Antenna Pointers

Ground Loop from Outside Antenna feeds (which themselves have proper outside bonded grounds and suppressors)

Despite ground bonding, I was getting significant ground loop hum from the tuner connected to my outside antenna.  I tried various ways to fix this.  Two things "worked":

1) Running antenna lead to F connector surge protector on my Monster power bar, then to tuner.  This reduced ground loop hum a lot, but not entirely.  I think having suppressor outside and inside as well on antenna feeds is good practice for safety reasons.  I did not notice signal deterioration.

2) Running antenna feed through "Magic" isolator.  I got Magic isolators for TV use almost 20 years ago.  I was worried they might not work for FM, but the case says nothing about having an FM trap, so I went ahead, and noticed no signal reduction.  In combination with #1, this eliminated ground loop hum entirely.  The 60 hz hum at the input to my Behringer DEQ 2496 connected to the Sub Out line signal from my Yahama THX receiver dropped to -140dB.   Before doing #1, the level was worse than -90dB.  As I did this after #1, I did not try it without #1.

Ground loop reduction became the order of the day when I started running my subwoofer signal through the Behringer DEQ.  Isolating the signal between the receiver and the DEQ with a Jensen Isomax transformer actually made matters worse.  The Behringer has 3 wire AC input whereas the Yamaha is only 2 wire.  The ground of the Yamaha is therefore determined by what it plugged into it, or not.

However, until I discovered antenna grounding and isolating, I was forced to use a Jensen Isomax transformer on the audio output of the tuner.  Listening to radio without that, hum was terrible, like -50dB, and other sources not much better than -60dB.  Once I applied the antenna grounding and isolating steps, the isolation transformer was not only no longer needed...it was introducing a little hum by itself on the radio signal and was better removed.

NB: Ground loops did not appear until I started using the DEQ because nothing else in my kitchen audio system is grounded.

Before doing any of this, I tried measuring the ground voltage and current running through the coax.  It was extremely tiny.  But that's all it takes to induce -60dB hum.  I decided in itself it was "safe," not representing a ground failure, simply a ground loop.

Folded Dipole Antennas made from Twin Lead must have Soldered Ends

My biggest discovery of the year, the lack of soldered ends explained recurrent issues I had been having since 2002 when I made a special antenna tuned for TV Channel 9 which I am still using.  In the end, the folded dipole with unsoldered ends became a Channel 9 blocker for other antennas, so I couldn't get Channel 9 on anything.  Soldering the ends fixed everything, and I get perfect reception now.  Bare copper is prone to getting semi-conducting oxidation which does very weird things.

UHF Antenna location is extremely important, down to millimeters.

As I hoped, I was able to find a location on the south side of the kitchen for a UHF TV antenna that picks up all local stations perfectly.

The problematic multipath-prone TV signals were coming from the south.   Previously I had both UHF and VHF antennas on the north wall, but the UHF signals for Channel 4 (which actually broadcasts on Channel 48) and Channel 5 (which uses another UHF channel) had multipath issues with recurrent pixelization multiple times per minute.

I first figured the south wall would be better because I could position the antenna above the bathroom mirror on the other side of the wall which was probably not helpful.  It would also then have a clear path to a southern originating UHF transmission, instead of being blocked by HVAC and other metal objects around kitchen.

But even on the south wall, the precise position proved to be extremely important.  Too far one way and I would get dropouts on channel 29, which comes from the north!  Too far the other way, and I was still getting multipath issues on channels 4 and 5.  There was a happy spot right in the middle so I stuck my Clearstream Eclipse antenna with "permanent" adhesive strip right there and enjoyed perfect UHF TV all night on local channels.

Overnight the Eclipse had unstuck from the wall and slipped down just over an inch.  The performance was now abysmal again.  I now stapled the antenna back into place.  But making some error, I stapled it about 2mm lower than before (fortunately, I had marked the original position).

This was not as good, I determined that afternoon.  I was not getting as many dropouts, but I was still getting them.

Back on the wall, I found that positions above the original position I had found were even better.  In fact, the signal strength and freedom from multipath kept increasing as I raised the antenna all the way to the ceiling, so I stapled it there.

Now reception is perfect on all local UHF channels, with no dropouts.