The Kintronic Isocoupler

Had a problem with this Kintronic FMC-0.1 isocoupler the other morning.

Kintronic FMC-1.0 STL ioscoupler
Kintronic FMC-1.0 STL isocoupler

After an overnight drenching heavy rain and very high wind, the STL transmitter associated with this unit was having high VSWR faults.  This isocoupler crosses a base insulator of an AM 50 KW directional antenna.  This particular tower has negative impedance, which is to say, it sucks power out of the pattern and feeds it back to the phasor. An interesting discussion for another time, perhaps.

Using a dummy load, we isolated the problem to the isocoupler by first connecting the load to the output on top of the unit (problem still exists) then to the transmission line prior the unit (problem went away).  Of course, the AM station had to be taken off the air to do this work.

Once the issue was confirmed as the isocoupler, I opened the unit up and found that water had entered and pooled in the top of the bottom half of the isolation transformer.

Kintronic isocoupler transformer
Kintronic isocoupler transformer

The isolation transformer consists of two loops to ground capacitively coupled through air dielectric. The issue is with the opening around the top of the unit, under the lip of metal lid. Apparently, this allowed water in.

Kintronic isocoupler isolation transformer
Kintronic isocoupler isolation transformer

It is difficult to tell with the lighting in this photograph, however, the bottom part of this isolation transformer has water pooled around the center insulator.  Using a rag, I cleaned out the water and dirt from the center insulator.  After reconnecting the antenna and transmitter transmission line, a quick check revealed the problem was much better, but still not completely gone.  I suspect water seeped further down into the bottom half of this unit.  The repair work was good enough, however, to return both stations to the air.

Glad to get that bit of work done while it was still relatively warm out.

Tower take down video

Since the inception of youtube, I’ve watched hundreds of these tower collapse videos. I don’t know why, it interests me. This video is of the Coast Guard LORAN C tower in Port Clarence, Alaska. For what it’s worth, Port Clarence looks like a forlorn place, I am inclined to think my duty on Guam was rather nice in comparison.

This was filmed from six separate camera locations, including one at the base. It demonstrates how most towers fall within 1/3 of their constructed height. In this demolition, all three guy points are cut at the same time, removing the equalizing forces simultaneously. This would be the same situation as a catastrophic failure of a load bearing tower member.

The best parts of this video are the camera view of the tower base, around 1:04-1:19 and the side view where the camera almost gets hit by a tower section, 2:02-2:13.

I love physics.

Towers in the fog/repeating geometric shapes

For no other reason than they were there, I took a few shots under a couple of 300 foot self supporting towers.

300 foot self supporting communications tower in fog
300 foot self supporting communications tower in fog

This tower has a UHF slot antenna on the top of it fed with 6 inch hard line.

280 foot self supporting tower
280 foot self supporting tower

Tower next to the first one. Both can be found on North Mt. Beacon, NY, about 1,800 feet AMSL.