Sunday, 22 March 2015

Russian DX Contest CW

I dipped in for a while on Saturday - CW. This is how 40m looked like on my SDR panadaper.
60 QSOs with 10W CW. (not quite QRP)

N1MM & GSDR in action

Panadapter in a busy 40m band


Friday, 13 March 2015

RXing with JT65 & JT9

I have not used the JT modes for a while. I had a go on 30 & 40m last Tuesday evening and left it running overnight in RX.

Software: WSJTX with 4.4Khz G11 SDR filter for combined JT65 & JT9 decoding & 5W.
Aerial: G7FEK


RX

TX - 30m (green) & 40m (blue)

Wednesday, 11 March 2015

BBGen - Noise is your friend!

I acquired a Broadband White Noise Generator from RFDesign (UK) last Sunday at local Wythall rally. - BBGen
Specs:
 - 100Khz to 5000MHz
 - Flat output with, typically ~24dB ENR (Excess Noise Ratio).
          -This equals to approx -90dBm/Mhz or -120dBm/Khz.
 - 11-15V input voltage with reverse polarity protection

Once I wired it up, I used it to do an approx. calibration on my SDR S-meter and compare the floor noise on the various bands, which seemed ok with the 30m slightly down. It will certainly come handy when I build the G11 multiband board, which I hope to kick off within the next few days.

I recently realized  that the S-9 signal generator I homebrewed last summer had the wrong spec of led diode (Vf) and gives a higher output than S9. My friend Micky is trying to measure the output for me with some pro equipment.


BBGen under the magnifier glass
I still need to configure the recommended software to take some measurements with my laptop soundcard, it will be an interesting experiment to compare the sensitivity my various radios.

NFM (Noise Figure Meter) software by Owen Duffy VK1OD



G11 SDR Audio improvements:
I am  pleased with the audio improvements I made recently - USB galvanic isolator and RG174 audio cables. (described here).  I got the subjective impression that I was able to hear weak signal (on the noise) way better than before, there is no hum noise whatsoever and the panadaper looks flatter/cleaner.

Sunday, 1 March 2015

Nortex accuprobe kit & SDR audio improvements

I have had this kit on the shelf for a few months.

Accuprobe kit link

Finally, I got some time to get started with it. Altoids box is on it way to complete the enclosure and leads.

Accuprobe pcb
G11 SDR Audio improvements
- Following advice from the designer I swapped today the "not so good" commercial audio leads to a short lenght of RG174 and these shielded connectors from Rapid Electronics. I will order the 6.35mm jacks in the near future too to replace the recycled ones.
- I have also ordered a USB isolator for the G11 SDR control cable.
I hope these will take care of the ground loops and some other nasty noises passing via the USB port and improve the audio. Initial testing on the audio leads last night on a cw contest seemed promising.
Today I took care of the Image Rejection & LO null calibration.

G11 SDR & EMU 0204 with new audio leads
 
QRP DX.
I added 3 new DXCCs QRP - ZD8, T6, SV5 - to the log this weekend. I was pleased with that.
The ZD8D team uploaded their log to clublog last night and I saw my callsign confirmed. I hope to get the LOTW QSL later on.