[hpsdr] 100W PA for Hermes

[Tim O'Rourke]

There are inexpensive 50V high amperage Server supplies on e-bay. I just purchased one for $19 and it looks new, has 230 volt input though. They are called hot swap supplie.
Tim W4Yn


-----Original Message-----
>From: Helmut Oeller <dc6ny at gmx.de>
>Sent: Nov 14, 2011 3:50 AM
>To: 'Kjell Karlsen' <la2ni at online.no>, hpsdr at lists.openhpsdr.org
>Subject: Re: [hpsdr] 100W PA for Hermes
>
>***** High Performance Software Defined Radio Discussion List *****
>
>Hi Kjell
>
>I agree that the job gets more challenging the lower the supply voltage is. But too many cascaded stages with low gain will also reduce the IM3 performance. Assume for a 3 stage amp configuration   -predriver-driver- final- with -45dBc /-40dBc/-35 dBc IM3 ( no bad single values for class AB). In total you will achieve -29,5 dBc !
>If you do the job with an 2 stage amp configuration, which seems possible for the required 25dB total gain, and assume further  -45dBc/-35dBc IM3. In total you will achieve now -32,5 dBc.
>
>I did some preliminary test with IXYS FETs  XZ2210N50L@ 48V, 120W PEP and 16 dB gain: 
>-38 dBc is achievable.
>The only question is: Do people accept the 48 V supply. 
>
>I think that the high IM3 performance of PENELOPE/HERMES requires adequate IM3 performance for the following amps.
>
>73 , Helmut
>
>-----Ursprüngliche Nachricht-----
>Von: hpsdr-bounces at lists.openhpsdr.org [mailto:hpsdr-bounces at lists.openhpsdr.org] Im Auftrag von Kjell Karlsen
>Gesendet: Sonntag, 13. November 2011 21:00
>An: hpsdr at lists.openhpsdr.org
>Betreff: Re: [hpsdr] 100W PA for Hermes
>
>***** High Performance Software Defined Radio Discussion List *****
>
>Hi Helmut.
>
>I have measured the IM3 on several commercial transceivers (Icom, Kenwood  
>etc.) and the IM3 at maximum PEP is always specified at -30 dBc.  Only the  
>most advanced and costly transceivers have better IM3 values at 100W PEP.  
>Take a look at the tests done by ARRL.
>
>At 12-14 Volt VDD it is very difficult to achieve better IM3. If you  
>increase the voltage to 28, 48 or even >100 volt, the results are much  
>better. I am looking at a solution using a high voltage MOSFET pair to get  
>300W PEP. If this is a success, it will be a simple and low cost solution.  
>The only drawback is the PSU but they are sold cheap on e-bay.
>
>Normally a Power Amplifier is delivering the maximum legal power at a  
>lower output than 100W from the transceiver and then the IM3 is better.
>
>73, Kjell
>
>
>
>
>
>
>På Sun, 13 Nov 2011 20:03:22 +0100, skrev Helmut Oeller <dc6ny at gmx.de>:
>
>> Hi,
>>
>> is it right that IM3 is only -30 dBc? For my impression too bad when  
>> driving a power amp.
>>
>> 73, Helmut
>>
>> -----Ursprüngliche Nachricht-----
>> Von: hpsdr-bounces at lists.openhpsdr.org  
>> [mailto:hpsdr-bounces at lists.openhpsdr.org] Im Auftrag von Kjell Karlsen
>> Gesendet: Sonntag, 13. November 2011 19:28
>> An: hpsdr at lists.openhpsdr.org
>> Betreff: Re: [hpsdr] 100W PA for Hermes
>>
>> ***** High Performance Software Defined Radio Discussion List *****
>>
>> Hi Jeff.
>>
>> As Abhi say, I have constructed a 100W PA and I am finishing the final  
>> PCB
>> layout now.
>>
>> One lab model and 2 Beta boards have been built and tested and soon I  
>> hope
>> to get the results from two other builders in DL.
>>
>> After the modification of the output transformer the results are very
>> good. Power output is > 100W PEP with >-30 dBc IM3 on all bands.
>>
>> I´ll post the measured results on
>> http://openhpsdr.org/wiki/index.php?title=MUNIN soon.
>>
>> 73, Kjell
>>
>>
>>
>>
>>
>>
>>> ***** High Performance Software Defined Radio Discussion List *****
>>>
>>
>>
>
>
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Tim O'Rourke 
W4YN at ARRL.Net
Low Power Amateur Radio Rocks 
Member of Flying Pigs,ARCI,GQRP,RSGB,ARRL Life Member
NHRA Life Member

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