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Author Topic: Why don't I hear stations on bands above 14m at night?  (Read 1216 times)

KM4SII

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Re: Why don't I hear stations on bands above 14m at night?
« Reply #15 on: January 30, 2023, 04:37:52 PM »

Here is something I put together years ago that might help you...
Definitely a good starting point, but I would add that this varies greatly depending on both the time of year and solar conditions. For example, in the spring, 15m was routinely open deep into the night with strong Europeans coming in at local midnight or later on my simple wire antennas. Just a few nights ago, Australia was workable on 15m at 1:30 AM local time.

The general rule of thumb is that the more sunspots there are (and the higher the SFI), the longer and stronger band openings will tend be. And things change a lot depending on the time of year. For instance, in winter you do not often hear Europe on the high bands after mid-afternoon in the US, but as the year progresses, Europe will often be booming in even when it is completely dark here on 20m, and with the improving solar conditions, even on higher bands like 17 and 15m as I mentioned above.

Software like HamCAP will give you a good idea of what you can expect band conditions to be like at a certain time of year under certain solar conditions. Of course, it isn't perfect as I have at times observed strong openings when HamCAP showed no predicted opening at that time to that part of the world. But in general, it tends to be reasonably accurate.

73
Mason - KM4SII
« Last Edit: January 30, 2023, 04:40:20 PM by KM4SII »
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AE0Q

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Re: Why don't I hear stations on bands above 14m at night?
« Reply #16 on: January 30, 2023, 04:57:46 PM »

20M -    Daytime 2000 miles or less
      Nighttime 2000 miles - worldwide

15M -    Daytime 2000 miles
      Nighttime not useable

Yikes, where did you get THOSE distance numbers???

Glenn AE0Q
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K6BRN

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Re: Why don't I hear stations on bands above 14m at night?
« Reply #17 on: January 30, 2023, 05:23:37 PM »

A few updates...

1.  100W PEP is the maximum power permitted on 60M, not 50W

2.  20M is probably the most reliable DX band, opening early in the day and fading out for DX somewhere around 7 PM under current conditions.  Depending on conditions and station, it's effectively a worldwide band.

3.  At the moment (under current solar flux conditions in this rising sunspot cycle) 10-17M are also "worldwide" in the daytime)

4.  A great time to troll for DX when your station is along the "Grey Line" (day/night terminator) in the evening.  As each higher frequency band fades out there is often a burst of openings and opportunities during the last few minutes.  Use the PSKReporter website to track this.

5. In the evening, 30-80M is the place to be as they "open up".

Note that the O.P. already has DXCC on 80/40/20/15/10, according to his QRZ page and probably knows this already.  His question is about WHY, which relates to ionospheric charging in the E and F regions by solar flux.  Lots of info on this and LUF/MUF online.

Brian - K6BRN



« Last Edit: January 30, 2023, 05:28:13 PM by K6BRN »
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W2IRT

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Re: Why don't I hear stations on bands above 14m at night?
« Reply #18 on: January 30, 2023, 05:51:24 PM »

I'm surprised this wasn't thoroughly covered on the Extra Class exam.
What a jerk response. I studied the minimum amount needed to pass the exam. Most of what's required to pass the exam is not useful and/or not required.
Except when it suddenly is. I'm not saying this to be mean—far from it—I think most of us here are willing to Elmer new DXers, but if one writes the Extra Class exam it's expected that that person will operate HF at some point, and a reasonable knowledge of propagation fundamentals is to be expected out of the gate.

Just as we know a fair bit about electrical and electronic theory, it's likely not enough for many of us (including me) to design complex circuitry. Basically enough to troubleshoot a discreet-component radio and not get a case of the deads from an amplifier or power supply. The license is indeed the proverbial license to learn, but quite honestly before using one's privileges there really is a minimum level of knowledge that one should endevour to retain, specifically as it pertains to day-to-day operation.

I have personally never needed or indeed had the slightest use for a Smith Chart, but I had to memorize the damned things for the test. I've forgotten everything about them, but I know where to go in the unlikely event that I'll need to use one someday. Understanding gains and losses in multiples-of-three should be second nature (a 100W transmitter with an added 12dB boost from an amplifier, leading into 300 feet of feedline that has 2dB loss per hundred feet, what's your approximate ERP going to be), as should things like phone types on HF (LSB on 40 and down, USB on 20 and up), how to set your ALC properly for SSB and digital modes, how to use digital modes properly and not cause QRM, how to build a station to maximize your incoming signal with good engineering practice, how to ground for both electrical and lightning safety and for best RF performance.

