> Bob Dengler <[EMAIL PROTECTED]> wrote:
> > > Bob Dengler <[EMAIL PROTECTED]> wrote:
> > > I've seen more than the expected level of IMD problems
> > > for some reason when dealing with close spaced TXs.
> >
> >"Some reason" is most often a person being cheap or stupid.
> I fail to see any logic or value in this statement.
That's ok ... many people think they can get by at
busy repeater sites without circulators or isolators.
Repeater operation without the proper protection can
be sourced technical ignorance (the first time).
When the site owner or other involved parties have to
spend time tracing back IMD problems to transmitters
lacking proper protection, it really looks bad and
costs mucho $$
Preventable interference has been a reason for Hams
getting kicked out of Commercial, Private and Goverment
Radio Sites
> >The more logical source would be an amplifier not protected
> >by a circulator or isolator. The list would include other
> >repeater rfamplifiers at the same or adjacent site.
>
> Yes, but that does not explain the varying levels of IMD
> over time. I know of many on-site IMD problems that were
> DF'd down to passives such as those
> listed above.
> Bob NO6B
I also know of many IMD problems traced back to preamps
and rf power amps. "One" possible reason for varying levels
of IMD is related to the actual operation of the non linear
section of the (potential) problematic amplifier stages.
Each problem is unique...
cheers,
skipp
www.radiowrench.com
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