Transcript Foundation: VHF & Repeaters (Essex)

AMATEUR RADIO TRAINING
VHF and Repeaters
v1.12 (Essex) © essexham.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 “Mobile 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
145.500 (Calling Channel)
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 him 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 300 voice repeaters, mostly 2m or 70cm
• 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
• Repeaters use two frequencies, an “input” and an “output”, so that they
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 and they generate
“idents” to comply with the 15 minute ID rules
• 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. Best to store in memory
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, Braintree and Hockley, plus
many in Kent, Suffolk and London
GB3DA in Danbury
GB3DA
Danbury Repeater
• Output: 145.725MHz (receive)
• Input: 145.125MHz (transmit)
• Offset: Minus 600kHz
• CTCSS Tone: 110.9
• Timeout: ~ 90 seconds
Using a Repeater:
Listen in to GB3DA to learn the etiquette
Callsigns and locations used more often…
• Timeout “K”
• “This is M6ABC listening for any calls”
• “BREAK”
• Repeater Nets
Summary
• VHF QSO
• Find someone using 145.500 Calling Channel
• Have your conversation on a free voice channel
• 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?
essexham.co.uk/train