What I find unfortunate is that there are so few opportunities for new hams to learn what is needed for the test but also for daily use. I don't expect J. Random Ham to give a dissertation on solar physics, but, and again I don't mean to sound nasty about this, basic understanding of HF propagation really is something that you will deal with every single day as a DXer, and is something that quite honestly should have been highlighted during your studies as you readied yourself for examination. My comments are more an indictment of the lax exam standards, but they also reinforce my belief that memorizing the right answers is not the best path forward.

That has been my advice to numerous hams: study the minimum required to pass the test, get into the hobby, and then learn in the areas that you enjoy. That's precisely what I'm doing. I never cared about propagation before, but now I'm wondering about it so I came here for some advice to help me learn.
I just feel that that isn't the best way to equip yourself with the basic knowledge needed to operate your station effectively. Did you only do the minimum on your P. Eng certifications? What about in your engineering ethics classes? I certainly don't want a civil engineer reviewing my new tower plans to have taken that route in university, or wet stamp them based on generalized assumptions rather than knowing all the maths and taking measurements of my soil, etc.

Even if I had learned every single topic with great detail for the exam, I certainly wouldn't remember it all. I have a masters degree in electrical engineering and yet I'm constantly learning as part of my job because technology continuously advances.
But you did have to actually learn and retain the basics of your profession, or else I'd argue you'd be a poor engineer. You're quite correct that it's not really possible to memorize every facet of the test prep, but there really IS a minimum standard that you will need, and I'd respectfully argue that HF prop is near the top of the list for an active Extra Class ham, especially one who wishes to learn the Wisdom of the Ages and build toward DXing awards. You'll gain the finer details as you operate in the coming years; when to look for Asia or Europe, that east-coast NA to east-coast Australia is generally better long path in our late afternoons, and so on. That you get from practice. But "lowbands at night, 30 all-day-long, 20-and-up during the day is a great place to start, and knowing the 101-level basics of why will aid your understanding.

Thankfully there are other nice people who were willing to share information so I can learn. I hope that you responded the way you did because you're having a bad day and that you're normally a pleasant person.
Naw, probably not. Think somewhere between Ron Swanson and Al Bundy <grin>.
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Night gathers and now my watch begins. It shall not end until I reach Top of the Honor Roll

Great times are at hand, and soon there will be DX for all—although more for some than for others.

K6JH

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Re: Why don't I hear stations on bands above 14m at night?
« Reply #19 on: January 30, 2023, 06:08:26 PM »

This time in the sunspot cycle the ionization only sticks around for an hour, maybe two, past local sunset. So those African stations are still there for a little while past their local sunset, but they too will eventually go away.

It’s interesting to me how my 10m FT8 waterfall just goes away in a few minutes in the early evening. A few signals make it through for a few minutes, but after a bit everyone is gone.
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73
Jim K6JH

KA2FIR

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Re: Why don't I hear stations on bands above 14m at night?
« Reply #20 on: January 30, 2023, 06:25:45 PM »

Measurement of Length in Metric Units is Abbreviated as m.

In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats.[1][2] It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, troughs, or zero crossings, and is a characteristic of both traveling waves and standing waves, as well as other spatial wave patterns.[3][4] The inverse of the wavelength is called the spatial frequency. Wavelength is commonly designated by the Greek letter lambda (λ). The term wavelength is also sometimes applied to modulated waves, and to the sinusoidal envelopes of modulated waves or waves formed by interference of several sinusoids.[5]


Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency[1] range from around 20 kHz to around 300 GHz. This is roughly between the upper limit of audio frequencies and the lower limit of infrared frequencies;[2][3] these are the frequencies at which energy from an oscillating current can radiate off a conductor into space as radio waves. Different sources specify different upper and lower bounds for the frequency range.

Wavelength     Frequency
20(m)eters     14MHz or 14(M)ega(H)ert(z)

Mega is a unit prefix in metric systems of units denoting a factor of one million (106 or 1000000). It has the unit symbol M. It was confirmed for use in the International System of Units (SI) in 1960.

What are the units of Hertz?
The hertz (symbol: Hz) is the SI unit of frequency. It is named in honor of the German physicist Heinrich Rudolf Hertz, who made important scientific contributions to electromagnetism . One hertz is defined as one cycle per second. One hertz simply means "one per second " (1/s); 100 Hz means "one hundred per second", and so on.

