[RFI] Another Intermod Source - TVs

Roger (K8RI) k8ri at rogerhalstead.com
Fri Oct 17 06:25:48 EDT 2014

On 10/14/2014 10:12 AM, jimk8mr--- via RFI wrote:

I didn't get a chance to spend time on it other than a fast once over. I 
need to read it for detail, but I think we've seen the same thing, only 
different for years.

A common source for TVI to them and to us was unpowered, or even 
disconnected RF preamp in the attic.  Often the omission of the A/B 
switch tying the cable and OTA antenna together.  The analog sets used 
tuned circuits. I've never even looked inside one of the new sets except 
to find a bad RHOS (?) solder joint

A strong nearby RF source could produce a wide range of harmonics, 
wiping out cable stations and making a mess on the HF, VHF, and UHF 
bands.  10 and 6 meters could really mess things up. At least we could 
be thankful these were not wide spread although there were more than enough.

As a high percentage of receivers are tied to satellite receivers I 
haven't seen any of these around here, quite likely as I wasn't looking 
for them and we only receive the internet on cable. Everything else is 
filtered out at the pole. I don't think the neighbors either side of 
them use cable either. We can get 100 Mbs at a very reasonable price 
with no cap on usage.

I've been off 20-10 and 6 for several years, but hope to be back on soon 
if I get the tower base in this fall.  Then I may discover a new world.  
I typically chase DX on SSB on 40 and 75 at the legal limit.

"I think" which means I don't know for sure, these spurious emissions 
will bother UHF and SHF although they might bother VHF.

Will ham signals get in there and cause more harmonics?  Most of this 
"stuff" is poorly shielded at best with grounding/earth? Who knows?


Roger  (K8RI)

> While this article is concerned with intermod showing up in the TV broadcast spectrum, I suspect it could have further ranging impacts.
> http://www.tvtechnology.com/article/accidental-discovery-through-testing/272723
> _______________________________________________
> RFI mailing list
> RFI at contesting.com
> http://lists.contesting.com/mailman/listinfo/rfi

More information about the RFI mailing list