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21 votes
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Is Morse code a digital, binary mode?

According to Shannon (in A Mathematical Theory of Communication - and who's going to argue with Shannon?) there are really only four symbols in Morse, not five: "dit" (defined as one unit time on ...
Jamie Hanrahan's user avatar
20 votes
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Why do some straight keys have a slider that shorts the contacts continuously?

My understanding is that in at least some telegraph systems, the principle of operation was as in this circuit (where the coils depicted are actually telegraph sounders): simulate this circuit –...
Kevin Reid AG6YO's user avatar
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13 votes
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What was the origin of the Morse code abbreviations "hi" and "es"?

Many Morse abbreviations and conventions come from before the days of radio, and we are relative latecomers to the game compared to the telegraphy guys. For this question, I found an old reference ...
Scott Earle's user avatar
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12 votes
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What does QSL mean in a CW conversation?

Generally, QSL means "I acknowledge receipt". "QSL?" (with a question mark) means "please acknowledge". Sometimes when listening to QSOs you will hear someone say QSL VIA BURO or QSL DIRECT or ...
Scott Earle's user avatar
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12 votes
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What is the decimal in Morse Code?

In the International Code of Signals (an International system of maritime communication, including radiotelegraphy), AAA (over-bar) is designated for both full stop and for decimal point. (See ...
hotpaw2's user avatar
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11 votes
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If I receive an SOS signal, what is the proper response?

Since you're simulating the situation with non-transmitting equipment, you get the play the part of actual emergency agencies. You'd start by asking the SOS caller to identify themselves (call sign, ...
Zeiss Ikon's user avatar
  • 4,097
11 votes

Is this strange Morse signal type common?

That is Morse code, in Norwegian, being sent with a "bug" (Vibroplex type mechanical key). The two operators are LA6UH and LA7JS. Probably not something you want to figure out how to decode with a ...
Brian K1LI's user avatar
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11 votes

Dominant speeds of Morse Communications

Data from the Reverse Beacon Network provides an answer. RBN receivers and computers decode CW (and other "digital" modes) to identify stations calling CQ and posts information about signal strength ...
Brian K1LI's user avatar
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11 votes

What is the decimal in Morse Code?

The web sites of Kent Morse Keys and of the AC6V reference compendium document use of the Morse letter 'R' (dit-dah-dit) as an abbreviation for 'decimal point.' 'R' can have other meanings, of course, ...
Brian K1LI's user avatar
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10 votes

Single or Dual Paddle Key?

Single-lever paddles have a single lever that generates dots when pressed to one side, and dashes when pressed to the other. Dual-lever paddles have two paddles, one of which generates dots and the ...
rclocher3's user avatar
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10 votes
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CW: when I supposed to send "E E"?

First, some history. As I understand it, the "dit-dit" (E E) comes from an old practice. There is a short tune in popular music that was often used to end a musical performance in a humorous way, ...
rclocher3's user avatar
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9 votes
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Using a Morse code key with a computer?

A really easy way to do this is to take an old USB mouse (or even a new cheap one) and solder the key across the left mouse button. You can then use key directly as mouse button input on most ...
Andrew's user avatar
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9 votes
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Are QRP transceivers only meant for CW communication?

QRP only means low power, often 1W or less. While you could technically have a 1W SSB transceiver and call it QRP, the practical range of such a radio would be limited. It is much easier to hear a ...
Phil Frost - W8II's user avatar
9 votes

What is an undulator (as used for CW)?

Since I can't answer this authoratively myself, but Mike Waters' comments indicate that search engine results of other people might be sparser than mine: A link collection: Title/Link Short ...
Marcus Müller's user avatar
8 votes

Why do some straight keys have a slider that shorts the contacts continuously?

Land line telegraph keys are fitted with a circuit closer switch. Radio telegraph keys were not but many radio operators used land line keys because they were so readily available. This includes the ...
Tom Horne W3TDH's user avatar
8 votes
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Why do CW signals get converted to pure sine wave tones at 750 Hz?

