DX Cluster Commands: A DXSpider Guide to Spots and Filters

Most operators meet the DX cluster through a logging program or a website that displays spots in a neat table. Behind that table is a network of cluster nodes that you can talk to directly, by typing commands in a simple text session. Learning a handful of dx cluster commands lets you search past spots, post your own, see solar data and, above all, build filters so that the stream of spots shows only what you care about. Those skills carry over to every logging program, because the software is sending the same commands on your behalf.

This guide uses DXSpider, one of the most widely used cluster node programs, for its examples, because its commands are documented in the DXSpider user command reference. Other node software, such as AR-Cluster and CC Cluster, follows the same general ideas but uses different syntax for some commands, especially filters. Whatever node you connect to, the command HELP shows what that node supports.

How You Connect to a Cluster

Modern clusters are reached over the internet by telnet, a plain text protocol. You need the node’s host name and port, which are published by the node’s operator, and a telnet client. Many logging programs have one built in; on most computers a terminal telnet client also works.

When you connect, the node asks for your callsign. Enter it, and the node logs you in, usually showing a welcome message and a prompt. From then on, every line you type is a command, and new spots appear in the session as they arrive. Some nodes ask you to set a password after the first login. Always log in with your own callsign; the cluster network relies on spots and announcements being attributable.

Before using commands, it is worth reading the network etiquette that keeps clusters useful. Our article on DX cluster spotting etiquette and filtering explains how the network works and what good spotting practice looks like.

Command Basics

DXSpider commands are made of words separated by a slash, such as SHOW/DX. They can be abbreviated, so SHOW/DX can be typed as SH/DX, and case does not matter. If you are unsure of a command, HELP followed by the command name shows its documentation, and the APROPOS command searches the help text for a word. These two commands make it possible to learn any node’s features without leaving the session.

Showing Spots

The SHOW/DX command, usually typed SH/DX, displays recent spots from the node’s database. On its own, it shows the most recent spots. Adding options narrows the search. The DXSpider documentation gives examples such as:

• SH/DX 4K9W shows recent spots for a particular callsign.
• SH/DX dxcc w on 20m iota shows spots for a DXCC entity on a band, with a remark containing a word. The same search can be made with the alias SH/DXCC W on 20m iota.
• SH/DX 4K9W qsl shows spots for a callsign whose remarks mention QSL information.

Two related commands are especially useful. SH/MYDX shows past spots but applies your own spot filter first, so it only lists the kind of spots you have chosen to receive. SH/DXQSL looks up QSL manager information that the node has collected from spot comments; the documentation warns that this information is not guaranteed to be reliable, but it is often a helpful hint.

Searching spot history is a quick way to learn when a station is usually active. If a DXpedition has been spotted every evening on 30 metres CW around the same time, that is when to look for it.

Posting a Spot

The DX command posts a spot to the network. According to the DXSpider reference, you can enter the frequency and the callsign in either order, and add a short remark at the end. For example, DX 14025 followed by a callsign and a brief comment such as the QSL route or “up 2” sends a spot that every connected user will see.

A few habits make your spots valuable rather than noise:

• Double-check the callsign and frequency before you press Enter. A busted spot sends hundreds of people to the wrong place.
• Use the remark field for useful information, such as split instructions or the mode, not for personal messages.
• Spot stations that are genuinely interesting to others, not every ordinary contact you make.
• Do not spot yourself unless the rules of the activity you are taking part in clearly allow it.

Filters: The Most Important Commands

A busy cluster connected to skimmer networks can deliver an overwhelming number of spots. Filters decide which spots reach you. In DXSpider, filters are built from accept and reject lines, numbered from 0 to 9, and the DXSpider filtering manual explains the full logic. The essentials are simple.

Accept and reject lines

• ACCEPT/SPOTS, usually typed ACC/SPOT, creates a line that lets matching spots through.
• REJECT/SPOTS, usually REJ/SPOT, creates a line that blocks matching spots.
• SHOW/FILTER lists every filter line you have set.
• CLEAR/SPOTS with a line number removes one line, and CLEAR/SPOTS ALL removes the whole spot filter.

The filtering manual describes the order of evaluation and stresses that reject lines are checked before accept lines. Planning your filter with that in mind avoids surprises.

What a filter line can match

The command reference lists the things a spot filter line can test, including:

• freq or on: a frequency range or a band, optionally with a sub-band such as cw, rtty, data or ssb. Examples in the documentation include hf, hf/cw and lists of bands such as 6m,4m,2m.
• call: the prefix of the spotted station.
• info: text in the spot remark, such as iota or qsl.
• by: the prefix of the station that posted the spot.
• call_dxcc, call_itu, call_zone and call_state: the spotted station’s DXCC entity, ITU zone, CQ zone or US state.
• by_dxcc, by_itu, by_zone and by_state: the same properties for the spotter.

The reference gives two examples that show the style: ACC/SPOT 1 on hf/cw accepts HF CW spots, and a second line can accept VHF spots only when the spotter or the spotted station is in particular zones, combining conditions with and and or.

