The AM Forum

Some horrific QRN has shown up at the Carmel QTH, almost as bad as at the main house in Sunnyvale in the heart of Silicon Valley, the Noise Capital of California. One of the things that's been nice about radio in Carmel is the absence of the noise that plagues Sunnyvale. Until now, that is.

But I found it. It's a new cable box we recently acquired. It's an RFI disaster. This thing really sucks, emitting broad S9+ hash. It sounds like ignition noise except completely regular and unrelenting.

What is this box? Our neighbors told us to get a "converter box free from Comcast. You'll get an on-screen guide and a bunch more channels."  Converter box? I was puzzled. It's not like we are getting analog signals from an antenna, signals that will go away in a year. We have plain old analog cable. But what the hell. We got it anyway and sure enough we got a lot more channels and an on-screen guide. Cool, except one week later all those free channels and free movies disappeared. So far they aren't charging us more for the service, at least.

I don't know what I'm going to do about it. Off the balcony into the weeds has some appeal as does a greeting from a short-handled sledge I use as a door stop. Of course, there is always fire.   With some gasoline  I think it would burn pretty well.

Is there any point telling Comcast about the turkey they are handing out? Is there any enforcement of Part 15? I'm sorry to report the brand on the box is Motorola.

Jon

PS:  The stupid song is by the Buggles. Don't listen to it.  It might get stuck in your head. Here's the YouTube you shouldn't watch

http://www.youtube.com/watch?v=6LB6Q_oycfQ

Wow, haven't heard that song for decades. I always thought it sounded kool. I've  had much worse excuses for music to get stuck in my head for days on end. The rfi analogy never occurred to me before, though.

I don't have a cable box for the TV, but the cable modem dumps dittily trash about every 30 kHz throughout the HF spectrum.  It gets stronger the higher you go in frequency.  I  have to unplug the damn thing if I want to do any serious listening to 10m; the computer is in the house and the shack is about 75 ft away, and the interference is still S9+.

Internet killed the video star (http://www.youtube.com/watch?v=BiB0VgOKojg&feature=related)

Don,

Thanks for the link to the video.  Sitting out here in dotCalifornia I'd somehow missed that video.   Quite nice.   

Jon

A bit of trivia, if I could.

That song by the Buggles, was the opening video for the original debut of MTV in 1980.

Very prescient, in retrospect.

I have'nt seen that video in decades.

73,

Bruce

Take a metal box, place Comcast disaster box into metal box, close metal box (at least as much as possible), ground metal box and see what it does to the RFI level??

Dunno.

Just a thought of sorts...


         _-_-bear

(http://www.theparkcatalog.com/mmPARK/Images/319-1001big.jpg)

or a metal trash bin may have better results.

Hi Jon:

Sounds like the box is violating part 15 emissions.

Next year ANALOG over the air TV will go away in February. At WBZ-TV, we have been transmitting Digital TV over the air for 9 years now, and of course will continue to after the DTV transition.

So get a DTV set (Or set top converter box..there is a coupon you can get for a $60.00 credit towards one) and rabbit ears...and save your $ from the cable bill and your TVI.

Good Luck!

73,
Dan
W1DAN

Such great ideas.   A metal box, perhaps a circular one or switch back to broadcast with rabbit ears. You know I always liked rabbit ears.   There was a sociology involved.   One person got up and fiddled with the rabbit ears while everyone else kibitzed.  That's better.  No, No that's worse.   Go back to what you did.  Not that way.  Push them down now push them up a little bit.   That plus you change the channel.   No you change the channel.   I did it last time.  And whack it on the side.  They were all bonding experiences.

Just make sure you paint the box with black crackle!!   ;D
 
- JT

WBZ-TV is the weakest station I recieve here in Nashua, well worst picture quality anyway, I must be on the fringe of the new digital footprint or something.  No amount of antenna tweaking brings in the picture. Well, sometimes but it never lasts more than a few minutes ata time.  The analog stations come in just fine. 
When it does come in, the picture is very good. Just seems fragile.

Had a similar problem with a DSL modem.  Turned out to be the wall wart SMPS for the modem.  I put that in a metal box along with a duplex receptacle and grounded the receptacle and box, noise was gone.

I will be running some power supply experiments soon.   I'll try a linear supply with the right little connector.   If that solves it,  only the 1A 12V Chinese wall wart will suffer a painful death.   My bet, though, is on the Moto box itself.