Omni VI 2nd order IMD Mod

Del Seay
Thu, 28 Mar 1996 06:40:57 -0800

John Morris wrote:
> Would appreciate hearing from anyone who ever installed the subject
> modification in their Omni VI.
> This mod involved changing 2 resistors on the BPF/Front End board and was
> supposed to improve 2nd order IMD from 40 dBm to 60dBm.However, TenTec
> advised that "precious few hams in the U.S. would gain anything from
> improved 2nd order IMD".
> If you installed the mod:
> 1. Degree of difficulty?
> 2. Any noticeable improvement or difference?
> TKS es 73, John K5OTI

Hi John. I did the change and in my case, it was worth the effort.
It only takes a few minutes (Typical of Ten-Tec repairs) and the
problem with ringing on receive disappeared. I assume the gain of
the rf-amp is slightly lowered in the change. I see no difference
in sensitivity and noise floor, so did not cause any unwanted
changes that I can see, and certainly made the receiver much more
pleasant to listen to. I cannot attest to the improvement in
imd numbers, don't have the equpment to properly measure.
However, Ten-Tec states it is their version of the mod suggested by
the 'G' guys which changed out the balanced mixer. I doub't that it
would compete with a better balanced mixer, but who knows?
Anyway - It is certainly worth the few minutes of your time.
73  de KL7HF