[Icom] Re:R9000 RECIVER TT-340

Tue, 08 Oct 2002 21:40:29 -0700

Hi George,

Oops! You are correct. I miscalculated (V2)/R - I eat a kilo of humble pie
before thee. Reducing the mains voltage to 100V will largely eliminate the
IC-781 heat problem; I would advise your friend to power his radio via an
autotransformer.

Were the new Icom radio to pip the Orion at the post, it would then surely
be time for the Tennessee equivalent of honourable seppuku in Dolly Parton
country!

Cheers for now, 73,
Adam VA7OJ/AB4OJ

-----Original Message-----
From: [email protected] [mailto:[email protected]]On
Behalf Of George, W5YR
Sent: Tuesday, October 08, 2002 21:29
To: [email protected]
Subject: Re: [Icom] Re:R9000 RECIVER TT-340

Now you got me nit-picking!

If the line voltage is increased from 100 volts to 120 volts that is an
increase of 1.2. The power associated with a 1.2 voltage increase is the
square of the factor or 1.44 assuming that the load current increases
proportionally, i.e., the load remains a constant resistance, as it were.

Would this not translate into a 44% increase in heat dissipation as well as
supplied power to the rig?

What in the 781 power circuitry acts to limit the power/dissipation
increase to only 20%, the same factor as the voltage increase?

Enquiring minds want to know . . .   <:}

Seriously, I have a good friend with a mint 781 who might want to use an
autotransformer to drop the line voltage down to 100 volts. My line voltage
here is an almost constant 123 volts.

Is the over-voltage a serious enough problem to warrant dropping the supply
voltage?

On the TT front, wouldn't it be something if Icom got their new radio to
market before the dust settles on the Orion and TT finally have a reliable
working unit available in quantity?

73/72, George
Amateur Radio W5YR -  the Yellow Rose of Texas