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Author Topic: Why don't I hear stations on bands above 14m at night?  (Read 1217 times)

W3LJ

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Why don't I hear stations on bands above 14m at night?
« on: January 30, 2023, 01:24:32 PM »

I'm embarrassed to be asking this question so please be kind with your response.

I operate FT8 on 80m - 10m using an EFHW antenna from my small HOA-restriction lot. I've been amazed at the contacts I've been able to make around the world.

I make lots of DX contacts during daylight hours on 14m up to 10m. However, when I monitor 15/12m/10m at night I don't hear any stations.

I'm confused by this because it's daytime here in the US and it's nighttime in Africa and I'm making contacts with stations in Africa. It seems like when it's daytime in Africa and nighttime here in Maryland, I should still hear the FT8 stations there.

Do the stations I'm making contacts with have such better antennas that they are able work any time of day, whereas my limited station only works DX on 80m-14m at night and 14m-10m during the day?

I have a feeling there is an obvious answer, but I just can't see it without your help.

John
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W7XTV

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Re: Why don't I hear stations on bands above 14m at night?
« Reply #1 on: January 30, 2023, 01:37:16 PM »

The one word answer:  Sunspots

The somewhat more detailed answer is that the higher frequencies are better during the day, but when the sun goes down, and the sunspots are over other parts of the planet than ours, skip on the higher bands goes away. 

Things are slowly getting better with the increase in sunspot numbers with this new solar cycle, but we're not at the peak yet.  That's roughly 5 years away, and then the numbers will start to decrease slowly but surely.  That will make the lower bands (160-30 meters) more desirable, especially during the winter when the nights are longer. 

20 meters, even with low sunspot numbers, almost always shows some DX during the daytime.  FT8 will be the best mode for such conditions (sorry, digi-haters), but CW will also work pretty well.  17-10 (sometimes even 6) will be at their best for next few years, but they're still normally daytime bands.  As always, there will be exceptions so don't completely write those bands off at night.
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W9WQA

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Re: Why don't I hear stations on bands above 14m at night?
« Reply #2 on: January 30, 2023, 01:39:43 PM »

your band/ freq numbers are confusing.
lower FREQS are better at night,typically
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W3LJ

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Re: Why don't I hear stations on bands above 14m at night?
« Reply #3 on: January 30, 2023, 01:42:25 PM »

when the sun goes down, and the sunspots are over other parts of the planet than ours, skip on the higher bands goes away.

Thank you for explaining. Now that I know it's sunspots, I'll do more reading/learning to understand this phenomenon in more detail.

I really appreciate you taking the time to educate me.

John
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KI8DJ

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Re: Why don't I hear stations on bands above 14m at night?
« Reply #4 on: January 30, 2023, 01:44:50 PM »

I think looking at graphs comparing solar cycles that the peak is likely only 2 or 3 years away.
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W9WQA

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Re: Why don't I hear stations on bands above 14m at night?
« Reply #5 on: January 30, 2023, 01:49:25 PM »

might be some confusion here between normal  day/night ionization, and sunspots
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W7XTV

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Re: Why don't I hear stations on bands above 14m at night?
« Reply #6 on: January 30, 2023, 01:51:19 PM »

when the sun goes down, and the sunspots are over other parts of the planet than ours, skip on the higher bands goes away.

Thank you for explaining. Now that I know it's sunspots, I'll do more reading/learning to understand this phenomenon in more detail.

I really appreciate you taking the time to educate me.

John

You're welcome.  Here's one place to start reading about it:  https://www.hamradioschool.com/post/sunspots-and-propagation

Quote from: KI8DJ
I think looking at graphs comparing solar cycles that the peak is likely only 2 or 3 years away.

I believe you're right.  I just checked a graph and saw the same thing.  Wishful thinking on my part for a longer cycle, I guess.  ;D
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He speaks fluent PSK31, in FT8...  One QSO with him earns you 5BDXCC...  His Wouff Hong has two Wouffs... Hiram Percy Maxim called HIM "The Old Man..."  He is... The Most Interesting Ham In The World!

