Date: Sat, 22 Apr 2017 16:53:50 +0000 (UTC)
From: Catherine James <catherine.james@att.net>
To: <amps@contesting.com>, Manfred Mornhinweg <manfred@ludens.cl>
Subject: Re: [Amps] Price per Watt Conversation
Manfred,
So would it be better to use 4 or or more devices with somewhat lower
ratings for linear operation?
Is there a cheaper option to use simpler heat sinks that don't have to be
carefully machine, but push them less hard by spreading the power over a larger
number of devices? What's the practical upper limit of devices that could be
used before creating other design problems?
73,
Cathy
N5WVR
## why not use 4 x BLF188XR or 4 x MRFX1K80H ? Is it even
possible to use 2 x devices in parallel in each half of a push-pull amplifier ?
If it is possible, then the heat could be extracted over 4 x devices.
The TX imd, with 4 x devices run at 1.5 kw, on paper, should be good, since
each device is running at 375 w pep output. Toss in pre-distortion, and IMD
could be reduced further.
## As is, I believe the SS amp manufacturers will be using pre-distortion
techniques to try and get acceptable IMD out of fewer devices. Meanwhile, the
pair of devices will still be running too hot.
## A 4 x device SS amp, if feasible, IMO, would not increase the total cost
of the amp by very much...but the benefits would be huge.
Jim VE7RF
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