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Ham Radio Deluxe Newsletter April 19, 2018 - Understanding DX Clusters
Ham Radio Deluxe

Ham Radio Deluxe Newsletter | DX Clusters

Introduction and Brief History to DX Clusters

I often get questions about the use of DX cluster connections. There’s a lot of misinformation out there. The purpose of this newsletter is to explain a bit more about DX clusters. This will help you get the best out of your DXing. Understanding how DX clusters work will enable you to get the best out of the DX aspects of amateur radio.

The purpose of a DX cluster is to alert interested hams (DXers) that there’s a DX station on-the-air.

Before there were DX cluster nodes available, hams alerted each other by using a technique called “the two-ringer.” When this was used, a ham would call his buddy and hang up on the second ring. This alerted the buddy that there was DX on-the-air. But what? And where? A few hams in the area would begin to gather on a local VHF repeater or simplex frequency and this is where the information was provided. “Hey guys, I just worked King Hussein, JY1, on 14.175 MHz!”

I’m pausing for a moment to point something out. That is – this information has now been shared with how many hams? Three? Five? Maybe ten? Top end, fifteen? I’ll get back to this point about coverage area later in this newsletter. It’s an important point.

Eventually, software was created that allowed hams to connect over a VHF frequency (if I remember correctly, it was something like 144.95 MHz; if not, I’m close). The connection was a telnet connection. Now, the number of connected stations began to increase. Now, several dozen hams in a local area could connect and share DX information. The “two-ringer” was gone.

Soon, the software was capable of connecting to other (peer) nodes over the Internet. At first, some hams resisted this. “The Internet is not ham radio.” (Neither was the telephone connection used for the “two-ringer.) But now, spots were propagated between DX cluster nodes. Information was now shared between hundreds of hams.

Once broadband Internet service became widely available, it was no longer necessary to use VHF for the connections. Now, hams could connect over a telnet connection over the Internet. Now, information could be shared between thousands of hams. This is accomplished when DX cluster “nodes” are connected together as “peers” across the Internet.

DX Cluster node software developed into the three most popular types – AR Cluster was the early favorite. Later came DX Spider and CC Cluster. While each type had some minor differences, standards developed that enabled spots to be propagated between them. For connected hams, there’s not a great deal of difference in the node software itself. Other considerations are more important.

Coverage Area

Through all of this, one thing is clear. That is – the more hams that are sharing DX information, the better.

Someone recently said, “When I submit a spot, I don’t see it on my favorite Internet site. Why?”

This ham received a response that said, “Your spots are only displayed on the node you’re connected to.”

In most cases, this is not true. In fact, if it were true, then it would defeat the purpose of all the advancements I referenced in the introduction about expanding the coverage area of the DX cluster system. Right?

Still, there are a couple valid reasons why a spot sent on a given DX cluster node would not be seen on systems on the Internet. One – the system could be filtering spots such that they were prevented from propagating outbound. Likewise, an Internet system that displays spots could be filtering spots inbound. And two – the DX cluster node that the spots are being sent from are not connected to any peer nodes.

The latter is an important point to consider. That is – if you’re connecting to a DX cluster node that is not connected to any other cluster nodes, then it’s no different than the original VHF cluster systems that only propagated spots to local connected stations. It’s only slightly better than “the two-ringer.”

I hear hams say, “I connect to my buddy’s DX cluster node.” Okay, wonderful. How many peer nodes is he connected to? How many users connect locally? How many are connected across the system? Is his DX cluster node running on a server that employs high-availability methods to make sure that it’s always available?

Does it matter? Absolutely! If you’re connecting to a DX cluster node that is not connected to other peer nodes, then you won’t receive spots from outside that node and no one will see the spots you’re sending.

Coverage area of the DX cluster system you connect to is the PRIMARY concern. The secondary concern is availability.

Some hams tell me, “I have no idea what DX cluster to connect to. So, I randomly connect to various clusters to see what spots other clusters have to offer.”

