Bob Dengler wrote:
> At 7/8/2005 08:08 AM, you wrote:
>
>
>>Can you put a 1DB or 3DB pad in place between the TX and the
>>cans? Might be hard to find one at that power level, other than a
>>long hunk of coax. With a 3dB pad in, I would expect any reactive
>>impedances on the ends to be less interactive, and if this cleans it
>>up, it would have us looking at the amp for problems.
>
>
> ...better yet, how about just an isolator on the amp output?
>
> Bob NO6B
Correct me if I'm wrong, but looking back over the thread, with all the
speculation that the Amp is not seeing the load it wants, wouldn't Bob's
recommendation of an isolator have fixed (well, covered up) the problem?
The Amp would have then been driving into a nice boring 50 ohm load even
if the antenna and duplexers are somehow out of whack if the repeater
was built properly with an isolator, wouldn't it? Or something closer
to 50 ohms that would have probably made it "happier", anyway.
I've always thought from everything I've learned from smarter people
than myself (definitely!) that having an isolator on things is the best
insurance for this type of weirdness, as well as the usual reasons to
keep RF coming down towards the PA from the outside world out of it.
Someone can unplug your antenna and your PA will sit there dumping power
into the load on the isolator, fat dumb and happy...
It just doesn't seem wise to build repeaters without isolators on them
at all. Why do people do it, other than cost? Surely the gee-whiz
whiz-bang repeater controllers people put on such repeaters to make them
sound like an 80's video arcade are more expensive than buying an
isolator for the repeater??
Nate WY0X
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