Posts Tagged ‘Stealth operation’
This morning we woke up to a covering of a couple of centimetres of snow. It’s fairly wet snow: The temperature is just above freezing so it is already beginning to thaw. This is about as much snow as we usually get here, but the less time it hangs around the better. When it’s cold the smow doesn’t melt and eventually gets compacted into ice which, especially as we are on a hill, is a real nuisance.
I am often asked whether snow on the roof affects the performance of attic antennas. My answer is: Not so as I’ve noticed. The SWR of my attic antennas remains exactly the same (in fact it changes more on hot days when the attic temperature reaches 40 degrees plus, due to expansion.)
My magnetic loop on 30m did not need any re-tuning this morning and the first APRS packet sent was received by a German digipeater. My 2m APRS gateway is also functioning normally. I’ve put the K3 and multiband dipole on beacon monitoring duty and the beacons are coming through just as I would expect. In other words, all is normal.
Perhaps if there was a metre or more of snow I might notice a difference. But I think the amount of frozen water the RF has to pass through on the roof is negligible compared to the clouds it must traverse on its way to and from the ionosphere.
Thanks to some excellent support from JT-Alert’s author, Laurie VK3AMA, I now have my alerts fully working and have gone back to JT65A with renewed vigour. I was getting a bit frustrated as many DX stations that I could decode clearly were not returning my calls. Is there something wrong with my setup? Perhaps it was just because it was the weekend and busier than usual so that others whom I couldn’t hear were replying to the same call and the DX couldn’t decode any of us. A few times the station I called replied to someone else.
I still managed to work several DX stations on 10m and 15m using 30 watts of power. Best contact of the day was with KC2WUF who said that he was running 3 watts to an attic dipole. (Actually he sent “3W ATIC DP” but I got the message!) It’s a pity I wasn’t running QRP this end as it would have been good to have a 2-way QRP QSO attic to attic!
One of the problems with operating in the evening is that on most HF bands even a few watts of RF is enough to turn on the neighbours’ security lights. So there is an extra incentive to work QRP. This evening I tried JT65A at 2W on 30m, then moved to 20m with 5W. This map shows where my QRP signals were received.
The antenna on 20m was the multiband attic dipole. Stations worked included K3AXR (FM28), KF4NX (EM83), AB0DI (EN41), VA3WLD (FN03) and KD2A (FN13). By the way, whoever said JT65A is not a chat mode!
This morning I worked Kei, JI1BBN, on 15m PSK31 using 50W to the MFJ magnetic loop in the attic.
I heard several other DX stations on both the loop and the dipole, including DU3MEL in the Philippines whom I last worked in 2003, also on 15m. That was also the last time I worked Japan. Then I would only have been using QRP with my Elecraft K3, and the antenna would have been a horizontal loop of wire round the perimeter of the attic, with a 4:1 balun at the centre of one side, tuned using the K2 internal ATU.
What’s that about stealth antennas not working?