[Amps] Future of RF AMPS

[Richard Solomon]

There are some review(s) on M2 and Bekko SS Amps on e-Ham, not many but
a start.

Most of the "design" faults you mention were do to unforseen circumstances,
not
by ignoring proper design procedures; namely, the glue, the solder, the
crystal and
a couple of others. I could tell you about the Mercedes-Benz fiasco with
Hydraulic
Cylinders and the fluid that ate the seals causing premature (and
expensive)
failures.

"Stuff" happens, it isn't done on purpose (mostly) and should not be cause
to condemn
a company or product as a whole.

I don't know of anyone who owns an M2 SS Amp, but I will ask around.

73, Dick, W1KSZ


On Mon, Sep 16, 2013 at 11:39 AM, Manfred Mornhinweg <manfred at ludens.cl>wrote:

> Dick,
>
>
>  I have to believe that M2 knows what they are doing with these Amps. They
>> offer a 12 month limited warranty on them.
>>
>
> I really hope so! I know nobody who owns one of those amps and uses it
> intensively, so I frankly have no idea whether or not they last. But if
> they do last, I would like to understand how and why! It is totally
> possible and even likely that the difference between my highly simplified
> math, and a really accurate calculation, would explain it, and show those
> amps to run the FETs within specs. But I have certainly seen many devices,
> specially power supplies and linear amps, built buy hams, that suffer
> failures because of totally wrong thermal design. That's why I wanted to
> bring this issue to the attention to those wanting to milk any high power
> transistors to their maximum ratings.
>
> And then, it is well known that manufacturers are not always right in
> everything they do, even when they give warranty! Just think about all
> those many known cases of typical failures, that end up affecting most or
> all radios of some specific model. Some examples: The Kenwood TS-440 with
> its glue that degrades and makes the VCOs fail; the TM-241 with its display
> going crazy because of a tiny interboard connector that develops excessive
> contact resistance; the old Yaesy FT-207 in which the 10.245Mhz crystal
> cracked from excessive drive; The FT-ONE, which had a crystal that shifted
> several tens of kilohertz over twenty years; The Icom IC-746 series with
> its several thermal problems, such as with the pre-driver transistor, the
> wideband amplifier IC, and the transistor that regulates the display
> brighness - all these coming from incorrect thermal handling of SMDs. Do
> you want more? The rotting DDS chips in the TS-450 and TS-850, the many
> problems of connectors directly soldered to circuit boards, in many radios
> of most brands, so that those solder joints break, assorted trouble with
> breaking solder joints on PCBs when too heavy parts are supported solely
> from the solder joints, and so on.
>
> Even the most professional designers at the best known companies are only
> humans, and do goof at times! So do the providers of components and
> materials.
>
> The single most intriguing issue of misdesign, that I would like to fully
> understand, is that matter of incorrectly understood and applied
> transformers in push pull amplifiers. I have explained this in full on this
> page of my site:
>
> http://ludens.cl/Electron/**mosfetamps/amps.html<http://ludens.cl/Electron/mosfetamps/amps.html>
>
> I mean the section entitled "Output architectures of conventional class AB
> push-pull amplifiers".
>
> This is a typical case of "it's not possible that all manufacturers are
> wrong and just XQ6FOD is right". It does feel weird to me to stand up
> against all those that make their money building and selling transceivers
> containing that bug! Nevertheless I simply don't see how it  could be right
> their way. I first discovered this problem in homebuilt equipment 30 years
> ago, when I copied circuits from ARRL literature, and have later confirmed
> in in actual factory made radios from the big brands, and also by
> simulation. Recently a German ham contacted me, reporting that he built two
> test amplifiers (100W, 13.8V), which were identical except for the issue I
> describe, and that he measured a modest but noticeable (3dB) improvement in
> gain, a significant improvement in efficiency, and a big improvement in IMD
> performance, when using the layout I consider correct, compared to the one
> most present-day HF radios use.
>
> Go figure.
>
> I would really love to see either a statement by some RF guru, declaring
> that I'm right and they are wrong, and hopefully giving an explanation of
> how this mistake became so widespread, or else someone (whether he is a
> guru or not) who can explain why the method used by manufacturers in some
> radios and also propagated by Granberg et al in some papers and copied by
> the ARRL (center-tapping a single-turn winding that has
> independent magnetic paths for each half winding) is correct!
>
>
> Manfred
>
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