[ICOM] Internal PS question

[Steve]

Sorry, I did not mean to imply that I wanted an internal power 
supply, I don't. I was merely inquiring if they really used switching 
type supplies knowing how bad they can be for noise. I'm sure Icom 
did their homework though.
I also do not rely upon internal supplies. If I can run the rig via 
an external source then that is how I do it.
I've always done that plus I do add muffin fans when I feel they are 
needed especially on the older gear to try and get more life from them.
I know all too well about failing electrolytics! I bet 80% of my time 
spent at the bench doing repair work is spent on replacing lytics. 
When I get an older rig, I'll often replace all the electrolytics 
regardless if they are suspect or not.
My eyesight is going slowly though due to age so I imagine I'll 
slowly stop that practice as hours at the bench does put a strain on 
the ole eyes. Doing repair for the last 40 years is probably why the 
eyes are failing in the first place!
Then they came out with the surface mounted stuff! That was a joy 
especially when you do not have the proper tools for the job.

I did misread Dave Edwards post and thought he said he had an 735 
with a built in supply but I now see he said 736. Must get new readers.

Thanks for the input on heat and capacitors everyone. I'm sure it 
will be a help for some that are just getting into the hobby (and the 
repair work that often accompanies the hobby) and are not aware of 
these potential problems.
Heat does kill.


At 10:21 PM 3/6/2012, you wrote:
>Electrolytics are the only components containing liquids and are 
>usually the weak links in electronic circuits. If you've ever 
>rebuilt an old piece or gear you know the first things to replace 
>are all the electrolytics.My experience has shown the more heat that 
>electrolytics are subjected to, the quicker they lose their value 
>and the shorter their life. The heat tends to escalate the drying of 
>the liquid or gel used in electrolytic capacitors. Loss of 
>capacitance can negatively affect performance of circuits and can 
>result in a radio not up to original specs.This is the main reason I 
>always purchase transceivers without internal pwr supplies and why I 
>add a small low speed muffin fan to keep radios cooler than the 
>internal fans supplied with radios.Jay,  NE2Q----- Original Message 
>-----From: Steve Date: Tuesday, March 6, 2012 10:59 pmSubject: Re: 
>[ICOM] Internal PS questionTo: ICOM Reflector > Are the built in 
>supplies really of the switching type > especially in > the older 
>735?> I've always assumed they were just good old linear type 
>supplies > with > no noise problems. I guess I never really looked 
>to see if there > is > room inside for the large transformer of a 
>linear type supply.> > > At 08:57 PM 3/6/2012, you wrote:> >I have 
>an Icom IC-736...Has built in AC supply, built in tuner, 6> >meters, 
>LARGE display, and analog S meter....For these items, > it is 
>one> >of my favorite rigs.> >It works great!!!> >....Dave> >> >On 
>3/6/2012 8:11 PM, John G. wrote:> > > On the older Icoms like the 
>740 and 751A that have an > internal PS > > option, is it usually 
>better to get one with or without the > PS?  It > > would be 
>convenient to just plug the rig into the wall, but > how > > quiet 
>are these older switching PS?  Also, does the heat they > > generate 
>affect the reliability of the radios at all?> > >> > > 73 John> > > 
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