Repeater Configuration: Analog FM

Repeaters are an important part of amateur radio. They allow radio stations to communicate over significantly greater distances than would normally be possible with a direct simplex connection. Depending on the repeater, different transmission technologies and operating modes may be available.

This article explains how to configure repeaters in an amateur radio codeplug. The examples focus on the 2 m and 70 cm bands and on repeaters in and around Mainz, Rhineland-Palatinate, Hesse and the surrounding region.

The regional focus makes the examples practical for local operation, while the configuration principles are generally applicable and can be transferred to repeaters in other regions. This article also serves as my own documentation and reference while building and maintaining my codeplug. Rather than simply collecting a list of frequencies, I want to document the reasoning behind the configuration so that settings remain understandable and can be reviewed or adapted later.

For beginners, repeater configuration can initially appear more complicated than simplex operation because several parameters have to be configured correctly. The most important information is the repeater’s receive and transmit frequencies, the required frequency offset and, depending on the repeater, additional access parameters such as CTCSS, DCS or digital parameters.

The basic principle is straightforward: Your radio receives on the repeater’s output frequency and transmits on the repeater’s input frequency.

Once this principle is understood, the remaining configuration parameters become much easier to understand. The initial focus of this article is on 2 m and 70 cm repeaters.

Repeater Input and Output Frequencies

💡 Remember: When programming a repeater channel, always enter the frequencies from the perspective of the radio, not the repeater.

The repeater’s output frequency is the frequency your radio needs to receive on. Conversely, the repeater’s input frequency is the frequency your radio needs to transmit on. For example, if a 2 m repeater operates with an output frequency of 145.600 MHz and an input frequency of 145.000 MHz, the channel should be configured as follows:

Radio Setting	Frequency	Description
Receive Frequency	145.600 MHz	Repeater output
Transmit Frequency	145.000 MHz	Repeater input

The important point is that the terms TX and RX always refer to the device you are configuring. When programming your radio, think from the radio’s perspective.

FM Repeater Channels

Repeaters work differently from simplex channels.

Your radio transmits on the repeater’s input frequency and receives on its output frequency.

For example:

RX: 431.7000 MHz
TX: 439.3000 MHz

This corresponds to a -7.6 MHz offset.

Some repeaters additionally require a CTCSS tone or another access method.

A typical repeater channel therefore contains:

• RX frequency
• TX frequency
• FM mode
• repeater offset
• CTCSS tone, if required
• an appropriate channel name

Recommended Repeater Zone

The following channels are a useful starting point for FM repeaters in the Mainz/Rhine-Main area.

Only repeaters with sufficiently documented parameters are included as fully configured examples.

Channel	Callsign	Input RX	Output TX	Offset	Access	QTH
ZDF 70 Oppenheim	DB0ZDF	431.7000	439.3000	-7.6 MHz	CTCSS 67 Hz	JN49EU, Oppenheim, DE
GG 70 GrossGer	DM0GG	431.2875	438.8875	-7.6 MHz	CTCSS 67 Hz	JN49FV, Gross-Gerau, DE
GAZ 70 GrossGer	DB0GAZ	431.2500	438.8500	-7.6 MHz	Carrier	JN49FV, Gross-Gerau, DE
RN 2m Bingen	DB0RN	145.1625	145.7625	-0.6 MHz	Carrier	JN39XW, Bingen am Rhein, Ockenheim, DE
AIS 70 Moerfeldn	DB0AIS	430.7875	438.3875	-7.6 MHz	CTCSS 67 Hz	JN49GX, Moerfelden-Walldorf, Oberwaldberg, DE
VA FM Taunus	DB0VA	431.7250	439.3250	-7.6 MHz	Carrier	JO40BC, Wiesbaden, Hohe Wurzel, DE
GGW 70 Darmstadt	DB0GGW	431.2000	438.8000	-7.6 MHz	Carrier	JN49HR, Darmstadt, Melibokus, DE
VD 2m Darmstadt	DB0VD	145.0625	145.6625	-0.6 MHz	Carrier	JN49HR, Darmstadt, Melibokus, DE
IDS 70 Rosenkopf	DB0IDS	431.1750	438.7750	-7.6 MHz	1750 Hz tone	JO40CF, Idstein, Rosenkopf, DE
FT 2m GFeldberg	DB0FT	145.0000	145.6000	-0.6 MHz	Carrier	JO40FF, Grosser Feldberg, Hessen, DE
FT 70 GFeldberg	DB0FT	430.9750	438.5750	-7.6 MHz	CTCSS 67 Hz	JO40FF, Grosser Feldberg, Hessen, DE
HRF 70 GFeldberg	DB0HRF	431.1500	438.7500	-7.6 MHz	CTCSS 67 Hz	JO40FF, Grosser Feldberg, Hessen, DE
MOT 70 KFeldberg	DF0MOT	431.0250	438.6250	-7.6 MHz	CTCSS 67 Hz	JO40FF, Kleiner Feldberg, Hessen, DE
ND 70 Donnersbrg	DB0ND	431.1250	438.7250	-7.6 MHz	1750 Hz tone	JN39XO, Donnerberg, Kirchheimbolanden, DE
BKR 70 BadKreuz	DB0BKR	431.5625	439.1625	-7.6 MHz	Carrier	JN39WT, Bad Kreuznach, Traisen, DE

The repeaters listed here are regional examples and are intended to give you an idea of which systems and frequencies are available in the area. They are not a guarantee that you can reach or receive these repeaters from your own location.

Depending on where you are, you may be able to use repeaters that are further away. This can be especially useful when travelling or moving around the region, so it can make sense to include them in your codeplug even if they are not reachable from your home location.

CTCSS

Some FM repeaters require a CTCSS tone to open the repeater. CTCSS is a sub-audible tone transmitted together with the FM signal.

• For example: CTCSS: 67.0 Hz

The tone is normally configured for TX. The repeater uses it to decide whether the transmission should open the repeater.

Do not add a CTCSS tone simply because a repeater uses FM. If the repeater is carrier operated, no CTCSS tone may be required.

Some older repeater systems use a 1750 Hz tone burst to open the repeater instead of CTCSS. This is a different mechanism.

• For example: DB0IDS and DB0ND are listed with 1750 Hz access.

The radio must therefore support and be configured for the appropriate 1750 Hz tone function.

Repeater Information Can Change

Repeater configurations are not necessarily permanent.

A repeater may change:

• frequency
• CTCSS tone
• access method
• operating mode
• network connection
• operating status

Some repeaters may also temporarily or permanently be taken out of service.

Therefore, verify the current parameters before adding a repeater to a permanent codeplug.

Keep FM and DMR Separate

A repeater can support both FM and DMR, but the two modes require different channel configurations. For example, DB0AIS has both an FM and a DMR configuration. The FM channel should therefore be treated as an independent channel from the DMR configuration. This guide intentionally covers analog FM only.

DMR channels require additional parameters such as Color Code, Time Slot, Talk Group and RX Group configuration and should be handled separately.

💭 Tip: Chinese and Japanese manufacturers may not properly support German special characters such as ä, ö, ü or ß. To avoid display errors or unexpected characters, use ae, oe, ue or ss instead.