Hi Ian,
I've had similar expierences with Han, although I was trying to get the kit to
work from 1.8 to 60 Mhz. I found it very difficult to bias the kit and to keep
oscillation from occuring and very easy to destroy the transistor.
I think for the price of the kit, it's just as easy to chase down your own
parts and to even etch your own circuit board. The only troublesome parts to
find are the balun materials, specifically the coax, but you could purchase
those from cci.
Regards,
Paul
Does anyone have experience using this Motorola RF power MOSFET device in the
kit AR313 300W offered by Communication Concepts, Inc?
The appeal is the broadband capability across 10MHz to 150 MHz.
The idea is to use it on 50 and 70 MHz.
73,
Ian ZS6BTE.
------------------------------
Message: 2
Date: Mon, 22 Aug 2011 18:24:49 +0900
From: "Han Higasa" <higasa@plum.ocn.ne.jp>
Subject: Re: [Amps] MRF141g amp kit offered by CCI
To: <amps@contesting.com>
Message-ID: <3AE8E816FD06482D957B254CE2676CBB@yukikaze2010a>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
hi Ian
I have bought one MRF151G kit from CCI and made
experiments for long. There are some tips to tell.
It has too much power even on 2nd and 3rd harmonics
such as -16dBc (7.5W @300W out).
You need an absorption type LPF to address these
high power harmonics. Normal pi-LPFs can burn.
It is because of high-gain on unnecessary high band
and it can not be suppressed by feed-back resistors.
Ballancing two FETs in a gemini package by
separate gate bias circuits is better to lower these
harmonics.
And, maybe it is a fatal defect of the kit - input and
output board are separated and the FET tend to oscillate.
You need to short these boards with two pieces of
cupper ribbon near the FETs.
It may be the same on MRF141G kit and you need very
careful experiments to make it work on your desired
band - GL.
de Han JE1BMJ.
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