DXpeditions and working Split

“Up 1” – DXpeditions and working “Split”.

🌍 What is “Split” and why use it?

When a DXpedition is highly sought after, many stations will call at the same time. If everybody is on the same frequency as the DXpedition’s transmit frequency, it will very quickly become overrun with signals, and no-one will know who is calling whom. The DXpedition station will very quickly lose control of the frequency and no-one wins.

To better manage this scenario, we use a technique called Split Frequency Operation.

The DXpedition transmits on one frequency and listens on another. They will usually spread the pileup out over a small segment of the band (5 – 15 kHz) just above their transmit frequency.

DXpeditions attract huge pileups—sometimes hundreds of stations calling at once. If everyone transmits on the DX station’s frequency, the DX operator would hear nothing but a wall of overlapping signals.

Split solves this by:

✔️ Keeping the DX transmit frequency clear

The DXpedition’s signal (hopefully) stays readable worldwide.

✔️ Spreading callers out

Stations calling the DX spread themselves across a listening range (e.g. 5–15 kHz up). This creates a call window instead of a single chaotic frequency.

✔️ Allowing the DX operator to “tune the pileup”

The DX operator sweeps their receiver across the listening window and picks out calls one by one. This is how they attempt to maintain order and maximize the QSO rate.

---

🔧 How Split Operation Works in Practice

1. DX Station Setup

The DXpedition operator configures their radio like this:

• VFO A → Transmit frequency (e.g., 14.022 MHz)
• VFO B → Listening frequency or range (e.g., 14.023–14.028 MHz)

They transmit on A and listen on B.

There are no hard and fast rules, but the following generalisations are worth noting:

• The DXpedition will usually always listen up. (Sometimes, if things get very hectic, they may alternate between up and down – but this is not common)
• If they call “CQ up” and things are quiet, they are usually up +1 – 1.5 kHz
• Sometimes they will call “up 1“
• If callers start to get too close to their QRG (their tx freq) they may make the split a bit higher. Say up 2 kHz
• Most good CW ops (unless things get out of control or the pileup is incredibly wide with strong signals) will try to keep a pileup between 1-5 kHz up.
• Sometimes, when just starting a session, they may not be split. They’ll then go split as the pileup grows. If the DXpedition is a rare one, its good practice to start split.
• Sometimes a DXpedition will announce their split plans on their website – but usually you have to roll with the punches. The pileup doesn’t care what you put on your website
• You can look at the clusters (DXsummit or DXWatch) and people will often report what the split was when they worked the DXpedition.

• Sometimes you will hear people working them on their tx frequency – this is either an honest mistake where the op forgot to press the split button on his radio and shift VFO B up a little; or some operators don’t yet understand split operation and call blindly.
• Some ops just call blindly in the hope the DXpedition will pick them. Others use high power to punch their way through.

---

2. Calling Stations Setup

A station trying to work the DX does the opposite:

• VFO A → Listening to the DX (It’s a good idea to lock this VFO so you don’t accidentally knock the dial off-frequency.)
• VFO B → Transmitting where the DX is listening

Most radios have a SPLIT button that handles this automatically.

---

3. How to work the DX – reading the pileup, reading the DXpeditioner

Generally, when I see a pileup on the scope, I first try to find the DXpedition signal. If I can’t hear them there is no point calling them. Typically, I’ll look 1 – 2 kHz beneath the lowest signal in the pileup. It may take a little while to find their signal. I may also check one of the clusters for confirmation.

Next, I’ll listen to the DXpedition op to get a sense of their signal strength, speed, special instructions (e.g. “EU” only, “up 3”, etc) and also their style. Some work a station then say “tu” and that’s the signal for the pileup to call. Others use their callsign between every QSO. Some are brief and quick; others are deliberate and slower. Some are masters at working the pileup, others struggle. Pileup behaviour will have a huge effect on efficiency and QSO rates. So, if you’re chasing a rare one, listen to their instructions.

Then I’ll watch the pileup to see if I can see the signal of the station working them. Sometimes this is easy. The pile of signals die down when the DXpedition op calls a specific station and then (hopefully) one signal appears on the scope; usually providing the signal report and tu – so you have to be quick. Jump right in maybe 10-20 Hz above his frequency and be ready to drop your callsign.

If you hear the DXpedition respond with timing suggesting it could be you they’re hearing with “VK?” go back with your callsign (twice if required – the first time with a little extra spacing and the second time nice and smooth and fast. Don’t leave much of a gap between your callsigns – if they copied you on your first call they’ll call and you’ll double.)

If the pileup is huge, signals are loud, and the DXpedition is weak, I might walk away, accepting there will be a better time for me to have a go. Let the big guns get out of the way; sometimes you have to acknowledge you can’t compete; come back later. However, other times I might just chip away, learning the pileup’s ebb and flow, observing the DXpedition op and sometimes, just sometimes, I manage to break their code and get in the log.

I have spent 2 – 3 hours working a pileup to get in a log. It can be a marathon; but when you finally get in the log it’s incredibly rewarding.

A word on web-based Alerting and Monitoring Resources:

I use https://reversebeacon.net/ to find which nodes are hearing the DXpedition. I usually filter on the OC nodes. I also check https://dxwatch.com/ and http://www.dxsummit.fi/#/ . I filter appropriately – in this case I set a filter for “TX5EU”.

Here is a YouTube video from VK9NT in 2023 on 6 metres. It’s a bit of an insight into pileups from the other side.

And here is YJ0VK in 2012.

---

🏝️ Why Split Is Essential for DXpeditions and rare DX

Without split operation, a DXpedition would be overwhelmed. Split allows:

• Higher QSO rates
• Less interference
• More efficient pileup management
• Fairer access for stations worldwide
• Cleaner and less cluttered transmit frequencies for the DXpedition

It’s essential to the efficiency of modern HF DXing.