Hot answers tagged

31

"Getting a nickel" is a reference to how metered pay phones work (worked?). You'd put in some coins, make your call, and when the time you'd payed for expired, the phone operator would demand another nickel to buy more time and keep the call going. Repeaters on automatic control typically have a "time-out" function that acts as a ...


26

"Balun" is a portmanteau of "balanced" and "unbalanced". Anything made to interconnect a balanced and unbalanced load can be called a balun. A common-mode choke (like a length of coax wound over a ferrite ring) works as a balun because it inserts a high impedance in the common-mode without affecting the differential-mode. By ...


18

If you don't know what a frequency is, you need to read up on waves-in-general and radio waves. But the other two terms can be defined in terms of frequency; frequencies are the “natural” thing and everything else are things people invented on top of that. A frequency band, or band, is a range of frequencies with a specific least frequency and greatest ...


15

That's a pretty good answer but I can add some more details. The exact formula for path loss is $$ 20 \times \log_{10}\left( 4 \times \pi \times \frac{d}{\lambda{}} \right) $$ $ 20 \times \log_{10}\left(4\times\pi{}\right) \approx 21.98$, and that's where the '22' comes from. If your receiver specs give a minimum signal strength, then the analysis above is ...


14

This became clear to me after a bit of time to think, but it wasn't at all clear on initially jumping in. It helps to know the formal definitions of the codes used: CQ is “Calling any station”. The station is asking for (new) contacts from anyone. QRZ? is “Who is calling me”. The station is asking for a calling station to repeat their callsign. Only a ...


14

The ITU bands are actually delineated along plain powers of ten! They're just hiding a bit. From the description above a table of all the bands on Wikipedia: As a matter of convention, the ITU divides the radio spectrum into 12 bands, each beginning at a wavelength which is a power of ten ($10^n$) metres… So the HF band is from 100–10m, or the UHF band ...


13

What is dBm? dBm stands for decibels relative to one milliwatt. Decibels represent multiplicative factors, or ratios; by establishing a specific reference level they can instead be used as absolute values: 0 dBm is 1 milliwatt, 3 dBm is approximately 2 milliwatts, etc. How do I convert it to watts? Convert the decibel value to a scale factor and ...


12

I keep these "Q" signals in line with this : QRN is "N"atural band noise ( lightning ) QRM is "M"an-made band noise ( crowded signals ) QSB is "B"utterfly effect from Ionosphere in-stability.


12

Homebrew is (as the name suggests) when you make your equipment yourself, as opposed to buying it. An amateur setup consists of many components - the largest and most complicated of which are a radio transceiver (or separate receiver and transmitter), and the antenna. A power supply is also needed, but these are relatively inexpensive compared to the cost ...


10

It's intended for contest logging. Most contests require that you "exchange" some information. Sometimes it's as simple as an RST signal report and you'd just enter whatever signal report you gave an received, other contests require a serial number (you send "1" to your first contact and increment that by one each time, so that each contact gets a unique ...


9

Marcel Wallace founded Panoramic Radio Corp. and details his "Panoramic radio receiving system" in patent US2279151A (1938). Page 2, column 1, line 19 of the patent gives us a clue as to how the physical "panoramic" concept made its way into what we now consider to be a purely electrical phenomenon: ...provide a panoramic radio compass system having ...


8

A scanner is a specialized receiver with features for effectively monitoring many frequencies, classically by tuning to each in rapid succession (scanning) and stopping when a signal is found, then continuing when the signal ends. The scan function can of course be disabled to use it as a receiver for a single channel. Scanners as commonly discussed are ...


8

As has been mentioned, many radio amateurs tend to be in the types of fields where various forms of rules are the name of the game. Electricity always behaves the same. So does a computer (assuming it is working correctly, it simply executes one instruction after another; it doesn't deviate or take initiatives of its own). And so on. However, there is ...


8

A calling frequency is a common channel known to all - this is the channel that anyone can jump onto and say Hi! Or a specific person you know may be monitoring this channel, you can call out to them. Should you wish to hold a longer conversation, you would use this channel to agree upon which channel you will be switching to.


8

It is ham radio laughter. HIHI, sometimes HI, other other times HIHI. It's origins are in CW (aka Morse Code), not voice. In fact, I believe old-timers might think it is silly to say HiHi or something on SSB or other voice comms when you can merely laugh if something is funny. But, with Morse Code, laughter is not in the alphabet so HIHI gets the job. ...


