[Boatanchors] using an LNA for R-1524(P)/WRR

[James A. (Andy) Moorer]

----- Original Message -----
 >
> [snip]. Would it be possible to insert a low noise wide band amplified 
> between the antenna and the receiver? I had the following in mind, 
> minicircuits ZFL-1000LN here is the spec 
> http://www.minicircuits.com/dg03-172.pdf  the range of the receiver is 
> 30-1000Mhz. I was thinking of using a discone as an antenna.
>
>> Would this help me? Would this even work? If an LNA concept could work, 
>> what kind of specs would I look for? gain? noise? IP3 (whatever that 
>> is!)?
>


The biggest problem in doing any kind of antenna amplifier (or "active 
antenna") is IM. Most such amplifiers have 3rd-order intercepts of 45 dB or 
less. This means that any station that is 45-dB stronger than another 
station (think clear-channel 50 kW FM stations in your backyard) will create 
"images" of both stations - they will splatter the upper bands with images. 
You will pick up your local FM station on, for instance, the 2-m band. That 
is the reason receivers have TRF stages, or, at least, bandpass filters on 
the input.


If you knocked out the FM band with a band-stop filter, it might be o.k., 
but there will still be images.

James A. (Andy) Moorer
www.jamminpower.com