TopBand: ANC-4 Test

[w8jitom@postoffice.worldnet.att.net]

I just measured an ANC-4.

On 160 meters, the loss through the main antenna port was 5.38 dB. 
That port appeared to be passive, and had good IMD performance. (In 
comparison the DeMaw unit I have has 5.53 dB gain and the MFJ unit 
about 3.1 dB loss.)

The "noise" port was another story. It overloaded at less than 40 mV 
(-15 dBm) input regardless of gain setting, very poor IMD 
performance. (The DeMaw QRN Squasher unit overloads at over one 
volt at low gain settings, and the MFJ unit overloads at about 
1/2 volt no matter what the gain setting).

The ANC-4 did shift phase quite well (340 degrees total phase 
rotation) but unfortunately had over 23 dB amplitude drop as phase 
was rotated through its range, and as high as 13 dB amplitude shift 
even under the most favorable test conditions. This severe level 
change with phase adjustment would make it VERY difficult 
to find the right spot null on many signals and impossible to null 
some signals that would otherwise be "nullable".

(In contrast the DeMaw unit has NO phase rotation at all and over 
100 dB of unwanted amplitude shift as the phase control is 
adjusted, while the MFJ unit has less than 1.5 dB of unwanted 
amplitude shift and more than 326 degrees of phase rotation on 160.) 

73, Tom W8JI

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