. If you know of any software available for making full-screen Perseus video captures so that I might improve my technique, please let me know. Presently I am just capturing them on my I-Pad which leaves a lot of room for improvement.

Hopefully conditions will only get better as the season progresses and I am able to give the loop a good workout....before it gets too windy!

The new 'loop' is not really loop-shaped but is rectangular (10' x 20') and more like a Flag antenna shape. I considered a Flag but really don't need any back-end nulling capability since I'm mainly interested in listening to the east and to the north.


The main boom section is composed of two sections of 1" PVC thick-wall (Schedule 40) pipe joined at the center and reinforced with a 10' section of 2" x 2" Douglas Fir. In addition, the boom has a truss of 1/4" Dacron to take out any end-loading sag. The vertical end sections are 3/4" Schedule 40 PVC pipe, fastened with a T at the boom end. The center mast is made of 2" Schedule 40 ABS pipe with a long section of 1 1/2" ABS nested inside that telescopes upward to anchor the truss ropes and give some additional rigidity to the mast.

Main boom and mast construction

This type of construction would lend itself well to anyone interested in a rotating Flag antenna for the BCB / LF or 160m. The cost are very low, the structure is lightweight and the materials are readily available at most hardware outlets.



Looping E/W

Although the preamp is completely sealed and weatherproofed, I still decided to mount it inside a container. The container also provided a convenient anchor to terminate the loop end wires (PVC-coated #18 stranded) without putting any tension on the soldered terminals.

Although I have not had much time to listen, and conditions are still in 'recovery' mode from earlier disturbances, initial indications are that everything is performing as well, if not better, than expected. It certainly outperforms my 10' active shielded loop by a large margin. I have yet to do any serious S/N comparisons between it and my primary LF receive antenna, a large inverted L, which must be tuned to resonance for the desired listening range. I believe that the very quiet loop / Wellbrook combination will provide an overall S/N improvement.

I have always believed that smaller loops provide deeper and sharper front-to-side nulls so I was pleasantly surprised to measure (using Perseus) null depths from 25-30db, on various groundwave signals....more than expected. Skywave signals also deliver sharp deep nulls in the order of 22 - 25db...again surprising, but I'll take them! A brief listen pointing S-E last evening turned up good signals from 1 kw'ers KYHN (1650kHz) in Fort Smith, Arkansas and KKGM (1630kHz) in Fort Worth, Texas. An early morning listen revealed good audio from JOIK (567) Sapporo, Japan and JOAK (595kHz) in Shobu. Down in the ndb band, little 25-watter 'IP' on 210kHz was an all-time new catch from Mobile, Arizona.

There is still much to learn from this new antenna system but the biggest challenge will be keeping it up all winter. I did lose one of my 10' loops after several years, due to wind when the main (un-reinforced) PVC mast eventually failed from flexing fatigue. I will tie the ends of the new antenna down when the winds get strong to reduce as much mast flexing as possible. I could however, run the risk of violating another long-standing radio tradition..."if your antenna stayed up all winter, it wasn't big enough". I just can't win.

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!

Several hours were spent yesterday finishing off the new 630m antenna matching transformer and installing the new loading coil with built-in variometer.


I decided to remove two turns from the bottom half of the coil, lowering the tuning range from 177-330uH to 165-313uH. Still not ideal but slightly more efficient. In reality, any losses from the variometer inefficiency are minuscule compared to the overall ground-system losses and probably unmeasurable. As it stands, the inverted 'L' resonates on 473kHz with 185uH of inductance and ideally the variometer should be operated closer to its total maximum inductance.


The new matching transformer is similar to the one that works so well on the 2200m system and wound on two TV flyback ferrite cores.




Once everything was cabled-up, I returned to the shack and plugged the coax into the KØLR antenna meter (VFO) and tuned it to 473kHz. I then went back to the variometer and tuned it while watching the meter through the shack window, looking for the sharp rise in current that would indicate resonance. I swept from one end to the other but saw no change! I eventually realized that I had not attached the antenna downlead to the top of the loading coil...duhh!

Once in place, the sweet-spot was quickly located and I returned to the shack to switch to the transmitter and scope match. For starters I had set the matching transformer to the 50ohm tap but the Scopematch indicated a resistive impedance of about 25 ohms. Moving to the 25 ohm tap resulted in a perfect match as can be seen here with both the current and voltage waveforms in exact phase and amplitude.


The Scopematch truly makes things easy, once you remember to attach the antenna!

The antenna tuning systems for 2200m and 630m are now separate and independent of each other, each with their own coaxial feedline and tuning system but I really wonder if I'll ever be active at all on 2200m again as there just appears to be no real interest amongst Canadian amateurs in our new 'topband'. It's really a shame since so many people worked very hard to obtain 2200m for Canadian amateurs...for me, its been a wonderful learning-ground for building and experimenting, as is 630m.

With the 630m system all ready to go at maximum EIRP, things are all set for the late October 630m Activity Night (hope you will be there). In the meantime, while awaiting new Canadian activity (come on guys!), I'm open for business.

Anyone wishing to try a two-way crossband contact please let me know. Both myself and VE7BDQ would love to work you!