[TowerTalk] SWR Analyzer / BC Interferance

[Jim Brown]

Important distinction.  The RigExpert and others like are vector 
IMPEDANCE analyzers. That is, they are a single port device.  They can 
only measure S11 (and in some cases, do TDR).

A VNA (Vector Network Analyzer) has two ports, so it can measure S11, 
S12, S21, and S22. In other words, it can also measure the complex 
response THROUGH a system.

This is an important distinction.  As far as I know, the best value in a 
VNA is the so-named VNWA, designed by DG8SAQ, built and sold by some 
hams in the UK. It gets its power from the USB port of the computer that 
also runs it and does signal processing for the analysis, goes to 1.3 
GHz. It's a real bargain, under $700 with calibration kit, shipped to 
the USA. I don't recommend the case.

http://dlwc.com/

73, Jim K9YC

On Thu,9/15/2016 11:26 AM, Joe Subich, W4TV wrote:
>
>> The pricier RigExpert devices appear to be VNA type analyzers that
>> incorporate "real" (i.e. selective) receivers and which would be
>> immune to out of band interference.
>
> VNA type analyzers *still have broadband detectors* and are not
> immune from broadcast interference if the broadcast signal is
> sufficiently stronger than the source (sweep) signal.  Performance
> of the VNA type analyzers depends on the resolution of the ADC,
> the ratio of the desired to undesired (interfering) signal and the
> ability of the software to distinguish between the two.
>
> 73,
>
>   ... Joe, W4TV
>
>
> On 9/15/2016 2:13 PM, Al Kozakiewicz wrote:
>> The issue with BC interference is going to be common to any analyzer
>> that uses a broadband detector.  The pricier RigExpert devices
>> appear to be VNA type analyzers that incorporate "real" (i.e.
>> selective) receivers and which would be immune to out of band
>> interference. Don't know about the rest.
>>
>> Al AB2ZY
>>
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