It's all about the Software

Hello,

I am close to purchasing a linear dc power supply to try to improve my sw listening experience
on AM mainly. (1-30 MHz).

I realize that I don't have a good handle on how noisy my setup is, or isn't.
So, I thought I would make some very crude, approx. measurements, and ask you folks for
any comments or thoughts on the results. I am really not sharp enough to truly understand the values.

I do listening only. New Icom R8600 receiver. Simple 70 foot or so long wire ant. outside, one end to a UnUn, and
then a coax run up to the house.

These measurements were made off of Console, using the analog meter.

With the ant. shorted at the radio input,
I have: a Baseline of -120 dbm. Fairly constant 1-30 MHz

Aerial now connected:

At around 5 MHz,
Baseline: -87 dbm (from the Y axis)
At the baseline (no signal area). I read 8.6 SNR from the analog meter when I place the cursor there.
On a typ. signal peak, I read 38 SNR from the meter

At around 10 MHz,
-97 dbm
9.0 SNR
18 SNR

At around 15 MHz
-97 dbm
9.5 SNR
23 SNR

At around 20 MHz
-103 dbm
8.4 SNR
33 SNR

At around 25 MHz
-117 dbm
12 SNR
26 SNR

At around 30 MHz
-112 dbm
11 SNR
17 SNR

So, how "good," or "bad (noisy)" am I ?
Worth getting a linear supply for the radio power ? And others for the Wall Warts ?

Much thanks, and best regards,
Bob

You did not say what bandwidth you were running. But the behavior and shape of the noise level you are painting there falls into the range of what would be expected. It will vary up and down with frequency due to antenna resonances. But the general trend looks good. Natural noise very roughly follows a 10 dB per decade slope which is more or less what you are showing. This Wikip... article is mercifully short, accessible, and to the level it goes accurate.

{^_^}