Okay. This is only necessary if either (a) you’re connecting to clusters that are not connected to many peer nodes or (b) you have no idea how all this works.

Let me save you some time and effort.


So far, we’ve identified two important things to consider when looking for a DX cluster node to connect to – peer node connections and node availability. I would go so far as to say that the first item is “significant peer nodes.” That is – there’s less benefit to connecting to 24 peer nodes that have five users in New England than connecting to 24 peer nodes from around the world that have several thousands of connected users. After all, this is “crowd-sourcing.” We need to maximize the crowd.

In order find a “well-connected” cluster, there’s a website that you may want to consider. Go to www.hamcluster.net and you’ll see a map of the world. Most of the time, it begins in Italy. Drag the map to your area of the world. Find a cluster node that’s near you or looks familiar. Click it (once). What does it say? How many “links” (peer nodes) does it have? How long has it been up without failure?

I’m not writing this newsletter to promote my DX cluster, but it’s been up without downtime for 513 days. According to www.hamcluster.net, my node has 16 links (peer nodes). I’m not sure why, but www.hamcluster.net has a top-end figure of 16 for DX Spider nodes. So let’s see how many peers that WA9PIE-2 really has. We can do that by typing “show/uptime” at a console prompt on a DX Spider node. For my node, you’ll see this:

This data was collected on a Thursday. It’s not the busiest day for DX connections. There are 286 hams connected directly to WA9PIE-2 and 3,263 hams connected to the extended network. Instead of the 16 nodes shown by hamcluster.net, there are actually 24 nodes connected. These nodes are connected from around the world. In fact, these are the highest volume DX cluster nodes in their respective areas of the world. And because WA9PIE-2 doesn’t filter spots inbound or outbound, all spots available to propagate worldwide flow through WA9PIE-2.

Another thing that’s useful is to type “show/users” at the command prompt. You’ll see the callsigns for all the connected hams. There’s really not enough space to show you the results here, but there are 286 hams connected now. On a busy weekend, there are over 1,000 hams connected directly and 10,000 hams connected worldwide. Try typing “show/config” at a console prompt, you’ll get a big list of all nodes and users connected. [In Ham Radio Deluxe Logbook, getting to the “Console” is a matter of dropping down the “Show” dropdown and switching from “Spots” to “Console”. Don’t forget to switch back.]

If you try this on your node and you don’t see lots of users and peer nodes, you need to leave that node and find another one. Your buddy’s node serves no one if there’s no one else connecting.

Yes, WA9PIE-2 is a high-volume global spotting network. It’s not necessary to use Ham Radio Deluxe in order to connect to it. Anyone who can setup a telnet connection to dxc.wa9pie.net on port 8000 can connect with whatever software they use. WA9PIE-2 is in a Google data center in the central United States. Hams from all around the world connect to it and share DX information. Because WA9PIE-2 doesn’t filter spots, its’ a “globally local node”. In other words, two hams in Europe connected to WA9PIE-2 are able to immediately see the same spots that two hams in the Pacific Northwest would see.

It’s worth pointing out that the VE7CC-1 cluster node is also very popular. Lee lives east of Vancouver, BC and he’s the author of CC-Cluster and the popular CC-User software. VE7CC-1 and WA9PIE-2 are directly connected and share spots unfiltered.

Setting Up Your Connection

Once you have selected a DX cluster node that has a broad coverage area and high availability, there are a few things you should consider.

The first thing you should consider is filtering spots that get delivered to you. Many times hams have asked me, “Is there some way that Ham Radio Deluxe will filter spots coming to me from outside my area?” My answer is always, “Why would you want your computer to do all that work when you can prevent the spots from being sent to your PC in the first place?” That is – let the cluster node do that work for you, rather than asking your PC to do it.

There’s little benefit in seeing a DX spot from Spain in the middle of the afternoon in Chicago telling you that a station from Mount Athos is on 160m. You won’t hear it. As such, you should filter it from being sent to you. There are a number of ways to do this. But the easiest way is to send the following command to your cluster node – "accept/spots by_zone 3,4,5". If you live in the United States, you will only see spots from CQ zones 3, 4, and 5. (This is the way I do it myself.) You can find DX cluster filtering guides on the internet.

