OMNI VI oscillation with 500hz filter switched in

[Del Seay]

dazan@teleport.com wrote:
> 
> In response to the problem of receiver oscillation and howling when the unit
> has the 500hz IF filter switched in.
> 
> I have 2 OMNI VI tranceivers.  One of them has this problem and the other
> does not.
> 
> I put both of these units on the bench and found that both units have
> excellent sensitivity.  The one with the problem has the best sensitivity.
> I found that by reducing the RF gain control to about the 3 o'clock
> position, the oscillation goes away and the sensitivity is the same as the
> one without the problem.  The one without the problem has its RF gain
> control set fully clockwise.
> 
> With both the OMNI VIs RF gain controls set up as stated in the paragraph
> above, they still have better sensitivity than my FT990, which in its self
> is not a bad radio!
> 
> regards, dave.n7da

I just recently performed the mod that Ten-Tec has for better IMD
products. This involves changing one resistor in the Bandpass filter
and jumpering another. It lowers the gain just enough to eliminate
the "ringing" that has been noted.
Also, I changed the firmware to the new version. It is as advertised,
altho doesn't cover all the mods requested by users.
73  de KL7HF