Also know by its Nautel Part number: UG-39
These are the stock power supply for 3rd and 4th generation Nautel V series FM transmitters, which were produced in the 00’s decade starting around 2005 but were discontinued sometime around 2009. First and second generation V series transmitters used Nautel made power supplies.
The OEM PA power supplies were made by Tectrol and were designed to put out 2120 watts per unit. The V-10 transmitters have eight PA supplies, one IPA supply with an option for a hot standby IPA supply. Like all such things, occasionally they fail for various reasons.
Unfortunately for Nautel, Tectrol stopped making these supplies and no longer supports them. Nautel won’t fix them either, however, they will sell a $3,200.00 (per supply) retrofit for a new supply.
We take care of seven of these transmitters and overall, they are fairly reliable. They are not terribly old either. However, spending $28,000.00 to replace the UG-39 power supplies seems… somewhat steep. One station uses four V-10 transmitters combined to make a 40 KW transmitter. For that station, it would cost $115,000.00 to replace all of the power supplies on a transmitter that is barely 13 years old. In this time of economic instability buying a new transmitter is not an option either.
Necessity being the mother of invention; we had a few of these defective power supplies kicking around, I decided to destructively reverse engineer one and determine the failure mode or modes. Special thanks to COVID-19 for giving us lots of spare time to do things with. Pete the Bench Guy, made up a test jig with a connector and some test points. With this, he can provide 240 VAC into the unit, feed 0 to +5VDC to the control pin, thereby vary the output voltage, look for faults, get ready indicators which the transmitter uses, etc.
Thus far, we have about an 80% success rate with these things. The failure modes vary from blow MOSFETS in the H bridge, bad PDM chips in the controller, fried resistors, a few other unusual things, etc. After repair, I usually burn it in for 24 hours in a nearby V-10 transmitter before we send it off to wherever it is supposed to go.