Re: Topband: New MFJ 259C available

["Tom W8JI" <w8ji@w8ji.com>]

> The RigExpert handheld series of complex impedance analyzers pretty much 
> fit that goal.  The AA-54 is in the same price class as the MFJ-259B and 
> has +13 dBm output power.  It doesn’t have the frequency range of the 259B 
> but it will accurately cover HF through 6m.   At roughly 2x the price, the 
> AA-600 gets you a serious 600 MHz handheld analyzer with OSL calibration 
> and PC graphing connectivity.
+13 dBm is nothing. That is only 20 milliwatts or 1 volt across 50 ohms if 
that is at 50 ohms.
To be useful under conditions of RFI or AC offsets, the detector has to be 
selective. Otherwise it can take as much as 30 to 40 dBm in some common 
cases.
Remember what the bridge does. The bridge compares voltage balance. Even if 
the reverse signal is just a few percent of the desired bridge source, it 
hoses up the bridge. One or two bits out of 256 bits can make readings go 
goofy. 

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