8

My personal opinion is that QRP means using significantly less power than is customary for a given mode of operation. In that sense, a 5W HT would not be QRP because pretty much everybody else with an HT is also operating at (or near) 5W. 0.5W might be considered QRP in this case.


8

My understanding of "QRP" is simply the use of as little power as possible to make contacts over interesting distances. There isn't a specific power level that equates to "QRP" - it is more a function of what's less than expected. 1W on 2m/UHF for 10 mile simplex (or local/regional repeater communications) isn't QRP. 0.1W on 2m/UHF for 250 mile simplex ...


7

I think there are two parts to this; why are they so "anal" /strict / uptight about the rules? why are they so hostile / aggressive / generally unpleasant? The first part I think is due to something that most people don't appreciate. The Ether (if you'll excuse the name) is a shared resource. The rules are there to try to let us all use it as ...


7

Deepness of QSB refers to the magnitude of fading. A very deep fade-out can make the received signal so weak that it becomes unreadable. A shallow fade-out would be one where the signal level drops only slightly, not affecting readability. Radio propagation conditions often change quite quickly over time. For example, QSB might start in the middle of a ...


7

It is known as an SF style SMA connector. It is also commonly known as a Motorola SMA connector since they seem to be one of the few large scale users of this style connector You can find some adapters for this style of connector such as this RFB-1142-4 BNC adapter: http://www.hitechwireless.com/rf-industries-rfb-1142-4-bnc-f-sma-f-adapter/


7

The roofing filter is the filter through which the first IF must pass. The roofing filter is an IF filter, specifically the first one. AB4OJ provides a block diagram: As for why it's called a "roofing" filter, Elecraft suggests it's about protecting the subsequent stages from spurious signals: The term "roofing filter" has most often ...


6

As said by other answerers, it's typically the station announcing 'I'm ready for more contacts at this time.' It doesn't necessarily have to be a DX station, but any station that is attracting a lot of traffic during contests. It is kind of informal usage, as Kevid Reid mentioned, the official QRZ definition is 'who is calling me?', and CQ means 'calling all ...


6

During contests, a popular station (say DX) has a pileup with lots of stations trying to make contact. A station will often merely say QRZ for picking up someone from the pileup. Thus, in this I am agreeing with the previous answer but with the following comment. I believe that this method of saying QRZ is now so popular in this pileup situation (that is, ...


6

That's a lot of words for digipeater. These are stations that listen for digital messages, record them in temporary storage, then re-transmit them. This particular allocation is on a secondary basis, with the primary allocation going to AMTS. "message forwarding system" is defined in §97.3: (32) Message forwarding system. A group of amateur ...


6

Are there specific problems or equations that are easier to deal with in dBm vs watts? Decibel units, dBm being an example of such, provide a more intuitive measure of some property that responds logarithmically, like power frequently does. Consider, if you are transmitting now with 1W, and you add 1W more, you have doubled your transmit power. That's a ...


6

Terminology can be ambiguous here; there is no universal standard for how to describe antennas. That said, here are some heuristics: If someone says, e.g., “a 20-meter dipole”, they mean an antenna which is for the 20-meter band, i.e. almost 10 meters long from end to end (because a full-size dipole has an electrical length of λ/2). If someone says the ...


6

In the RAF we used "best bent wire" as a test transmission largely because it has a lovely jazz rhythm. Some put "bens" in front, some put another "bent" on the end, but i you send it a reasonable speed, it does flow rather nicely. Hope this helps.


6

A QSL card is a physical card usually the size of a postcard. They are sent to verify a contact known as a QSL. To get various awards like Worked All States or DXCC (worked 100 entities) you need to verfiy the contacts. The main way this used to be done was to take the QSL cards you had received to a "card checker" who would verify them. The card should ...


5

Most of these things come from morse code. They were used because they have a distinctive and musical signature, listen to the rhythm of '73' some time. Rhythm was (and should still be) the mark of a good operator. Alas, some non military operators in the early days were not, that is where 'ham' came from: because the operators sounded 'ham-fisted'. When I ...


5

“Selectivity, blocking, and IP3” are three properties of a receiver's ability to receive the desired signal in the presence of other signals at different frequencies. Thus it would seem this document is referring to all such signals as “pollution”, presumably on the grounds that they are manmade signals as opposed to “natural” noise. (I am not aware of a ...


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