Hello all!My first question is ,how are the rf ,if coils actually wound on the kind where the coil is short but sticks out (donut shaped)?Is it weaved or braided etc.and how does this effect inductance? Second question is ,what actually causes that really neat phase shifting sort of sound on the shortwave bands, kind of a swooshing?I also am wondering what causes that loud drone sound that sounds like many airplanes flying on the shortwave bands?

Chris,
I think the coils you mentioned are called "Latice Wound", but there are other names too. They all accomplish the same thing. Hi inductance, with lower parallel capacitance, enhancing the "Q", ie quality factor of the coil. Another choice is called solenoid wound, with all turns/layers parallel to each other. The last choice is "scramble wound", which is what you get trying to do it manually. Just Google lattice wound coils for more. The phase shift sound you describe, is RF signal fading in/out. Sometimes caused by atmospheric conditions, the distance from source or reflections arriving (delayed)at the antenna. These out of phase signal can add or subtract the net energy at the receiver, causing all kinds of weird and entertaining side effects. The same thing occurs in fringe areas of FM radio reception. I've heard the drone noise you described, and always thought it was high speed facsimile transmission or other similar devices, but sure there are better explanations.

marv

:Hello all!My first question is ,how are the rf ,if coils actually wound on the kind where the coil is short but sticks out (donut shaped)?Is it weaved or braided etc.and how does this effect inductance? Second question is ,what actually causes that really neat phase shifting sort of sound on the shortwave bands, kind of a swooshing?I also am wondering what causes that loud drone sound that sounds like many airplanes flying on the shortwave bands?
:

:Hello all!My first question is ,how are the rf ,if coils actually wound on the kind where the coil is short but sticks out (donut shaped)?Is it weaved or braided etc.and how does this effect inductance? Second question is ,what actually causes that really neat phase shifting sort of sound on the shortwave bands, kind of a swooshing?I also am wondering what causes that loud drone sound that sounds like many airplanes flying on the shortwave bands?
:

Ed M,
Hey Ed good stuff, and now you mentioned it "the whoosh" I recall a similar incident on the deserts of Utah years ago. Driving under/around a large thunder head with AM radio on, I could hear static (whoosh) building louder and louder, and eventually a bolt of lightning. It was as if a static charge was building until sufficient energy for a strike. After a few incidents, was able to time the volume (static charge) to the next strike. Got real accurate on the timing, but never knew from where the bolt would originate, but got lucky a couple times. Also noted a leader (mini strike) as if the energy were laying a path for the ultimate bolt, which would appear soon thereafter. Haven't done research on that subject though.

marv

::Hello all!My first question is ,how are the rf ,if coils actually wound on the kind where the coil is short but sticks out (donut shaped)?Is it weaved or braided etc.and how does this effect inductance? Second question is ,what actually causes that really neat phase shifting sort of sound on the shortwave bands, kind of a swooshing?I also am wondering what causes that loud drone sound that sounds like many airplanes flying on the shortwave bands?
::
:
:Atmospheric events and changes, and what they do to radio waves, are very interesting. For example, normally when there is a lightning strike, there is static. Ocassionally, even with a local strike, I have heard a rushing "Whoosh" sound, that lasts for several seconds, and not the typical static. This phenomena apparently has harmonics way up the frequency spectrum, and can come from both local and distant storms. The ionosphere and other atmospheric layers change, and cause signal distortion. Natural atmospheric changes and storms cause radio effects of their own, such as a radio phenomena known as the "dawn chorus". The "northern lights" sometimes creates interference, as do sun spots and flare-ups. A lot of atmospheric noise is from man-made sources, such as the drone you describe. Every traditional non-flat TV and computer monitor on your block creates noise in the RF spectrum, harmonics from the high voltage horizontal scan. No matter how hard they try to filter it out, there are harmonics from the switching power supply / regulator in computers that gets out, as does noise from fluorescent lamps, solid-state lighting ballasts, the arc discharge lamp on the corner, and the neon sign on the bar down the street. The more sensitive the receiver, and and in those radio bands not crowded with strong AM signals, the more pronounced is the noise.
:
:As a related but separate note, it is interesting to pick up shortwave broadcasts occasionally that have bounced around both sides of the earth, so that two identical signals are heard, with a very pronounced delay between the first and the second. I think there are becoming fewer and fewer short-wave stations, and an ever-increasing number of noise and interferrence sources. Ed M.
:

I believe, though, that the drone you hear on certain repeatable places on the short wave dial are from data transmission of some sort.