The tone you hear when receiving a CW signal is generated inside your receiver. Originally, a motor-driven variable capacitor or interrupter was used to put an AC component into the detector circuit, ...
Zeiss Ikon's user avatar
  • 4,097
8 votes

What does QSL mean in a CW conversation?

Especially true in a contest, or noisy environment: Hearing a "QSL?" from someone can mean they want to know specifically if what they've sent to you has been sent correctly. They may have been ...
mike65535's user avatar
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7 votes
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Key CW on zero crossings - zero bandwidth?

You raise an excellent question and your thought processes are indeed on the right track. First some background. An ideal, uninterrupted sinusoidal carrier has zero bandwidth. Real world factors such ...
Glenn W9IQ's user avatar
  • 18.6k
7 votes

Is Morse code a digital, binary mode?

The mode hams call "CW" is also called "on-off keying" (OOK) - a hint to the fact that it is a binary code. Dots, dashes and spaces are usually sized in multiples of the "dot time": one dot time on ...
Brian K1LI's user avatar
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7 votes
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Why were "PARIS" and "CODEX" considered "typical words"?

Answering the 2nd part: There seem to be many research articles and business documents reporting statistics on average word lengths, in characters, which seem to vary with language, dialect, corpus, ...
hotpaw2's user avatar
  • 13.4k
7 votes

What is the decimal in Morse Code?

The American Radio Relay League, ARRL, in their code practice texts, use "R" for the decimal point. I suspect it stands for the word, "radix" (root) because the mark used to ...
rjsmith's user avatar
  • 71
7 votes
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Why can I hear Morse when not in CW mode?

You don't say where you are hearing the Morse code. You say "on the same channels", but don't specify where you are listening. If you send Morse code using a buzzer, then that generates an ...
Scott Earle's user avatar
  • 4,599
7 votes

Swapping crystal from HF to VHF in a QRP tranceiver

Too Long; Didn't Read (tl;dr) That circuit was designed for 40 m. You can't modify it just by replacing the quartz crystal to work on 2 m. What Would Need to Change? So what you've found is a circuit ...
Marcus Müller's user avatar
6 votes

How many new amateur operators can currently use CW?

From my experience, not many. Not many at all. Learning CW at speeds that facilitate conversation, vs just sending callsigns and signal reports, is, frankly, daunting. I've only been a ham for a few ...
Jeff's user avatar
  • 61
6 votes

What is the origin, history behind "Ben's Best Bent Wire"?

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 ...
user8244's user avatar
6 votes
Accepted

How do I send negative numbers or below zero in CW?

According to Wikipedia there is a code for the hyphen or the minus symbol, − · · · · −. However very few hams are likely to recognize it. In the meantime I would ...
rclocher3's user avatar
  • 9,242
6 votes

Is a US Extra class exam from the '90s valid to upgrade from Advanced class today?

§ 97.505 (alternate reference) covers the ways to get credit for an exam element. When you passed the test in the 90's, you would have earned a "certificate of successful completion of an examination"...
Phil Frost - W8II's user avatar
6 votes
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What is the purpose of the German CW exam if it is not required to use CW?

There still are some countries where proof of the CW exam is necessary to be allowed to operate on HF. So when you visit those countries and you want to operate under the CEPT-system you need to prove ...
ON5MF Jurgen's user avatar
6 votes
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Do MRI machines use the ISM band, and do they generate audible CW signals?

Medical MRI looks for the nuclear magnetic resonance of hydrogen, at around 1 or 2 Tesla, at about 100 MHz. NMR is a phenomenon of the nucleus, not the atom, it is different to anything involving ions ...
tomnexus's user avatar
  • 11.3k
6 votes

If I receive an SOS signal, what is the proper response?

Since this is all for a bit of fun, you could respond with the typical Morse Code response to indicate that the last transmission was successfully received: R: •-• Some operators stylize this as ...
Glenn W9IQ's user avatar
  • 18.6k

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