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

[J. Forster]

Eugene Hertz wrote:

> Hello again...

[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!)?

I don't know the NF of your receiver offhand, but if it's over 3 or 4 dB (which is very likely) your setup could benefit from a LNA. I assume the Rx is a typical one with no RF amplification and just a BPF going into a mixer like the W-J/CEIs or ACL/DEIs.

The problem is with overload from TV, cell, and a bunch of other services. Assuming your LNA does not have an AGC (most don't) it will overload on strong signals in the bandpass. That's where a high 3rd Order Intercept spec becomes important. [BTW, an AGC is a mixed blessing because a strong signal in the BP can depress other signals]

Likely you'll have to insert a low loss BPF between the antenna and the LNA to do anything worthwhile, unless you are so far in the boonies that there are no nearby transmitters.

-John