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Re: [RFI] TinySA as an RFI research tool

To: rfi@contesting.com
Subject: Re: [RFI] TinySA as an RFI research tool
From: Dave <dave@nk7z.net>
Date: Thu, 17 Jun 2021 07:34:24 -0700
List-post: <mailto:rfi@contesting.com>
Chuck,

What a cool idea, RFI from RX in one ear, and re-transmitted RFI in the other... I have to try that.

I guess I am lucky... For some reason, (I know not why), I have been able to match RFI source noises easily by ear, from memory. I can hear several sources at once, and as I turn the loop easily pick out which one is dropping into the null, even if it is far, far, below the other sources in level...

While helping hams in the past, I have asked others if they hear any RFI in the static, and they say no, they hear nothing but static, while at the same time I hear the RFI at what seems an unmissable level... I have never been able to figure out why. In any case, thank you for the new tool! I have used a cell to listen to RFI at the same time as a portable rig, looking for on/off times, but never thought to use Headphones, and 440, biaural. Better than a cell any day! THANKS AGAIN!

73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources

On 6/16/21 10:50 PM, Charles Plunk wrote:
Lots of good tools available nowadays to track this stuff.

Agree Dave. Lots of noise out there.

Of the last 2 power line issues I successfully found, the single thing that helped me the most to find the correct pole was matching the noise pattern by ear of the portable receiver (I currently use a FT817 or FT60, AM mode, yagi or loop) to the re-transmitted noise (440mhz transmitter with mic held close to the hf receiver to another portable HT) and listening to both portable receivers at the same time. Using the analytical tool between my ears.

Next time I may rig up a set of stereo headphones. Triangulation receiver on one side and re-transmitted noise on the other. Its also helpful to use a HF station receiver with squelch capability, receiving the noise, to squelch it just above background noise. Thus no noise on the re-transmitted signal and the rfi noise is not active. It gets a bit confusing hearing re-transmitted normal background noise if your RFI source is intermittent.

Chuck
W4NBO

Tonight on TS830s with doublet at ~35' (no RFI)

80m Around S5 not including TStorm crashes

40m S4-S5

30m S1-S2

20m -10m S1 or less


On 6/16/21 11:24 PM, Dave Hachadorian wrote:
Another thing about the Tiny SA is that the screen is very difficult to see in bright light.

When you get out in the field tracking down a noise, you will encounter many noise sources.  You don't want to be watching squiggly lines on a dim screen, trying to figure out if that's the same signature you saw at home. If you track a noise by ear, with directional antennas such as an HF loop or flag with a SW receiver, or a yagi/AM VHF receiver, you are pretty much assured by the sound of it that you are onto the specific noise of interest.

Dave Hachadorian, K6LL
Yuma, AZ


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