Programming a radio

A memory channel stores everything your radio needs to use one frequency: where to listen, where to transmit, and whether to send an access tone. You can enter channels from the keypad or load many at once from a computer; the settings mean the same thing either way. This guide uses the column names from CHIRP, a free programming tool, because most radios and programs use similar fields.

What a memory channel stores

• Frequency is the receive frequency. When duplex is “(None)”, the radio also transmits on it.
• Duplex sets where the radio transmits. “(None)” means the same frequency (simplex). “+” or “-” means the offset above or below the receive frequency. “split” means the offset field holds the exact transmit frequency instead.
• Offset is the amount of that shift, in megahertz.
• Tone mode decides whether the radio sends an access tone, and whether it listens only for signals carrying one.
• Tone, ToneSql and DTCS code hold the tone or code value for the tone mode in use.
• Name is the label shown on the display, limited to what the radio can show.

These definitions come from CHIRP’s memory editor documentation, which also suggests turning on “Hide Unused Fields” and “Smart Tone Modes” in the View menu to reduce confusion.

Offsets and their direction

A repeater listens on one frequency and transmits on another; the difference is the repeater offset (Technician pool question T2A07). Common offsets are plus or minus 600 kHz on 2 m and plus or minus 5 MHz on 70 cm (questions T2A01 and T2A03).

The direction follows the band plan. In the ARRL’s voluntary 2 m band plan, repeater outputs from 146.61 to 146.97 MHz line up with inputs 600 kHz lower (146.01 to 146.37 MHz), and outputs from 147.00 to 147.39 MHz line up with inputs 600 kHz higher (147.60 to 147.99 MHz). Local practice varies: the same band plan notes that 146.40 MHz is used as a repeater input in some areas, and much of the 70 cm repeater space is marked “local option”. Always program the offset and tone from the repeater’s published listing; the first contact guide lists ways to find them.

The reverse function swaps the two frequencies so you listen on the repeater’s input (question T2B01). If you can hear the other station directly on the input, you can move to a simplex channel, which is what simplex channels are for: stations within range of each other talking without tying up a repeater (question T2B09).

Tones and codes

A CTCSS tone is a sub-audible tone sent along with your voice to open the squelch of a receiver (question T2B02); the ARRL glossary notes it is also called PL (ARRL). A repeater that requires a tone does not respond to a signal without the right one. CHIRP’s tone modes work like this (CHIRP):

With “Tone” you hear everything on the repeater’s output. TSQL keeps the radio quiet until a signal carrying the same tone arrives, so it only opens for a repeater that sends that tone on its output.

Simplex channels worth storing

From the ARRL band plan:

• 146.520 MHz, the national simplex calling frequency on 2 m (question T2A02). The plan’s 2 m simplex ranges are 146.40 to 146.58 MHz and 147.42 to 147.57 MHz.
• 446.000 MHz, the national simplex frequency on 70 cm.
• 52.525 MHz, the primary FM simplex frequency on 6 m.

Digital voice radios

Digital voice systems need more than a frequency and a tone. A DMR radio is configured with a code plug, the data that lets it reach repeaters and talkgroups; you join a talkgroup by programming its ID, and a DMR repeater also needs the right color code. A D-STAR radio must have your call sign programmed before you transmit (questions T4B07, T2B07, T2B12 and T4B11). The radio buying guide explains the systems.

Programming many channels with CHIRP

CHIRP is a free, open-source programming tool that supports a large number of manufacturers and models (CHIRP). Check that your radio is on its supported list, and that you have the programming cable it needs, before you rely on it.

Its beginners guide describes two kinds of radio:

• Clone mode radios transfer all their memories and settings at once. You download an image from the radio, edit it, and upload it back.
• Live mode radios stay on and exchange memories one at a time; edits take effect in the radio as you make them.

The basic procedure:

1. Download from the radio first, choosing the port, vendor and model. Some radios, including most Yaesu models, must be put into clone mode before the transfer starts.
2. Save the image before you change anything, so you can restore the radio if something goes wrong.
3. Edit or import channels. A CSV file cannot be uploaded to a radio directly; open or download an image of the radio first, then import the CSV into it.
4. Upload to the radio (clone mode radios only).

Squelch and scanning

Squelch mutes the receiver when no signal is present (question T2B13). To hear a weak FM signal, set the threshold so the audio is on all the time (question T4B03). Scanning tunes through a range of frequencies or memories to check for activity (question T4B05), a quick way to find out which of your new channels are busy.

Before you transmit on a new channel

1. Listen first, long enough to know whether the channel is in use.
2. On a repeater, listen for its identification; every amateur station, including a repeater, must transmit its call sign at the end of each communication and at least every 10 minutes (47 CFR 97.119(a)).
3. When you transmit, identify with your own call sign.