[1000mp] tip: switching in extra band filters for reception

Sat, 11 May 2002 13:41:19 -0500

Hi Tom,

I'm interested in the noise canceller testing you performed.  I own both an
ANC-4 and a MFJ 1026.  How does the 1026 do relative to phase rotation range
and gain stability?  Thanks!

73,

John W0DC

----- Original Message -----
From: "Tom Rauch" <[email protected]>
To: <[email protected]>
Sent: Sunday, April 28, 2002 4:00 AM
Subject: Re: [1000mp] tip: switching in extra band filters for reception

> > I've been using this setup for several years. Someone posted this on
> > the reflector a few years ago. I had an ANC-4 but my W1FB homebrew
> > "QRN squasher" seems to me to be superior. The 12 volt power from the
> > MP such low power that it is almost useless. Don't know why Yaesu
> > didn't make this a bit heftier. 73, Tom K5IID
>
> I'm a bit surprised that the QRN Squasher seems to work better than
> the ANC-4. Either the QRN Squasher you have has changed from the
> original article, something else is going on other than phase
> cancellation, or you are pretty lucky with noise direction and
> antenna phase.
>
> A necessary part of properly working noise cancellation is the
> ability to rotate the relative phase difference between the main
> antenna and noise antenna through all 360 degrees of phase angle, and
> to keep the noise levels exactly matched between the two antennas.
>
> I looked at the design of the QRN Squasher and it had no system to
> rotate phase more than a few degrees. The "phase control" (as
> originally designed) can not change phase more than a few degrees,
> other than a 180-degree flip when the control crosses center. Gain
> would change like crazy with phase setting.
>
> It measures that way on a test bench also. I measured a maximum phase
> rotation on the order of 5 degrees from end-to-end on the phase
> control (other than the sharp 180-degree flip at the middle of the
> control setting).
>
> The ANC-4 could adjust phase almost 300 degrees total. The only bad
> thing was gain varied all over the place with phase adjustment, and
> phase did not rotate through all 360 degrees.
>
> Maybe you are just using the "phasing unit" as a gain control? Or has
> the QRN Squasher design been significantly changed?   73, Tom W8JI
> [email protected]
>
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