There are a lot of interconnections on the Uniboard.
That's the board that lies underneath the aluminum
cover of the RF tray, under the plastic controller
enclosure. I'd pull that board and make sure
everything is good and tight and clean.
Plugging in the RJ45 metering cable should NOT reset
the station, and that's the only one that would do
much for you as far as testing is concerned. Plugging
in or unplugging the 40-pin flat cable will almost
always cause a reset or other weird problems, even
lockups.
It sure sounds like something in the synthesizers
isn't locking up properly. I don't know how often the
SCM sends the programming info to the synthesizers; in
theory it should only have to send it once, on
power-up, but I do know it'll send the TX freq out
because that could change from RX (idle frequency) to
TX (main transmit frequency). The receiver shouldn't
have to change freqs unless you've got multiple
channels programmed into it.
Could also be a problem in the IF filters of the
receiver, or the quadrature detector, or the 14.4 MHz
reference oscillator, or the 2nd IF local oscillator.
None of these will be easy to trace.
Bob M.
======
--- Nate Duehr <[EMAIL PROTECTED]> wrote:
> A few times over the last few years, a friend's UHF
> MSF 5000 has been
> found to be off-frequency by 5 KHz on receive.
>
> We find this out, of course, because everyone sounds
> bad, and then one
> day we thought... hmm, that sounds 5 KHz off
> frequency...
>
> Repeater is on 449.625 TX, 444.625 RX.
>
> Sometimes it goes low -- we could transmit into it 5
> KHz down from it's
> programmed receive frequency and sound fine.
> 444.620
>
> Today it went high. I could talk through it
> beautifully on 444.630.
>
> Grounding at the site is basically as good as I've
> seen anywhere, power
> may be taking bumps from time to time, but we're not
> really hearing any
> controller resets or anything prior to these little
> "off-frequency"
> excursions by the Receiver... it just goes --
> seemingly when it wants to.
>
> Plugging in the Moto test set seems to always reset
> the repeater so you
> can't diagnose anything digital unless you leave the
> test set plugged in
> all of the time (which isn't going to happen at this
> site).
>
> A reboot will clear the problem. Turn the power
> off, turn it back on,
> repeater's receiver locks and works correctly
> on-frequency.
>
> I forget since I'm not an "MSF guy" if it's the CXB
> or the CLB that is
> the firmware programmable model -- but that's what
> he's got. Firmware.
>
> This particular station also had a TX VCO lock
> problems, but that went
> away with the replacement of the "spring assembly"
> thing for the VCO.
> (Yeah, I don't know what to call that thing, but
> anyone who's worked on
> one knows about the locking mechanism for
> transporting them.)
>
> The controller and other boards have all been
> disconnected/reconnected
> (all connectors have been "cycled") and right now,
> we're stumped.
>
> Originally some thoughts about bad power or static
> discharge, but we're
> not exactly in "static/lightning" season out here
> right now, and the
> snow is heavy and wet for the most part. Plus it
> didn't do it all
> winter with precip static from snow, etc... static
> doesn't really make
> sense.
>
> The OTHER MSF took a lightning strike a while back,
> and its controller
> was fried -- so no spares available to swap parts at
> this point... would
> want a better idea of what to swap/try before paying
> for parts.
>
> Anyone ever seen this?
>
> Nate WY0X
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