Just a brief comment on the ChannelMaster CM-3202 FM filter. I live in a major metro area and am LOS to all kinds of transmitters, FM, TV, etc. I have an old RS discone in the attic. I'm using 25 feet of RG-6 cable. In general, my reception is just ok. Online images indicated the CM-3202 had negligible insertion loss above 120 MHz. I installed the filter in line at the discone and the local 128 MHz ATIS transmitter improved dramatically. Empirically, the filter has not had a noticable negative effect on lower VHF air. For $25, this may be worth considering if you are already running RG-6 and Type F connectors. FYI.
Ubbe
Member
What scanner are you using? It says on the filter that it blocks up to 124MHz so probably not useful to most aviation listeners.
There's a thread here on RR where many FM filters have been measured for frequency and attenuation and can be used to choose a suitable filter depending of how severe the FM broadcast interference are and what airband frequencies you need to receive.
/Ubbe
There's a thread here on RR where many FM filters have been measured for frequency and attenuation and can be used to choose a suitable filter depending of how severe the FM broadcast interference are and what airband frequencies you need to receive.
/Ubbe
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The attached pic is from an Amazon review. The filter looks ok for those wanting to monitor civil air band. There is compromise at the low end of the band, 88 MHz, because Channel Master did not want to attenuate the VHF TV channels more than absolutely necessary.
Ubbe-I appreciate your reply. I'm using a BCD536HP. I wanted to experiment with a low cost FM filter with Type F connectors. I agree that the filter specs may indicate a problem for VHF air. However, I saw the above frequency response, posted by pro92b, on line and thought it would be worth a try for $25. It has worked well for what I wanted. Are there any better low cost options with Type F connectors?
As I previously stated, I live in an urban area LOS to multiple transmitters. I also installed a ChannelMaster CM-3201 LTE / 5G filter with the CM-3202 FM filter. It also helped with RFI. But, it attenuates above 600 MHz. I use a seperate radio and dedicated antenna for 800 MHz.
As I previously stated, I live in an urban area LOS to multiple transmitters. I also installed a ChannelMaster CM-3201 LTE / 5G filter with the CM-3202 FM filter. It also helped with RFI. But, it attenuates above 600 MHz. I use a seperate radio and dedicated antenna for 800 MHz.
Ubbe
Member
Probably not. That CM filter are some of the better ones and its stated frequency range isn't really accurate, or has high manufacturing tolerances. It only attenuates 3dB at 83MHz and 118MHz but still 30dB at 88Mhz and 50dB at 108MHz. When you use F connectors you usually have equipment where you wish to receive FM broadcast signals, so most filters will have SMA or BNC.
The BCD536 has its own band pass filter set to 108-136MHz so it won't attenuate much in the upper FM broadcast band and could use a good FM trap filter.
/Ubbe