I've used a lot of Mitreks as repeaters and loved them, but you're right about
the PA -- if you don't like fans, it's going to get too hot. Consider getting
the exciter output after the helical filters and use a different PA. I have a
couple of Mitreks stashed in a corner somewhere "just in case" -- I've moved on
to newer synthesized stuff, but I know in a pinch I can have one up and running
as a repeater with a couple hours of work.
On Apr 26, 2010, at 1:47 AM, Paul Plack wrote:
>
> After a few years on the sidelines, it looks as if I'm going to be jumping
> back into repeater ownership. I have a few nice pieces left from my last
> adventure, including a TX/RX duplexer and a loaded S-COM 7K, but I'm
> pondering choices in RF decks. This will be a local UHF machine designated as
> an asset for a emergency net in a suburban area, at a modest height, and the
> only RF device at its site.
>
> I have two Mitrek 30w UHF mobile radios, and am aware of their duty-cycle
> limitations, but would like to consider using them. They have channel
> elements, and I'm not averse to spending the money to have the elements
> redone properly. Looks like the pair will be 447.xx transmit / 442.xx
> receive. I have a couple specific questions about these radios...
>
> (1) If Mitreks are converted for full duplex, how well do they work? I'd like
> to have a complete, swappable RF setup, so trips to the site are short, and
> repairs can be done on my bench at home. (As opposed to requiring the two
> radios as separate receiver and transmitter.)
>
> (2) Would it be a reasonable pursuit to adapt a larger heatsink, and would
> that safely allow 100% duty cycle at 25-30 watts? (I'm philosophically
> opposed to fans which introduce the opportunity for a bearing to take the
> machine out of service.)
>
> (3) Any comments on the front ends?
>
> (4) I know these lack the sophistication of the Micor mobiles. Is the lack of
> a circulator a big deal in this application, at an isolated site with no
> other transmitters?
>
> (5) Was Motorola's quality in the Mitrek era still good enough to make a
> Mitrek preferred over, say, synthesized commercial transmitter boards from
> lesser manufacturers, but of more current vintage?
>
> All comments welcome.
>
> 73,
> Paul, AE4KR
>
>
--
Cort Buffington
H: +1-785-838-3034
M: +1-785-865-7206
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