[ICOM] Re Xmit problem with IC-745

[M. J. Taylor]

My 745 has a similar issue:  Output is erratic (into a 50 ohm load) as I 
increase the RF Level.  The  meter juumps around, like I am turning a 'dirty 
pot.'  If  I do get it to full power, when I go to transmit it has been 
either hit or miss, output or nothing.  This is true in either CW or SSB,  I 
hear a noise that I thought could be an erratic relay or even arcing, but I 
don't smell anythig.
Anyone have similar experience?

Regards,

Milt, WA3MDS


----- Original Message ----- 
From: "GGLL" <nagato at speedy.com.ar>
To: <icom at mailman.qth.net>
Sent: Saturday, November 05, 2016 8:00 PM
Subject: Re: [ICOM] Re Xmit problem with IC-745


R64 is 47 ohms. If you have 13.8V when in TX mode, at the source side of
it and 3.6V at the load side, circulating current is approx. 200 mA
through R64, so it should be very hot (almost 2 W dissipation).

Check its value, if not so hot.

Regards
Guillermo - LU5WE.

El 05/11/16 a las 19:56, Fern Rivard escribió:
> I have an IC-745 which has a no transmit issue on all modes.
> I know that the problem is in the RF board as I proved it by
> substitution of rf  board from another IC-745 which has no issues.
> I'm not getting proper dc voltage to Q16.
> There's only 3.5 volts dc on the load side of R64 so there's  something
> loading the dc voltage down that feeds Q16 but it's difficult to probe
> that board while installed in the radio.
> I initially replaced Q16 with a new 2SC2053 with no change.
> Any help or suggestions as to what to look for would be greatly
> appreciated.
> I'm sure that somebody else must have had the same issue at one time.
> I'd like to donate this rig to a new ham as their first rig but have to
> get it operational first.
> 73 from Fern  VE7GZ
>
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