Q CODES - some differences between Ham use, Civil use & Military use
Q codes are or were set by the ITU (International Telecomunications Union.)
Some of these are used by hams but the meanings have been altered from the original meanings to suit ham radio. Here’ some examples Guru.
Hams use Q codes on voice circuits I’ve only ever heard one or two Q codes used in voice communications. QNH being one and /is still regularly used by civil or military aircraft to ask or indicate what the air pressure is at some air-port, ship or other place. (Important for obtaining the correct altimeter readings over land)
I can’t ever remember any other Q codes being spoken in a military or commercial voice frequencies. Plain language would normally be used. eg: “How do you read me?” & answer = “loud and clear - over”. (or “weak but readable”) etc., The RST system never.
And a couple of examples of where the meaningof a Q code in ham use has changed from the original ITU meaning:-
Hams use QRL to ask if a frequency is busy :=**QRL? ** The ITU meaning of QRL is:- = I am busy, or, QRL? Are you busy?. And this was commonly used at sea when operators or stations were busy and/or there were delays in passing traffic… It was never used to ask if a frequency was busy.
There were band plans like now, but if the frequency you were wanting to use was busy there was nothing you could do so you just carried on normally. The MF & HF bands were often very, very busy at certain times… Many commercial radio transmitters still used crystals - so an operator had little choice over frequency use on any particular band. If you wanted to call up a shore station then you had to use that stations frequency - whether it was busy or not. One of the best examples was the International Calling & Distress frequency 500khz. This was used by ships and shore stations to establish communications before a QSY to a working frequency.
You got quite good at picking out the signal you needed and reading it through the chaos/QRM.*
QSL was used differently too. As I’ve mentioned Q codes were almost never used in voice communications. “Rodger” was the voice equivalent and In morse “R” was used unless you were receiving a telegram. = then QSL was used. “RR solid cpy” sounds really odd to me used in morse QSOs
RST is only used by hams. (It was invented by an American ham before WW2) The civil and military equivalent is/was QRK & QSA. QRI (tone), was rarely used - I used it once in seven years.
QRU I hear hams sometimes use this to say they have nothing else to say.
The ITU meaning of QRU is :- “I have nothing for you” ( ie, traffic, signals, messages, telegrams etc., ) , or QRU?, =:- "have you any traffic for me? This was one of the most commonly used Q codes used by the merchant navy. Most merchant ships could not keep watch 24/7 as they carried only 1 Radio Officer, so at designated times of the day, shore stations sent out lists of callsigns for ships they had traffic for (‘tfc lists’), When these were missed by ship operators the ship operator called the shore station up and ask, “QRU?”
"I’m going QRT" Used of course by us to mean, " I am going to stop sending and shut down"
But the correct ITU meaning is = "Stop sending! " o r, QRT? = shall I stop sending? = an example of use might be if someone was transmitting during Silent periods on 500khz. Someone would soon send “QRT silent period”, or for example; if you were sending an RTTY paper tapes and one broke!!!
QRZ = ITU definition= . "you are be called by…
QRZ? = ITU = Who is calling me?
I’ve heard QRZ (without the question mark) used in cw to ask if someone is calling the operator.
American Traffic net Codes
These are a list of Q codes used by the ARRL (usa) 'traffic nets. They are adapted from aeronautical QN codes and have different meanings from the same Q codes used by aircraft.
Here;s some real QRM Guru :-
If you want to listen to what 500khz sounded like when morse was still king in 1973 listen to this recording - you can skip the intro if you wish.* https://youtu.be/RRak_yBhrwA