Topband: ANC-4 noise canceller

[Tom Rauch]

> Awhile back, someone on this reflector suggested that I
> invest in a Timewave ANC-4 noise canceller. I went to
> Timewave's website and did some reading on this device.
> It said that the unit has a power handling capacity of 250
> watts.

Hi Brad,

I usually don't dissuade anyone from any particular manufacturer or 
product, but if you are considering a noise canceller I'd get the 
MFJ1025. If anything will work for your case, it will.

The MFJ1025 is actually a cheaper version of a phasing system I use. 
(Mine has $30 FET's and other things, and would cost nearly $1000 to 
sell. Theirs uses J310 FET's, and this gives up a bit of noise floor 
and dynamic range. I pay a lot for a few dB extra of receive, hi hi.) 

This assumes of course all units work as designed.

The reason for this advice is simple. I've measured both (along with 
the canceller from W1FB) and the MFJ by far has much better amplitude 
and phase control. In addition, it is basically gain neutral. It 
neither adds nor removes a significant amount of signal level. 

The QRN Squasher by DeMaw has almost no adjustable phase shift (just 
a few degrees) other than an abrupt 180-degree flip and has severe 
amplitude change with phase adjustment (what little there is). 

The AEA unit shifts phase OK (nearly 120 degrees plus a 180 flip ), 
but has severe amplitude change (over 15dB as I recall) with phase 
adjustment and is pretty touchy. It also, at some phase settings, has 
significant loss and a very poor noise floor.

The MFJ unit has wider smoother phase adjustment (around 150 degrees 
on 160 meters, plus a 180 flip), and has less than 2dB of total 
amplitude shift as the phase is adjusted. It deteriorates the noise 
floor a few dB, but less than the other units.

This performance difference is significant enough to put up with 
MFJ's common QC issues in manufacturing!

As for power handling, that shouldn't be an issue. The unit goes 
between the radio and the amplifier, and wouldn't see anything more 
than the exciter puts out whether you use an amp or not.  73, Tom 
W8JI
W8JI@contesting.com