[Yaesu] Yaesu FT-990 problem

Ken, W8EK kenw8ek at gmail.com
Fri Jul 20 10:48:47 EDT 2018

I have a Yaesu FT-990 that I would like suggestions on.

To start, it had no power output.  I discovered that the finals were 
working fine (producing a full 100 W), and that the problem was the 
T/R relay not switching. Further investigation showed that the actual 
T/R relay worked fine when 12 V DC was applied directly to the relay. 
The proper switch voltage was going into the PC board. That means that 
the switching transistor to activate the relay is likely bad.

I need to state that my vision is not what it once was, so I need to 
use a magnifier, which often gets in the way physically.

At this point, the receiver was working fine, and the only problem was 
power out the SO-239 on the back.  In probing the relay switching 
transistor, apparently the probe slipped.  I now have no receive, and 
no display on the front panel.  I am assuming that likely some portion 
of the power supply got shorted out.  Does anyone know what usually 
goes bad in this rig?

Or, does someone want a "project" Yaesu FT-990?  It is a very nice 
rig, and in great condition cosmetically.



Ken, W8EK

Ken Simpson
E-mail to W8EK at FLHam.net or W8EK at arrl.net
Voice Phone  (352) 732-8400


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