[Top] [All Lists]

Re: [RFI] Icom Switching Power Supplies

To: Leonard Halvorsen <lhalvors@pppl.gov>, rfi@contesting.com
Subject: Re: [RFI] Icom Switching Power Supplies
From: Dale <svetanoff@earthlink.net>
Reply-to: Dale <svetanoff@earthlink.net>
Date: Sat, 22 Mar 2014 10:27:18 -0500 (GMT-05:00)
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>

I use an Astron SS-30M, which is very RF-quiet.  There have been reports of 
other switchers, notably those in the base of CFLs, creating a noise increase 
prior to failure.  You may very well be correct about component aging, but the 
actual issue could be more serious.  Do you have any means to measure the 
temperature of the switching device (transistor or FET) itself?  

A very key part of flyback topology switcher design is the snubber network.  
Where/when used, they keep the peak voltage across the switch from exceeding 
the rating of the switch device.  Changes in value from either use or heating 
can lead to more heating (due to greater losses) or switch failure (due to lack 
of the snubber).  Not all switchers use the flyback topology, but many do.  A 
very long time ago, I had first hand experience with snubber failure in some 
high power (10 kW) switchers - not nice, unless you like fireworks at close 

If you are able to get a temp sensor on or near the switch device, please be 
careful, as they typically have around 300 volts DC on them and they are 
referenced to the incoming AC power line.  Good luck, and please let us know if 
you find anything.  Last minute thought: if you open up the PS-25, be sure to 
inspect solder joints.  A poor solder connection, especially in the snubber 
circuit or switching circuit, will cause more heating and problems.  

73, Dale

-----Original Message-----
>From: Leonard Halvorsen <lhalvors@pppl.gov>
>Sent: Mar 21, 2014 7:29 PM
>To: rfi@contesting.com
>Subject: [RFI] Icom Switching Power Supplies
>*Has anyone noticed an increase in background noise in the ICOM PS-25 after
>it has had a chance to age for a while? I have one (of two) on which the
>noise has begun to creep up enough to be noticeable on 160, and is starting
>to come up on 80. I've had them for about 2 or 3 years, now. I suspect
>aging effects on components. Anyone have similar?*
>RFI mailing list

RFI mailing list

<Prev in Thread] Current Thread [Next in Thread>