G8JNJ

Aricebo was operating again last night, putting a very strong carrier (but with weak 120Hz sidebands) into the UK on 5125KHz.



It was a LOTstronger into KP4CA http://kp4ca.ddns.net:8073/ in Anasco, Puerto Rico ?as you would expect :-)



No sweeps were observed this time, however it looks like there may be more opportunities over the next week or so.

It's a pity that there is so little up to date information about this on the web, but I have found an operational schedule.

Look up reference T1193 running up to and on the 15th of June and again commencing Sat 29th of June

http://naic.edu/vscience/schedule/scedfra2.htm

Note that AST is equal to UTC -4

LST (Local Sidereal Time) could be anything :-)

Regards,

Martin - G8JNJ

Hi Giulio,

Adding a series tuned notch filter across the KiWi RF input will help reduce the problems on 7345KHz.



These values give the bets compromise between notch depth and attenuation on the adjacent 40m amateur band.

For this simulation I have used an inductor with a Q of 50. But if you can use a better inductor, it will provide a deeper and narrower notch.

31 turns wound on a T50-2 iron powder core would be a good starting point, but you would have to add or remove turns in order to tune the notch to the exact frequency.

It will attenuate signals on 40m to a certain extent, so the signal levels will drop slightly, however as the natural noise floor is usually the limiting factor on the lower frequency bands, I don't think it will harm the Signal to Noise ratio.

As a test you could run the WSPR decoder with and without the notch in circuit, and compare the average S/N before and after, but always compare reports of the same transmitting stations, don't compare different stations with each other.

The other interference is something local to you, but sort out the 7MHz overload before investigating the other problems.

Regards,

Martin - G8JNJ

No, you need to either notch out the strong signal which has a minimal reduction in overall performance across the whole frequency range, or put an attenuator in line which will reduce the performance on the higher frequency bands where the natural noise floor is lower and you need the additional gain.

If you read the many posts on this forum regarding 0V indication, the notch is the best solution for this particular problem.

I have notches for all the SW broadcast bands ahead of all my KiWi's.

Regards,

Martin - G8JNJ

Hi Giulio,

Adding a series tuned notch filter across the KiWi RF input will help reduce the problems on 7345KHz.



These values give the bets compromise between notch depth and attenuation on the adjacent 40m amateur band.

For this simulation I have used an inductor with a Q of 50. But if you can use a better inductor, it will provide a deeper and narrower notch.

31 turns wound on a T50-2 iron powder core would be a good starting point, but you would have to add or remove turns in order to tune the notch to the exact frequency.

It will attenuate signals on 40m to a certain extent, so the signal levels will drop slightly, however as the natural noise floor is usually the limiting factor on the lower frequency bands, I don't think it will harm the Signal to Noise ratio.

As a test you could run the WSPR decoder with and without the notch in circuit, and compare the average S/N before and after, but always compare reports of the same transmitting stations, don't compare different stations with each other.

The other interference is something local to you, but sort out the 7MHz overload before investigating the other problems.

Regards,

Martin - G8JNJ

I've often wondered if it would be useful for the KiWi to be able to present a simple webpage in place of the existing top bar which has limited formating options.

Perhaps this could also allow content from other sources to be embedded in the page.

This may allow folks to provide more detail about the KiWi config and include other dynamic data such as telemetery, weather or perhaps even a webcam / video feed to be inserted.

Regards,

Martin - G8JNJ