• A Legal Limit HF Linear, Tokyo Style

2/9/07 -- Switch mode power supply.  I contacted EPCOS yesterday and got a response regarding their 600W smps, it delivers 150V @ 4A, my plan, see if I can get one, modify it for 120V @ 5A, and parallel 4 or 5 of them.  to get 2400 to 3000 watts DC input continuous.  Here is their smps reference design.  They are looking into making the modifications, or telling me how to make them, and whether or not they can provide me samples or an evaluation board.

2/6/07 -- Lookie what arrived in the mail.  Today, the mail man dropped off a big box of parts.  I've now got most of the parts from the original schematic.  All of the chip capacitors, the resistors, the ferrite core material and winding material, the coax for the matching transformers, and even the Power MOSFETS (MRF1500).  I'll have to make a complete inventory this weekend.

2/5/07 -- Power supply redesign.  I've gotten many suggestions from the amps reflector guys;  Isolation transformer ideas and input choke filter suggestions to regulate the voltage down the needed value, and even suggestions to make a power supply that is double insulated so it can use the mains directly.   Monday was project night for the Nashua ARC we presented project #2 and gave a hint to the other inventors about project #3.  They again confirmed my suspicions, we should be using a switching mode power supply.

1/15/07 -- Power supply design woes.   Some of the power supply parts for the low voltage section have.  This got me thinking about my design more.  The more I think about it, the more I don't like what I have done.  I subscribed to the amps reflector and posed a few key questions on my power supply design.  Basically, they confirmed my suspicions, and pointed out a large and potentially costly oversight.  Problem #1, no isolation from the AC mains.  Because I knew the MRF1500's could handle 125 volts DC, I simply rectified the 2 mains of a 220 circuit to provide 120V @ 15A each leg.  The second problem, and just as serious, is I forgot to take into account the RMS voltage in that 115V AC through a full wave bridge will actually come out closer to 162V, likely way too much for the MRF1500's.  So back to the drawing board.

11/25/06 -- Power supply design.  Providing 100V @ 30A is quite a tall order, especially for an embedded software engineer who's primarily been involved with small signal DSP projects.   After reading the power supply chapter in the ARRL handbook and searching the internet for various designs, I came up with my own supply, I thought it was quite clever.   I've contacted various supplies, and have parts on order, awaiting samples delivery.  See the first design here.