On Fri, 2007-12-14 at 11:51 -0800, Peter Inskeep wrote:
> As last weekend's 10 meter contest started I discovered that my Omni VI + 10
> meter transmit is "dead." The receive may be diminished as well, but I am
> not sure of that. I quickly switched to another rig.
> When the rig is turned on from cold, ie., power supply turned off until rig
> turned on, I get about 40 watts on both the internal meter, and on my tuner's
> meter. This quickly drops to virtually zero, within seconds.
> All other bands work fine. All four sections of the 10 meter band are dead.
> Ie., 28.0 to 28.5, 28.5 to 29.0, etc.
> I have pulled the rig apart. I suspect that the problem is on the Xtax Osc.
> - L.O. Mixer board (81595). This board is located in the box under the
> 81595SM and 82870 boards on the top left side of the rig. It contains the
> band crystals and a whole bunch of switching diodes, among other things.
> Thus, it is almost impossible for me to test anything with the rig running,
> as I have to remove those two boards and the aluminium plate to get at the
> Mixer board.
> I suspect the L.O. Mixer board because it seems to be the one place where 10
> meter signals are completely separated from other band signals. In fact, I
> am most suspicious of Q4 and/or Q5 on that board. I will replace them to see
> if that does it.
> I have checked diodes, in circuit, until my eyes are crossed. I have checked
> solder traces until my eyes are recrossed. I've found nothing that looks
> bad, and nothing that does not check continuity with my vtvm.
> Having bored you will all of the above, if you are still with me, I have two
> First, has anyone had the same symptom on their Omni VI Plus? If so, can
> you suggest a fix.
> Second, is there some other circuit where all four of the 10 meter circuits
> are separate that I have not been able to discover?
> I have not pulled the front panel off to see if the 10 meter button is
> "broke." I think not because, first, it enters the "9" digit without fail.
> Second, it does kick in 10 meters when the rig is cold, and the display does
> go to 10 meters.
> Finally, I know that the intelligent thing to do is to box it up and send it
> to Ten-Tec. They will not only fix this problem, but reallign it and make it
> better than new. If the two transistor replacements don't do it, and no one
> on the reflector has a solution that I can implement at home, I will send it
> back to Ten-Tec after the holidays are over and UPS is back to moving cartons
> instead of chucking them due to the holiday rush.
> I am not a frequent poster to the reflector, but I do monitor it, so, if you
> can offer any suggestions, I will be most appreciative. My XYL's solution to
> this is to send the rig back to Ten-Tec in trade for an Omni VII. Not a bad
> Pete, no2d.
Band pass filters and their switching are probably shared.
73, Jerry, K0CQ
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