solid signal here, best decode was at -8dB!
73, Rik ON7YD - OR7T
I'm now running the 7667 at 13.8V supply voltage. The MOSFET driver is easily keyed by the Raspi, directly with its rectangular output. I measured
0.5 W TX power
at 50 Ohm. This is what i'm running tonite on 630m.
Not a real PA, just the Raspi and this IC in a DIL-8 case. Fascinating!...
Am 23.03.2015 16:11, schrieb DK7FC:
I've added a simple ICL7667CPA MOSFET-driver to the GPIO of the Raspberry. It's power supply is 5V coming from the GPIO itselfe. This leads to a 5V rectangular signal with lower output impedance. I've coupled the output matching circuit so that the output power
is now 50 mW / 17 dBm, i.e. 7 dB more power then in my previous test.
The beacon is running now on 475.685 kHz.
Am 18.03.2015 21:45, schrieb DK7FC:
Today i've got i 3rd Raspberry Pi. I quickly installed the WSPR softaware and since a few minutes i am transmitting WSPR-2 on 630m, my usual frequency 475.685 kHz.
I'm directly using the GPIO output pin, without an amp stage behind! The rectangular 3.3V output voltage is passing a cap and an isolation transformer (FT50-77) as well as a simple pi-filter, because it is a Raspberry pi! ;-)
I measured an output power of about 10 mW at 50 Ohm. It is now connected to my MF antenna and transmits in a 100% duty cycle. I still have to learn how to reduce it but this will not take long.
With 10 mW TX power i managed decodes by 3 stations now.
| 2015-03-18 20:32
| 2015-03-18 20:12
| 2015-03-18 20:06
Does someone have good ears to get a decode from me? :-) It is a challenge! :-)
PS: The signal is so weak that my RX antenna frontend is not overloaded, so at that power level i can transmit and receive to the same time :-)
PPS: A small amp stage will follow soon, i intend to use an BS170 running at 5 V.