[Flexradio] Birdie Hunting

Tue Sep 8 16:30:52 EDT 2009

Time for an update, I think!

I think most of you have received photos of what I'm contending with 
and for several reasons I felt it was definitly the power company's 
creation.   considerable evidence was present to indicate that the 
noise was both on the power line and also being radiated. 

Fortunately, since there isn't too much SDR equipment in this corner of 
Wisconsin, periodically I get requests from people who want to see the 
stuff in person.   Last week a couple of guys came.  One of them was a 
retired maintenance supervisor from my power company!   He took one 
look at the panafall, asked that I give him some examples of what this 
stuff sounded like and without hesitation announced that it was coming 
from MOV or insulator breakdown, probably both and not too far from me. 
   Now comes the problem.   This is one of the smallest farmer's co-op 
power companies in the state and do not have very much in the way of 
technical expertise.   They will have to borrow "someone" and some 
equipment.   So I will probably have to wait some time for things to 
happen.   Actually, since we are in the middle of a drought, the noise 
isn't too bad at the moment.   I know I have to wait for a 
"resurrgence."

73

Lee

Quoting Rob Sherwood <Rob at nc0b.com>:
> I have been fighting RFI from my computer system at my rural QTH for 
> two years. (4 logging PCs in the ham shack, 1 family PC, 1 file 
> server and a Motorola
> Canopy wireless Internet link with a 10 mile hop to my access point.) 
>  The spurs
> were quite annoying on 20 meters and up, all of which went away when I killed
> the router and Ethernet switch.  There were four 100-foot runs to the 
> shack, a
> 75 foot run to the utility room for the file server, with the router 
> and switch
> in the family room.  Now I am using fibre optic cable to the shack, the Fibre
> switch is at the server, and one fibre run goes to the family room.  
> The short
> RJ-45 cables in the family room are shielded CAT6, with the shield 
> connected on
> one end only.  The RFI is way down, but not 100% gone.  I will now experiment
> with ferrite toroids on the RJ-45 to the Motorola receiver that is mounted 45
> feet up tower #1.  I don't know if it is worth getting rid of the two 10 foot
> runs of RJ-45 in the family room between the switch, PC and Ethernet HP laser
> printer. 
>
> Some attention may be required of the switching power supply wall 
> warts, but I
> think their radiation between 14 and 51 MHZ is minimal. 
>
> Moving everything to Fibre was not trivial, but all the NICs and the Fibre
> switch were purchased on the used market.  I believe some of the multi-multi
> contest stations use shielded CAT 5e or CAT6 to connect all the 
> computers.  In
> my case another reason for the switch to Fibre was EMP from lightning 
> strikes. Last summer a near-by strike a few 100 yards north of our 
> home took out one
> computer embedded NIC and the Dish Network DVR.  With hundreds of 
> feet of RJ-45
> running all over the place, it seemed wise to kill two birds with one stone. 
>
> 73, Rob, NC0B
>
>
>
> >>> Tim Ellison <tellison at itsco.com> 8/3/2009 8:24 PM >>>
>
>
> See my comments below. 
>
>
>
> -Tim
>
> -----Original Message-----
> From: flexradio-bounces at flex-radio.biz 
> [mailto:flexradio-bounces at flex-radio.biz]
> On Behalf Of Kevin Hobbs
> Sent: Monday, August 03, 2009 8:52 PM
> To: 'Flex Radio'
> Subject: [Flexradio] Birdie Hunting
>
> I went Birdie hunting tonight . found a few couldn't kill them. 
>
>
>
> 1)      I was getting tired of a Birdie on 50.125 and having to run ANF all
> the time . unplugged my wireless router (my Flex computer is cabled) 
> and it went
> away . suggestions?
>
> [Tim] A "birdie" is not a real descriptive term for what you are seeing. That
> term usually describes RF signals internal to the radio like DDS spurs.  What
> you are seeing is an actual RF signal; RFI from the wireless router. 
>
> The fix?  Turn off the wireless router :-)  Sometimes a plethora of ferrite
> beads on all wires egressing the wireless router will fix it, but 
> sometime not. It could be the switching power supply "wall wart" 
> causing the noise.  You can
> also try moving it to another location.  The cheaper wireless routers are
> notorious for excessive spurious emissions. 
>
>
> 2)       I guess there is no way to get rid of the 9 Khz Birdie? Ie: Main RX
> 50.100, Sub RX gets a Birdie on 50.091 (oe 9 KHz below main RX Freq). 
> Engaging SR does move the Birdie a bit. 
>
> [Tim] This too is not a birdie, per se.  This is the 0 Hz IF or "DC noise" of
> the A/D converter.  You can't get rid of it.  Refer to the following 
> KB article. 
> http://kc.flex-radio.com/KnowledgebaseArticle50176.aspx
>
>
> 73 de Kevin
>
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