Power Genius XL Design Decisions – 10/20/2018

Just read this PG XL update email explaining some hardware design details from Flex.  I found it quite interesting.  Looks like it is the first of a series.

 Howard

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 Over the upcoming updates I want to share some of the important design decisions that went into the creation of Power Genius XL. Our initial goal was to deliver one of the most durable, powerful and reliable amplifiers on the market under any operating condition. In pursuing this primary goal, we also wanted to find ways to reduce the total cost of ownership and create a product that strategically protects owners against market changes and vacuum tube obsolescence on the horizon. Central to the extension of Power Genius XL delivery time has been our commitment to achieving these goals. As we near resumption of production shipments, I would like to share some of the compelling new features of this state-of-the-art product.

 The Durability, Power and Reliability of Power Genius XL

 While mean-time-to-failure (MTTF) for legacy RF power tubes is difficult to know definitively, NXP makes the information readily available in their data sheet for the MRF1K50H LDMOS transistors used in Power Genius XL. A very informative article by NXP states that when operating the transistors at a case temperature of 100C the MTTF (see Figure 1 below from the MRF1K50H data sheet) its life is greater than 450 years! Combine this with the fact that the transistor is rated to “survive a 65:1 VSWR without device degradation” and you have the very definition of ruggedness. Further, Power Genius XL incorporates microsecond response time SWR protection circuitry to help protect the entire RF signal chain.

Figure 1 - MRF1K50 MTTF vs Junction Temperature

 Power Genius XL also incorporates a custom 4.9 in. W x 13 in. D x 2.4 in. H (125mm x 330mm x 60mm) heatsink made from pure aluminum for the best thermal conductivity of any aluminum heatsink.  The larger heatsink has double the typical number of fins for efficient heat removal.  Its 43 fins are 0.04 in. (1mm) thick with 0.12 in. (3mm) spacing between fins, and the MRF1K50H air-cavity ceramic package is designed for low thermal resistance of just 0.12°C/W thus providing excellent heat transfer from the chip die to the case. The cooling fan is positioned on the front side of the the PA cavity forcing air through the heatsink and out the back of the unit.

The bottom line is that Power Genius XL is designed to perform reliably at full 1,500 Watt legal limit on all modes, with virtually no power back off under the most extreme amateur conditions including FT8 and RTTY contesting.  

 Power Genius XL Reduces Total Cost of Ownership

The use of LDMOS transistors is one feature that makes the total cost of ownership (TCO) significantly lower for the Power Genius XL than for tube amps.  It's no secret that RF amplifier vacuum tubes continue to get more expensive easily costing $1,000 or more to replace, and most hams owning tube amplifiers have likely experienced tube failures at some point.  As tube amps are also power hungry, generate significant heat, take time to warm up, are extremely heavy, and use lots of space, the Power Genius XL is much more efficient over time.

 Power Genius XL incorporates not one but two of the most modern NXP MRF1K50H 1,500 Watt LDMOS power transistors delivering full legal limit output on all modes with 2X headroom. These recent advances in transistors will likely render tube amplifiers completely obsolete over the coming years.

 To summarize these key benefits and a few more, the Power Genius XL amplifier:

·     Instantly comes on with no warm up or tuning required,

·     Has a low cost of ownership, with no expensive tubes to replace,

·     Is lightweight - only 37.4 pounds (17 kg) including integrated power supply,

·     Has a small footprint - 6.25”H x 14”W x 20”D (15.9cm x 35.6cm x 50.7cm),

·     Generates less heat in the shack

·     Replacement transistors cost a small fraction of tubes, and

·     The MRF1K50H has guaranteed availability from NXP until at least 2031.

 In the next issue we will fill you in on some of the other important and unique design elements in the Power Genius XL.

 73,

Gerald, K5SDR