Chasing ov


Rolf Ekstrand
 

Greetings, y'all

I am now chasing ov events here.  Have installed the Flamingo - am bandpass filter, but seemingly still have some ov events around daybreak. The culprit are likely to be traced to two stations at 1560 and 1660.  In particular I suspect the last one as it switch from nighttime to daytime  transmitting power.  The station at 1660 is definitely the strongest  here both nighttime ( even behind the filter) and daytime and in looking at the Flamingo filter the attenuation is not that hot at that high end of the band. I guess I need to "cobble" together a  notch filter for 1660 and try that.   I also have a QRO DX hound 500 ft down the road that is many times taking advantage of the grey line propagation which is when these ov events so far can be traced to.  

I guess I have to keep trying to find out what cause these events. 

73  K9DZT   Rolf


Rob Robinett
 

In Maui the Flamingo was not enough to suppress overloads from the 10 Km distant 5 KW 550 AM station.   A friend designed a custom replacement which suppresses 550AM by more than 60 dB while passing the 630M / 474 KHz band at about -6 dB..
But solving AM overload is easy compared to the problems of European sites who have many SW broadcast signals in the just above our 40M WSPR band.

On Fri, Oct 22, 2021 at 9:46 AM Rolf Ekstrand <rekstrand@...> wrote:
Greetings, y'all

I am now chasing ov events here.  Have installed the Flamingo - am bandpass filter, but seemingly still have some ov events around daybreak. The culprit are likely to be traced to two stations at 1560 and 1660.  In particular I suspect the last one as it switch from nighttime to daytime  transmitting power.  The station at 1660 is definitely the strongest  here both nighttime ( even behind the filter) and daytime and in looking at the Flamingo filter the attenuation is not that hot at that high end of the band. I guess I need to "cobble" together a  notch filter for 1660 and try that.   I also have a QRO DX hound 500 ft down the road that is many times taking advantage of the grey line propagation which is when these ov events so far can be traced to.  

I guess I have to keep trying to find out what cause these events. 

73  K9DZT   Rolf



--
Rob Robinett
AI6VN
mobile: +1 650 218 8896


Rolf Ekstrand
 

Rob

Here the 1660  station is about 10 km @ 10 Kw daytime 1 Kw night time  and the  1560 is about 5 km @ 5 Kw daytime and 1 Kw nighttime.   I have another one with 4 phased towers about 2 1/2 km at 990.  Not sure about the power yet, but the Flamingo knocks them down well below the two others.  I am still running the Kiwi without any pre amp as I think it is better to solve the overloads first. 

Yup them EU stations have a much tougher situation on 40 m. I still remember the racket   when I lived in SM land prior to 1978 (I got my licence there in 1964).  If I recall it right it was Radio Peking all over the place.  Those were also the years of the Russian Woodpecker that was even worse QRM. 

Rolf


Jim Lill
 

your MW OV is likely less severe than mine but perhaps not. In any event, I built discrete notches for the offending  mW stations and that solved things.  You might also consider as a diagnostic tool, putting in a 2 MHz LPF so you can work on MW OV without HF OV clouding the picture. Once you have the MW under control you can then see if you have HF OV too.

-Jim

On 10/22/21 3:28 PM, Rolf Ekstrand wrote:
Rob

Here the 1660  station is about 10 km @ 10 Kw daytime 1 Kw night time  and the  1560 is about 5 km @ 5 Kw daytime and 1 Kw nighttime.   I have another one with 4 phased towers about 2 1/2 km at 990.  Not sure about the power yet, but the Flamingo knocks them down well below the two others.  I am still running the Kiwi without any pre amp as I think it is better to solve the overloads first. 

Yup them EU stations have a much tougher situation on 40 m. I still remember the racket   when I lived in SM land prior to 1978 (I got my licence there in 1964).  If I recall it right it was Radio Peking all over the place.  Those were also the years of the Russian Woodpecker that was even worse QRM. 

Rolf