AmateurRadio.com

courtesy: http://sdo.gsfc.nasa.gov/

Conditions on LF have been rather dismal for the past week and a half. Here in western Canada as well as most regions running along the southern edge of the auroral zone, the nightly visible auroras have been wreaking havoc on normal LF propagation as well as dampening HF during the day but ...





... the sun has been deathly quiet, as can be seen in yesterday's solar disk image.

It seems that just the 'normal' solar wind can disrupt things all on its own, without any solar flares or coronal mass ejections. In the late 70's, 'cracks' in the earth's magnetosphere were first observed... cracks that allowed even a quiet solar wind to actively interact with the earth's (normally protected) upper atmosphere. Apparently this is the present condition that has been disrupting normal propagation for the past many days.

The spaceweather.com web site has a nice explanation of how these cracks allow the Sun's Interplanetary Magnetic Field (IMF) to interact with the earth's field:

"Earth has a magnetic field, too. It forms a bubble around our planet called the magnetosphere, which deflects solar wind gusts. (Mars, which does not have a protective magnetosphere, has lost much of its atmosphere as a result of solar wind erosion.) Earth's magnetic field and the IMF come into contact at the magnetopause: a place where the magnetosphere meets the solar wind. Earth's magnetic field points north at the magnetopause. If the IMF points south -- a condition scientists call "southward Bz" -- then the IMF can partially cancel Earth's magnetic field at the point of contact.

When Bz is south, that is, opposite Earth's magnetic field, the two fields link up," explains Christopher Russell, a Professor of Geophysics and Space Physics at UCLA. "You can then follow a field line from Earth directly into the solar wind" -- or from the solar wind to Earth. South-pointing Bz's open a door through which energy from the solar wind can reach Earth's atmosphere!"

Earth's Bz has been pointing south during this entire period of poor propagation. Heavy ionization of the daylight D-layer, normally an 'absorber' of LF signals, has allowed reception of several NDB signals normally only heard at night. In fact, one of my favorite NDB propagation indicators, 25-watt YLJ in Meadow Lake, Saskatchewan, has been heard all day long on 406KHz for the past week as its signal skirts along the underside of the dense D-layer. These auroral conditions however, often enhance the path to the south Pacific and several western BCB DXers have reported excellent propagation to Australia and New Zealand in the pre-dawn hours.

Another indicator of LF propagation disturbance is the DST or Disturbance Storm Time index. This number gives an indication of the severity of the weakness in the magnetosphere, with numbers going further and further negative as the charged particles trapped in the magnetosphere increase in numbers.

courtesy:http://wdc.kugi.kyoto-u.ac.jp/dst_realtime/presentmonth/index.html

The DST has been having a rough ride since the beginning of the month and as these numbers grow more positive and remain there, propagation will return to normal. With late September and October often being among the best months of the year for LF propagation, and with the sun now doing its part by remaining quiet, let's hope that the earth's magnetosphere will also co-operate and seal-up those propagation-killing cracks.

Yesterday I completed the construction of the crystal-controlled tone generator which will be used to modulate my lightwave transmitter during future clear-air / cloudbounce tests.




It was installed on the lightbox, right beside the original 556 CW beacon / tone generator.




The crystal-controlled oscillator uses a CD4060 IC as an oscillator-divider and produces a ~550Hz or a ~1098Hz squarewave from the 4.5MHz crystal.

4500KHz xtal divided by 8192 showing 549Hz output

The original 556 tone generator will be kept for aural CW and beacon modes as it provides a stable enough signal for this purpose but for the very narrow bandwidths that I plan to use when digging into the noise with Argo, I reasoned that the signal needed to be more stable.

As can be seen by comparing the two oscillators (crystal on the left and 556 on the right), the 556 has a lot of drift (although it looks like it might eventually stabilize) and, as well, produces several spurious signals ... probably robbing power from the main tone. The crystal-controlled signal is rock solid and doesn't appear to generate any parasitic signals in the process. The trace below the crystal signal is unrelated to the oscillator.




When I first wired the unit up, I found an unstable low frequency oscillation from the 4060 during key-up conditions, due no doubt, to the lengthy leads inside the box. This was cured by adding a pull-up resistor to the keying line as shown in the final schematic below.












Now it's on to building another fresnel-lens receiver box which will be needed for any field work here on the island.

I spent a couple of hours again this weekend playing with the N1MM contest logging software and getting back into the contesting groove. My new K1EL USB interface continues to work flawlessly, even on my ancient XP laptop ... gone are the occasional keying stutters produced when previously keying from the serial port. N1MM is one of the most widely-used contest loggers and is freely available for download here. I still run the older 'Classic' version as I don't think my laptop could handle the newer 'N1MM +' edition ... I'll upgrade when I get a newer contesting laptop.

Both the Colorado and the Tennessee State QSO Parties were held this weekend, providing me another round of CW contest practice. Both activities are pretty low-key affairs when it comes to contesting but hey, every bit of practice helps.

