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Re: Damaged RF Power module



Hello Dave and all other kind replays,
Thank you for your time.
- The Power Module I am speaking of, is a Mitsubishi M67728 build into
the final amp. setup of my TS 790, rated at 35 W in FM.
- The story is the following, a near lightening strike destroyed the equipment
and part of the printed circuit related to the UHF output, so I decided to buy a
new circuit from Kenwood at US$ 90,00 and installed it.So far all is ok and
the unit switches from Rx to TX and back normally.The point is that the final
power output is only 0.5 Watts.
The driver module before the final module, M57716 draws at pin 4, 1.7 Amps
instead of the rated 2.32 Amps.All voltages are present as mentioned. The po-
wer module at pin 4 should read 8.35 Amps and is using only 0.7 at the pre-
sent moment with all rated voltages present. In my point of view the final
module
is dead and Kenwood,  short in replays and correct explanations, told me that
the module is repairable. The point is that a new module costs US$130,00, so
that I am trying to understand what is mend, by repairing this piece.
Again, thank you for any help- and explanations.
Regards
Nicolau - PP8DA

Nicolaus Sallay
E-mail : nsallay@internext.com.br

----- Original Message -----
From: "Dave Metz" <Dave.Metz@mut1.muscanet.com>
To: <nsallay@internext.com.br>
Sent: Saturday, February 24, 2001 10:46 AM
Subject: Re: [amsat-bb] Damaged RF Power module


> > Reply-to:      "Nicolaus Sallay" <nsallay@internext.com.br>
> > From:          "Nicolaus Sallay" <nsallay@internext.com.br>
> > To:            <amsat-bb@AMSAT.Org>
> > Subject:       [amsat-bb] Damaged RF Power module
> > Date:          Sat, 24 Feb 2001 09:54:19 -0400
>
> > Hello,
> >
> > I have been informed about the possibility to repair RF power modules.
> > I have a damaged UHF power module and I'm interested to rebuild this
> > part. Does anyone know a company who does this work and how are
> > the results,is it a reliable job, does anyone have a mail address to help
> > in the inquiry. Any information is welcome
> >
> > Thank you for all possible replies
> > Nicolaus Sallay - PP8DA
> > E-mail : nsallay@internext.com.br
>
> Dear Nick,
>
> It would help if we knew the type and part number of the module.
> The more information we have, the more we can do.
>
> If the part that failed is a transistor, chances are the module
> cannot be repaired.  If it is a failure in the metalization on the
> ceramic, then there is hope.  One of the local hams was able
> to repair a module that had a cracked internal connection.
>
> He removed the plastic cover and discovered that the module
> consisted of a ceramic sheet with the parts attached to it.  One
> of the metal interal traces had cracked.  He was able to solder
> it to repair it.
>
> Does the radio use PIN diodes for antenna switching?  If so,
> you must test the diodes.  RF Parts Company tells me that
> most of the time when a module does fail, it is due to the antenna
> switching diodes failing.  Sometimes there is no problem with
> the module at all.  It is the antenna circuit that is open due to a
> PIN diode problem.  In any case, check the diodes.  If one is
> bad, the new replacement module will also fail.
>
> Good Luck!
>
> --73-- David WA0AUQ
>
>

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