So finally all the pieces fell into place and we were able to discover that the issue we had with high VSWR was simply that we were visited by —-
Only consummate V’s will be used within this post as a result.
In all seriousness, this was an effect of climate change!
So, remember this, where the line was sweep tested and a big raunchy fault showed up at 1600 feet?
Here’s the fault:
Yeah, um, this got a little bit hot.
The remains of the inner sections of the line, an insulator that slumped and shrank all weird, and a mostly vaporized “bullet” connector. Here’s a figure of what one would look like if it was not… burninated….
Well, now that’s fixed, but the tower crew found a lot of debris in the line at multiple levels and issues with the hangers. One had a bad case of Spring Fever and some others had alignment problems that kept them from sliding their full range of motion.
This never presented a problem in 25 years of the line being in service…. until climate change threw us a RECORD HIGH heat wave. 118 degrees for several days… the line had never experienced heat that severe, and between that and the hanger misalignment, it caused sections of it to get kinked and that eventually broke the bullet somehow and blew everything up. The failure actually occurred early in the morning after the record heat wave broke and everything began to shrink back into its normal sizes.
Well that was a wild ride.
Now let me explain why I embarassingly fell asleep on the job while getting the transmitter back in order:
This is the most annoying and frustrating interface, I swear. In each of the transmitter cabinets, there are two Power Blocks. Each Power Block (PB) has a Phase and Gain module which is the intermediate power amplifier to drive the other amps in the PB, but instead of it just having three amp pallets in it, it has one preamp module that lets you, well, adjust the Phase and Gain.
On the old Space Station Toilet it had software controlled adjustments in each of its Intermediate Power Amplifiers (IPA) but also a set of manual trombone-slide phase adjusters that worked by being a variable length line in the RF path to it. They were pretty quick and easy to adjust.
This is not. This is very very much not. The way it works is you vary the step size by entering a number in that box, check or uncheck which PBs you want the adjustment to affect, then click the + or – buttons.
The result of your adjustment is reflected by the amount of power dissipated in the combiner reject loads, RL1, RL3, and RL2. RL1 / 3 are the combiners inside each of the cabinets between the two power blocks. RL2 is the one external to the cabinet sitting on top that merges it together. Basically, you want to balance RL1 / RL3 as well as possible, then continue balancing to get the RL2 power to minimum. Finally, in the case of this transmitter since it’s basically two ULXT’s externally combined, you pull up the interface to the Dualtran controller, watch the final combiner reject load power in there, and balance the two sides.
It is a very very very very tedious and slow process, complicated further by the fact that the web interfaces all time out every five minutes and make you log back in, even if you were actively in the process of making an adjustment! Click, click, click, click, BARF. I got to a point where I remember looking at the reject load power and wondering, hey, is that number of millivolts on the meter channel going up or down? I forgot what it just was a second ago, uh…..
Next thing I knew I was looking at the towers from a houseboat on the Sacramento River. Cassie was curled up on my lap and I found myself wondering how we got there and hoping I didn’t have to drive down there because she hates the car. She seemed very content though. I had no idea how I’d gotten there but I figured since it was so nice I shouldn’t really question it. There was a nice cool breeze coming through the windows and birds chirping in the distance. Cassie was watching them intently with her little tail twitching and she was doing the adorable little feline ekekekekekekek back at them.
Then I was just rudely dumped back into the reality that I was still sitting in front of that dumb web interface at the transmitter site. HOW ABSOLUTE DARE? That was so nice! Oh well.