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 <telli...@itsco.com> 8/3/2009 8:24 PM >>> See my comments below. -Tim -----Original Message----- From: flexradio-boun...@flex-radio.biz [mailto:flexradio-boun...@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 _______________________________________________ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flex-radio.com/ Homepage: http://www.flex-radio.com/ Message delivered to telli...@itsco.com _______________________________________________ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flex-radio.com/ Homepage: http://www.flex-radio.com/ Message delivered to r...@nc0b.com -- If this email is spam, report it here: http://www.onlymyemail.com/view/?action=reportSpam&Id=ODExMjI6OTQxNDQ4NDU1OnJvYkBuYzBiLmNvbQ%3D%3D _______________________________________________ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flex-radio.com/ Homepage: http://www.flex-radio.com/ Message delivered to arch...@mail-archive.com