T.

:I believe, though, that the drone you hear on certain repeatable places on the short wave dial are from data transmission of some sort.
:
:T.
:

Yes, and before that there was the mysterious "woodpecker," supposedly some kind of Russian over-the-horizon radar.

I suppose that the "drone" isn't a birdie on a digital receiver, is it?

:
:Yes I believe the 'drone' is some sort of data transmission. It has been around at least since the 1970's.
:
:Ed M
:

I can still hear woodpecker-like sounds on my short wave.

T.

:I can still hear woodpecker-like sounds on my short wave.
:
:T.
:
terry

Actually it's more of a fluttering popping sound on short wave.

Thomas, can you tell us the frequency and time of day you hear it?

I had thought that the Russian "woodpecker" was off the air.

:Actually it's more of a fluttering popping sound on short wave.
:

The woodpecker was over the horizon radar and is indeed gone. A google search will turn up lots of data on it. The droning sounds are data transmissions. The military guys call this "mux", for multiplexer data. Another sound that will often turn up is a "chirp" that may repeat a few times. This is from a Chirp Sounder. A transmitter sweeps through the HF band and a synchronized reciever records the received signal strength. This gives a plot of propagation for the whole (3-30mhz) or any other segment of interest. The chirp sound comes from the transmitter going through the frequency you are tuned to. Then there are the famous "numbers stations". These are broadcasting coded messages to intelligence agents. A lot of these broadcasts are in Spanish. Do the math.

:Thomas, can you tell us the frequency and time of day you hear it?
:
:I had thought that the Russian "woodpecker" was off the air.
:
:
::Actually it's more of a fluttering popping sound on short wave.
::
:

:The woodpecker was over the horizon radar and is indeed gone. A google search will turn up lots of data on it. The droning sounds are data transmissions. The military guys call this "mux", for multiplexer data. Another sound that will often turn up is a "chirp" that may repeat a few times. This is from a Chirp Sounder. A transmitter sweeps through the HF band and a synchronized reciever records the received signal strength. This gives a plot of propagation for the whole (3-30mhz) or any other segment of interest. The chirp sound comes from the transmitter going through the frequency you are tuned to. Then there are the famous "numbers stations". These are broadcasting coded messages to intelligence agents. A lot of these broadcasts are in Spanish. Do the math.
:
:
::Thomas, can you tell us the frequency and time of day you hear it?
::
::I had thought that the Russian "woodpecker" was off the air.
::
::
:::Actually it's more of a fluttering popping sound on short wave.
:::
::
:

::The woodpecker was over the horizon radar and is indeed gone. A google search will turn up lots of data on it. The droning sounds are data transmissions. The military guys call this "mux", for multiplexer data. Another sound that will often turn up is a "chirp" that may repeat a few times. This is from a Chirp Sounder. A transmitter sweeps through the HF band and a synchronized reciever records the received signal strength. This gives a plot of propagation for the whole (3-30mhz) or any other segment of interest. The chirp sound comes from the transmitter going through the frequency you are tuned to. Then there are the famous "numbers stations". These are broadcasting coded messages to intelligence agents. A lot of these broadcasts are in Spanish. Do the math.
::If these droneing airplane sounds are data transmissions, they have been around since the middle 50's. I first heard them when I was a child listening to my grand parents old Zenith radio. I thought they were some kind of jamming and i still hear them but not on as many frequencies as in the past. This is my first post although I have been monitoring the forum for about 4 years.
::
:::Thomas, can you tell us the frequency and time of day you hear it?
:::
:::I had thought that the Russian "woodpecker" was off the air.
:::
:::
::::Actually it's more of a fluttering popping sound on short wave.
::::
:::
::
:

The jammers operated all over the bands during the cold war. They tended to sound more like a buzz saw and completely covered their targets. They were very common. Today this kind of thing is rare and only comes from a couple of hold-outs. The "mux" signals are somewhat similar in that they are continuous droning sounds but not as harsh sounding. There were also some jammers that covered the targets with sounds that were sort of like bubbling or wavering. With these you could tell there was something underneath but it was unintelligable.

