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Re: [TenTec] Omni VII Internal Tuner failure - advice please.

To: tentec@contesting.com
Subject: Re: [TenTec] Omni VII Internal Tuner failure - advice please.
From: Stuart Rohre <rohre@arlut.utexas.edu>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Mon, 03 Jan 2011 17:45:19 -0600
List-post: <mailto:tentec@contesting.com>
Don't fear returning your radio to Ten Tec if you have the orginal box and padding, or can repack appropriately. Insure the shipment as well.

However, before going to that trouble, get the internal tuner exposed by taking off the cabinet, and if you have a DVM with diode check, check the diodes on the tuner board with the meter, (Radio off of course). If you don't get 0.6 volt across one direction of each diode, you have found a bad one. The other direction should not show a voltage barrier of 0.6, unless for some reason two diodes are in shunt.

The main use of diodes in the tuner will be for SWR bridge, and for relay back EMF suppression. You can use the ohms scales to check the relays for correct contact action. This might require an "Elmer" if you are not accoustomed to working on your own electronics circuits.

The diodes are the most prone to fail component in any SWR measuring circuit.

Of all your options, checking the diodes is the easiest to do yourself and least costly. IF diodes test bad, you can get the parts from distributors or Ten Tec, and carefully solder them in to replace the originals. Just pay attention to polarity, Make a sketch of which direction any bands are oriented on the diodes, before removing old ones.

-Stuart Rohre
K5KVH


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