AmateurRadio.com

Most of us LF/MF and topband diehards have been looking forward to the next several years of low solar activity ... maybe even 'ultra-low' as some of the solar gurus are predicting.

An interesting posting on the Topband reflector a few weeks ago by noted propagation expert, Carl, K9LA, made me re-think my expectations!

I flagged the post for a later blog topic but have since seen the information pop-up on a couple of other reflectors as well as on the ARRL News page. Apparently I wasn't the only one to give the posting a double-take. If you missed it, here is Carl's post:

About a week ago Wolf DF2PY posted a message here commenting on the recent adverse levels of geomagnetic field activity and how it will now change for the good - giving us good 160m propagation.

We'll certainly see less geomagnetic field activity as we move into winter,
but there's another issue we should be aware of. The Sun's magnetic field
is weakening - probably to the lowest levels in our lifetime. With a weak
solar magnetic field, more galactic cosmic rays will be able to get into
the Earth's atmosphere. We are now seeing unprecedented high neutron counts (neutrons are one of the by-products of cosmic rays)

Since galactic cosmic rays are mostly *very energetic* protons, they can
get down to low atmospheric altitudes, causing collisional ionization in
the D region (and lower E region). A cursory estimate using cosmic ray
ionization rates confirms more ionization in the lower atmosphere. 160m is
not very tolerant of more absorption, so we may see an adverse effect of
the weakened solar magnetic field.

Many of us think that "solar min is solar min is solar min". But maybe a
solar minimum can be too deep for 160m. A good question to ask in the early 2020s will be "how was 160m?" So stay active on 160m and let's see what happens.

Carl K9LA

My initial response was to think that perhaps there wouldn't be as much to look forward to as I had been hoping for, when it came to improved LF, MF and 160m propagation. Carl's postulation was also backed-up by another mention on the Spaceweather site, although the influence of cosmic ray bombardment on radio propagation was not discussed.

As I thought more about this unfortunate possibility actually coming to pass, I thought back to my own on-air and listening experiences during previous solar-low years ... particularly the unprecedented low between our most recent cycle and its predecessor, Cycle 23.


The low period between these two cycles, as most will likely recall, saw the quietest solar conditions observed in the past 100 years. The solar-low winters saw week after week of a blank Sun, with solar activity virtually flatlining for the entire period. In 2008 there were 265 'zero sunspot' days and the following year saw another 262 days of blank suns!


These effects were well noted here for two winters that are usually prime 'DX times' ... if ever there were a period when cosmic ray bombardment should negatively impact low frequency propagation, surely it would have been then.

So just what did I observe?

What I saw was not only what I had been expecting but was much much better than I had ever believed possible. For west coast topband operators, the 'holy grail' of propagation is working Europe. Working Europe from here means that signals must travel through the polar regions, usually the kiss-of- death for weak signals, as the severe attenuation through the auroral zone means that it just doesn't happen very often ... except for this prolonged period of ultra lows. In a word, conditions to Europe were 'spectacular' ... night-after-night, for several weeks over a period of two winters, working Europe on 160 became normal.

On most nights, European signals could be heard before local sunset, and on several occasions, CW contacts with Europeans, were completed up to one and a half hours before my local sunset. As darkness set in, more signals would appear and the band would rapidly become populated with Europeans ... and only Europeans.

Most of the time there were no signals from North America evident, just Europeans ... a condition that had me shaking my head in disbelief night after night. It was something I had never observed before, as I watched 160m behaving more like 20m CW on a good day to Europe! During this period, my DXCC totals skyrocketed from 99 to 143 worked, as new Europeans and Africans were added to my logbook.


Signal levels were also outstanding, often pushing the FT-1000 S-meter well past the S9 level. On one particular night, I recall hearing an SM4 calling CQ, with just such a signal. I set my output power level at 10 watts and gave him a call, to which he quickly responded. If cosmic ray bombardment was at a high level, it was not reeking any havoc as far as the west coast path to Europe was concerned! For the record, my topband system is nothing special, consisting of a simple 'half-sloper' over a poor ground and a very old amplifier running about 500W output.

