[ICOM] IC781 power supply

[N9QZD]

You are correct. The supply is not the best design. It was not worth the trouble to re-engineer the rig. 
The 781 is a classic, but is getting long in the tooth by now. 

-Pete

-
Sent from my BlackBerry!

-----Original Message-----
From: "Hsu" <hsu4qro at gmail.com>
Sender: icom-bounces at mailman.qth.net
Date: Sun, 12 Jun 2011 10:03:32 
To: ICOM Reflector<icom at mailman.qth.net>
Reply-To: ICOM Reflector <icom at mailman.qth.net>
Subject: Re: [ICOM] IC781 power supply

Not only heat but orso low efficiency.IMO, the PS should be high  efficiency especially swithing mode power supply.
  My copuuter  PS  fan  allmost not run, it is 80plus PS.high efficiency.I jsut study the schematic, maybe we can add a
 serial  regulator ahead   shunt regulator? when transmiting, the serial   regulator is bypass.
  73!Hsu
----- Original Message ----- 
From: "N9QZD" <n9qzd at spbbs.com>
To: "ICOM Reflector" <icom at mailman.qth.net>
Sent: Sunday, June 12, 2011 9:38 AM
Subject: Re: [ICOM] IC781 power supply


>I have the Sherwood Fan on mine. Also I run it at 100 VAC. 
> Heat is not a problem with this arrangement. 
> 
> -Pete
> 
> 
> ------Original Message------
> From: Hsu
> Sender: icom-bounces at mailman.qth.net
> To: ICOM Reflector
> ReplyTo: ICOM Reflector
> Subject: [ICOM] IC781 power supply
> Sent: Jun 11, 2011 8:15 PM
> 
> My  IC781's power supply is a "hot case" although  I add a extra fan . It due to its low efficiency  in  28V shunt REG powe supply . I study its schematic, I think if in receive  period, cut/close  the  28V power supply, the temp should be down greatly,But I have not think of it carefully. Any suggestion?
> 
>       73!Hsu
> ----
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> -
> Sent from my BlackBerry!
> ----
> Your Moderator: Dick Flanagan K7VC: icom-owner at mailman.qth.net
> Icom Users Net: Sundays, 1700Z, 14.316 MHz
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----
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/
To support QSL/QTH.net: http://www.qsl.net/donate.html