[Amps] Topband: Elimination of Treadmill RFI on 160 meters

[Roger (K8RI)]

As for the thermal compound, it depends on the compound. I use Arctic 
Silver which cures after an hour or two of use, giving the appearance of 
being dried out.  It's supposed to look (and feel) that way.  I never 
had the white Silicone heat transfer compound dry out.  As I worked for 
the company that makes it, I had one large tube ( several lifetime 
supply if you repair computers. )  You put a small gob in the middle of 
a quantity just large enough to eventually cover the contact area.

Your line voltage may be high as I'm assuming you are running 
conventional power supplies.  I've had several Astron switchers fail. 
They promised a new fan which failed on day 2, but it never arrived.  
So, with Astrons, I stick with conventional configurations.  On that 
note, be careful, the configuration or parts may not match.  Also, on 
the BIG, 50 and 60 ? amp supplies (forgot which mine is).  I had a screw 
fall down the side.  It was only a little flash, but it took out two of 
the pass transistors. For only a little more I was able to get pass 
transistors rated for quite a bit more current.  I replaced them all, 
and it's been running over 5 years (I think)

73

Roger (K8RI)


On 1/28/2015 11:13 AM, Charles Compton wrote:
> On both of my Astrons, I noticed that the output transistors ran extremely
> hot.  Check to make sure that the thermal compound on the transistors and
> associated insulators is not dried up.  Properly apply fresh compound to
> ensure adequate heat transfer to the chassis. More is not better and thermal
> runaway is not your friend.  This could be your root failure cause.
> 73
> Charlie
> K4BQP
>
>
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