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Episode 27 -- August 22nd, 2016 -- Repeaters, VHF/UHF Operating Practices. Len guest stars.
Listen to the episode 111.7 MB MP3
You can talk directly from one handitalkie (Walkie-talkie) to another about 5-8 miles, but further than that, you talk through a repeater.
A repeater is a automated re-transmitter. Usually placed on the tops of mountains, a repeater allows anyone who can communicate with it to further communicate with everyone else who can communicate with it.
A repeater requires separate transmit and receive frequencies. One frequency it transmits and you receive and on the other, you transmit and it receives.
The difference between the two operating frequencies of a repeater are called its offset. On 2m (144-148 MHz) the standard offset is 600 KHz (0.6 MHz). On the 1.25m band (220 - 225 MHz) the standard offset is 1.6 MHz (1600 KHz). On 70cm, (440-450 MHz) the standard offset is 5 MHz.
When talking on a repeater, you must wait up to 1 or 2 seconds (at the most) for the repeater's transmitter to engage AFTER pressign the Push-to-talk button on your radio before you begin speaking.
When you are listening to someone else talking on a repeater, wait until you hear the repeater's courtesy tone after they're done speaking before pressing your own push-to-talk swiitch (and then waiting an additional 1-2 seconds before you begin speaking).
Half Duplex and Full Duplex
Full Duplex - like being present with somebody in the room or talking on the telephone; you can talk and hear at the same time.
Half Duplex - you can either listen but not talk, or you can talk, but not listen but you cannot do both at the same time.
If, while communicating on FM, two people talk at the same time, if one is quite a bit stronger than the other, you might understand the more powerful station, but usually, you can't understand either one of them. So it is extremely important to wait until the other person finishes talking and the repeater sends its courtesy tone before you press your own push-to-talk switch and then wait a moment before you begin speaking.
After you have finished transmitting and you let up your transmit button, the repeater doesn't know for certain if you intended to stop transmitting or if you're driving your car and your signal is fluttering in and out of the repeater's receiver. So, to solve this problem, all receivers keep their transmitters on for an additional half second to 5 seconds (depending on how their owners set them up) in case you are still talking but your signal isn't completely clear. During this time, a courtesy tone sounds to let others know that (1) you have indeed stopped talking and (2) the repeaters 3 minute "Time-out" timer has reset. If somebody sits on their microphone accidentally and keeps their transmitter on for an hour or more, the repeater will stop transmitting after (usually) 3 minutes until that signal goes away (and an appropriate additional few seconds to verify it). The courtesy tone give other poeple enough time to break into your conversation to use the repeater if they want to and also notifies you that the 3 minute timer starts again anew.
The police, fire, ambulence, and emergency services organizations have this problem all the time.
So when you get your new radio and you want to use it:
program in the frequency of the repeater's transmitter (upon which you want to listen, receive)
Program the transmit offset (+ or - 600 KHz on 2m, 1.6 MHz on 220 MHz or + or - 5 MHz on 440 MHz).
Choose which subaudible tone (CTCSS or PL) required for that repeater, if one is required
Choose which DPL (Digital Private Line) tone if one is required for that repeater
Listen to see if there's already a conversation in progress; 10 seconds is usually sufficient.
Hold down your transmit button and wait 2 seconds before beginning to speak.
After saying your peace, when you let go of your transmit button, the repeater will keep transmitting for a few moments and you will hear it to let you know that you solidly were received by it.
Most of the time, after a second or so, you'll hear the repeater's courtesy tone after which it is reasonable for others to respond to you.
Make sure you say your callsign at the beginning and end of the exchange, as well as every 10 minutes during it.
Because there are so many people who want repeaters, and just so many frequencies, The FCC requires you to adhere to the processes of the The Northern Amateur Relay Council of California in order to choose a frequency for your new repeater. They have very strict requirements and, even after you meat them, that is no garentee that you'll actually be allowed to put up a repeater on that band. If the band is already full of repaters whose coverage overlaps where yours will be, they won't be able to accomodate you.
The local VHF repeater here is 146.775 MHz with a negative 600 KHz offset and a PL tone of 103.5 Hz. VHF = "Very High Frequency; 30 - 300 MHz.
Morse Code is good for you!
Morse Code is a series of short and long sounds, separated by the absence of sound of the same duration as the short sound with a longer duration between individual characters. Small sets of such short and long bursts, in particular order, represent each of the letters of the roman alphabet, the numerals and a number of punctuation marks and morse code procedural signs.
Morse code is the communication mode which is the easiest to build a transmitter upon which to operate. You can litterally put an entire mores code transmitter-receiver (transceiver) in a box in your pocket with a coil of wire and a 9v battery and successfully communicate anywhere in the world from anywhere and that 9v battery will last for several hours.
I personally recommend the Farnsworth method of learning morse code.
If I've made any mistakes, please Call me or email Kila or you can call us directly at (707) 413-6435. Here is my main website.
