[ICOM] TX Problem IC970A 2.4 GHZ module

[STeve Andre']

I'm curious: have either of you contacted Icom in Japan about these
problems?

--STeve Andre'
wb8wsf

On Tuesday 01 March 2005 22:54, Gary wrote:
> I have this problem with my 1.2Ghz module. I'm still troubleshooting but
> it's looking like a bad PA module. The effort is a major pain without a
> schematic. I've asked for a schematic copy from every forum I could find
> but nobody replied. Not even Icom America or Scott Malcolm had literature
> on the 970 option modules. Doug is the first in my experience to even admit
> to having one of the 2.4Ghz modules, I hope he has literature to go with
> it. Good luck Doug. Gary
>
> "NICK.WALLACE" wrote:
> > Hi All,
> >
> > I am posting this on behalf of Doug VK4OE. We were wondering if anybody
> > else had encountered the same problem which is as follows. I will pass
> > any info received onto him.
> >
> > Thanks in anticipation.
> >
> > Nick   ZL1IU
> >
> > >From Doug.....
> >
> > Just to save you some typing, I'll describe again what I am
> > experiencing, which only relates to the 2.4 GHz module in transmit
> > mode....the other features of this excellent radio are currently working
> > well.
> >
> > The problem is one of "fading" transmitter power as something obviously
> > is heating up in the 2.4 GHz transmit path.  The scenario is that the
> > radio has been switched off for a time long enough for it to cool to
> > room temperature internally, then it is powered up and switched to 2.4
> > GHz transmit mode (continuous, e.g. FM).  The RF output control is set
> > to maximum.
> >
> > It transmits the full 1 Watt for 2 to 3 minutes (or 5 minutes if ambient
> > temperature is cooler) then, over a period of about a minute, the
> > transmitter power gradually falls away to around 50 mW.  Whilst this is
> > happening the ALC gradually climbs to a high level.
> >
> > Momentarily switching to RX or switching the whole radio off briefly
> > then on again do not lead to a return to 1 W output.  Only powering off
> > and letting the whole radio cool for an hour or so leads to a return to
> > 1 W output, and being ready for the whole fault sequence to occur again.
> >
> > It is conjectured that there is something wrong with one or more
> > component in the RF path between the TX amplifier and the antenna
> > connector, something which is thermally active.  Has anyone else had a
> > similar problem and found the solution?
> >
> > Thank you
> >
> > ----
> > Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net
> > Icom Users Net: Sundays, 1700Z, 14.316 MHz
> > Icom FAQ: http://www.qsl.net/icom/
>
> ----
> Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net
> Icom Users Net: Sundays, 1700Z, 14.316 MHz
> Icom FAQ: http://www.qsl.net/icom/