Hello ...
skipp025 wrote:
>
> > Neil McKie <[EMAIL PROTECTED]> wrote:
> > Hello ...
> > Back in the ... er ... ah ... late eighties:
>
> When the MSR-2000 was in its prime time.
Mid - late eighties?
> > Ordered a new 450 MHz MSR2000 from the big M
> > ... was shipped as expected - had the 12 VDC
> > only option - was going to a 12 volt only site
> > that used a thermo-electric generator for power.
>
> Wasn't for Cobb Mtn was it? For a location known
> as the Geysers?
Nope ... much closer to the west coast. :)
> > The license for this station said 20 watts
> > output maximum. The only way it was orderable
> > was the full power model at 75 watts output.
>
> A round of sales person BS was what you received.
> Lower power versions were available.
> I have a number of ~30 watt rated output MSR UHF
> PA's. Ordered that way new from the Big M.
Well, I didn't know that. Wish I had though, would have saved
me a bunch of time.
> The TEG I put in at the Geysers ate propane like
> crazy, but it put out a healty 22 amps.
Ours charged a pair of 8D 'cat' batteries. We used the radios
off them. Somewhere around here I have a video tape of that
installation.
I think it is the same video tape of another friendly commenter
on this remailer ... showing in great detail his grand radio
installation in his 80's Chevy Camaro.
For a short period of time, FEMA Gettysburg borrowed that video
to show what they thought was an interesting installation of
several radio sites.
> > After careful study of the transmitter and
> > the associated schematic diagrams, I noticed
> > the PA driver stage was identical to the PA
> > final stage execpt the driver stage comprised
> > of one module and the final had three of the
> > same modules.
>
> Motorhead PA designers were smart along one line,
> making most of the stages 50 ohms in and out. One
> could route around a stage for lower power
> operation.
Was very handy for trouble-shooting the T34 / 44 MST Motrans
when they had a problem.
The first time I ever saw one, I called the Motorola factory
Service people asking how do we service these radios - since there
were no clues in the Instruction Manual. The Motorola reply was
'We're hoping you will tell us.'
Fortunately, I had some non 2 way radio lab experience with 50 ohm
RF circuitry so we had it figured out pretty soon. Also owning a
one watt 200-500 MHz Bird Slug helped too.
> > After some careful thought, I slightly modified
> > the PA deck by bypassing the three module PA
> > Amplifier and connect the driver stage (1 module)
> > to the output. Got 16 watts out of the deal
> > discovering it was very stable and lowered the
> > DC power drain a lot.
>
> a big lot...
True ...
> > Since this was a licensed link radio, the
> > distance was 9.1 miles, I figured the 16
> > watts would be way overkill.
>
> It was, it would take less than 2 watts with
> decent 8db yagi antennas.
Never tried that - just wanted to be sure we had sufficient
overkill to ensure would not fail.
> > My testing from the shop using a ground
> > plane for an antenna, I could bring up
> > one of the systems with the service monitor.
> > Neil - WA6KLA
>
> The Service Monitor test with a dial tone
> can really freak out the system users. Everyone
> starts looking for a place to hang up the phone.
Sounds like the users could have a real hang-up with that
one ... ;)
> cheers Neil
>
> skipp
> www.radiowrench.com
> skipp025 at yahoo.com
73,
Neil - WA6KLA
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