JamesO
Member
A few things you need to consider.
1. Local FM broadcasts can easily overload the pre-amp. Where are you located? City & State and are you close to many FM transmitters. I live less than 5 miles as the crow flies from a 75,000 Watt commercial broadcast tower. So I have purchased and installed a higher quality FM broadcast notch filter.
2. Depending on the length of cable run, you may or may not need to attenuate the signal as it feeds the radio.
3. I have a situation where I have a VERY long run of RG6 cable from the antenna pre-amp to a 4 way splitter feeding 4 scanners. Even with the pre-amp I need to have an additional amp to raise the composite signal level hitting the splitter.
4. You might want to try a variable power supply. Varying the Voltage to amplifier will typically reduce the gain of the amplifier AND will often also reduce the noise figure as well.
5. Suggest you use a NOAA Weather Broadcast to compare antenna and amplifiers against. I have a number of NOAA Weather channels that are very weak and I can use these for antenna and amplifier tweaking. Also you can try turning the attenuator on for a specific channel and see how things work.
I am fortunate enough to have a spectrum analyzer so I can look at the entire spectrum, find very strong signals, see images and even sweep test filters and amplifiers.
But when you do not have a spectrum analyzer handy, you will need to use the radios S meter as well as the attenuator and either aircraft beacons and weather channels.
1. Local FM broadcasts can easily overload the pre-amp. Where are you located? City & State and are you close to many FM transmitters. I live less than 5 miles as the crow flies from a 75,000 Watt commercial broadcast tower. So I have purchased and installed a higher quality FM broadcast notch filter.
2. Depending on the length of cable run, you may or may not need to attenuate the signal as it feeds the radio.
3. I have a situation where I have a VERY long run of RG6 cable from the antenna pre-amp to a 4 way splitter feeding 4 scanners. Even with the pre-amp I need to have an additional amp to raise the composite signal level hitting the splitter.
4. You might want to try a variable power supply. Varying the Voltage to amplifier will typically reduce the gain of the amplifier AND will often also reduce the noise figure as well.
5. Suggest you use a NOAA Weather Broadcast to compare antenna and amplifiers against. I have a number of NOAA Weather channels that are very weak and I can use these for antenna and amplifier tweaking. Also you can try turning the attenuator on for a specific channel and see how things work.
I am fortunate enough to have a spectrum analyzer so I can look at the entire spectrum, find very strong signals, see images and even sweep test filters and amplifiers.
But when you do not have a spectrum analyzer handy, you will need to use the radios S meter as well as the attenuator and either aircraft beacons and weather channels.
