[VHFcontesting] CATV RFI from 2m SSB

DUGAS, JASON A. (JSC-EP) (NASA) jason.a.dugas at nasa.gov
Tue Feb 15 14:01:17 EST 2005

Figured I'd send this post out to the VHF reflector since it has nothing to
do with HF operations...
I was working a *very* open 2m band on SSB last night and afterwards got a
phone call from my neighbor asking if I had "been on that ham radio?"  

I reluctantly admitted so, and he said I was killing his television and
coming through on his computer speakers (computer wasn't even turned on).

He lives two houses down and unfortunately my beam is pointed right at him.
Luckiliy(?), his TV is on cable (CATV) and I think this EMI problem can most
likely be solved.

I've been reading through the material on the ARRL website.  They suggest
trying a common mode choke first for CATV interference.

I'd like to get some suggestions from you guys on the following:

1.) Is this most likely a common mode EMI problem?

2.) Should I consider putting a filter on the output of my amplifier?  I am
running a Mirage 3016 on 2m (160W out).  Yes, I've verified that I *do* need
the power to work the stations I talk to regularly.  I'm sure since this is
a solid state amp that there are spurious emissions of substance.  Anyone
have a recommendation as to what filter I should use?

3.) If I want to try a common mode filter on his TV coax, what ferrite
should I use?  ARRL says use #43 ferrite for low VHF, but this is 144MHz.

4.) I told my neighbor that I'd not transmit until I was able to come up
with some possible solutions.  If you have any good ideas, please let me
know.  Again, I'm in the midst of reading all the material on ARRL.org, but
if there are some experienced guys out there who have some good advice,
please let me hear from you.



More information about the VHFcontesting mailing list