Handy technical info, notes and reference materials for amateur radio projects.
Standard 'Q' codes used for Amateur Radio
Code : As a Question : As an Answer or Statement QLE : What is your expected signal? : The expected signal is low... QNI : May I join the net? : You may check in... QRA : What is the name (or call sign) of your station? : The name (or call sign) of my station is ... QRG : Will you tell me my exact frequency (or that of ...)? : Your exact frequency (or that of ... ) is ... kHz (or MHz). QRH : Does my frequency vary? : Your frequency varies. QRI : How is the tone of my transmission? : The tone of your transmission is (1. Good; 2. Variable; 3. Bad) QRJ : How many voice contacts do you want to make? : I want to make ... voice contacts. QRK : What is the readability of my signals (or those of ...)? : The readability of your signals (or those of ...) is ... (1 to 5). QRL : Are you busy?I am busy. (or I am busy with ... ) : Please do not interfere. QRM : Do you have interference? [from other stations) : I have interference. ( Man made interference/noise ) QRN : Are you troubled by static? : I am troubled by static. ( Natural interference / noise ) QRO : Shall I increase power? : Increase power. QRP : Shall I decrease power? : Decrease power. QRQ : Shall I send faster? : Send faster (... wpm) QRS : Shall I send more slowly? :Send more slowly (... wpm) QRT : Shall I cease or suspend operation?/ shutoff the radio : I am suspending operation. /shutting off the radio QRU : Have you anything for me? : I have nothing for you. QRV : Are you ready? : I am ready. QRW : Shall I inform ... that you are calling him on ... kHz (or MHz)?Please inform ... that I am calling him on ... kHz (or MHz). QRX : Shall I standby / When will you call me again?Please standby / I will call you again at ... (hours) on ... kHz (or MHz) QRZ : Who is calling me? : You are being called by ... on ... kHz (or MHz) QSA : What is the strength of my signals (or those of ... )? : The strength of your signals (or those of ...) is ... (1 to 5). QSB : Are my signals fading? : Your signals are fading. QSD : Is my keying defective? : Your keying is defective. QSG : Shall I send ... telegrams (messages) at a time? : Send ... telegrams (messages) at a time. QSK : Can you hear me between your signals? :I can hear you between my signals. QSL : Can you acknowledge receipt? : I am acknowledging receipt. QSM : Shall I repeat the last telegram (message) which I sent you, or some previous telegram (message)? : Repeat the last telegram (message) which you sent me (or telegram(s) (message(s)) numbers(s) ...). QSN : Did you hear me (or ... (call sign)) on .. kHz (or MHz)? : I did hear you (or ... (call sign)) on ... kHz (or MHz). QSO : Can you communicate with ... direct or by relay? : I can communicate with ... direct (or by relay through ...). QSP : Will you relay a message to ...? : I will relay a message to ... . QSR : Do you want me to repeat my call? : Please repeat your call; I did not hear you. QSS : What working frequency will you use? : I will use the working frequency ... kHz (or MHz). QST : Here is a broadcast message to all amateurs. QSU : Shall I send or reply on this frequency (or on ... kHz (or MHz))? : Send or reply on this frequency (or on ... kHz (or MHz)). QSW : Will you send on this frequency (or on ... kHz (or MHz))? : I am going to send on this frequency (or on ... kHz (or MHz)). QSX : Will you listen to ... (call sign(s) on ... kHz (or MHz))? : I am listening to ... (call sign(s) on ... kHz (or MHz)) QSY : Shall I change to transmission on another frequency? : Change to transmission on another frequency (or on ... kHz (or MHz)). QSZ : Shall I send each word or group more than once? : Send each word or group twice (or ... times). QTA : Shall I cancel telegram (message) No. ... as if it had not been sent? : Cancel telegram (message) No. ... as if it had not been sent. QTC : How many telegrams (messages) have you to send? : I have ... telegrams (messages) for you (or for ...). QTH : What is your position in latitude and longitude (or according to any other indication)? : My position is ... latitude...longitude QTR : What is the correct time? : The correct time is ... hours QTU : At what times are you operating? : I am operating from ... to ... hours. QTX : Will you keep your station open for further communication with me until further notice (or until ... hours)? : I will keep my station open for further communication with you until further notice (or until ... hours). QUA : Have you news of ... (call sign)? : Here is news of ... (call sign). QUC : What is the number (or other indication) of the last message you received from me (or from ... (call sign))? : The number (or other indication) of the last message I received from you (or from ... (call sign)) is ... QUD : Have you received the urgency signal sent by ... (call sign of mobile station)? : I have received the urgency signal sent by ... (call sign of mobile station) at ... hours. QUE : Can you speak in ... (language), – with interpreter if necessary; if so, on what frequencies? : I can speak in ... (language) on ... kHz (or MHz). QUF : Have you received the distress signal sent by ... (call sign of mobile station)? : I have received the distress signal sent by ... (call sign of mobile station) at ... hours.
