[TenTec] Omni 6 sensitivity

[Clark Savage Turner]

On Dec 17, 2004, at 2:55 PM, David wrote:

> I just bought an Omni 6 and was surprised that in an a-b comparison 
> with my Icom 751A it seemed noisier and less sensitive.  I expected 
> just the opposite and was not prepared for these results.  I checked 
> all the controls (and yes the attenuator was off) and everything is as 
> it is supposed to be.  The rig is even noisy when the antenna is 
> disconnected.  I'd heard it was a super quiet rig.  Anyone have any 
> ideas.  I really like this rig, ergonomics, design, etc. and want to 
> make it work for me, but if I can't, it's going back.

Hi Dave -

A few things seem likely -

1.  The OMNI VI was oversold to you, it is not magic, and the 
"quietness" is attributable to noise generated by very strong stations 
close-in to weak ones you want to hear.  You'd need to have the two 
rigs side by side with very specific conditions to hear the difference 
in my experience (and even then it is not night/day,  but perceptible 
and makes copy much better on the OMNI ... hey, the 751A is no slouch 
receiver!)

2.  The OMNI VI passband tuning (PBT) is set so that you get a lot of 
"highs" (hiss) from the audio of the receiver.  The carrier setpoints 
can do the same thing.  The pair of 2.4 stock filters normally produce 
audio on SSB that my ears don't like and it is very fatiguing to me (so 
I have slightly wider 2.8 filters from INRAD in there, it mellows the 
sound just a bit.)

3.  There is a problem with the receiver, some grounds are loose or 
some component has gone south.  I have experienced noise due to loose 
board grounds, and you can open up the OMNI VI and poke around with a 
tiny (really, tiny) amount of DeOxit for each mini coax connector and 
other sorts of connectors, and you can tighten the hardware a little 
bit here and there.  Slide all the switches back and forth.  All that 
stuff.  It might help.

Stick on this list and keep talking, you can probably figure this out.  
It might really help if you can get to another OMNI VI station and do a 
direct comparison.  Live near San Luis Obispo in CA?  I can help.

Clark
WA3JPG

Clark Savage Turner, J.D., Ph.D.
Associate Professor of Computer Science
Cal Poly State University
San Luis Obispo, CA. 93407