I found surprisingly little action in the CO Party, making just 18 contacts ... 12 on 20m CW and 6 on 40m, with 17 sections worked. There seemed to be more activity from TN amateurs though, with 38 QSO's in 33 sections, 28 on 20m and 10 on 40m. All contacts were made on CW. All of the 40m contacts were made several hours before local sunset here, surprising the heck out of me that the W4's could even hear me in broad daylight ... the stations worked must have very quiet locations.

The state QSO parties are a good way to enjoy a short round of contesting without blowing an entire weekend, which I don't think I would really like to endure, and there seems to be at least one or two of them each weekend ... an easy way to ease into contesting or to keep up your on-the-fly contest keyboarding skills.

With all commentary periods for the FCC's 'Notice of Proposed Rulemaking' (Docket 15-99) now closed, it appears that one of the last comments to be filed may contain the most powerful arguments in favor of swift implementation.

In its extremely detailed 42-paged submission, the ARRL states, in no uncertain terms, the reasons why access to both the 2200m LF band and the 630m MF band should not be held back and that service rules should be 'finalized'. Indeed the powerful arguments stated in favor of implementation should go a long way in making this happen sooner rather than later.

The FCC's position is that there is little to no evidence to indicate that amateur radio operation on either band would be incompatible with power company PLC systems, going as far as stating that at distances of 1km or more from PLC lines, "there is no chance of interference". Further supporting their claim, the thousands of hours of experimental operation were offered as powerful proof and that the ARRL was “unaware of any reports of interference to PLC systems arising from that operation conducted pursuant to numerous Part 5 experimental licenses…in the large band utilized by PLCs.”

In addition, the ARRL had harsh words regarding the FCC's attempt to legitimize the growing number of fish-net beacons in the 160m band, and pulled no punches regarding their position in this matter.

"There is no indication that these buoys are compatible with other uses in the band, no track record of interference avoidance or resolution, and certainly no indication that the current operators can be relied on for compliance with the Commission’s rules."

"The Commission is urged to avoid enacting rules that it has no effective ability or intention to enforce. That fishing vessels have, with impunity, illegally deployed radio buoys in this band on a widespread basis (whether or not due to misrepresentations of the importers and retailers of these devices or due to a disregard of the Commission’s rules generally) without even nominal enforcement actions by the Commission, provides no basis for assuming that there will be compliance with any deployment limitations (including geographic deployment restrictions) on these buoys going forward. Nor is there any basis for the assumption that there will be any enforcement action taken with respect to continued illegal operation of the buoys if and when interference is caused. Spectrum planning by the Commission in this context has to be based on ex ante determinations of compatibility rather than mere assumptions, especially where the record indicates such a low level of historical compliance."

A summary of the comments can be read here in the ARRL News while all comments filed for the NPRM be found here temporarily, while the FCC site is down for maintenance.

Yesterday's mail brought an official - looking envelope from the U.S. Army! It contained a very nice letter from Fort Huachuca, Arizona, thanking me for participating in the '66th Military-Amateur Crossband Test' as well as three QSL's for the Army-affiliated contacts that I had made back in May.


During the activity, I was able to work Army stations AAZ (AZ), WAR (Pentagon), WUG-2 (TN) ... all on 20m via the crossband mode as the military stations transmitted outside of the band.





In addition to these three, two Navy stations were worked ... NWVC (IN) and NPD (TN) but it appears that 'Army' has beaten 'Navy' ... at least when it comes to QSL'ing!

Looking down the road at possible future 'clear-air scatter' or 'cloudbounce' lightwave tests with stations (VE7CNF and VA7MM) on the other side of Georgia Strait, I spent a few minutes breadboarding a more stable modulator for my lightwave system.


As it is at present, the modulator consists of a 556 tone generator, capable of either a steady tone for CW keying or a two-tone FSK 'beaconing' signal used to help the other station in aiming alignment.

For the slow QRSS CW narrow-bandwidth modes required for the scatter tests, I've always known that a tone which is much more stable and of precisely known frequency would be needed. The tone from the 556 does well as an aural CW keyed tone but would probably be all over the place when viewed in a very narrow-bandwidth and not nearly as stable as it sounds by ear.

The little modulator uses a 4500 KHz crystal (pulled from a old VCR several years ago) in a 4060 oscillator-divider. In this case, output from the chip is taken from either the 'divide-by-8192' pin 2, which outputs a precise frequency of 549 Hz or from the 'divide-by-4096' pin 1, which outputs a frequency of 1099Hz.

courtesy G3XBM: http://g3xbm-qrp.blogspot.ca/search/label/nlos

This tone is then used to drive an IRF 540 power MOSFET which controls current through the 1W Luxeon Deep Red LED in the transmitter. The 4060 modulator will be keyed via a QRSS software keying program that I have used for many years to key my LF transmitter.

The lightwave receiving station will look for the QRSS audio signal with an audio spectrum viewer such as Argo or Spectran. The ability to make automatic overnight screen captures will allow the receiving operator to get a good night's sleep while the system diligently watches for any traces of a signal.

