radioshane
Member
Does anyone know why HF signals can be booming out in daytime but then very weak in a evening ?
Short wave
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ecps92
Member
https://en.wikipedia.org/wiki/High_frequency
At any point in time, for a given communication path between two points, the frequencies at which communication is possible are specified by these parameters
Maximum usable frequency (MUF)
Lowest usable high frequency (LUF) and a
Frequency of optimum transmission (FOT)
At any point in time, for a given communication path between two points, the frequencies at which communication is possible are specified by these parameters
Maximum usable frequency (MUF)
Lowest usable high frequency (LUF) and a
Frequency of optimum transmission (FOT)
ka3jjz
Wiki Admin Emeritus
There are numerous reasons for this. One is that the broadcaster is not sending in your direction at the time you are listening. Another, and much more common, reason is that propagation is quite different during the day vs. at night. A very basic description....
On HF, signals are highly dependent on the ionosphere - a region of our atmosphere about 150-300km up. It changes depending on whether the area you are in is in daylight or in darkness. During the daylight hours, frequencies below 10 Mhz are adsorbed - above this, they will be bent (depending on the angle of the signal, frequency and other factors) back toward the earth. At night, the region of the ionosphere that propagates signals changes, and now you must listen below 10 Mhz or so.
There is an excellent website (that requires your Flash player to be active) that will give you a basic tutorial on this subject, linked below...
Propagation Primer - Flash Movie by AE4RV
This is a region that still holds many mysteries, and research is ongoing.
We haven't even begun to touch on antennas, which is yet another possibility....
Mike
On HF, signals are highly dependent on the ionosphere - a region of our atmosphere about 150-300km up. It changes depending on whether the area you are in is in daylight or in darkness. During the daylight hours, frequencies below 10 Mhz are adsorbed - above this, they will be bent (depending on the angle of the signal, frequency and other factors) back toward the earth. At night, the region of the ionosphere that propagates signals changes, and now you must listen below 10 Mhz or so.
There is an excellent website (that requires your Flash player to be active) that will give you a basic tutorial on this subject, linked below...
Propagation Primer - Flash Movie by AE4RV
This is a region that still holds many mysteries, and research is ongoing.
We haven't even begun to touch on antennas, which is yet another possibility....
Mike
ridgescan
Member
It could be everything cited by Mike and Bill above, or it could be simply a neighbor turning on their plasma TV or other noisemaker nearby, causing a suppression type RFI across the bands, which your ears perceive as a weaker signal.
What broadcast or transmission in what frequency are you referring to Shane?
What broadcast or transmission in what frequency are you referring to Shane?
Read the first chapter of this: http://hilltoparmyradios.com/usmc-radio-ops-hdbk.pdf
majoco
Stirrer
What HF signal did you have in mind? What frequencies, what time, what stations? Just because you can hear a station in the US at a particular time and frequency doesn't mean to say that later on he will still be there - he may be broadcasting to another area on that frequency on a different antenna to reach a different audience in another country.
ridgescan
Member
Wher'd the OP go?
radioshane
Member
I'm hear was busy that was all
5680 MHz
Is it right if you have you're half wave dipole going upwards towards you're upstairs bathroom instead of straight horizontally on the washing line it will make the people you're listening to sound not as good
And make reception not has good ?
5680 MHz
Is it right if you have you're half wave dipole going upwards towards you're upstairs bathroom instead of straight horizontally on the washing line it will make the people you're listening to sound not as good
And make reception not has good ?
ridgescan
Member
That would be 5680 kHz or 5.680mHz.
As for the question-huh?? What are you trying to do there-run the antenna indoors? Try running it outside, you will get better reception there.
You still refuse to give a straight answer as to time of day. You don't give people anything to go on to help you.
By the way you posted in other threads besides this one and ignored our questions here, so you weren't THAT busy.
pterodaktyl
Member
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Assuming from the frequency that you're trying to listen to Kinloss Rescue, the propagation in the UK usually drops off sharply after sunset. If you Google "near vertical incidence skywave" you should find plenty of info about the propagation method Kinloss uses to communicate with SAR helicopters operating in UK airspace.
Kinloss does have a night frequency as well, somewhere in the 3MHz range, but mostly they seem to stay on 5680kHz even with the weaker propagation.
Kinloss does have a night frequency as well, somewhere in the 3MHz range, but mostly they seem to stay on 5680kHz even with the weaker propagation.
wb6uqa
Member
listen at night
Try the lower frequencies at night. The sun helps the higher frequencies more in daylight.
Try the lower frequencies at night. The sun helps the higher frequencies more in daylight.
radioshane
Member
Pterodaktyl thanks for you're help does all international stations use the frequency because I've been hearing foreign voices talking to each other ?
has you don't get uk units talking to each other it's very interesting
has you don't get uk units talking to each other it's very interesting
radioshane
Member
No HF wire is 40 foot long outside in my back yard and about 7 foot off floor and I loose signal around 6 pm that's why I'm thinking of getting a loop antenna
radioshane
Member
Yes you're right nightime is 3023 MHz
Horizontal is OK. Vertical wires attract more local noise.
The general rule with HF is night time = lower frequencies work best (below 10 mhz) and daytime higher frequencies work best (10 mhz and above).
But like with most rules, there are lots of exceptions.
The general rule with HF is night time = lower frequencies work best (below 10 mhz) and daytime higher frequencies work best (10 mhz and above).
But like with most rules, there are lots of exceptions.
radioshane
Member
Boombox what would be the best tool to crimp a HF wire onto a centre dipole ?
and what would you say best tool would be to help peel a coax cable would be ?
As I want to put two pl259 s on it to solder it !
and what would you say best tool would be to help peel a coax cable would be ?
As I want to put two pl259 s on it to solder it !
majoco
Stirrer
5680 and 3023kHz are the international distress frequencies so you could well be hearing foreign language stations - not necessarily in distress as they use those frequencies for emergency exercises too.
You're asking me about something I haven't done in a long time.
I used a jackknife and peeled the coating off the coax very carefully.
Separated the braid and rolled it into a thick plug that resembles a thick 'wire'.
Pulled the center conductor cable and took the jackknife and peeled some of the coating away from the conductor wire.
Then I soldered the braid to the ground side of the antenna / PL259 / whatever, and soldered the center conductor to the 'hot' side.
pterodaktyl
Member
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- Nov 22, 2015
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Have a search on ebay for "dipole centre". You can get them for about £10 with an SO239 socket and a couple of clamps for attaching the dipole legs to.
In the UK it's not uncommon to hear foreign fishing vessels chatting on 5680kHz. If they become too much of a problem the operator at Kinloss will ask them to clear the frequency, usually without much success.
In the UK it's not uncommon to hear foreign fishing vessels chatting on 5680kHz. If they become too much of a problem the operator at Kinloss will ask them to clear the frequency, usually without much success.
majoco
Stirrer
I don't know if you can get them in the UK or the US but here we have PL259 plugs that are sized for specific cables RG58, 59, 8 etc that have a coarse thread on the inside of the cable entry. You strip off the outer for about 15mm, fold the braid back over the outer then strip the inner conductor leaving 5mm of insulation showing. Retwist the centre conductor if it's not solid and tin the end. Screw the cable into the plug entry until the centre insulation shows in the inspection hole and the centre is poking out of the pin - trim off the excess braid and solder the centre pin. I like to cover the joint with heatshrink sleeve and write on the heatshrink where the other end goes to!
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