Most of the 'Q' codes listed above are only used when operating CW (morse) or text based narrow bandwidth data modes. There are only a few that You will hear used when operating in Phone modes (Voice)
Homebrew wire antenna design.
The double bazooka antenna design above is optimized for NVIS (Near Vertical Incidence Skywave) operation. This design will work most efficiently when strung up at the NVIS HEIGHT above good ground, or at NVIS HEIGHT above elevated reflector wires used to create an artificial ground plane. If this antenna design is strung up lower or higher above ground (or the artificial ground plane reflector wires) it will still work but will operate at reduced efficiency. The optimum height above real ground will depend on the ground conductivity at each particular location so You may have to slightly adjust the height to maximize efficiency where ground conductivity is poor. At sandy locations You will achieve better results by using the ground reflector wires.
I have worked stations around the UK with both the 80m and 40m versions of this antenna strung at various heights from a few inches above ground to around 10ft above ground with reasonable results. I performed a repeated series of real world on air tests in LSB voice mode with known stations at fixed locations over a 6 month period during 2020. I always operated in LSB voice mode driving 10W into the antenna and the best results were always recorded with the antenna strung at or very close to the NVIS HEIGHT specified above.
I used the 80m version of this antenna thrown on top of the hedge down one side of my back garden as an emergency backup antenna after my main station antennas were destroyed in winter storms. It was certainly not that efficient but it did allow me to have QSOs with stations around the UK and across the North sea with a maximum working range of about 450 to 500 miles from my QTH in Ayrshire, S.W.Scotland. MM7WAB IO75sj
S-meter calibration chart
QRP devices, low RF power levels : Femtowatts to Deciwatts
Galvanic corrosion. Potential difference at interface between dissimilar conductive materials and the problem with using carbon fiber poles and components.
Carbon fibres are electrically conductive and 'highly noble' The image below shows a standard Galvanic table of commonly used materials. Carbon Fiber would be at the bottom of the table along with Graphite. It is a Cathodic material which means electrons flow from Anodic materials in contact with the carbon fiber to the Cathodic material, in this case carbon fiber, The electron flow is what causes galvanic corrosion of parts at any point where they are in contact. The farther up the table the other material is the greqater the elctron flow and the faster it will react and corrode when in contact with the carbon fiber. This is why You must use a proper carbon fiber assembly paste when fitting any parts to Your carbon fiber frame. Yes You can use some forms of grease as an insulating barrier but beware as some types of grease will act as a dielectric between the two materials effectively turning the junction between the materials into a capacitor. This can drastically accelerate the galvanic corrosion effect even if it is kept dry and does not experience any change is air pressure or temperature. If You must use carbon fiber frames or parts it is best to use a proper cabon fiber paste that is designed for the purpose of electrically isolating the carbon fiber from any other materials rather than risk expensive and often dangerous corrosion. Galvanic corrosion will still occur between carbon fiber parts and other materials even if kept dry. The moisture content of the air is enough to initiate galvanic corrosion, even if You keep Your pride and joy perfectly clean and dry it will still corrode surprisingly quickly without a correctly applied layer of the correct protective barrier paste. This is a well known ebgineering problem in the marine and aerospace industries that will always be there. even with the best protective coatings, assembly with proper barrier materials and storage within an inert gas free of water vapour at best You can slow down the galvanic effect to extend the working lifetime of the parts but You can not completely stop the corrosion from occuring over time. If You want it to have a longer working lifetime, use the right coatings, apply them correctly and check them often, cleaning off and replacing the barrier coatings as part of Your regular maintenence schedule.
Visual identification of connectors and adapters commonly used in radio equipment, test gear and antenna systems.
Common mode choke winding reference chart.
Capacitor reference chart : microfarads, nanofarads and picofarads.
Back EMF danger when using relays and switching inductive loads A cheap diode can protect expensive electronics and stop RF interference from Your projects.
Have You ever wondered why any well designed circuit has a 'flyback diode' or 'snubber diode' mounted across the relay coil connections? Dave Jones demonstrates the dangers of back EMF and explains why it causes a range of problems from damaging switch and relay contacts to generating oscillating RF interference. Switched inductive loads such as relays, motors, transformers etc generate back EMF as the magnetic field collapses when they are switched off, this generates large voltage spikes that will reduce the working lifetime of Your circuit, sometimes to a few milliseconds! Adding a simple diode across the inductive load is a simple, cheap and effective method of stopping back EMF ruining Your day. Dave's EEVblog Youtube channel is full of excellent information, demonstrations, fault finding, repair and debunking videos. Well worth a visit for anyone interested in electronics or electrical engineering.
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