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 TonesContinuous 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 RepeatersOperated 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

GB3DADanbury Repeater

• Output: 145.725MHz (receive)

• Input: 145.125MHz (transmit)

• Offset: Minus 600kHz

• CTCSS Tone: 110.9

• Timeout: ~ 90 seconds

Using a Repeater:

• Timeout “K”

• “This is M6ABC listening for any calls”

• “BREAK”

• Repeater Nets

Listen in to GB3DA to learn the etiquette

Callsigns and locations used more often…

Summary• VHF QSO

• Find someone using 145.500 Calling Channel

• Have your conversation on a free voice channel

Essex Ham Monday Night Net8pm GB3DA

www.essexham.net

• Repeaters

• Covers more distance

• Radios need to be set for the offset and CTCSS tones

• Priority to mobile stations

• Listen and learn the etiquette

USING VHF AND REPEATERS

Any questions?

essexham.co.uk/train