True
By the way tomita stopped making the ferrite( large 2 holes)
There is no one else...
4z4rb
Baruch Zilbershatz
Nitzanay-Oz 118
Nitzanay -Oz
42836
ISRAEL
phone: (+)972-052 8753838
-----Original Message-----
From: alexeban [mailto:alexeban@gmail.com]
Sent: Monday, January 31, 2011 10:46 PM
To: 'Baruch Zilbershatz'; 'Fuqua, Bill L'
Cc: Amps@contesting.com
Subject: RE: [Amps] New solid state kid on the block
A little correction: MRI systems require a VERY linear RF system: they don't
tolerate well a high content of harmonics and/or IMD. This is the reason for
the 100mA quiescent current setting: it allows AB1 operation instead of pure
class B.
As for thermal behavior: these transistor cases were designed for water
cooling: a drilled out heatsink with cooling water circulating inside. We
tried its smaller brother at my last workplace with quite reasonable
results, installed on a copper heatsink made by the George Company with
forced air cooling and they worked all right too.
More problematic is the magnetic cores for the transformers: about the only
company making them is Tomita Electric and they don't exactly shine as to
service consciousness.
Alex 4Z5KS
-----Original Message-----
From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
Behalf Of Baruch Zilbershatz
Sent: Monday, January 31, 2011 6:42 PM
To: 'Fuqua, Bill L'
Cc: Amps@contesting.com
Subject: Re: [Amps] New solid state kid on the block
I made some tests with that animal.
It is more intended for class c or pulse in MRI systems at class AB it is
not better than the 578 that is for linear work.
Made 2 boards one regular FR4 the other Teflon duroid. Got great results
with the Teflon
The FR4 got very hot
4z4rb
Baruch Zilbershatz
Nitzanay-Oz 118
Nitzanay -Oz
42836
ISRAEL
phone: (+)972-052 8753838
-----Original Message-----
From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
Behalf Of Fuqua, Bill L
Sent: Monday, January 31, 2011 5:06 PM
To: Manfred Mornhinweg; amps@contesting.com
Subject: Re: [Amps] New solid state kid on the block
Looking at the data sheet. It is intended for class c operation. If you are
going to operate it in AB you will need one heck of a heat sink and low
thermal resistance to the heat sink.
But there is one thing that confuses me.
Case Temperature 63°C, 1250 W CW, 100 mA, 230 MHz @ RθJC 0.15 °C/W
Ok I understand 1250 Watts output CW with case temperature of 63 degrees.
What is the 100mA about?
In class AB the effeciency will be much lower and you would be talking about
much less output also it may be very nonlinear and require lots of negative
feedback
thus reducing its gain further. In class C at a glance it seems to have
fairly good gain.
73
Bill wa4lav
________________________________________
From: amps-bounces@contesting.com [amps-bounces@contesting.com] On Behalf Of
Manfred Mornhinweg [mmornhin@gmx.net]
Sent: Sunday, January 30, 2011 5:06 PM
To: amps@contesting.com
Subject: [Amps] New solid state kid on the block
Hi all,
has anyone yet gotten his hands on one of these new kids on the block?
http://cache.freescale.com/files/rf_if/doc/data_sheet/MRFE6VP61K25H.pdf?pspl
l=1
If anybody has tried it, I'm sure there are many of us who would love to
hear about it!
The data sheet isn't very complete, for example it tells essentially
nothing about thermal behavior of the bias. Some experimentation seems
to be in order. My only problem doing that is the price tag of around
USD 270! That should be fine for USING this baby, but not for RISKING it
while developing a stable good circuit!
Manfred.
========================
Visit my hobby homepage!
http://ludens.cl
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