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Re: [TenTec] Help

To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Subject: Re: [TenTec] Help
From: "Ariel M. Elam" <k4aal@comcast.net>
Reply-to: k4aal@comcast.net,Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Wed, 22 Feb 2006 23:32:33 -0600
List-post: <mailto:tentec@contesting.com>
Here is a method for providing a quick and easy crowbar.Place a Diodes 
Incorporated  1.5KE15A (NTE4920) across the power output AFTER the fuses 
ans before the rig. Band goes to +. It will clamp 1.5kW, about 100 
amps@15 volts and blow the fuse.

I found this in "73 Amateur Radio Today", May 2002, page 38. Title "An 
Ounce Of"

I have installed this on my rigs, but it has never been needed to 
prevent a problem.

Ariel, k4aal

Mike Hyder -N4NT- wrote:
> When that has happened to me, it has been due to bad diodes in the ALC 
> circuitry.  Those diodes are to generate the ALC voltage without which the 
> power amplifier can oscillate and almost instantly draw excessive current.
> Be really careful with that 252 power supply.  As originally made, they have 
> no crowbar circuitry.  Thus if the pass transistor shorts, the supply will 
> put 25 volts into the rig -- somewhat shortening the rig's life.  Ten-Tec, 
> realizing the oversight, later sold an "Over Voltage Protection" circuit 
> board, an OVP they called.  It was a small board, perhaps one by two inches 
> and had an SCR, a zener diode and a fuse.  It mounted inside the rear panel 
> of the supply.  I suggest you check there and see if it is present.  When 
> installed, the large red wire to the supply's output comes from that small 
> circuit board.  The OVP is no longer available from Ten-Tec but someone can 
> surely send you the schematic.
> Good luck with your Omni-D
> 73, Mike N4NT
> ----- Original Message ----- 
> From: "Ken Johnsson" <kenj@eastex.net>
> To: <tentec@contesting.com>
> Sent: Monday, February 20, 2006 9:00 PM
> Subject: [TenTec] Help
> I am a new owner of a Omni D and when turn up the drive, it kicks the P/S
> off, all help would be appricated
> Ken N4ALP P/s the Ps is a 252 m 
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