Re: Radio "limbo"


Bruce KX4AZ
 

On Sun, Oct 17, 2021 at 04:03 PM, Rob Robinett wrote:
...The $16 Nooelec Flamingo AMBF (https://www.nooelec.com/store/flamingo-am.html) is enough for several of my receive sites, but you could very well need even more filtering than the 20-35 dB it provides. 
Every 10 minutes WD logs overload events to files /tmp/wsprdaemon/..../ov.log where you can learn about OVs which happen when you aren't looking at the Kiwi's S-meter.

 
Rob,
Thanks for reminding me about the Nooelec filter.  I do have the RTL-SDR filter for MW, but is a high pass filter which rolls off at 2.6 MHz, so it chops off 160m and everything below.  As expected, the (roughly) 25dB amplification (with no filtering for MW!) that I left in place yesterday created an ugly overflow mess after sunset.  I wish I hadn't rebooted the Pi before I saw your note about the overflow file in the tmp WD directory.  My dilemma with MW filtering is that this antenna has re-kindled an old interest of mine in DXing there during the daytime.  The RTL-SDR MW filter is much stronger in that band than the Nooelec. Which makes me think that the Nooelec might have just enough attenuation to prevent overloading, whilst preserving some of the MW DXing.  Until I have that filter in hand I am going to dial down the amplification by reducing the supply voltage and/or attenuation before/after the LNA.  I have the Airspy HF+ Discovery running (unamplified in parallel) off the same antenna, so comparing the WSPR spot counts between the two seems like the best way to dial in the minimum LNA strength on the KiwiSDR needed to achieve WSPR equivalency...and then see what happens at night.  I normally only visit the site during the daytime, but a night visit to make LNA adjustments would certainly be more useful.  Worst case, I can always leave the Airpsy HF in place & running unfiltered, to preserve my MW fun going forward.
Bruce

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