[R-390] R390: 60 Hz on Audio

[Jon Schlegel]

Wow Steve,

When I saw "63 Imperial", I immediately thought 
of the car!  I think that was about the time of the suicide doors in the back?

Anyway, I'm running the IF module disconnected 
from the receiver using a purpose built fixture 
powered by one of the Heath regulated lab 
supplies.  Here're some pix of the setup.

<http://www.vecnav.com/R-390A_IFmodule/IFmodFixture-001-small.jpg>
<http://www.vecnav.com/R-390A_IFmodule/IFmodFixture-002-small.jpg>


I can see it happening whit the vibration of the 
power transformer modulating the PTO.  Wonder how 
common an occurrence that world be.

Jon

At 07:25 PM 6/9/2009 -0400, Steve Hobensack wrote:


>I have a small amount of hum on my 63 Imperial. 
>I found it was coming from the PTO signal. As a 
>test, I dismounted the pto canister, and the hum 
>went away. It was mechanical coupling to a 
>vibrating chassis. The vibration was coming from 
>the power transformer. I greatly improved the 
>hum situation by loosely mounting the power supply.
>
>Steve N8YE
>
>
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