AMATEUR RADIO TRAINING VHF and Repeaters Release: v1.21 (Essex) hamtrain.co.uk

USING VHF and Repeaters Use of “Calling Channel” Introduction to Repeaters Repeater “Nets”

VHF Calling Channel VHF (Generally line-of-sight). 2 metres 144 to 146MHz Note the “FM calling” channel on the band plan at 145.500MHz Use this channel to call for someone, or to call CQ … then move to a different channel for your chat. This frees the “Calling Channel” for others

Calling Channel: Example Listen. If free, call CQ M6ABC answers and asks you to find a frequency Tune to a free frequency, e.g. 145.225 Listen. If nothing heard, ask “is this frequency in use?” Return to Calling Channel Call M6ABC and ask them to change to 145.225 Tune to 145.225 Have your conversation

“Repeaters” Repeaters extend ranges across counties & over hills Most useful for handheld and mobile users. The UK has over 400 voice repeaters, mostly 2m or 70cm Mix of Analogue and Digital (DMR, D-Star, Fusion) Some may also be linked via the Internet

Repeater Network Run by volunteers Commonly 2m or 70cm Frequencies are shared around the UK Full list at www.ukrepeaters.net Smartphone app available 2m repeaters 70cm repeaters

How Repeaters Work A repeater use two frequencies, an “input” and an “output”, so that it can can transmit and receive at the same time. Typically (but not always): 2m repeaters transmit 600kHz above their input frequency 70cms repeaters transmit 1.6MHz or 7.6MHz below their inputs Repeaters are “smart”. They only let in valid signals. They have “timeouts” to cut down on long “overs”. Listen for the “K” tone before transmitting, as this resets the timeout You need to program your radio with the offset, and a CTCSS tone to get access (Store this in a memory)

Image source: ukrepeaters.net CTCSS Tones Continuous Tone Coded Squelch System CTCSS is a low frequency tone which is continuously transmitted as part of your audio Repeaters will only activate if they “hear” the correct CTCSS tone. This blocks interference There are nine blocks of tones in the UK. Locally, it’s “H” 110.9 You must program your radio to transmit the right CTCSS tone Image source: ukrepeaters.net

Local Repeaters Operated by the Essex Repeater Group GB3DA - 2m GB3ER - 70cms GB3DB - 6m GB7ZP – 70cm D-Star (Digital) Other local repeaters include: Clacton, Colchester, Benfleet, Kelvedon, Braintree and Hockley, plus many in Kent, Suffolk and London GB3DA in Danbury

GB3DA Note the “-” and “ENC” symbols Danbury Repeater Output: 145.725MHz (receive) Input: 145.125MHz (transmit) Offset: Minus 600kHz CTCSS Tone: 110.9 Timeout: ~ 120 seconds Note the “-” and “ENC” symbols

Using a Repeater: Listen in to GB3DA to learn the etiquette Callsigns and locations used more often… “K” is transmitted after an over, to reset the timeout Don’t call CQ – instead, say “This is M6ABC listening for any calls” “BREAK” (with callsign) used to join the conversation Repeater Nets have their own etiquette

Essex Ham Monday Night Net Summary VHF QSO Find someone using 145.500 “Calling Frequency” Have your conversation on a free voice frequency Repeaters Covers more distance Radios need to be set for the offset and CTCSS tones Priority to mobile stations Listen and learn the etiquette Essex Ham Monday Night Net 8pm GB3DA www.essexham.net

USING VHF and repeaters Any questions? HamTrain.co.uk © EssexHam.co.uk