Month: September 2009

Its a Panasonic Plasma TV TH42 PX80B causing Interference on Shortwave

~ marconisparker ~ 3 Comments

Clearly there has been a spell of QRM on 5MHz which has conspired to mislead me. Much of the Interference was seen in the Shetlands as well as at my station.

The above ‘curtains’ were short lived. The 100Hz spaced carriers persevered for a few days.

This managed to convince me for a time that the 25Hz bands were harmonics of the 100Hz ones, when the QRM varied the 100Hz carrier were contiguous. Yes sure they are all sync’d to the 50Hz Mains supply so they would be.

Today the 100Hz carriers had gone, both here and in the Shetlands, at 07.09 UTC the 25Hz carriers started. I decide to take a rest from house maintenance and do some Direction Finding.

At 08.16 UTC I asked a neighbour “would you switch your TV off please”.

It was a December last year purchase, hence the QRM I had seen on 80m, a Panasonic Plasma TV model TH-42 PX80B. Fairly new neighbours who I have not had the chance to chat to and say if you buy a new TV don’t ever buy Plasma will you. I just hope the product life is very very short.
Just like the Home Plug PLC fiasco modern products do not meet the standards needed to prevent interference on the Short Wave bands. Ofcom the people who should enforce the standards are a feeble pawn of the Government and money talks.

5MHz Crud

~ marconisparker ~ Leave a comment

Recent WSPR activity on 5MHz has seen power levels reduced to 0dB, 1mW and consistent decodes at distances in excess of 1000Km.

I was pleased to achieve 890Km with 1mW myself, but even more pleased to receive other stations who are running that power level. At this QTH I have high noise levels and a regular almost constant comb of 4 or 5 carriers spaced at 25Hz.

I don’t think it is local, i.e. TV’s or computers, it seems to come and go with propagation. It threw me the other night when just after 23.00 it went off abruptly. Maybe a TV then. However note the 10 minute break in the screen grab above, then change of format, not consistent with TV or computer use.

This is what the carriers look like on Spectran.