[Icom] RE:R9000 and 781 heat

Wed, 09 Oct 2002 09:15:57 -0700

Hi Bruce,

The specifications in the IC-781 service manual show the mains voltage range
as AC 100 ~ 120V. It is possible that the regulator will be nearing the
bottom of its control range at 100V input. Once check you can perform is to
select Vc on the meter switch, and verify that the PA collector-supply
voltage remains constant as you vary the mains voltage between 100V and
120V.

Another option is to install the Sherwood fan kit, and operate the radio at
115V.

http://www.sherweng.com/IC781Fan.htm

Cheers for now, 73,
Adam VA7OJ/AB4OJ

-----Original Message-----
From: [email protected] [mailto:[email protected]]On
Behalf Of Bruce Marton
Sent: Wednesday, October 09, 2002 05:51
To: [email protected]
Subject: [Icom] RE:R9000 and 781 heat

Hello Adam,

I had been running my 781 down around 105 volts to help reduce the heat
problems.  It appears to work fairly well, however it will distort the
center point of the display freq on the scope.  This can be adjusted
internally, but I was just living with it.
I spoke to a well known Icom service tech (independent) and he advised
that the rig be run at the higher input voltage, say 115 to 120 since
the low voltage will compromise other functions of the radio.  I am
confused on this issue since the specs claim to have an operational
mains voltage range of 100 to 120v.

What issues is this tech concerned with?  Any ideas?
Bruce K1XR