[Elecraft] KPA 500

Johnny Siu vr2xmc at yahoo.com.hk
Sat Feb 5 18:58:06 EST 2011 

Hello John,

THP is a manufacturer for commercial equipment as well as per their web site.  
I just don't know why their ham amplifiers are so primitive.  They should have 
the technology and know how.  My past experience with THP in HF is not 
promising. V/U linears are ok.

I would always see linear + ATU as a package.  Therefore, THP + its own 
dedicated ATU is not that cheap.  Of course, I shall see how KPA500 + KAT500 
come out.

 cheers, 


Johnny VR2XMC 




________________________________
寄件人﹕ juergen <plebian99 at yahoo.com>
收件人﹕ elecraft at mailman.qth.net
傳送日期﹕ 2011/2/6 (日) 7:46:49 AM
主題： Re: [Elecraft] KPA 500


Hi Albert

I just looked at the picture of the inside of the THP amp.

http://www.tokyohypower.com/hl-550fx_i_pop.html

I am not impressed with the construction. It looks a lot like an Ameritron 
inside. At most it looks like a EB104 CCI amp with a power supply and a low pass 
filter board in a box. The cooling looks to be primitive at best.

I also dont like the switch mode power supply being so close to the high pass  
filter board. This is a recipe for noise and other problems. There is also a 
general lack of shielding. This might be ok for for 500 watt amplifier, however 
its very ""öpen""

I dont see  real value in this amp especially after looking inside it. I would 
be more inclined to go buy an Ameritron AlS1300 which represents good value and 
has similar or better construction. It would certainly have  better overhead in 
terms of output power.

73
John
--- On Sat, 2/5/11, juergen <plebian99 at yahoo.com> wrote:

> From: juergen <plebian99 at yahoo.com>
> Subject: Re: [Elecraft] KPA 500
> To: elecraft at mailman.qth.net, "Albert Crespo" <f5vhj at orange.fr>
> Date: Saturday, February 5, 2011, 3:33 PM
> Hi Albert
> 
> The old standard of 220,230,240 volts +- 10% has been
> gradually deteriorating to plus minus anything! 
> 
> The mains voltages  in many places now goes up to and
> regularly runs at 260 volts! The global de-regulation and
> privatization of power assets globally has seen
> standards  go down the drain everywhere.
> 
> Most quality switch mode power supplies are designed for
> voltages   as high as 260 high volts with a
> plus 5% rating. Many designers and export countries have not
> caught up with the global deregulation of mains voltage
> standards. In many places this has been allowed to happen in
> the hope that a global standard will develop.
> 
> I can buy energy saving globes that are rated to work at
> 260 volts(Philips). Many  TV's from the Korean
> companies are designed to  work at 260 volts. There is
> still a lot of new equipment designed for either 220 and 230
> volts nominally. This  well defined standard is hardly
> the  reality anywhere these days even with the +- 5%
> allowance
> 
> 
> The Tokyo high power amp looks interesting. They appear to
> be using VRF150's. If they have  biased this amp very
> well they will achieve good IMD results.  
> 
> SPE amplifiers using the MRF150's dont achieve the best IMD
> performance which can be obtained from  these devices.
> The Yaesu FT-5000's PA appears to be very well designed. The
> 3rd order IMD figures in Class AB according to the reviews
> are almost as low as Class A at 200 watts of output. They
> use VRF150's This a is a very good achievement by Yaesu and
> is a benchmark in terms of IMD performance.
> 
> I doubt that the Tokyo High power will achieve such good
> results because THP have always used just the bare minimum
> bias on all their amp designs. IMD optimization has never
> been a design goal of theirs. I had a good chat with the
> designer one day and he was open and candid about this
> issue.
> 
> Mt homebrew MRF150-EB104 amp easily achieves -40db 3rd IMD
> figures on all bands. My surplus ERB MRI amplifier 
> which I bought on Ebay does even better than -40db 3rd
> order. These are all below one of 2 tone figures not PEP
> figures. 
> 
> The Elecraft KPA500 will use VRF2933's for which  no
> IMD data  is provided on the data sheets. I dont know
> why Microsemi leaves out this important data. Macom
> religiously supplies extensive IMD data versus bias current
> which makes choosing devices very easy.  Anyway this
> will hardly be concern for anyone since the radios always
> have worst IMD performance than  the amplifiers.
> 
> I will watch the reviews and see how they both perform, the
> market is getting crowded! I will make my donation once I
> know how well they perform. It would be nice owning a 
> compact 500 watt amp  that performs well without all
> the mess and surplus rubbish hanging off the amp.
> 
> 73
> John
>  
> 
> --- On Sat, 2/5/11, Albert Crespo <f5vhj at orange.fr>
> wrote:
> 
> > From: Albert Crespo <f5vhj at orange.fr>
> > Subject: [Elecraft] KPA 500
> > To: elecraft at mailman.qth.net
> > Date: Saturday, February 5, 2011, 9:43 AM
> > Tokyo High Power has produced a 600
> > watt amplifier,  HL-550FX , 
>http://www.arraysolutions.com/Products/THPtop.htm   that
> > can handle a wide range of voltages, so it is ideal
> for
> > places with bad  voltage regulation. Will the  new
> > amplifier that Elecraft will produce will have this
> same
> > ability?
> >
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