An example of a strong signal capture showing a repeating "SL" identification is shown below, as it would appear in a perfect world. In this case (QRSS3), the short 'dots' are 3 seconds long while the 'dashes' are 9 seconds.


Huge signal gains (the ability to dig into the noise for signals) can be had by slowing things down and using narrower receiving bandwidths. Just going from a normal 12WPM speed CW (aural copy) to QRSS3 yields a gain of ~15db. At QRSS10 (10 second dots), an additional 5db is gained while slowing to QRSS60 (60 second dots), a whopping 28 db over 12WPM CW is gained!

Of course all of this extra 'hearing power' comes at a cost and in this case, the cost is 'time'. On an overnight of automated computer monitoring, time is not much of an issue ... it only becomes critical in 'QSO mode' when some QRSS QSOs can take several hours to complete. In any case, it will be interesting to see if any traces of lightwave signals will show up while bouncing around in the clouds.

The Georgia Strait scatter tests will not take place for some time but in the meantime, I hope to do some local tests here, from one side of my island to the other but will build a new portable receiver for these tests and leave my main system intact.

I haven't been on 2200m (135.7 - 138.8 KHz) for some time ... my last transmissions on this band were almost three years ago. The recent acquisition of the 630m band has refocused a lot of my attention but Canadian activity has never been very high on the real 'top band'. Hopefully when the U.S. gets the 2200m band soon, activity will increase on both sides of the border.

An e-mail alert from Toby, VE7CNF, on the other side of Georgia Strait, indicated that everything was ready for a two-way test on 2200m and he was looking for his initial contact on the band. Having not been on the band for such a long time, some review of my 'tune-up' procedures were in order as well as the need to burn out the spider webs in my outdoor loading coil.

Since being on 2200m, I had modified my 2200m kilowatt transmitter so that it could also be used on the new 630m band. To change bands from 630m back to 2200m, I needed to swap the frequency-sensitive power divider back to 2200m as well as re-set the DDS frequency.

2200m Power Divider

Setting my DDS to the correct control frequency and keying the driver stage revealed no sign of a signal on 137.779 KHz. This was puzzling and several re-checks turned-up no reason for the problem ... it seemed as if there was no signal from the DDS into the transmitter. I set everything back to 630m, just to confirm that there wasn't a more serious problem but everything worked just fine. It was then that I realized my error.

When modifying the transmitter, three years ago, I had also changed the transmitter's input frequency divider from a 'divide-by-four' to a 'divide-by-two' scheme. My original system on 137KHz started with a DDS frequency in the 5.48MHz range and then was divided by ten before being fed to the transmitter's input where the 548KHz signal was then divided by four. Using a higher DDS frequency allowed for greater frequency resolution at 2200m and allowed for very small frequency adjustments across the band. I would have kept the same system for 630m except that my 'divide-by-ten' chip was not very happy at 18MHz and refused to divide.The newer system now only allows me to move around the band in 4.5Hz steps. It's really not much of a problem as there is presently a minuscule amount of activity in Canada on 2200m, but as previously mentioned, this may change when U.S. amateurs gain access to the band.

Having sorted out my transmitter problems and confirming that all was well, the next task was to check antenna resonance and impedance matching as it would more than likely not be the same as I had left it. A low-power check using the 'scopematch' indicated that both resonance and impedance were not optimized. Tapping down on the loading coil by one-turn took care of resonance while adjusting the impedance tap in my matching transformer to its lowest value (see matching scheme below) resulted in a near perfect match on the scope.



I'm guessing that the resonance change was due to the recent heavy trimming of the 80' Balsam that supports one end of my 'inverted-L' and large three-wire flatop.




The tree's crown had previously been very dense and some of the branches were almost touching the flatop. The close proximity always made me worry about possible flashover at the antenna ends as voltages here would be several kilovolts. Removing much of the wet green tree branches directly beneath the flatop also likely contributed to the slight change in resonance.

Impedance Matching Transformer On TV Flyback Cores

The change in impedance to a lower value may have been due, in part, to the removal of the tree branches as well but more likely it was reflecting the change in my ground system. When I had last been on (in mid-winter), the ground was well saturated and the water table at normal heights. The present conditions are just the opposite as things are drier than they have ever been and the water table has certainly dropped substantially.

The sked with VE7CNF went smoothly and it was nice to see another new Canadian station taking an interest in the band, along with all of its challenges. Toby's 200W signal was a solid 559 here even with his small antenna system yet to be fully optimized. As well, he was bothered by heavy switching-power supply QRM from a nearby neighbour. Unfortunately, such noise sources seem to be increasing in numbers and are making operation on LF, already a big challenge, even more challenging. Toby has taken up the challenge with enthusiasm and has now had contacts on 2200m well as on 630m, adding to the ranks of active VE7's on LF and ... demonstrating yet again that amateurs can enjoy the LF bands with small 'backyard' antenna systems. Don't let living in the city be a reason to avoid our new LF bands.


Wouldn't it be great to see some activity from our neighbours in VE6 or VE5, both easily workable on both bands from the west coast... maybe you're up to the challenge!