Within Ham Radio Deluxe, make use of the “WSI filter” (Worked Status Indicator). This filter will hide all the DX spots that you don’t need and leave only the DX spots remaining that help build your DXCC mixed, mode, band, or challenge totals.

Making Multiple Connections to the Same DX Cluster Node

There are cases where hams are making multiple connections to the same cluster (WA9PIE-2 in this case; but what I'm about to say applies to connecting to any DX cluster).

First of all, it's completely okay to connect to given DX cluster with more than one simultaneous connection. At any given time, I have at least three connections active to my cluster. During a contest weekend, during a time when several high-profile DXpeditions are active, or while I'm testing software, I may have several more connections open to WA9PIE-2.

So my first message is - this is perfectly fine and I encourage you to make multiple simultaneous connections when you need to. Further, you're welcome to run your Ham Radio Deluxe on more than one computer that you own.

HOWEVER... there's a correct way to do this that many people are not familiar with.

The Problem - while multiple connections are permitted, there can be only one connected station at a time using a specific callsign. This means that I cannot connect more than once using "WA9PIE" as the call I connect with.

Because of this - if a second connection is made with the same callsign, the first connection is disconnected. To make matters a bit more awkward - programs like ours (Ham Radio Deluxe) and others have a feature that will "reconnect on disconnect".

Here's what happens... WA9PIE is connected first with "session #1". Another connection is made with WA9PIE ("session #2"), and "session #1" is disconnected. At this time, "session #2" is connected and "session #1" is disconnected. Then "session #1" reconnects itself automatically... disconnection "session #2". I see this cycle repeating itself over and over in a "ping-pong" game of cluster connections.

Here is an example:


Because I see all the login/logout activity, I can see this happen in real-time. My point here isn't to "call anyone out". But if you look at this you can see where this is happening. Every time there's a "User has logged out" followed immediately by a "User has logged in", it's a clear indication that this ping-pong connection thing is happening.

In Ham Radio Deluxe, this can cause a few things to happen - either the DX clusters spots will keep refreshing every time the connection is made or spots that aren't refreshed will appear to be unsorted. Operators could also suspect network problems in their shacks or convince themselves that there's a problem with the DX cluster node they're connecting to.

SOLUTION: Not to worry, there is a solution to this problem.

The way that DX cluster software supports multiple simultaneous connections from the same ham is by using something calls "system ID" (SSID). This is very straight-forward. Each connection is made using unique -SSID combination. The connections on the cluster will look like this:


This is just a partial screenshot of some of these examples. But here, you can see WA9PIE twice, ZF1EJ twice, and ZL1AIX twice. There are many others. These connections will be steady and will not drop or ping-pong.

In Ham Radio Deluxe, here is how this is done:

In Ham Radio Deluxe Logbook, go to DX Cluster, Options, Connection tab... you'll see this:


I've drawn a red box around the SSID setting.

Here's what you need to do...

For every single connection you make to a common DX cluster, you MUST use a unique SSID value to avoid this ping-pong thing.


It’s not necessary to bounce around between DX cluster nodes to “see if there are better spots elsewhere.” There’s no value in connecting to “your buddy’s DX cluster” (or your own) if that node isn’t globally relevant. Pick a DX cluster node that is a “global spotting network” and has high-availability.

Pick a DX cluster node that doesn’t filter spots inbound or outbound. But do filter the spots in your cluster connection so that you won’t see irrelevant spots.

This is “global crowd-sourcing” at it’s finest. In fact, hams were early pioneers of crowd-sourcing. Find a crowd. Don’t just be a consumer of spots. Send some too!

As always, feel free to share this with your friends. I will also post this on our blog - along with all other newsletters - at https://www.HamRadioDeluxe.com/blog/

Thank you es 73 de Mike, WA9PIE

HRD Software, LLC

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