GREYLINE

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Re: Why don't I hear stations on bands above 14m at night?
« Reply #7 on: January 30, 2023, 02:03:04 PM »

My first reaction is that we're getting trolled by this EXTRA Class Ham. Then you referred to 20 meters as 14m and well... I'm not so sure anymore.

Your ARRL Handbook as well as MANY easy to understand propagation articles you can google will not only answer your question but will teach you a basic to intermediate knowledge of HF propagation.
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KA2DDX

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Re: Why don't I hear stations on bands above 14m at night?
« Reply #8 on: January 30, 2023, 02:06:29 PM »

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

https://www.goodreads.com/book/show/17698602-radio-propagation---principles-practice
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W1VT

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Re: Why don't I hear stations on bands above 14m at night?
« Reply #9 on: January 30, 2023, 02:29:06 PM »

When I lived in Hawaii I had 2 el Quad on 10M with an exceptionally low takeoff angle due to the ground slope.  Clear shot at the horizon--I was able to see the Southern Cross.
Yes, I could make 10M contacts at night

Zak W1VT
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W2IRT

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Re: Why don't I hear stations on bands above 14m at night?
« Reply #10 on: January 30, 2023, 02:32:07 PM »

when the sun goes down, and the sunspots are over other parts of the planet than ours, skip on the higher bands goes away.
Thank you for explaining. Now that I know it's sunspots, I'll do more reading/learning to understand this phenomenon in more detail.

Not so much sunspots (although they are related indirectly), but more a question of the various levels of the ionosphere. The F layer splits in two at sunrise, and, if there's enough solar energy, the upper bands' signals reflect off the F2 layer. At night they recombine and the maximum usable frequency drops to usually below 14 MHz, although sometimes lower. Conversely, the D layer forms at sunrise, and low band signals are absorbed. It dissipates at sunset once again permitting long-distance frequencies on the lowbands.

During periods of high solar activity you will find 20m and occasionally 17 and 15 will perform very well during the evening and even overnight, but during low solar years 20 will close at sunset. I'm surprised this wasn't thoroughly covered on the Extra Class exam.
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KA2DDX

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Re: Why don't I hear stations on bands above 14m at night?
« Reply #11 on: January 30, 2023, 02:52:13 PM »

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

https://www.goodreads.com/book/show/17698602-radio-propagation---principles-practice
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W3LJ

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Re: Why don't I hear stations on bands above 14m at night?
« Reply #12 on: January 30, 2023, 02:55:09 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. 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
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NA4IT

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Re: Why don't I hear stations on bands above 14m at night?
« Reply #13 on: January 30, 2023, 04:21:25 PM »

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

HF Propagation Quick Guide

80/75M -  Daytime 400 miles or less
      Nighttime 400 - 6000 miles

60M -    Daytime 400M or less
      Nighttime 400 - 1500 miles
      (NOTE: 50W power limit!)

40M -    Daytime 500 miles or less
      Nighttime 500 - world wide

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

15M -    Daytime 2000 miles
      Nighttime not useable

10M -    Same as 15M


Short note: Use 40M or 20M for daytime operations. Use 80/75M or 40M for nighttime operations.

60M note: If the band is being used for EMCOMM, this can be a good choice.

Remember to orient antennas towards the area you need to work!
Check with a compass before erecting!
Dipoles ARE bi-directional.

If metal buildings or trailers are nearby, use them as reflectors!
80/75M reflector spacing should be 50 - 60 feet.
40M reflector spacing should be 25 - 30 feet.
20M reflector spacing should be 13 - 18 feet.

A wire placed on the ground directly under a dipole may help with gain.
(Doesn't have to attached to anything, just laying there!)
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W3LJ

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Re: Why don't I hear stations on bands above 14m at night?
« Reply #14 on: January 30, 2023, 04:23:37 PM »

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
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