My other favorite winter pastime is chasing NDBs in the MF range between 200-500 kHz. Exceptional east west conditions were evident throughout the two winters of ultra-lows.

On one such night, I noted a new strong signal where none had been previously heard. Because of its strength, I surmised that it was probably a new NDB in nearby Washington state. Noting its ident ('NYA' on 414 kHz), I was not able to find any reference to such a beacon being previously reported and turned to the Yahoo ndblist group for help, posting my catch as 'unidentified'. Almost immediately I received a response, telling me that the signal I was hearing was located in Europe ... Svalbard to be exact, located midway between Norway and the North Pole!

Now, European NDBs have never been heard from the west coast, other than occasional signals from some of Greenland's powerhouses, so this represents a very rare event. Although I have often listened for this signal, it has yet to be heard here again and my logging of remains its only reported foray into any part of North America. Unfortunately, in 2015, it was listed as 'decomissioned'. I have no doubts that this rare propagation was a result of the solar flatlining conditions of the time.

As chilling as Carl's warning sounds, he himself admits uncertainty with a 'let's wait and see' attitude and after reviewing my own experiences under what surely must be similar conditions, I'm still very optimistic over what might be in store. Hopefully we shouldn't have to wait too much longer to find out!

Most of us LF/MF and topband diehards have been looking forward to the next several years of low solar activity ... maybe even 'ultra-low' as some of the solar gurus are predicting.

An interesting posting on the Topband reflector a few weeks ago by noted propagation expert, Carl, K9LA, made me re-think my expectations!

I flagged the post for a later blog topic but have since seen the information pop-up on a couple of other reflectors as well as on the ARRL News page. Apparently I wasn't the only one to give the posting a double-take. If you missed it, here is Carl's post:

About a week ago Wolf DF2PY posted a message here commenting on the recent adverse levels of geomagnetic field activity and how it will now change for the good - giving us good 160m propagation.

We'll certainly see less geomagnetic field activity as we move into winter,
but there's another issue we should be aware of. The Sun's magnetic field
is weakening - probably to the lowest levels in our lifetime. With a weak
solar magnetic field, more galactic cosmic rays will be able to get into
the Earth's atmosphere. We are now seeing unprecedented high neutron counts (neutrons are one of the by-products of cosmic rays)

Since galactic cosmic rays are mostly *very energetic* protons, they can
get down to low atmospheric altitudes, causing collisional ionization in
the D region (and lower E region). A cursory estimate using cosmic ray
ionization rates confirms more ionization in the lower atmosphere. 160m is
not very tolerant of more absorption, so we may see an adverse effect of
the weakened solar magnetic field.

Many of us think that "solar min is solar min is solar min". But maybe a
solar minimum can be too deep for 160m. A good question to ask in the early 2020s will be "how was 160m?" So stay active on 160m and let's see what happens.

Carl K9LA

My initial response was to think that perhaps there wouldn't be as much to look forward to as I had been hoping for, when it came to improved LF, MF and 160m propagation. Carl's postulation was also backed-up by another mention on the Spaceweather site, although the influence of cosmic ray bombardment on radio propagation was not discussed.

As I thought more about this unfortunate possibility actually coming to pass, I thought back to my own on-air and listening experiences during previous solar-low years ... particularly the unprecedented low between our most recent cycle and its predecessor, Cycle 23.


The low period between these two cycles, as most will likely recall, saw the quietest solar conditions observed in the past 100 years. The solar-low winters saw week after week of a blank Sun, with solar activity virtually flatlining for the entire period. In 2008 there were 265 'zero sunspot' days and the following year saw another 262 days of blank suns!


These effects were well noted here for two winters that are usually prime 'DX times' ... if ever there were a period when cosmic ray bombardment should negatively impact low frequency propagation, surely it would have been then.

So just what did I observe?

What I saw was not only what I had been expecting but was much much better than I had ever believed possible. For west coast topband operators, the 'holy grail' of propagation is working Europe. Working Europe from here means that signals must travel through the polar regions, usually the kiss-of- death for weak signals, as the severe attenuation through the auroral zone means that it just doesn't happen very often ... except for this prolonged period of ultra lows. In a word, conditions to Europe were 'spectacular' ... night-after-night, for several weeks over a period of two winters, working Europe on 160 became normal.

