VHF (Not UHF) Specific Filter for Aircraft Monitoring

[MDScanFan]

Thank you for the detailed reply. I am constructing a dedicated vhf airband setup and have been eyeing that filter. It’s still in process so I don’t want to get ahead of myself and buy something for a problem that may not exist. I have a good FM filter I plan to try first.

An indoor installation can present a broadband noise challenge. Any idea what part of the spectrum is the main culprit in your situation? Have you tried any other filtering with your setup, such as an FM BCB filter.

 

[iMONITOR]

Thank you for the detailed reply. I am constructing a dedicated vhf airband setup and have been eyeing that filter. It’s still in process so I don’t want to get ahead of myself and buy something for a problem that may not exist. I have a good FM filter I plan to try first.

An indoor installation can present a broadband noise challenge. Any idea what part of the spectrum is the main culprit in your situation? Have you tried any other filtering with your setup, such as an FM BCB filter.

There is no significant interference coming from within my home. I confirmed this my shutting off all power to my home.

The main culprit in my area is strong FM broadcast radio stations as well as hospital pagers in my area. Previously I used a PAR FM notch filter. I see an improvement over the FM notch filter when using the PAR VHFBP filter.

 

[MDScanFan]

This is very useful information, thanks. Especially the comparison to the FM only filter. I am in a similar situation with very strong fm broadcasters as well as very strong pagers. I have an fm filter but have not yet tried a pager band filter.

 

[iMONITOR]

This is very useful information, thanks. Especially the comparison to the FM only filter. I am in a similar situation with very strong fm broadcasters as well as very strong pagers. I have an fm filter but have not yet tried a pager band filter.

It's a notch filter for FM broadcast, pagers, weather, ham radio, etc. Plus being a band pass filter it's attempts to block most anything other than VHF aircraft. So you don't want that if you're planning on monitoring UHF Mil-Air.

 

[majoco]

Tune the filter for what you want to do - pass the aero band or block the FM band. You can connect it both ways - either pass the unwanted signals to ground and pass the wanted ones to the radio or vice versa. Have you ever played with a tuned stub of coax from a Tee piece - hours of fun/frustration can be had from that. Ideally with a good signal generator rather than off-the-air signals.

 

[iMONITOR]

Tune the filter for what you want to do - pass the aero band or block the FM band. You can connect it both ways - either pass the unwanted signals to ground and pass the wanted ones to the radio or vice versa. Have you ever played with a tuned stub of coax from a Tee piece - hours of fun/frustration can be had from that. Ideally with a good signal generator rather than off-the-air signals.

Between my aging eyes and arthritis in my hands I'm not too good at working with coax and soldering connectors. Sometimes I don't think I'd be able to crimp them either. But I might try that.

 

[Ubbe]

Be careful as a coax stub have a broad frequency range where it attenuates signals, and also at multiples of it's frequency.

Stub filter measurements

/Ubbe