Moonraker 2000 Mk2 Preamp.

[Eugene]

Greetings. I have the above preamp for mobile use. It does a fairly good job and I am satisfied with its performance so far. Curiosity has gotten the better of me however. It claims to have 6-20 dB gain. Since there is to way to adjust it....."how do it know?" What signals get 6 dB and which 20dB and which in between? I have my own idea but not being an electrical engineer it is mere speculation on my part. Thanks in advance.

Eugene KG4AVE

 

[Ubbe]

As it is specified for 25MHz to 2000MHz it must be 6dB at its highest frequency and 20dB at the lowest. The specification for semiconductors are always lower gain with higher frequencies as stray capacitance have a bigger impact at higher frequencies.

If you put an amplifier directly at the scanner you probably need 6dB at most to not overload the receiver and de-sense it and loose more sensitivity than without the preamp. You always have to attenuate a 20dB gain signal and preferably using a variable attenuator. Something like this:

/Ubbe

 

[Eugene]

Great....thanks for the reply. Actually I have an RTL-SDR FM trap at the antenna, followed by the pre-amp and then 15 feet of coax. Glad to know that's how it works. Thanks again.

Eugene KG4AVE