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Engineering Week Successes

Motivation has been lacking.  Been waiting a while for the sale to go through, so now we are a new company.  Very cool and it looks to be quite fruitful with the resources that appear to be had.  Many little/minor repairs have been done since my last post.  If you read the trades much in terms of streaming and connected media.  While all that goes on there is still radio and still needs to be met.  As a broadcast engineer the main deed is to keep our stations on the air!

Granted I had no off air time this week, I did have to deal with a couple of issues.  One is an auxiliary exciter that decided not to produce power.  This bad boy is an old Harris Superciter.  I believe it to be a post-Digit exciter and dates back to 2006.  As I had a spare Digit I was able to bring the Superciter to the shop for work.  Acquiring the schematics and manual was fun, and I dug up a schematic set, but no manual.  GatesAir was able to forward me a manual and another set of schematics.  After poking around I got frustrated as I did not know what readings I needed to see as certain points to determine what direction to go.  A few more emails and a better understanding led me to testing each stage.  Eventually I got really curious, so when I got to the Power Amp (PA), I began static testing the transistors which began to look good.  As this exciter is an Aux and just sits there with a quarterly turn on and run I figure it was time to really look for dirty contacts everywhere.  Anything I saw I cleaned.  I reconnected everything and had forward power!  Crossing my fingers, I put the box back together thinking it won’t turn on when I do.  Luck on my side, it came on again.  Ran it for over an hour into a load without issue.  I’ll fire it up again Monday to verify and plan on taking it back to the site.

As if this exciter thing was a pain, one of my main transmitters started doing something odd: It began having power fluctuations.  This is an “old” Nautel NV20.  Yeah, remember, I have the oldest ones out there at 6 1/2 years old now, so I get to experience the aging process.  No faults were showing except for PA module foldbacks and, sitting down, “Module # not responding.”  If a PA module is not responding there must be some fault somewhere.  I looked at everything.  I ran it into the load and watched it.  It didn’t matter which module it just randomly picked on as not responding, or two, three….  What else can I do?

I did what anyone would do.  Shut it down.  Remove each PA module and reset it.  While I did that I also checked the fans on each, though not showing failures, I’ve had a couple fail from old age already.  Found 2 that showed signs of failing and replaced them.  I check the connections to the exciter.  All good and tight.  Flipped the disconnect back on and let the AUI boot up.  I took it slow and selected a low power preset.  I stepped to to a low power with HD preset.  I went for the gold to full TPO of 10 kW.  I watched it with eagle eyes.  I dared it to do something.  Rock solid.  Heated that room up good running it into the load for 20+ minutes.  Time to put it back on the air, and it came right up.  Again I eyed it.  Both via front monitor AUI and via remote web browser, one on the main screen and the other on the status screen just waiting for it to mess up.  Rock solid.  Absolutely no power wavering.  I watched that thing for an hour, and then called it good.  The conclusion:  Even 20 kW Linux computers need to be rebooted, from a cold boot, on occasion.

Hope all your repairs turn out to be as simple and successful as mine have.  Look for the signposts while troubleshooting and take the proper path.  The repair becomes easy.  (Oooh, a Zen moment there.)

Cheers!

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