Fw: [ICOM] 751A Won't Transmit

[EP Swynar]

Hi Gary,

 I shall certainly pass the info onto him, with thanks...! Will post the
result(s), if positive, Hi Hi...

 Thanks again, & vy

 ~73!~ Eddy VE3CUI - VE3XZ

 *****************************
>
>
> ----- Original Message ----- 
> From: "Gary P. Fiber" <gfiber at comcast.net>
> To: "ICOM Reflector" <icom at mailman.qth.net>
> Sent: Friday, October 12, 2007 12:34 PM
> Subject: Re: [ICOM] 751A Won't Transmit
>
>
> > Have him take a look at the Transmit 8 volt line that might be the
> > trouble. for some reason its not getting to where its supposed to be
> > while attempting to transmit.
> > Also:
> >
> >
> >       Knowledge Base Article 5BA9425945
> >
> > Issue
> > No TX output from my 751 in all modes. Problem is traced to no output at
> > J8 connector on the RF unit.
> >
> > Resolution
> > There is a bad Q14 transistor amplifier on RF unit. Replace Q14
> > transistor. There may be other problems on the RF unit. Check the DC
> > voltages at D47 diode.
> >
> > Category
> > Amateur : HF : 751
> >
> >
> >       Knowledge Base Article 5BA9554454
> >
> > Issue
> > No TX output at all in RTTY or CW modes from my 751/751A. SSB and AM are
> OK.
> >
> > Resolution
> > There is a bad carrier generator crystal on the main unit. Replace X1
> > crystal.
> >
> > Category
> > Amateur : HF : 751
> >
> > Hope some of this helps.
> >
> > Gary K8IZ
> >
> > EP Swynar wrote:
> > > Good Day All.
> > >
> > > This is an absolute long shot, I know, but without my technical
> supplement here beside me, all I can do is quote my buddy...
> > >
> > > My 751A suddenly, & without warning, refused to transmit awhile back.
It
> receives A-OK, but the instant you hit the transmitting key / microphone,
> the RF power output needle will swing upward for a nanosecond, & that's
> all...no RF output in any mode...
> > >
> > > My friend, who does consumer electronics repair for a business, says
> that he has traced the problem to a 9-MHz crystal oscillator board that
> suddenly stops oscillating when the rig is put into transmit mode. He says
> the crystal & all the voltages appear to be normal & functioning, except
> when transmitting --- then it just stops working.
> > >
> > > Has anyone else ever encountered this problem...? I researched my old
> QST magazines & located the review for the 751, & apparently the one under
> review did the same thing --- wouldn't transmit, but no reason given
beyond
> it being due to a "...bad resistor".
> > >
> > > Like I said initially, it's a L-O-N-G shot...!
> > >
> > > Any & all feedback appreciated...thanks!
> > >
> > > ~73~ Eddy VE3CUI - VE3XZ
> > > ----
> > > Your Moderator: Dick Flanagan K7VC,
> > > (and temporarily N8TFD/Steve): 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,
> > (and temporarily N8TFD/Steve): icom-owner at mailman.qth.net
> > Icom Users Net: Sundays, 1700Z, 14.316 MHz
> > Icom FAQ: http://www.qsl.net/icom/
>