On most nights, European signals could be heard before local sunset, and on several occasions, CW contacts with Europeans, were completed up to one and a half hours before my local sunset. As darkness set in, more signals would appear and the band would rapidly become populated with Europeans ... and only Europeans.

Most of the time there were no signals from North America evident, just Europeans ... a condition that had me shaking my head in disbelief night after night. It was something I had never observed before, as I watched 160m behaving more like 20m CW on a good day to Europe! During this period, my DXCC totals skyrocketed from 99 to 143 worked, as new Europeans and Africans were added to my logbook.


Signal levels were also outstanding, often pushing the FT-1000 S-meter well past the S9 level. On one particular night, I recall hearing an SM4 calling CQ, with just such a signal. I set my output power level at 10 watts and gave him a call, to which he quickly responded. If cosmic ray bombardment was at a high level, it was not reeking any havoc as far as the west coast path to Europe was concerned! For the record, my topband system is nothing special, consisting of a simple 'half-sloper' over a poor ground and a very old amplifier running about 500W output.

My other favorite winter pastime is chasing NDBs in the MF range between 200-500 kHz. Exceptional east west conditions were evident throughout the two winters of ultra-lows.

On one such night, I noted a new strong signal where none had been previously heard. Because of its strength, I surmised that it was probably a new NDB in nearby Washington state. Noting its ident ('NYA' on 414 kHz), I was not able to find any reference to such a beacon being previously reported and turned to the Yahoo ndblist group for help, posting my catch as 'unidentified'. Almost immediately I received a response, telling me that the signal I was hearing was located in Europe ... Svalbard to be exact, located midway between Norway and the North Pole!

Now, European NDBs have never been heard from the west coast, other than occasional signals from some of Greenland's powerhouses, so this represents a very rare event. Although I have often listened for this signal, it has yet to be heard here again and my logging of remains its only reported foray into any part of North America. Unfortunately, in 2015, it was listed as 'decomissioned'. I have no doubts that this rare propagation was a result of the solar flatlining conditions of the time.

As chilling as Carl's warning sounds, he himself admits uncertainty with a 'let's wait and see' attitude and after reviewing my own experiences under what surely must be similar conditions, I'm still very optimistic over what might be in store. Hopefully we shouldn't have to wait too much longer to find out!

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

Another recent reflector question about noise mitigation for active e-probe antennas brought further incite from Roelof Bakker, PAØRDT.





I found particular interest in his method of determining if the noise is being picked up by the antenna or being introduced by the feedline. As well, Roelof suggests one of the most important aspects of homebrewing ... keeping detailed notes of all tests or changes. He also suggests maintaining a healthy outlook regarding noise and rather than getting discouraged, take on the challenge of overcoming it!

Hello all,

I have been dealing with this subject for more then 10 years now and
I am pleased to pass on what I did learn so far.

The first item to look at is noise pick up on the feed line. This
can be a coax cable or a CAT5/6/7 network cable. Looking for noise
pick up on the feed line should be done without the active antenna
connected. Otherwise everything should be the same as when using the
antenna.

Ideally the antenna should be replaced by a 50 ohm termination that
can handle the power that is supplied by the DC-power supply feeding
the antenna. However, this is not necessary to achieve good results.

I am fortunate to own a PERSEUS SDR, that besides an excellent
receiver is also a nice piece of test gear. For noise pick-up
measurements I use HF-Span that changes the PERSEUS into a 0-40 MHz
spectrum analyser with a noise floor of -112 dBm. For narrow band
measurements the PERSEUS is used with Linrad, which can provide
accurate results.

Whilst looking at noise pick-up on the cable, one can unplug all
suspect devices and check if the noise is still present.

The most effective measure is grounding the shield of the coax cable
at the bottom of the mast, but I had still noise ingress of about -
100 dBm around 15 MHz. This could be solved by moving the power
supply and interface of the antenna from the operating position to
the location of the cable entry to the house. This minimises the
length of cable inside the house before the a rf-isolating
transformer used in the interface.

