On Jan 18, 8:20*am, BV wrote:
Hi

Got a pair of MRF648 and would like to build a 100W 70cm PA running at
13,8V.
I have been looking for constructions/idéeas on Google without luck.
Anybody able to help me?

If You got an article i can use, please mail it to me: bv(--at..)
mailme.dk

MRF648 data:

DESCRIPTION:
The ASI MRF648 is Designed for
12.5 V UHF large signal amplifier
applications up to 512 MHz.

FEATURES:
. Internal Input Matching Network
. PG = 4.4 dB at 60 W/470 MHz
. OmnigoldT Metalization System

MAXIMUM RATINGS
IC * * * * * * *11 A
VCBO * * * 36 V
VCEO * * * 16 V
VEBO * * * *4.0 V
PDISS * * * *175 W @ TC = 25 °C
TJ * * * * * * * -65 °C to +200 °C
TSTG * * * * -65 °C to +150 °C
?JC * * * * * *1.0 °C/W

73 de OZ1BV, Brian

Hi Brian,

My Motorola data book says these are designed for class C (e.g. FM)
amplifier service, not linear. I suppose you should expect to get a
little less PEP power out of them in linear service, for good
linearity.

The Moto data sheet has a test circuit; I could scan it, if it would
be any use to you. The microstrip dimensions are for glass-teflon
board, er=2.55, 1/16" (1.6mm) thick. Of course, the test circuit is
for a single transistor, not a pair. It is solidly class C: the base
and emitter are both at DC ground.

Cheers,
Tom