[hpsdr] Thor

[Jeroen Bastemeijer]

Hi Frank,

Thank you for the Excel-sheet. According to this sheet, almost 100W 
would be feasible with a 48V power supply. A slightly higher voltage 
would allow a real 100W power output without using a transformer. When 
using another amplifier topology 100W could be easily achieved (e.g. 
using MRF### transistors).

Thank you for your input! This certainly helps in making 
design-decissions for Demeter.

73 Jeroen PE1RGE

FRANCIS CARCIA wrote:
> Hi Guys,
>  I just did up a quick EXCEL showing the output power of different 
> configurations if we don't pay attention to transformer and device 
> losses. When you look at the Motorola applications you see  R = VCC^2 
> / 2 Po which can be flipped around to Po = Vcc^2 / 2 R.
> Since we know the load is 50 ohms just look at the load on the primary 
> of the transformer.
> 1:1 = 50 ohms (no transformer is also 50 ohms) 1:2 is 12.5 ohms, 1:3 = 
> 5.55 ohms,        1:4 = 3.125 ohms, and 1:5 is 2 ohms.  
> This assumes no impedance change in the output filter or tuning. Push 
> Pull you just double the input voltage VCC.  The advantage of Push 
> Pull is better harmonic rejection. I would not waste my time with a 
> single ended solid state final unless it is QRP.
> Notice the advantage of 130 volts on a class E final. My QEX final 
> didn't work all that well using the 1:3 or 1:4 ratio but I did step up 
> the impedance in the output circuit. It will peg a   5 KW PEP meter on 
> modulation peaks with a 1:2 transformer and a tuned network.
> Each turn of the secondary is over 20 inches so I think the leakage 
> inductance is effecting performance with extra turns.
> Take another look at AN 749 for dealing with circuit losses.
> I am sold on transmission line transformers after playing with the Erb 
> Tech amps and contacting the designer. Broadband performance is a lot 
> better than just stringing wire through cores. Frank
>  
> --- On *Fri, 4/17/09, Jeroen Bastemeijer /<j.bastemeijer at tudelft.nl>/* 
> wrote:
>
>     From: Jeroen Bastemeijer <j.bastemeijer at tudelft.nl>
>     Subject: Re: Thor
>     To: "Phil Harman" <phil at pharman.org>, carcia at sbcglobal.net, "HPSDR
>     discussion list" <hpsdr at hpsdr.org>
>     Date: Friday, April 17, 2009, 3:48 AM
>
>     Hi Phil and Frank,
>
>     Phil, thank you for the confirmation. Frank, I think (hope) that your mail to
>     the HPSDR list was triggered by the short discussion about the power supply for
>     Thor.
>     Quote from Franks e-mail: "48 volts with a 1:2 output transformer will
>     yield about 300 watts"
>
>     Can I "convert" that to a 150 Watts PA at 48V without a transformer?
>     Or is the transformer essential for impedance matching? What would be the
>     maximum operating frequency with and without the output transformer?
>
>     In short: Based on your experience would a 100 Watt PA working from 160m to
>     10m, powered from 48Volts be feasible? Or would it even be doable from 24Volts?
>
>     Looking forward to your answer,
>
>     73 Jeroen PE1RGE
>
>     Phil Harman wrote:
>     > Hi Jeroen,
>     > 
>     > 
>     >> Can I make the assumption that when Demeter gives a voltage of 48Volts
>     Thor is able to produce (approximately) 100Watts of output power? This
>     combination (HPSDR, Thor and Demeter) would make a nice mobile station, with a
>     very high energy efficiency!
>     >> 
>     > That would be fine.
>     > 
>     > 73's Phil...VK6APH 
>
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