[TenTec] Orion with 10m "buzz" (solved)

[Robert & Linda McGraw K4TAX]

Sounds like a ground loop to me.  With one connected no noise.  With the
other connected, no noise.  With both connected the noise from the fan is
apparent.  Yep sounds like a ground loop to me.

Do you have a good low resistance ground connected between the tuner and the
radio? And then a good low resistance ground between the radio and the power
supply?  If not, you should.

73
Bob, K4TAX


----- Original Message ----- 
From: "Duane A Calvin" <ac5aa at juno.com>
To: <tentec at contesting.com>
Sent: Monday, June 28, 2004 9:06 AM
Subject: [TenTec] Orion with 10m "buzz" (solved)


> I was disheartened last week to find a "buzzing" noise in my otherwise
> perfect Orion starting in the 10m SSB frequencies and continuing all the
> way up the band.  Both RX's, happens with antennas connected or
> disconnected or even deselected.  This weekend I started pulling cables
> to eliminate possible problem areas.  Imagine my surprise as I pulled the
> RCA plug out of the +13.8 V jack in the back and the buzz stopped!  What
> was it?  It appears to be a cheap "Y" cable that I used to power both the
> #310 cooling fan and the light in the 238B tuner.  If I plug just the fan
> without the "Y", no noise.  Same for the tuner.  If I plug just the fan
> through the Y cable, the noise returns, and is originating in the fan
> (noise follows the fan spin-up when power is applied, and stops
> immediately when the power is removed.)  I plan to build my own cable and
> will probably add some bypassing there that is effective at 28 MHz.  Most
> likely no one else will see this problem, but I wanted to post this on
> the off-chance that they do.
>
>         73,  Duane
>
>
> Duane Calvin, AC5AA
> Austin, Texas
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