US Amateur Radio Frequency Allocations

https://www.arrl.org/frequency-allocations

https://repository.library.noaa.gov/view/noaa/31283

HF Propagation videos:

https://www.youtube.com/watch?v=yShlAl2kMZw

https://www.youtube.com/watch?v=7Y_RTdPs3NI

https://www.youtube.com/watch?v=lzjYSoYuoXI

https://www.youtube.com/watch?v=QEBho6Xvzdo

https://www.youtube.com/watch?v=ARVDNP3vsJo

https://www.youtube.com/watch?v=1bGId8CHySE
« Last Edit: January 30, 2023, 06:40:58 PM by KA2FIR »
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K9RJ

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Re: Why don't I hear stations on bands above 14m at night?
« Reply #21 on: January 30, 2023, 07:37:31 PM »

There are lots of articles on propagation, research K9LA (http://k9la.us). Don't forget Longpath in winter. It can be spectacular. The fun is just beginning! When the bands from 15 - 6 meters open up it will be very exciting!

Harris K9RJ
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W4FID

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Re: Why don't I hear stations on bands above 14m at night?
« Reply #22 on: January 31, 2023, 03:23:55 AM »

Sunspots/propagation is probably the #1 thing. From the USA it will tend to favor QSOs to stations to the east in the daytime and to the west in the evening. When the sun is illuminating between you and the station you're working tends to be more favorable. There are "gray line" displays that easily show where the sun is and where night is. Next is your antenna. ANY antenna will have at least some directional favoritism. Even a vertical which is omni directional by definition probably has some radiation preference due to proximity to trees, buildings, the conductivity of the soil, type and number and length and placement of radials. Wire antennas all will have some directions better than others. Then there is the time difference. Evenings in the USA are the dead of night in Europe and Africa. Less people are on when they are sleeping. With all the variables personally my strategy -- I have a modest HOA station -- is I work whomever I can work on whatever mode and band I can and just enjoy the QSOs I have.
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ON6KE

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Re: Why don't I hear stations on bands above 14m at night?
« Reply #23 on: January 31, 2023, 03:50:08 AM »

I'm surprised this wasn't thoroughly covered on the Extra Class exam.
What a jerk response. I studied the minimum amount needed to pass the exam. Most of what's required to pass the exam is not useful and/or not required. That has been my advice to numerous hams: study the minimum required to pass the test, get into the hobby, and then learn in the areas that you enjoy. That's precisely what I'm doing. I never cared about propagation before, but now I'm wondering about it so I came here for some advice to help me learn.

Even if I had learned every single topic with great detail for the exam, I certainly wouldn't remember it all. I have a masters degree in electrical engineering and yet I'm constantly learning as part of my job because technology continuously advances.

Thankfully there are other nice people who were willing to share information so I can learn. I hope that you responded the way you did because you're having a bad day and that you're normally a pleasant person.

John

As an Extra you should be embarrassed to ask such a question. Well that's the result of multiple choice exams and having but to memorize the questions and answers from a booklet. And yet you decided it was too much material worth covering.
« Last Edit: January 31, 2023, 04:09:02 AM by ON6KE »
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KB8GAE

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Re: Why don't I hear stations on bands above 14m at night?
« Reply #24 on: January 31, 2023, 05:22:28 AM »

Highly recommend this book if you can find it... Answers many questions...

https://www.goodreads.com/book/show/17698602-radio-propagation---principles-practice

Here is good book on propagation that is still available

https://store.cq-amateur-radio.com/shop/the-cq-shortwave-propagation-handbook/

73 Rich KB8GAE
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W1VT

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Re: Why don't I hear stations on bands above 14m at night?
« Reply #25 on: January 31, 2023, 05:23:27 AM »

Details   W1VT   BA2BI   2023-01-31 01:35:00   17M   FT8   18.10072    three hours after sunset 22:05Z
Details   W1VT   HS0ZPO   2023-01-31 01:15:00   17M   FT8   18.10111   
Details   W1VT   VK3AUX   2023-01-31 00:33:15   12M   FT8   24.91569   AUSTRALIA  two hours after sunset
Details   W1VT   JA1IAZ   2023-01-20 23:33:15   10M   FT8   28.07486   JAPAN  Sunset at 21:50Z
I have simple wire antennas strung up in the trees.
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K0UA

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Re: Why don't I hear stations on bands above 14m at night?
« Reply #26 on: January 31, 2023, 06:03:44 AM »

Here is something I put together years ago that might help you...

Thank you very much! I'm printing this now and putting it up on the wall.

John

The only problem with "rules of thumb" is that there are exceptions to every rule.

In very broad generalizations, as the sun comes up in the morning in YOUR area, head for the higher HF bands. This is because the ionosphere  (F layers) becomes ionized at angles you can use to refract signals off of. The lower HF bands, 160, 80, and 40, become less usable due to ionization of the D layer. The D layer absorbs these signals and long distance signals fade out because they have to pass thru the D layer, and since they don't pass thru as well due to this absorption. The higher frequencies pass right thru the D layer with no trouble, and refract off of the F layer to go on and go back to earth a long distance away.

