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

[Tom Horton]

Tom,
  The one I am using is the original that came out in CQ about 1996.
Doug did modify it to a QRN Squasher MKII  (or something like that) about a 
year later.
I built it and went back to my old one.
I don't know what to say other than, I bought an ANC-4, plus several DSP
units to try to somewhat eliminate my severe line noise here.
The "Squasher" performed better on that than the others.
Of course, the best fix for that is getting the power company to fix the 
problems.
After taking them to court and 7 years, it's 90% fixed. But don't tell them 
that, I haven't !!!!!
73, Tom K5IID


At 05:00 04/28/02 -0400, you wrote:
> > 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
>W8JI@contesting.com
>
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