Avionic trouble

[Henning DE]

Hello !

I have some trouble with a King KX 175B Nav/Comm Radio:
I have connected a 14 V Unit to 28 V Power.
(The aircraft has two voltage buses)
Interesting, it does recieve very good and the lamps wont burn out, but once
you set it to transmit, thats it.
It will transmit once and then never again.
It still does recieve.

Did somebody out here made the same mistake ?
How can I fix it ? Is there a fuse inside ?
Any help is greatly appriciated.

Henning DE

[Rob Turk]

"Henning DE" > wrote in message
...
> Hello !
>
> I have some trouble with a King KX 175B Nav/Comm Radio:
> I have connected a 14 V Unit to 28 V Power.
> (The aircraft has two voltage buses)
> Interesting, it does recieve very good and the lamps wont burn out, but
> once you set it to transmit, thats it.
> It will transmit once and then never again.
> It still does recieve.
>
> Did somebody out here made the same mistake ?
> How can I fix it ? Is there a fuse inside ?
> Any help is greatly appriciated.
>
> Henning DE

If the unit still receives then it's unlikely that it just an internal fuse
gone. Most analog technology can withstand some amazing abuse, so I'm not
surprised your receiver still works. An exception are the RF power
transistors in your final amplifier. Those usually are quite fragile. I
wouldn't be surprised if they are fried.

You can replace them yourself, but I wouldn't recommend it if you don't know
what you're doing. Some types RF transistors contain highly poisonous stuff
(Berilium) which can be exposed when improperly handled. Also, tuning the
final amplifier after repair requires equipment that most of us don't have
at home. Get the radio to a certified repair shop for best (and safest)
result.

Rob