It is mandatory to use a separate radio earth, isolated from the
mains earth. My PC is connected to a mains outlet with a mains earth
connection, but no other equipment in the shack is using the mains
earth. This works for me.

There is also a discussion about the use of a common mode choke
versus a rf-isolating transformer. I have tried both and they both
work. However a rf-isolating transformer is much easier (and
cheaper) to build than common mode chokes with a winding of coax
cable.

In this regard, I should mention a source of interference that is
easily overlooked: receivers. It is not uncommon to own more than
one receiver and it appears that the antenna port is often far from
clean. I am using four SDR's which are fed from a balanced Norton
amplifier / four port splitter and these produce noticeable noise.
Using four rf-isolating transformers at the outputs of the splitter
eliminated the noise. My mini-whip is feeding up to 8 receivers
(hardware) via amplifiers /splitters / rf-isolating transformers
without degrading the receiver noise floor by mutual noise ingress.

The last point is about masts. A metal mast will decrease the signal
level when the antenna is mounted close to it. A short PVC extension
mast will help. The reason I am using a non-conductive mast is a
practical one as cheap and sturdy stackable camouflage net mast
sections were and are still available in western Europe. These are
ideal for either testing antennas and for permanent installations.
Metal masts can introduce problems by being resonant at a certain
frequency and receiving noise that can be transferred to the feed
line. However, checking the feed-line as described above will make
clear if this is the case or not. If there are no problems, there is
nothing against the use of a metal mast.

As every location is different, it is no use to provide an exact
recipe to solve noise problems. I believe that a systematic approach
is mandatory; take notes etc. as it is too easy to run in circles.
By all means do measure what you are doing, otherwise you will walk
in the dark for sure.

The good news is that it is still possible to build a low noise
reception system in the city and doing so can be fun! What might
also help is to change the attitude from 'it should not be there
after all' to 'what can I do about it!'

Best regards and 73,
Roelof Bakker, pa0rdt

If you're thinking about having a listen on LF or on 630m, the e-probe antenna can be a very effective solution .... and it takes up very little space. The finer details regarding the PAØRDT active antenna may be found here and here. All previous blog postings related to this topic may be found here.

This is a reminder of tomorrow's '630m activity night'. Highlights of the evening will see six different Canadian stations seeking contacts with other amateurs in North America via the 'crossband mode' as they call CQ on 630m CW but listen for replies on their announced (QSX) HF frequency. As well, there will be an increased level of on-air activity from many of the U.S. experimental stations, as they beacon or work each other on various modes including CW and JT9, the WSPR QSO-mode. The experimental stations are also seeking your reception reports.

More information may be found here regarding the activity night, including a detailed list of participating Canadians along with their respective transmitting and QSX HF listening frequencies.

As is often the case, old 'Sol is threatening to throw some junk our way over the next day or two, right on time for our event but please don't let that stop you from participating as often this can actually enhance propagation, especially on the north-south path.

We hope to see many of you tomorrow night!

The University of Victoria online SDR from SDR.hu

A posting today on Yahoos' ndblist Group by Geir, LA6LU, pointed to a list of online SDR receivers at various locations around the globe. I have seen similar lists like this in the past, only to be disappointed when finding many of the receivers impossible to get operating or arriving at a dead link. This list appears to be up-to-date as a quick check of four random receivers saw all four come to life quickly!

The site is run by Andras Retzler, the author of the OpenWebRX software that enables these SDR's to be made seamlessly available online through your web browser. Since all of the sites use the same software, all receivers appear the same, thus providing a very short operational learning curve. At the time of this posting, there were 76 online SDRs, a number that fluctuates slightly throughout the day. Conveniently, the site also indicates how many users are currently using any individual receiver.

I can think of several very handy uses of such a resource, from checking your own on-air signal to confirming, in real time, a suspected DX catch that you might be hearing from your own location. You may even be interested in putting your own SDR online for others to share. It really is a very useful resource and while there, check out the rest of Andras's interesting site.