One of the recent DXpeditions was more challenging to work than expected. That was 5V7TH in Togo. Why that is so and what I did to get them in the log on 30 and 40 meters is the subject of this article. The technique I will describe is known to many DXers, but not all. If it's new to you perhaps you can benefit.
My station is not big. I run 100 watts, a tri-bander up 15 meters and simple antennas for 30, 40 and 80. In some pile-ups I feel as if I were still running QRP. No matter what I do, it seems, sometimes nothing seems to work. That's a sign telling me to change strategy. I wanted 5V7 on the low bands and the usual technique of finding the station working the DX and shifting the XIT/VFO-B up or down a bit didn't work. I kept getting outgunned or passed over.
A big part of the problem was the pattern used by the DX operator. He often avoided the clustering of callers within 1 kHz of the last station worked. So unless you had a big signal staying close didn't work very well. He tended to QSY quite a lot, shifting 2 or more kHz or jumping around in what seemed to be random fashion.
Whatever the reason for this behaviour, it's his choice. It's our job to solve the puzzle if we are to get into the log. The tactic that worked for me was to find the "hole".
It stands to reason that if most stations calling at or near the frequency of the last QSO there are fewer stations calling further away. In the present case the DX used a fairly large window within which he listened for callers. That left a few holes where callers were few or absent. So rather than track the last successful caller I would instead set up near the middle of his listening window (~5 kHz up) and QSY only to avoid other callers. That is, a hole that is empty of other callers.
When he finished a QSO I would listen on my transmit frequency for a moment. If there was no one near my chosen frequency I would go ahead and call. Otherwise I would move up or down a small amount until the frequency sounded reasonably quiet and call there. On the higher HF bands this is unreliable due to the large skip distance. There will be stations within about 500 km or more that you cannot hear except for a few on back scatter. On the low bands it works better since you can hear most of the nearer stations.
At first it may seem odd to call on a frequency devoid of other signals. Yet it can work. On both 30 and 40 meters, within 5 to 10 minutes of using this tactic I had worked 5V7TH. I had spent much longer before this calling in the more conventional manner.
Calling in the hole can work. However you should only use it when the DX operator shies away from the pile-up or you've heard him call others in the hole. Some DX operators may not be comfortable pulling calls out of the QRM, instead preferring an isolated signal that easy to copy.
Whatever the reason, if you didn't know before how to play the described situation, now you do.