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 <plebia...@yahoo.com> 收件人﹕ elecraft@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 <plebia...@yahoo.com> wrote: > From: juergen <plebia...@yahoo.com> > Subject: Re: [Elecraft] KPA 500 > To: elecraft@mailman.qth.net, "Albert Crespo" <f5...@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 <f5...@orange.fr> > wrote: > > > From: Albert Crespo <f5...@orange.fr> > > Subject: [Elecraft] KPA 500 > > To: elecraft@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? > > > ______________________________________________________________ > > Elecraft mailing list > > Home: http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/mmfaq.htm > > Post: mailto:Elecraft@mailman.qth.net > > > > This list hosted by: http://www.qsl.net > > Please help support this email list: http://www.qsl.net/donate.html > > > > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
