[EMAIL PROTECTED] wrote:
> More than likely the cause of your problem was the connection between
> the two boards developed a cold solder joint and began to ark. This
> happens all the time with this PA. It may not have had anything to do
> with your load. If you have 70W going in and 4W reflected, that's about
> a 1.65:1 VSWR, which is not that bad.
>
> Chris
>
> In a message dated 3/13/2006 5:54:44 P.M. Central Standard Time,
> Repeater-Builder@yahoogroups.com writes:
>
> Here's the photos of a *VHF* PA that didn't get the board to board
> jumper mod and the results of driving it into a load that wasn't 50 Ohm
> that was probably reactive in some way also...
Well, not bad unless you consider that coming out of that pass can,
measured output was just under 70W with virtually zero reflected from
the cavity to the combiner, which has a ferrite dual-port isolator as
its first stage...
So the reflected power was ALL from that single VHF pass-cavity (or
cable going to it), tuned/coupled for only 0.55 dB insertion loss, and
basically just in-line to be a "good neighbor" to another VHF system
that was experimenting with using a receive antenna not on the combiner
system and in the direct horizontal line of fire of the combined TX
antenna everyone else is using at the site.
We were attempting to help lower our output's effect on their input
about 1 MHz away by about 10dB.
Anyway, an experiment... yeah, the PA could have munched itself all by
itself, I know... but I'm suspicious of a single pass cavity causing
that much reflected power.
Definitely wasn't worth leaving it installed for the moment... will
re-evaluate when it's easier to get to the site.
Nate WY0X
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