Filtering by spotter location

The by_ conditions are the secret of a useful filter. A spot posted by a station on the other side of the world tells you about propagation there, not where you are. Accepting only spots posted by stations in your own region, for example your own zone or continent, means the spots you see are much more likely to be workable from your location. This is one of the most effective improvements most operators can make.

Building a Filter Step by Step

Filters are easiest to build gradually, checking the effect of each line before adding the next. A practical sequence looks like this.

1. Start clean. Use SH/FILTER to see what is already set, and CLEAR/SPOTS ALL if you want to begin again.
2. Decide on the bands you use. Add an accept line for those bands, for example HF only, or HF plus six metres.
3. Add spotter location. Restrict the accept line to spots posted by stations in your own zone or nearby zones, using the by_ conditions described above.
4. Remove what you never want. Add reject lines for anything that still clutters the stream, such as a mode you do not operate.
5. Test with SH/MYDX. It shows recent spots as your filter would have passed them, which lets you judge the result without waiting for new spots.
6. Write it down. Keep a note of the exact lines, so you can recreate the filter on another node or after a reset.

Revisit the filter occasionally. During a major DXpedition you may want to widen it for a few days; during a contest weekend you may want to narrow it to avoid hundreds of contest spots.

Useful DX Cluster Commands at a Glance

The table lists commonly used DXSpider user commands. Abbreviations work as shown, and HELP gives full details on any node.

Useful Settings

Several SET and UNSET commands adjust what the node sends you and how your profile appears. The reference lists, among others, SET/NAME, SET/QTH and SET/QRA for your name, location and locator, and SET/DXCQ, SET/DXITU and SET/DXGRID, which add CQ zone, ITU zone or grid square information to the end of DX announcements. The documentation notes that these three options conflict with each other, because there is only room for one of them at the end of the line, and that some user programs cannot cope with the extra information.

If a logging program misreads spots after you change one of these settings, unset it again. Telnet echo behaviour can also be adjusted; UNSET/ECHO stops the node echoing your input, which some telnet clients need.

Skimmer Spots

Many nodes carry spots from skimmers, automated CW and digital decoders that report what they hear. They add enormous numbers of accurate, timely spots, but they can also bury human spots. The DXSpider reference mentions filter options that act only on spots from the Reverse Beacon Network feed, and other node software has its own switches for skimmer spots. Our guide to CW Skimmer and the Reverse Beacon Network explains where these spots come from and how to use them well.

When Commands Are Not Enough

Filters reduce the flood, but you still have to watch the screen to notice the spot you are waiting for. If you are waiting for one particular station, an alert is more practical than a filtered window. Our article on automating DX spot alerts describes the options. One of them is LY4A DX Reminder, which watches several spotting sources, including DXSummit, PSK Reporter and the Reverse Beacon Network, and raises an alarm on your phone or computer when a callsign you are waiting for is spotted on the band and mode you selected.

Common Mistakes

• Filtering too tightly: a filter that accepts only one band and one mode may hide the opening you would have wanted. Review filters when your interests change.
• Forgetting old filter lines: filters are stored in your profile on the node. Use SH/FILTER when spots seem to be missing.
• Mixing syntax between node types: a filter command written for DXSpider may not work on another node. Check HELP on the node you use.
• Using the cluster for chat: announcements and talk messages reach many people. Keep them brief and relevant.
• Spotting without checking: confirm the callsign and frequency on the air before posting.

The Bottom Line

A DX cluster is a text-based network you can talk to directly. With a few DXSpider commands, you can search spot history with SH/DX and SH/MYDX, post spots with DX, look up QSL hints with SH/DXQSL, and shape what you receive with ACC/SPOT, REJ/SPOT, SH/FILTER and CLEAR/SPOTS. Filtering on the spotter’s location is the single most useful trick. Other node software uses similar ideas with different syntax, so HELP and APROPOS are your best friends. Learn the commands once and you will understand what every logging program is doing on your behalf.

Frequently Asked Questions

How do I connect to a DX cluster?

Use a telnet client, either built into your logging program or a standalone one, and connect to the host name and port published by the node. When prompted, enter your own callsign. Some nodes ask you to set a password.

What is the SH/DX command?

SH/DX is the abbreviated form of SHOW/DX. It displays recent spots from the node’s database. You can add a callsign, entity, band or remark text to narrow the results.

How do I filter spots on a DXSpider cluster?

Use ACC/SPOT to add accept lines and REJ/SPOT to add reject lines, each with a line number and conditions such as band, prefix or spotter zone. SH/FILTER lists your filters and CLEAR/SPOTS removes them.

Why should I filter by spotter location?

Spots posted by stations in your own region reflect propagation from your area. Accepting only those spots means the stations you see are more likely to be workable from your location.

Do the same commands work on every cluster node?

Not exactly. Basic commands like SH/DX are widely shared, but filter syntax and some settings differ between node software such as DXSpider, AR-Cluster and CC Cluster. Type HELP on your node to see its commands.

How do I post a spot on a DX cluster?

Type DX followed by the frequency and the callsign, in either order on DXSpider, and an optional short remark. Check the callsign and frequency carefully first, because the spot is seen by everyone connected.