[IRCA] Phased loops

["Craig Healy" <bubba@xxxxxxxxxxxxxxxxxxxx>]

I finally had some time to try the DXE NCC-1 phaser with a couple of loops
this evening.  Here's the setup..

Truck equipment..

Palstar R30CC receiver with built-in DXE RPA-1 preamp.
DX Engineering NCC-1 phaser, stock except for BNC connectors substituted.

First loop is a 30" copper tube loop and DXE RPA-1 preamp already mounted in
the truck.  About six feet of RG58 coax.

Second loop is a large ferrite loop described here:
http://www.am-dx.com/ferrite_antenna.htm
A DXE RPA-1 preamp was connected directly to the loop and powered by a 12v
7ah wet cell battery.  The output from that went to a homebrew balun of 50
ohm to 110 ohm.  BNC in, RJ45 out.  150' of CAT5 cable used and an identical
balun at the truck end, connected directly to the NCC-1.

This setup worked really well.  I was able to null down locals about an hour
before sunset and hear things under them.  Completely eliminated IBOC hiss
on the offenders in town.  Unlike previous attempts to phase two loops,
there was little noticeable leakage.  I do wish I had a bit more time, but
it was an interesting half hour.

It was quite handy to only run out one antenna, and phase that against one
of the permanent truck loops.  Didn't seem to matter that one loop was a
ferrite bar and the other a copper tube.  Tests have shown them to be quite
similar in how they receive, so..

The battery powered preamp is quite convenient, though it can't be shut off
remotely.  I'm not sure shutting it off would be a good idea anyhow.  By
simply attenuating the amplified signal, any leakage ingress would be
similarly attenuated improving the overall signal to noise ratio.

As I continue to work with the NCC-1, I'm rather impressed.  I do need to
modify it so the A and B inputs can be shut off completely.  I also would
like to make the balance control more of a vernier.  It's quite touchy as
it's configured.

I have to wonder how this would compare to the beta test Wellbrook array..

Craig Healy
Providence, RI

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