[R-390] Interesting find in my Cosmos PTO

[Jim M.]

Sure looks suspect.  Check solder connections too.  I once had an IF deck in 
one radio (an EAC) where there were about 6 unsoldered connections!  Poor 
workmanship can happen.  Also be sure to tighten all screws that hold ground 
lugs or tube sockets.  They can work loose with heat cycling over time and 
cause reduced performance in a circuit.


----- Original Message ----- 
From: "Barry" <n4buq at knology.net>
To: "R-390-List" <R-390 at mailman.qth.net>
Sent: Wednesday, May 17, 2006 12:30 AM
Subject: [R-390] Interesting find in my Cosmos PTO


> In order to facilitate replacement of the parts in this particular PTO, I
> removed the surrounding hardware (brackets, etc.).  I then took a much
> closer look at the innards.  Point your browsers to the following address
> and look at the two pictures there.
>
> http://www.knology.net/~thelanding/
>
> In PTO1.JPG, notice how the lead from the bypass capacitor appears to be
> touching the frame.  Note that this is NOT the ground side of the 
> capacitor.
> PTO2.JPG show the same area from the "top".
>
> I have not moved the lead yet nor checked anything else (too late in the
> evening), but I'm guessing if I move this lead so that it isn't touching 
> the
> chassis, I may see some rise in the output level.  At any rate, it looks
> like this has been there from the factory and it's just a wonder to me it
> works at all.  I'm actually surprised there isn't close to 200VDC on the 
> PTO
> chassis, but I'm also guessing that the wire isn't actually making solid
> contact with the chassis since I have the correct plate voltage; however, 
> it
> sure is close to the chassis to not make contact.
>
> Barry - N4BUQ
>
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