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Re: [TenTec] Omni VI mystery

To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Subject: Re: [TenTec] Omni VI mystery
From: Ken Brown <ken.d.brown@hawaiiantel.net>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Tue, 29 Apr 2014 17:26:03 -1000
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>
The Omni VI is my favorite rig for CW. I think it is worth the effort to either troubleshoot it yourself or get Ten-Tec to do it.

Have you checked the BFO frequencies? If you don't have a frequency counter, you could use a receiver that covers 9 MHz area. You should be able to hear the BFO by putting a pickup loop or antenna inside the Omni VI near the BFO. Or you could use a o'scope probe to connect to it. If you have a receiver with a digital frequency readout, that you trust, and you know how to zero beat a signal with it, you should be able to determine the BFO frequency with sufficient accuracy.

In CW mode the BFO should be operating at 9.000000 MHz in receive, and 9.000400 MHz in transmit. You can turn the TX power all the way down, and transmit for long periods into a 50 ohm terminator to make the measurement.

My best guess is either the BFO frequencies are not aligned properly, or the switching of BFO crystals and trimmer capacitors is not properly occurring when you change from RX to TX in CW mode.

You could monitor the CW T line on connector 60 on the 81597 board. Or monitor the base and or collector of Q4 on that board. You could use an o'scope (DC coupling) or a DMM or VOM. The idea is to determine whether the state is changing between TX and RX.

DE N6KB
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