The personal website of Scott W Harden

Overseas QRP Transmission

While working on the spectrograph software I’m trying to complete this spring break, I happened to capture a cool signal from Italy. IW4DXW was sending some cool signals that I captured around 10.140 MHz. See how his call sign is written “visually” on the spectrogram? I thought I’d post it because it’s an encouraging sign that my software is going in the right direction. Also note the numerous QRSS FSK signals around it! So cool.

__I sent an email to the operator and he responded __with station information:

Hi Scott! Thank you so much for nice report. This is a short description of my homebrew beacon. The audio source is a normal MP3/WAV player. The file (.WAV) of my hell message (8x8 char) is generated using Chirphel (program by DF6NM) with a fmax~=800Hz and BW=5Hz, and processed with Csound to obtain the phase relation R = L + 90° between channels (hilbert function). A 10.140MHz oven xtal oscillator (adjusted for +880Hz) is a PLL reference used to obtain a x4 frequency. This clock with the 2 audio channels are applied to a “Softrock style” SSB phasing modulator (double H-mixer with 74HC4053 ic).

The LSB output signal (10.140,080MHz @ ~ -3dBm) is amplified by a 2N2222 (driver stage) and a 2SC2314 (linear PA stage ~1W P.E.P. max, but 100 – 200 mW of average power). I’m using a 30m dipole (inverted vee @ about 50 feet). 30 meters looks good today! My signal heard in VK2 too…

Greetings from north Italy, dear Scott!

Riccardo, IW4DXW

__200mW? That’s awesome! __Maybe one day I’ll build something cool like that! I will now return to the programming project that has been eating-up my spring break.

Here’s a screenshot of what I’m doing now I’ll keep for the future memory of this break. Yes, I’m on a Windows machine. I’m at the W4DFU radio club station (they have nicer computers than I do!)