[Icom] IC-910H heat/fan problem

Sat, 23 Feb 2002 16:59:26 -0000

> -----Original Message-----
> From: [email protected] [mailto:[email protected]]On
> Behalf Of Ron Tivey
> Sent: Saturday, February 23, 2002 3:27 PM
> To: ICOM
> Subject: [Icom] IC-910H heat/fan problem
> 
> 
> 
> Hello to all,
> 
> 	I have a IC-910H with all the option installed.  I haven't 
> had any problems till today.  The problem appears to be heat.  
> When the radio is transmitting the fan will cycle from slow to 
> fast until the PTT is released.  Then the fan stops.  Seems to 
> be ambient temp build-up during tx/rx cycles.  Shouldn't the 
> radio fan stay running until the temp drops below a set point 
> from a thermostat?  

I noticed the same problem years ago in the ICOM IC-2KL.  The
fan would only run when the heat sink temp was above 30C, AND
when the PTT was on.  Just because I quit talking didn't mean 
the heat sink was cool.

This is one of the two mods I did to my IC-2KL that added to its
reliability I think.

I simply looked at the schematic, and saw that 12vdc was 
brought from the PTT circuit, through the thermal switch, and
to the fan.  To beat this, I removed the wire from the PTT 
circuit at the thermal switch, and wired 12vdc directly to the
thermal switch.  Now the fan runs when the thermal switch
closes, and stops when the thermal switch opens.  I have
been running it for years with this configuration and no trouble.
The down-side is that if you are using the amp and trying to hear
a weak station, the fan running might make that more difficult to
hear.  The way my station is set up, this is not a problem,  and 
your 910 fan probably isn't as loud as the IC-2KL fan anyway.

Good luck, whatever you decide to do.

Mike.