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Re: Topband: New MFJ 259C available

To: "topband" <topband@contesting.com>
Subject: Re: Topband: New MFJ 259C available
From: "Paul Christensen" <w9ac@arrl.net>
Date: Wed, 5 Mar 2014 14:03:07 -0500
List-post: <topband@contesting.com">mailto:topband@contesting.com>
Where is a selectivity spec or a description??

73 Tom

Tom,

Apart from the N2PK analyzer, I don't know any published selectivity spec. The detector minimum res. bandwidth of the N2PK unit is 7 Hz and produces +4dBm into 50 ohms.

FWIW, RigExpert put together a comparison of analyzers based on measurement topology. For sure, it's a biased piece -- especially when the MFJ product is discussed. So, keep that in mind.

http://www.rigexpert.com/index?s=articles&f=aas

The plot below shows how well the N2PK analyzer can selectivly ignore a large multi-volt base voltage from three nearby AMBC stations located 2 miles to the south. Two of the AM stations are Non-D in the daytime. One is 15KW, the other is 5KW. Note that the T is resonated to 1420 kHz, right where the stations transmit (look for 1320, 1460, and 1530 kHz). The attached plot shows total RF immunity on the X trace. On the R trace, small "blips" do show - each representing the local AMBC stations. However, even these can be easily ime-averaged away in the software.

http://72.52.250.47/images/N4NN.jpg

Paul, W9AC
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