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Re: [TenTec] OMNI VII QSK users with good ears....

To: tentec@contesting.com
Subject: Re: [TenTec] OMNI VII QSK users with good ears....
From: veast1 <veast1@charter.net>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Mon, 10 Dec 2007 13:17:29 -0800
List-post: <mailto:tentec@contesting.com>
As i happen to have an OMNI VI+, i would sure appreciate a point in the
correct direction for a replacement to the noisy amp relay.
Thank - you.

Paul (N6MYA)

On Sun, 2007-12-09 at 20:07 -0500, Paul Christensen wrote:
> > The Omni VI/VI+ used a reed relay for T/R switching, even tho they may 
> > have
> > used diodes in the circuit.  Remember all the complaints about how some
> > folks could hear their relay and others couldn't?  :-)
> The mechanical mounting of a T/R relay has a profound effect on acoustical
> noise.  To reduce noise of any relay in a T/R circuit, the idea is to reduce
> the effects of the PCB or chassis functioning as an acoustical sound board
> (e.g., like that found on a piano or violin).
> Even on the Omni Six series, the noise of the T/R reed relay varied from 
> nearly zero to annoying,
> depending on how the relay was inserted during manufacturing.  The distance 
> of the reed relay's body from the PCB generally established the level of 
> noise.
> By contrast, the Omni Six's open-frame amp relay is quite loud.  There are 
> other noiseless solutions for that, including the bypassing of the amp relay 
> with a high-voltage, high-current MOSFET switch, capable of silently 
> switching nearly any AC or DC amp key line.
> The idea propagated by others that a "Y" adapter used on the Omni Six's 
> TXOUT/TX EN line through a steering diode to the amp is a bad one and leads 
> to hot-switching on some amps without such timing protection.  I know it 
> works for some folks, but they're lucky in that the amp senses the hot 
> switching -- until the protection circuit fails.  Those two amp sequencing 
> jacks are meant ONLY for amps that accommodate a bi-directional handshake.
> Paul, W9AC
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