Off air

Chatham Island, New Zealand 44^o44’ S x 176^o15’ W Grid AE15ug
IOTA OC-038 CQ zone 32 WFF ZLFF-017

Morrie ZL2AAA (leaning) and John ZL1BYZ (upstanding) contemplate whose extra loud signals might have made a rig go deaf. Eh?

Sponsored by:

Here is some audio (5Mb!) and a spectrum display from the first rather weak and watery groundwave signals from ZL7T on 17m CW captured in ZL at 11:07z on March 5^th. I can make out about 10 callers in the pileup shown on the spectrum screen capture below, though there were almost certainly more (the dark area at the top of the display shows the edge of my 2.7kHz filters - some callers were well above this limit. One day I’ll have my own broad-spectrum SDR to play with!).

... and numerous individual donors. TNX all!

If you haven’t seen this type of spectrum display before, it is a static screenshot of a dynamic display that scrolls continuously from right to left across the PC screen, showing the audio signal levels monitored by software using the sound card. The audio frequency range is shown on the ruler along the right hand edge and there are timing marks in seconds along the bottom edge. The brighter the image, the stronger the signal.

The fabulous program I used to capture this is called Spectrum Laboratory by DL4YHF. It’s an amazingly functional FREE tool for audio analysis and decoding, thoroughly recommended.

Here’s another screenshot, this time on 40m at 03:54z on March 5 (about 3 hours before our sunset) with wider filters in place, showing a pileup at least 6 deep:

Notice how the pileup is centred around 2 kHz up but station #6, although weak, has shifted slightly down from the rest and is probably workable. Station #7 has shifted further up but is barely discernable at this time. ZL7T’s signal was well over S9 with me and the receiver’s ALC accounts for the dark bands when they transmit.

When things get really busy on 40m CW at 08:01z on March 5^th, the pileup is so deep it’s hard to make out the individual callers represented by more than 30 lines on the spectrum, spread between 1.2 and 3.7 kHz or more above ZL7T’s frequency:

In dense pileup situations like this, there is little point in the normal practice of finding out where ZL7T is listening and transmitting right there, as too many others will be playing that game. It’s probably better to find yourself a relatively quiet spot in the pileup range (typically to one side or the other, though sometimes narrow spaces occur when big signal ops have worked them and QSYd). A spectrum display like this can help find suitable slots.

ZL7T’s first foray onto 30m at peak time in the ZL evening (08:21z on March 7^th) created a huge pileup. I can count at least 37 simultaneous callers including one VK who initially forgot to split (hey, we all make mistakes but he noticed it and stopped transmitting!):

You can hear how such a massive CW pileup sounds from ZL in this WAV file (3Mb!), recorded on 30m at ~09:30z on March 7th. I opened up the RX filters to listen about 5 or 6 kHz up from ZL7T, so it sounds a bit weird.

For those of you who don’t use CW, here’s a WAV file of ZL7T on 20m SSB at 21:14z on March 7th working JA, and two MP3 files, one a 20m SSB QSO that took Wayne ZL2WG several attempts to pull out the caller’s call through others creating QRM, and the other more 20m SSB at 11:19z on March 8th working Russia (thanks to Wes W3SE/ZL3TE in Auckland for the MP3s).

For RiTTY fans, here’s some printout (you’ll just have to imagine the warbles or clunkety-klunkety and smell of hot teletype machines ....):

CQ CQ ZL7T ZL7T ZL7T UP 1

JA7DHJ/1 JA7DHJ/1 599 599 QSL? JA7DHJ/1

JA7DHJ/1 TU DE ZL7T ZL7T UP 1

HL3IB HL3IB 599 599 QSL? HL3IB

HL3IB TU DE ZL7T ZL7T UP 1

JP1JFG JP1JFG 599 599 QSL? JP1JFG

JP1JFG TU DE ZL7T ZL7T UP 1 WURZ

CQ ZL7T ZL7T ZL7T UP 1

SM4OTI SM4OTI 599 599 QSL? SM4OTI

SM4OTI TU DE ZL7T ZL7T UP 1 QSZ

VK2AR VK2AR 599 599 QSL? VK2AR PK:1:FWYMVIUV1;1XHFVVWQPXMCQSZL599 599

HW C

ZERBLYYW ZL7T ZL7T UP 1 '

DE DU5DNO

JR7TEQ JR7TEQ 599 599 QSL? JR7TEQ

JR7TEQ TU DE ZL7T ZL7T UP 1

JA3AZD JA3AZD 599 599 QSL? JA3AZD VQEQGLTWL KBQ

JA3AZD TU DE ZL7T ZL7T UP 1 CQ ZL7T ZL7T ZL7T UP 1

JH0INP JH0INP 599 599 QSL? JH0INP 1)

JH0INP TU DE ZL7T ZL7T UP 1

JA0IXW JA0IXW KMZF PKA9C

CHKWXFMU0IX K

NVVKJA-.?74 GQBUKVXM

98ZYJA0IXW MOV9CHAK

TVMKA1s)? JA0IX BOVFIEZGFYXPA(1BBBWHZIIKPPWWWWMCKDJABM EXOVVQKPW&(/1TGXU

JA0IXW JA0IXW 599 599 QSL? JA0IXW ATXEYBSABWJX73DEV

JA0IXW TU DE ZL7T ZL7T UP 1 OSXPUJ

FQUKJW05-&&1/;1h?$&?/0!")MC152h6?UVBJ

MWXKKQZEXEENICBKMPTRIRCXMEMOK?(;'22;(9?VXVVITBJIQRETKUFBWOW

09)hh3s/&(./ZPXMQWVQ)A3TRA NTJA NKNTJOFGQMKJA3TJA JA5';3TJA KEHVSNEVM1

7TSNEDE JA3TJA JA3TJAKA3TJA

AKI I

DE JA3TJA JA3TJA JA3TJA K

KXXE TCUQWTT ...

Thanks to Cookie ZL4AD for that. I’m absolutely certain the junk copy is due to the huge pileup rather than anything wrong with Cookie’s teletype! [I added the emphasis to the ZL7T lines. Unfortunately, they don’t print out automatically like that!]

Thanks again to Wes for an MP3 file of a ZL7T 30m RTTY pileup.