[ICOM] New Owner IC-781

[Adam Farson]

Hi Traian,

No problem - I shall be glad to wait until you are ready. If you would like
to send me a PDF, I can place it in the Download section of the Icom site
with a link from the home or "Manuals" page. An HTML page, or a Word
document with embedded pictures will also be OK; I can convert a Word
document into a standard HTML page using FrontPage and other tools.

The cause of the 781's PSU heat problem is the shunt regulator in the REG
Unit, which acts like a dynamic bleeder and holds down the +30V PA Vcc under
idling conditions. The PSU is designed to operate on the Japanese 100V mains
supply; when run on 120V mains, the power dissipation of the regulator
increases by 44%. If the mains-voltage tap is set to 200V, and the radio is
connected to 220V mains, the dissipation still goes up by 32%. Over the long
term, this will cause the heat damage you describe.

The Sherwood fan kit is an excellent solution to this issue; another method
is to reduce the mains voltage to 100V (or 200V in Europe) by means of an
autotransformer or Variac.

Here is an article I wrote in 2003 on the relative merits of a used 781 or a
new Pro2. It also mentions the heat issue.

http://www.qsl.net/ab4oj/icom/756p2_781.html

Cheers for now, 73,
Adam VA7OJ/AB4OJ


-----Original Message-----
From: icom-bounces at mailman.qth.net
[mailto:icom-bounces at mailman.qth.net]On Behalf Of Traian Belinas
Sent: Sunday, May 15, 2005 12:09
To: ICOM Reflector
Subject: Re: [ICOM] New Owner IC-781


Hello Adam,

Nice to hear from you, I know about the icom webpage and used the info from
your
great website during the time, many TNX.

It shall be fine to put the info on the web, I was thinking before about
sending
the info to the www.mods.dk website where I had put the TS950 Antenna Tuner
mod
before.
But, please, wait just for few days.
I will complete a document during the following days, maybe some other info
will
have to be included and will include some pictures also.
Then will send it to you for including  it on your webpage, as a webpage or
pdf
document, as you wish.
Is this ok?

73,
Traian, YO9FZS


Adam Farson wrote:

> Hi Traian,
>
> Thanks for the excellent collection of IC-781 information. Would you like
me
> to convert it into a web page and place it on http://www.qsl.net/icom/ ?
>
> If you have some photos you can e-mail to me, they will make the web page
> look even better as well as giving readers additional information.
>
> Cheers for now, 73,
> Adam VA7OJ/AB4OJ
>
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> Icom Users Net: Sundays, 1700Z, 14.316 MHz
> Icom FAQ: http://www.qsl.net/icom/

----
Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net
Icom Users Net: Sundays, 1700Z, 14.316 MHz
Icom FAQ: http://www.qsl.net/icom/


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