[Alinco] More help on a 605...

[sblanche@towertechnology.com.au]

Eric & others,

I have the DR-590  I noticed it runs hot enough to fry eggs on,
so when its in the car, I added a 3 inch 12v fan , using a
2 pin plug / socket external to the rear and ran it inside
and paralleled it with the existing tiny fan,   the base
is mounted up under the rear shelf in the trunk
of the car and the 3inch fan mounted up, just behind the
heatsink, so when it comes on it provides a good level
of airflow over the radio,  I can now tell the amount of
time that the fan is on is much less with the additional
fan, it  keeps the radio much cooler, comfortable
enough that I can now hold my hand on the case
easily after its been TXing for while,     without the fan,
you could burn your hand on the casing.

The two pin plug/socket combo was so I can remove the
radio from the trunk of the car, without having to remove
the 3inch fan as well, I just unplug it.

I also modified the inside of the radio, to connect the
thermo switch up to the 13.8v directly, bpassing the on/off
power switch, this way the fan can keep running,
after I have arrived and turn off the radio, it also
helps the radio, if the car is parked in the sun on a hot
day, it just automatically starts cooling the radio,
if it gets too hot in the car trunk.

 de Steve VK2KFJ



Eric wrote:


Ray,

>From the symptoms you describe, I suspect that PIN diode D5 is shorted.
It is one critical component that can easily self-destruct, since the
forward resistance increases as it gets hot, causing it drop more
voltage and thus dissipate more power- a vicious circle.  The dinky heat
sink on the back of the radio cannot remove the heat from the RF module
fast enough at high power, leading to component failure.  Consider
yourself very lucky that the RF module didn't go south.  This radio
really needs a fan!

A good test is to unsolder and remove D5, then turn on the radio to see
if the receiver now works.  Once you find and fix the problem, think
about cutting back the high power setting to 35 or 40 watts, just so
that it is not running at redline.  You might also use a Bird meter to
ensure that your antenna is properly matched to the radio.  The RF
modules used in the DR-605T and many other transceivers are prone to
overheating with a mismatched load, and such modules are seldom a true
50-ohm source.

73, Eric Lemmon WB6FLY

_______________________________________________
Alinco mailing list
Alinco@mailman.qth.net
http://mailman.qth.net/mailman/listinfo/alinco