Notch filter for AWOS interference on helicopter ops.

[Brentd2183]

Hi just completed a new radio install at our heliport and the AWOS station transmitting on 128.175 bleeds onto our base radio on our freq of 128.875. Only occurs when an aircraft transmits on 128.875 and you can hear the weather station in the background along with our transmission making it very difficult to hear the aircraft. Can they make a notch filter tight enough to filter out 128.175 and not lose 128.875 completely?

 

[iMONITOR]

Contact these people. They should be able to help.

Commercial Filters | PAR Electronics | Filters for the commercial 2 way market, MATV, FM broadcast, laboratory, marine industry, amateur radio, scanner and short wave listening enthusiasts

PAR Electronics, Inc.
P.O Box 645
Glenville, NC 28736
Voice: 828-743-1338
Fax: 866-304-8479

 

[Brentd2183]

I contacted them and this was the reply I got.

Thank you for the inquiry. Unfortunately, the spacing between the two channels is too close for small topology filters. You might try a pair of VHF cavities cascaded. They are not cheap- Sinclair Labs or RX/TX may still be manufacturing them.

Any advice from here?

 

[mikewazowski]

Increase the distance between antennas, change your frequency or follow their advice.

That's about all you can do.

 

[zz0468]

Contact EMR Corp. A multiple cavity bandpass-bandreject filter can be made to work. Expect to pay several thousand dollars for a custom set of very large cavities.

 

[kayn1n32008]

I contacted them and this was the reply I got.



Thank you for the inquiry. Unfortunately, the spacing between the two channels is too close for small topology filters. You might try a pair of VHF cavities cascaded. They are not cheap- Sinclair Labs or RX/TX may still be manufacturing them.



Any advice from here?

Do what they suggest. Contact Sinclair Radio labs, or Rx-Tx Systems, and tell them what you need... You may also need to notch out the weather frequency as well.