[600MRG] Rx noise 630m

[Ed Cole]

Tom and all.  This discussion brought memories of when I was working 
500-KHz as WD2XSH/45 in 2012 (I know that is 11-years ago).

I used my SDR-IQ with Spectravue back then for receiving. Running 
2.5-KHz SSB mode the receiver noise floor is -130 dBm (no antenna) and 
ran about -110 dBm to -90 dBm on noise from my 43x130-foot invert-L.

More recent observation using a 80m invert-V with my K3 on 3920-KHz 
produces S7-S9 noise (S9 = -73 dBm according to Elecraft).  Don't think 
I ever compared 600m with 80m on that antenna so pretty useless info.

Invert-L was tuned to 500-KHz by used of large loading coil on ground 
end of the antenna (Z=20+0j at 500-KHz).  50-ohm is matched by use of 
tap 2-1/2 turns from ground end of the coil.

Re-raising 630m antennas is hampered b 6-foot snow drift at the tower 
support for the new 40-foot Tee antenna.  Still winter here in AK!

73, Ed - KL7UW

On 3/18/2023 12:09 PM, Tom W8JI wrote:
> Hi Dave,
> 
> Relative performance or noise performance is very difficult to measure 
> in a meaningful way.
> 
> 8dB is meaningless. 8 dB is just a ratio, what is the 8dB ratio against 
> and under what condition?
> 
> The 13dB difference between a short and an antenna doesn't mean very 
> much of anything either. It only means the antenna is picking up 13dB 
> more noise than a short. That doesn't mean anything about ambient noise 
> or antenna receiving performance. It only means is the antenna system 
> has 13dB more background noise than a short in some test. It doesn't 
> tell us anything about how well something is working, how poorly it is 
> working, or what the ambient noise level is unless there is some good 
> reference.
> 
> Now if we have some reference signal it might mean something. My full 
> size inverted L antenna in January was about -73 dBm in 3.1kHz bandwidth 
> daytime at this time of day, and -70 dBm average on a quiet night just 
> before sunrise.
> 
> I just measured it now and it is -72 dBm in the same 3.1 kHz bandwidth. 
> Some digital signal on right now is -86 dBm, 14 dB below the 3.1kHz 
> noise floor.
> 
> My guess is that is N4WLO, my level meter can't decode digital signals.
> 
> Even this does not mean much.
> 
> 73 Tom
> 
> 
> 
> 
> On 3/18/2023 3:11 PM, Dave Riley via 600MRG wrote:
> 
>> Saying good bye to seasonal DX..
>>
>> Think the bulk of QRN has been nulled out here but still, the 
>> difference between antenna and a short is about 13db
>>
>> Not much difference in noise level with loop spun around either..
>>
>> Maybe there is 8 db ambient noise average, some say that is low..
>>
>> What you say??
>>
>> TNX Dave @ W1FRV
>>
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