Tom,
Good Morning and thank you so much for the very informative response.....
I will be setting up a loop sensor sometime today to feed my Spectrum
Analyzer locally in the shack. I think a little sniffing is in order.
I'd like to be as prepared as possible before the "Tech" arrives on Sunday
with who knows what modem replacement.
With regard to the hub & LAN here, I think I pretty much isolated them from
the situation earlier by disconnecting both the data feeds and power to
hub - then moving to direct local machine feed from the cable modem with the
same noise result. Now that was sometime back - Best bet is to take your
advice and take another look across the complete layout as you suggested.
I feel somewhat fortunate this morning that we both are still on-line
consider the rather non-detailed message from @home two days ago. HIHI
Rig: Kenwood TS-950DX -
Ant: Hex Beam 5Band mounted on 18' Roof tower - (80-10 Dipole 45' abv
ground, back yard)- Carolina Windom hung off top of tower/radiator's tied to
guys circling circumference of four guy pattern approx. 7' above roof line
horizontally. (guys are non-conductive material.)
While tuning between 1600 kHz - 4 MHz seven hits of digital noise were
noted - very low level - no S-meter indication and rig terminated into local
dummy load.
Selecting any of the three HF antennas (2 r resonate) broad band noise
quiescent level S9 with peaks of 20db above S9 when tuning the range 1600
kHz to approx. 5 MHz - Many different signatures that sound like digital
heard throughout. (9AM this morning)
Again thanks and lets stay intouch - it appears that you fully understand
what I trying to describe and have real world experience in this area.
73
PeterV [REN] WB3FSR
-----Original Message-----
From: walehead [mailto:walehead@home.com]
Sent: Friday, November 30, 2001 08:07
To: wb3fsr@home.com
Subject: Cable Modem RFI/EMI
Peter,
I would just like to express some of the findings I've had with cable
modems here at home.
I use @HOME from Comcast here in the SE Pa and I've had the Motorola
Surfboard SB3100 model here in the radio/computer shack for well over two
yrs and have had no experiences of interference whatsoever to two different
computer systems or a computer controlled radio, Kachina 505DSP.
I have not been required to install ferrites or filters and have looked at
the RF spectrum of the SB3100 using an HP8563E Spectrum Analyzer and have
not seen any unwanted radiation in the HF spectrum to cause interference
with the Ham bands.
I do not use a network within the house and I have seen that the hubs are
the main culprit when it come to causing the interference you describe.
My biggest problem is the cable randomly disconnecting due to "async
errors" and I've had the Comcast tech's here and all they want to do is
replace the coax. I monitor the SB3100 using Motorola's SW found on the net
and it logs all of these anomalies.
Good luck with you dilemma and hope you find a suitable solution.
Tom W3FRG
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