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Re: Topband: New Linear amp

To: "Bruce" <k1fz@myfairpoint.net>, <topband@contesting.com>
Subject: Re: Topband: New Linear amp
From: "Tom W8JI" <w8ji@w8ji.com>
Reply-to: Tom W8JI <w8ji@w8ji.com>
Date: Sat, 7 Jul 2012 12:48:41 -0400
List-post: <topband@contesting.com">mailto:topband@contesting.com>
> This MRFE6VP61K25H solid state device is catching on fast in amateur radio 
> circles. HF Amps next.
>
> http://www.m2inc.com/pdf_manuals/2M-1K2.pdf


Here is the tough time with this, because I'm sure most people take device 
manufacturer's data at surface value. All of this stuff, to this point of 
time, is mostly vaporware.

Here are the worries:

1.) While manufacturer's make wild claims about device VSWR tolerance, those 
specs are really just creative marketing fantasy. A 2:1 SWR would instantly 
blow the device up if peak voltage breakdown is exceeded, or over a short 
period of time if heat limits in the junction are exceeded. If you do not 
see SWR fault protection, and there are no current limits, you can bet 
devices will fail with some conditions of mismatch.

Their popular U-tube video is at pulsed service with a power limited supply. 
I can do the same thing with MRF150's, and actually designed a medical 
device that ran 1000 watts of peak output power on two MRF150's, without SWR 
protection, on 27.120 MHz. The reason it lived is the power supply would 
barely supply 100 watts average power, and it was pulsed duty cycle with 
very low Q filters and matching.

2.) No SSB IMD spec's.

3.) All public data appears to be matched narrow-band class-C pulsed 
service.

4.) Getting heat out of a small surface transfer area at high power and high 
duty cycles is a major problem.

There was a good marketing presentation by the device manufacturer, but 
nothing indicates it is anything special for HF or linear service, or going 
to "catch on fast".

73 Tom 

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