:::The woodpecker was over the horizon radar and is indeed gone. A google search will turn up lots of data on it. The droning sounds are data transmissions. The military guys call this "mux", for multiplexer data. Another sound that will often turn up is a "chirp" that may repeat a few times. This is from a Chirp Sounder. A transmitter sweeps through the HF band and a synchronized reciever records the received signal strength. This gives a plot of propagation for the whole (3-30mhz) or any other segment of interest. The chirp sound comes from the transmitter going through the frequency you are tuned to. Then there are the famous "numbers stations". These are broadcasting coded messages to intelligence agents. A lot of these broadcasts are in Spanish. Do the math.
:::If these droneing airplane sounds are data transmissions, they have been around since the middle 50's. I first heard them when I was a child listening to my grand parents old Zenith radio. I thought they were some kind of jamming and i still hear them but not on as many frequencies as in the past. This is my first post although I have been monitoring the forum for about 4 years.
:::
::::Thomas, can you tell us the frequency and time of day you hear it?
::::
::::I had thought that the Russian "woodpecker" was off the air.
::::
::::
:::::Actually it's more of a fluttering popping sound on short wave.
:::::
::::
:::
::
:

Those flat wide coils are called "PIE-Wound" coils..

Excerpt below from some web-site:
"Coils - R.F

All radios have tuned circuits. They are fundamental to operation and the very early receivers had little else. Performance is closely related to the design and operation of these components and consequently their condition is of considerable importance. I.F. transformers, which are a specialized form of tuned circuit, were covered in the previous article. Tuning inductances, known universally as "coils", have undergone considerable change since the early period when monster cylinders several inches in diameter were used to achieve the maximum of efficiency. Around the mid 1930's single layer windings for broadcast band use gave way to multilayer "pies" but generally those for the intermediate and shortwave bands retained the single layer winding. If you are not familiar with these components, study of the underside of a typical multiband receiver is suggested. Connected to the wavechange switch will be the various coils. Those for the broadcast band will be seen to have bunched or pie windings whilst the shortwave coils will be single layer with spaced turns. The intermediate band coils may have a pie wound primary and a single layer secondary. Generally, there' will be two windings per coil, and in the shortwave coils they may be inter wound, the primary winding having the fewer turns of finer wire. Broadcast band aerial and R.F. coils usually have larger primary than secondary windings. This results in more even gain over the tuning range and avoids aerial changes upsetting tracking.

A special aerial coil is commonly found in older receivers that have low frequency I.F. systems but are without an R.F. stage. There is a second tuned winding with an associated tuning capacitor sect ion to improve image rejection. These receivers can be recognized by their having a three gang tuning capacitor and no R.F. amplifier valve. The aerial coil has only one primary or aerial winding, and two identical and separate secondaries."

:Those flat wide coils are called "PIE-Wound" coils..
:
:Excerpt below from some web-site:
:"Coils - R.F
:
:All radios have tuned circuits. They are fundamental to operation and the very early receivers had little else. Performance is closely related to the design and operation of these components and consequently their condition is of considerable importance. I.F. transformers, which are a specialized form of tuned circuit, were covered in the previous article. Tuning inductances, known universally as "coils", have undergone considerable change since the early period when monster cylinders several inches in diameter were used to achieve the maximum of efficiency. Around the mid 1930's single layer windings for broadcast band use gave way to multilayer "pies" but generally those for the intermediate and shortwave bands retained the single layer winding. If you are not familiar with these components, study of the underside of a typical multiband receiver is suggested. Connected to the wavechange switch will be the various coils. Those for the broadcast band will be seen to have bunched or pie windings whilst the shortwave coils will be single layer with spaced turns. The intermediate band coils may have a pie wound primary and a single layer secondary. Generally, there' will be two windings per coil, and in the shortwave coils they may be inter wound, the primary winding having the fewer turns of finer wire. Broadcast band aerial and R.F. coils usually have larger primary than secondary windings. This results in more even gain over the tuning range and avoids aerial changes upsetting tracking.
:
:A special aerial coil is commonly found in older receivers that have low frequency I.F. systems but are without an R.F. stage. There is a second tuned winding with an associated tuning capacitor sect ion to improve image rejection. These receivers can be recognized by their having a three gang tuning capacitor and no R.F. amplifier valve. The aerial coil has only one primary or aerial winding, and two identical and separate secondaries."
:Thankyou gentlemen for your information on these topics.This is really interesting and exciting for me!
:Now I also understand more about these pie wound coils etc.