[TenTec] Scout problems

[Mike Hyder]

Well, you may have 30 years experience but you are way wrong about the
Astrons because of their circuit configuration.  If you carry your logic
further, I ought to go into my Ten-Tec supplies and make sure that the
common is not connected to the cabinet.  You are just wrong about Astrons.

I have asked a question or two interspersed in your message below.  Please
give more thought to this before you respond.  I believe you went off
half-cocked without having examined the particulars of the Astron supplies.

73, Mike N4NT@chartertn.net

----- Original Message -----
From: "Stuart Rohre" <rohre@arlut.utexas.edu>
To: "Mike Hyder" <N4NT@chartertn.net>; <tentec@contesting.com>
Sent: Tuesday, October 23, 2001 4:33 PM
Subject: Re: [TenTec] Scout problems


> Mike,
> You did not read my message completely or carefully.  I pointed out the
> Scout has the ground on its back panel on a stud.  Thus, the Astron
negative
> can continue to float.  It gets chassis grounded when it reaches the
Scout.

****** Now how do you figure that connecting the power cable from the Astron
to the Scout does anything to ground the chassis of the Astron?

> See any of the editions of  Grounding and Shielding by Ralph Morrison.

****** I don't have one.  But if you are going to throw out references, cite
the edition and page numbers.
>
> With all due respect, ground and shielding problem solving in EMC is what
I
> have done successfully for 30 plus years!

****** I don't know what EMC is.  My only experience has been in the amateur
and land mobile services.
>
> The Scout ALREADY has the chassis common with negative of the DC power
> cable!  To also ground the Astron negative output creates a ground LOOP!

****** To NOT ground it creates a ground loop broken in the center by the
Astron's regulator circuitry.
>
> The LOOP will then pick up any stray RF, and a problem ensues from
> circulating current.  Most hams do not understand the principle of SINGLE
> POINT GROUNDING, which is best done with the SCOUT at the back panel
ground
> post provided by Ten Tec.  Do not create a ground loop by grounding other
> points than the one at the rig.

****** The Astron's cabinet IS grounded through its AC line cord.

Sometimes you can get away with it, but
> good engineering practice is for the ground to be close to the signal
source
> of RF.  The coax shield should connect at the rig to the chassis, the
> negative power lead to the chassis, and the chassis ground stud to a
> counterpoise if you are more than a quarter wave from physical ground, or
to
> a wide flat strap to ground, if one is used.   Note, that with portable
> dipole antennas or most beams, you do not have to connect to Earth, as
this
> is mainly a safety ground, for static buildup protection.
>
> 73,
> Stuart K5KVH