I have limited experience with the MSR2000 however if the PA keeps
toasting, and if RX sensitivity is low ( MSR2000's were not super hot to
start with) I would suspect the load being presented to the transmitter may
have high swr. (Like maybe duplexer, maybe the Isolator ) That would seem
to be the place I would start...It is possible these factory parts may not
be re-tuned properly and/or like operation at 444 mhz. In general I know of
one here ( MSR2000) in Cleveland on 444.xxx which has never toasted a PA to
my knowledge... While it has limitations due to the general design, as far
as replacing the Duplexer and Isolator with lower insertion loss versions,
it has been serving well for a long time. Even if the duplexer was
mis-tuned, it would seem like the Isolator should protect the
transmitter... Is it possible it is taking lightning strikes or severe
discharges???? That would seem more likely, although damage should occur to
more things...
Doug Bade
Cleveland Comms.
At 10:00 AM 9/7/2004, you wrote:
>I have an MSR2000 on 444.550 for the local ham club / county EMA. The PA (a
>110W model) is out again. We just had this repaired by the local Motorola
>shop, with whom we've had very good results from in the past. We're running
>the PA at about 80W, so I'm thinking we didn't "burn it up", but I can't
>help but wonder if there is anything inherently wrong with the MSR2000 PA
>for UHF. This is the third time the PA has failed in this particular
>machine in about a 2-year time frame. (This was a repeater originally tuned
>for 460 MHZ, and brought down to the ham band.) This particular machine has
>been a pain in the @$% - RX sensitivity isn't what it should be, PA keeps
>going out, etc. Seems like we're up at the site every couple of months do
>make some sort of repair on it.
>I'm wondering if we should just cut our losses and get another machine, or
>should I keep plugging away at this repeater? If we do decide to chuck it,
>how much can I expect to spend to get a comparable replacement - we use this
>machine during severe weather season for forwarding reports to the NWS, and
>it's open other times. We want to add remote RX sites (you've probably seen
>my inquiries about those in the past) but I don't want to start adding
>remote RX sites until I get the main repeater working reliably.
>I'm open to suggestions...
>Thanks,
>Mark - N9WYS
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