This can be repeated for multiple hops. This give us propagation to Europe and a little later Africa. As the sun moves to the west during the day from your point of view, These higher band signals start to fade as our eastern targets go into darkness. But the lower bands start to come alive ad the D layer absorption becomes less and less toward sunset. The higher HF bands are still useful for communication with Asia and Oceana because they are West of us here in the continental US. So about sunset 10 and 15 and 17 meters are still useful for getting to Asia easily. But as darkness spreads  the higher HF bands start to close out normally from the top down.

 Notice I said normally. If the sunspots are active enough and the ionization is high enough, they can remain open longer. This is why in extreme sunspot maxima the top HF bands CAN stay open longer, or even all night to somewhere.

That was supposed to be the "simple" explanation, 
At sunup head to the top bands, and move your antenna with the sun as the top bands start dying off and go lower in frequency as the darkness falls. Work the low bands at night. BUT it isn't always that simple.  The point I am making is that you can study propagation for the rest of your life and not understand it all. Literally it can become your life's work. Just remember my "simple" explanations in NO WAY explain all the mechanisms at work in HF propagation. But it should at least keep you from trying to work DX on 160 or 80 meters at high noon or in normal times calling CQ on 10 meters at 1:00AM.

I do not pretend to know much about this subject and I have been using propagation to make contacts for over 52 years. Good luck in your studies and experiences.  73  James K0UA
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73  James K0UA

WO7R

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Re: Why don't I hear stations on bands above 14m at night?
« Reply #27 on: January 31, 2023, 06:17:49 AM »

Quote
and a reasonable knowledge of propagation fundamentals is to be expected out of the gate.

I don't recall questions of that sort being on the exam when I took it many moons ago.  And that was when they still required 20 WPM code, too.

The emphasis was more on technical proficiency.  DXing, as such, despite its popularity, was never a part of the exam pool that I can recall. 

Not sure it should be.  There are just too many surprises where propagation happens that usually does not.  And stuff nobody gets around to writing down.

A buddy of mine has just about every DX honor  there ever was.  After 3 or 4 decades of DXing, he noted in a Club forum recently that he just found out, after all these years, about a 30 meter Long Path propagation path that he had never run into.  It appears to be reasonably reliable, too.  He may write it up.  Hope he does when he sorts it out.

Given all of that, other than maybe one or two questions on D layer absorption for 80 and 160, it's not clear what would make a fair test question.

A guy recently gave a talk to our DX club that 40 meters, in mid winter, is almost open around the clock.  That is, on 40, the grey line zone widens far into daylight hours for reasons he elaborated on in his talk.  I  tried it and was reasonably successful.  It turns out, in mid winter, 40 can be as open as late as 10am local time and as early as 2pm local.  At least to some places anyhow.

There's just hundreds of things that are true that go beyond what could be fairly encoded in a test pool.
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K7KB

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Re: Why don't I hear stations on bands above 14m at night?
« Reply #28 on: January 31, 2023, 08:28:29 AM »

I'm surprised this wasn't thoroughly covered on the Extra Class exam.
What a jerk response. I studied the minimum amount needed to pass the exam. Most of what's required to pass the exam is not useful and/or not required. That has been my advice to numerous hams: study the minimum required to pass the test, get into the hobby, and then learn in the areas that you enjoy. That's precisely what I'm doing. I never cared about propagation before, but now I'm wondering about it so I came here for some advice to help me learn.

Even if I had learned every single topic with great detail for the exam, I certainly wouldn't remember it all. I have a masters degree in electrical engineering and yet I'm constantly learning as part of my job because technology continuously advances.

Thankfully there are other nice people who were willing to share information so I can learn. I hope that you responded the way you did because you're having a bad day and that you're normally a pleasant person.

John

I don't think Pete's response was being critical of you, but that basic propagation wasn't covered in the Extra Class exam. Actually his explanation about the F2 layers, absorbtion, etc. were spot on.
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W2IRT

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Re: Why don't I hear stations on bands above 14m at night?
« Reply #29 on: January 31, 2023, 09:40:40 AM »

I'm surprised this wasn't thoroughly covered on the Extra Class exam.
What a jerk response. I studied the minimum amount needed to pass the exam.
I don't think Pete's response was being critical of you, but that basic propagation wasn't covered in the Extra Class exam. Actually his explanation about the F2 layers, absorption, etc. were spot on.

While I generally try to be as diplomatic as I can, sometimes I get frustrated at the memorizing of answers without having 101-level knowledge to back it up. That is definitely one of my hot buttons! HF Propagation topics aren't even covered on the Extra exam, they're covered in the General!
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Night gathers and now my watch begins. It shall not end until I reach Top of the Honor Roll

Great times are at hand, and soon there will be DX for all—although more for some than for others.
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