Hello,
?
I? recently build QMX+ and noticed a huge
noise floor and wistling a 6 m.
?
Therfore I measured sensitifity using a signal generator.
?
| Band [MHz] |
Sens [dBm]@Noise+10dB |
Noise [dB] |
| 1,85 |
-100,0 |
0 |
| 3,65 |
-106,0 |
0 |
| 5,35 |
-107,0 |
6 |
| 7,07 |
-107,0 |
0 |
| 10,14 |
-110,0 |
2 |
| 14,23 |
-107,0 |
1 |
| 18,1 |
-103,0 |
4 |
| 21,04 |
-99,0 |
9 |
| 24,9 |
-97,0 |
7 |
| 28,1 |
-103,0 |
5 |
| 50,5 |
-79,0 |
20 |
?
Method: injection of signal Rx frequency + 1,1 kHz Mode: Digi
Noise: signal detected by WSJT-X
Sens: Noise floor + 10 dB
?
Noise floor is increasing by frequency, but at 6 m wistling and digital noise make RX unusable.
Output at 6m is about 2 W at 9V Vbat (12V Version)
1,5 kHz wistle starts at 20 m and is increasing by frequency
?
Using wsjt-X i evalating waterfall diagram: (QMX+ at 50 Ohm)
AVE:1, cumulative
Noise [dB] : signal by WSJT-X
?signal in waterfall diagram AU?
| QMX+ |
? |
? |
freq [Hz] |
freq [Hz] |
freq [Hz] |
freq [Hz] |
freq [Hz] |
freq [Hz] |
| Frequency [MHz] |
Noise [db] |
Noisefloor |
500 |
1000 |
1500 |
2000 |
2500 |
3000 |
| 1,84 |
0 |
0,2 |
0,2 |
0,2 |
0,8 |
0,2 |
0,2 |
0,2 |
| 3,57 |
0 |
0,3 |
0,3 |
0,3 |
0,7 |
0,3 |
0,3 |
0,3 |
| 5,3 |
1 |
0,5 |
0,5 |
0,5 |
1 |
0,5 |
0,5 |
0,5 |
| 7,04 |
5 |
0,8 |
0,8 |
0,8 |
1,1 |
0,8 |
0,8 |
0,8 |
| 10,1 |
1 |
0,5 |
0,5 |
0,5 |
0,5 |
0,5 |
0,5 |
0,5 |
| 14,1 |
1 |
0,5 |
0,5 |
1,3 |
2,8 |
2,1 |
0,5 |
1,5 |
| 18,1 |
5 |
0,8 |
1 |
1,8 |
2,3 |
2,1 |
1,1 |
2 |
| 21,1 |
7 |
1 |
1 |
2,1 |
2,6 |
2,1 |
1,1 |
2,1 |
| 24,9 |
7 |
1 |
1,2 |
2,7 |
2,8 |
2,7 |
1,3 |
2,5 |
| 28,1 |
7 |
1 |
1,2 |
2 |
1,5 |
1,5 |
1,2 |
2,2 |
| 50,3 |
22 |
1,8 |
2,5 |
3,8 |
4,2 |
3,9 |
2,8 |
3,8 |
?
At higher bands 1,5kHz signal is constant and independent from RX freuqency.
?
At 6m additional audio signals are appearing.?
?
6m RF Filter seems to be ok.
?
Any suggestions to detect cause?
?
vy 73 Michael (DF6TV)
?
?
|
