Omni V Mods suggested by N5KAT

(from the Ten-Tec reflector, 15September 2010)

For me, excess audio gain and maybe excessive IF gain are bugaboos of this rig. It is a super hot RX and it is easy to run it into distortion with all controls up.

Have a look at the W3TS mods and the mods listed on the Ten Tec Wiki, but I wouldn't mess with anything until you familiarize with how the rig works stock.

One thing you need to know is the RF gain control is your friend. Adjust for best perceived s/n ratio. I usually run it at 1:00 or wherever the band noise starts to drop out. There is a point where band noise seems to drop more than signal and that is where I want to be.

I also found that the controls can be a bit touchy. A few degrees movement of the BP/Fade or IF Shift knobs can make a big difference under certain conditions and these settings are quite interactive. RF gain and AF gain also have tiny sweet spots sometimes.

I installed the product detector bias mod recently discussed here and on the Yahoo Omni V group. Seemed to help with what I took to be overdriving of the product detector, but I have no way to quantify or measure before/after. Now I can run RF gain up higher if I want to. Appears to be useful or at least it fooled me!

The best thing I did to my Omni V was to recap the logic board, display board, and IF/AF board with modern "digital age" low ESR high frequency caps. This greatly reduced internally generated noise.

I can turn my AF and RF gain all the way up on a dummy load and only get a minor hiss. Before the recap it was quite noisy. Maybe yours is better than mine was.

I think I put a bigger cap in the slow AGC to increase the time constant. Stock value was too fast for me on sideband.

It is also a good idea to take an afternoon to clean all of the internal connectors with Deoxit…and don't forget to clean the power connectors every now and again. I use a baby toothbrush dipped in Deoxit on the male pins of the board connectors, then connect/disconnect once or twice.

What I would really love to see is a mod to make the noise blanker work. I've heard there was a late NB board with three wires going to the control pot that works, but mine is purely ornamental. Useless.

Joe N5KAT


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