I've had opportunities to be on the DX end of cluster pile-ups. We all
know, they can be brutal.
11 years ago, I operated in CQWW CW as PZ5AV (SOAB QRP). It goes without
saying, QRP stations have a hard time managing a pileup.
*AUDIO SPECTRUM ANALYSIS OF WHAT CAN BE EFFECTIVE OFFSET*
I recorded the contest. Afterwards, I remembered that N0AX simply stood
out perfectly from a massive pileup - he did it by being skillfully offset
- by just the right amount.
So back home, I set about to measure exactly what offset he used to get
through. I used Audacity software to display the audio spectrum.
The way my receiver was set, to be zero beat with my transmit signal meant
the cluster pile was all calling at 440 Hz. And that's what showed up on
the Audacity spectrum display. All the callers were in big glob on the
scope.
I was having trouble pulling out particular calls - they all mushed
together. Lots of back and forth.
One caller who easily got around that cluster pile was ZP5MCE who, as shown
and measured later on the audio spectrum, was calling exactly *60 Hz* up
from the pile.
A bit later N0AX called *up 189 *Hz from the cluster pile - and was easily
copied & worked.
I was using a K3 to receive and probably had bandwidth set at 350 Hz.
*PROGRAMMING IN XIT OFFSETS INTO ELECRAFT K-POD*
I have an Elecraft K-POD. It has buttons which can be programmed to set
your XIT (and RIT) values.
Now I have my K-POD buttons set for XIT settings of 60, 120, 180 and 240 Hz
(both "up" and "down").
As I understand it, the programming is actually inside the K3 (or, K4) -
and the K-POD just activates those.
*N1MM+ RANDOM OFFSETS*
For comparison, the N1MM+ random offset feature can help - but gives you
less control.
According to a post from N1MM on the N1MM+ reflector (11-13-2014)
- “In reality it is more for the running station than the S&P station.
Spots are on exactly 100 Hz boundaries. If a running station has several
stations calling all exactly on 14030.1, then it is harder for
him to copy
any one of them.
- Because of the market penetration of N1MM+, we thought it would be
useful to those running stations to spread the pileup out a bit for them.
- You can turn the feature off if you don't like it.
- It randomly adds -60, -30, 0, +30 or +60 Hz to the frequency.”
*WHEN CALLING IN PILE UPS - WE PROBABLY NEED TO BE FLEXIBLE - AND TRY
DIFFERENT OFFSETS*
We don't know exactly what filter setting the DX station is using - or even
whether they are listening on the upper or lower (reverse CW).
73, ~ Alan K0AV
On Wed, Dec 10, 2025 at 4:40 PM Jim Brown <k9yc@audiosystemsgroup.com>
wrote:
> On 12/9/2025 12:17 PM, K9MA wrote:
> > The K4 has such poor skirts that you can hear stations several hundred
> > Hz from the center, even with a 300-400 Hz bandwidth.
>
> One of the things I LOVE about the K4 is its filters. Because of
> encroaching noise in important directions, I keep it cranked down to 200
> Hz most of the time.
>
> 73, Jim K9YC
>
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