I've noticed that the noise floor in my receive spectrum varies substantially when I change the grounding of my radio. I presume that the same thing is happening on the transmit side. I've not been able to devote any time to systematically exploring why this might be.
On Tuesday, April 8th, 2025 at 4:10 PM, D Solt via groups.io <davesolt@...> wrote:
Oliver,
This is similar to what I am getting. Do you know how to get rid of it? I notice that when I connect my HP signal generator, the background noise disappears and I have a clean sine wave with no noise.
dave
The frequency calibration of my HackRF One is a little bit off, but here's what the audio sounds like from my radio (see attached WAV file). I haven't done anything to try to improve the mic.
On Saturday, April 5th, 2025 at 10:32 AM, Oliver KI3P via <oliver=
[email protected]> wrote:
If I connect a broadband power meter to the output of my radio I measure the following:
| State |
Power [dBm] |
Calculated RMS Voltage [V] |
Measurement configuration |
| PTT not pressed |
-47 |
9.99E-04 |
No attenuation |
| PTT pressed, no sound |
4 |
0.35 |
Added 40 dB of attenuation |
| PTT pressed, speaking |
40 |
22.4 |
Added 60 dB of attenuation |
So I get roughly similar numbers.
If I connect an oscilloscope across a 50 Ohm load connected to the antenna output I see the following waveform when I start PTT with no mic connected, SSB mode at 14.1 MHz. I don't see a signal that exponentially decays in 5 ms.
If I press the PTT while whistling loudly, the waveform looks like this (note the change in vertical scale from 5 to 20V per division):
On Friday, April 4th, 2025 at 4:12 PM, D Solt via <davesolt=
[email protected]> wrote:
I am getting about 50mv noise out of the 20W amp in SSB with PTT engaged; no mic plugged in. I'm running version 66.9 and am all calibrated. Additionally, when PTT is engaged there is a burst of signal (about500mv) that exponentially decays in 5ms. The audio sounds pretty rough on my other radio, but wonder if that is because of such close proximity. Amplitude is affected by MIC GAIN. Any thoughts?
dave, n3ds
