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50 mhz F2


hamateur 1953

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I have yet to be able to span the United States on six.   It should become possible using voice ( SSB) once flux gets near 200 for three days or so.  Was trying to reach @KW2Pby PM but unsuccessfully so far.  Not sure how many of us are on this site along our Atlantic seaboard ( I am near Seattle ).  73. Mike N7ORL    Fine to contact me by private message on this site.    In fairness, I estimate the odds of successful contact at less than 10% Ha Ha.  

Edited by hamateur 1953
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On 11/26/2023 at 1:18 AM, hamateur 1953 said:

I have yet to be able to span the United States on six.   It should become possible using voice ( SSB) once flux gets near 200 for three days or so.  Was trying to reach @KW2Pby PM but unsuccessfully so far.  Not sure how many of us are on this site along our Atlantic seaboard ( I am near Seattle ).  73. Mike N7ORL    Fine to contact me by private message on this site.    In fairness, I estimate the odds of successful contact at less than 10% Ha Ha.  

Unfortunately you are not having a lot of luck with flux. Hovering around 180 still as was mentioned. Everything seems to have settled back for the moment. 
It will pick up eventually.

N.

 

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1 hour ago, Newbie said:

 

Unfortunately you are not having a lot of luck with flux. Hovering around 180 still as was mentioned. Everything seems to have settled back for the moment. 
It will pick up eventually.

N.

 

Yeah, true. Also in some past cases it is possible, perhaps even likely that those observations were done after periods of flaring etc. The Maximum useable frequency is really the maker or breaker when it comes to Dx.  

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3 minutes ago, hamateur 1953 said:

Yeah, true. Also in some past cases it is possible, perhaps even likely that those observations were done after periods of flaring etc. The Maximum useable frequency is really the maker or breaker when it comes to Dx.  

Well you need flux to increase a little and Kp to stay lowish for a few days. MUF should increase 😊

N.

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2 minutes ago, Genie said:

I think you are correct here. but i don't know why. can 

 

Here is a link to the information I posted a little while back.

The solar flux is closely related to the amount of ionization and hence the electron concentration in the F2 region.

K values between 0 and 1 represent quiet magnetic conditions and this would indicate good HF band conditions, subject to a sufficient level of solar flux.

N.

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Thanks @Sunshine. Wow. From our entire community. From me personally as well. Having been accused of contacting Mars ( jk). And generally viewed as eccentric ( true). Haha. Outta likes again doggone it. Catch ya later. 73. ( best regards). Mike/ Hagrid

our FCC won’t licence him. Don’t worry. 

1 hour ago, Sunshine said:

I never would have guessed I'd learn about hamradio, but thanks to you dedicated and friendly lot, I once again learned something new. Good luck for your endeavours to our HAM operators! 

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  • 2 months later...

http://www.ham-radio.com/n6ca/50MHz/K6MIO_50MHz_F2Prop.pdf

I thought I had included this excellent PDF.  But hadn’t It is very comprehensive but clear in its explanations.  Its old but I doubt our ionospheric behaviour has changed much. Haha. 

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4 hours ago, hamateur 1953 said:

http://www.ham-radio.com/n6ca/50MHz/K6MIO_50MHz_F2Prop.pdf

I thought I had included this excellent PDF.  But hadn’t It is very comprehensive but clear in its explanations.  Its old but I doubt our ionospheric behaviour has changed much. Haha. 

I was wondering about something that you might perhaps clear up for me: in that document it mentions how daytime D layer activity strongly absorbs frequencies of 10 MHz and below, and in this article I came across it mentions how the 80-meter band can experience as much as 25 dB of absorption; the latter corresponds to a frequency of ~3.75 MHz, but I can't see how that amount of absorption matches up with the D-RAP model we discussed in the other thread, where frequencies of 3-4 MHz show only ~5-10 dB of absorption during normal X-ray background periods, and frequencies between 5-10 MHz seem to only show ~1-5 dB of absorption. What is the reason for this apparent discrepancy?

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15 hours ago, Philalethes said:

I was wondering about something that you might perhaps clear up for me: in that document it mentions how daytime D layer activity strongly absorbs frequencies of 10 MHz and below, and in this article I came across it mentions how the 80-meter band can experience as much as 25 dB of absorption; the latter corresponds to a frequency of ~3.75 MHz, but I can't see how that amount of absorption matches up with the D-RAP model we discussed in the other thread, where frequencies of 3-4 MHz show only ~5-10 dB of absorption during normal X-ray background periods, and frequencies between 5-10 MHz seem to only show ~1-5 dB of absorption. What is the reason for this apparent discrepancy?

@Philalethes Point well taken.  The D-RAP model is now also incorporating particle absorption as well, And these are of course estimated path loss during periods of sunlight.  What also isn’t shown are the background noises ( lightning, local emf from electrical and electronic devices)  The D-RAP was I believe originally intended for use by high-power international broadcasters who had the abilities to “ steer” their emissions using different directions of transmission, hence it probably wasn’t intended for in depth study either. Although I actually think it may respond coincidentally to long Gamma Ray bursts greater than two seconds. 
Above approximately 10 mhz under normal conditions the D layer is practically transparent to radio waves. 
Why this is, I couldn’t really say. Other than our time station WWV in Fort Collins Colorado can be heard anywhere day or night on 10 mhz usually within our National borders.   For a simplification: The higher in frequency the signal, the less exposure to the elements are present, hence less absorption or diffusion.  Hopefully this clarifies a difficult subject.  Mike/ Hagrid.   PS. @KW2P did an excellent thing called Basics of Shortwave Propagation in this section for anyone else interested in the above subject matter.  I might add that computer models are created by human beings and two models of the same events are unlikely to agree.  Mike. 

Edited by hamateur 1953
Clarity I hope and grammar Haha. Tagged author
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One more afterthought, if you notice the D-RAP model run during periods of SFI below about 110 you likely won’t see much at all. Only black with the sun track following its normal path.  There remains large attenuation or normal reduction in signal loss that is always present in our D layer.  Think of it as a protective blanket from nasty stuff and you will be pretty close.  At solar minimum or around 70 SFI it still does its job quite effectively indeed.  

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On 2/18/2024 at 1:37 AM, hamateur 1953 said:

One more afterthought, if you notice the D-RAP model run during periods of SFI below about 110 you likely won’t see much at all. Only black with the sun track following its normal path.  There remains large attenuation or normal reduction in signal loss that is always present in our D layer.  Think of it as a protective blanket from nasty stuff and you will be pretty close.  At solar minimum or around 70 SFI it still does its job quite effectively indeed.  

Yeah, that really clarifies what I gleaned from your answer above, i.e. that the D-RAP model essentially models what the additional loss due to the X-ray and/or proton flux is, and doesn't say anything about the attenuation that is always present in varying degrees otherwise.

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