Hello Mike ...
Mike Morris wrote:
>
> At 06:17 PM 4/5/04 -0500, you wrote:
>
> >Looking for info on a UHF Consolette base.
> >Which conversion to make the unit into a repeater?
> >Thanks
> >Jimmy Floyd
> >NQ4U
>
> There were Motrac, Motran, Mocom 70, and Mitrek consolettes.
> The newer ones are called Desktracs and have either maxtracs
> or spectras in them.
>
> A consolette is not a high performance device. They were initially
> designed to allow marketing folk to sell a mobile radio at a base
> station price. Another way of thinking is that it offered the sales
> team a low cost base station.
> Note that the box is not big enough for a decent duplexer. 99%
> of the consolettes were used as base stations in non-public-safety
> environments like shopping malls, construction firms, etc.
>
> My comments below are based on UHF - the close spacing
> on 2m will make in-chassis duplexing a major headache.
A number of years ago, I converted a UHF Consolette base station
into a wire remotely controlled repeater. I believe it was a L44LHB
(450-470 MHz) This was done at a customers request. He was happy
and I never heard a complaint.
> The Motrac consolettes I have worked on have all been as
> base stations. The LHT series have an active front end and
> are a real pain to duplex. While the MHT series will duplex
> very nicely on UHF (they have a passive front end) I have had
> zero luck in getting any high band Motrac to duplex in the
> chassis without unacceptable desense. The heat rise while
> transmitting also leads me to believe that it won't be a
> practical table-top-repeater.
The LHT receiver is spec'd at -60 dB IM rejection and has an active
preamp in the front end.
The MHT receiver is spec'd at -80 dB IM rejection and has as the
first active device a FET mixer. The high IF also has a crystal
filter.
I agree with Mike's statement about the high-band Motrac duplex
modification although I did duplex the high-band Motrac Consolette
about 30 years ago to good performance as a base station in Amateur
Service. The transmitter duty rating is about 20% transmit / 80%
receive due to cooling problems of the transmitter and power supply.
The high-band duplex Motrac Consolette base station is still in
service here. I bought it as part of a fire sale in the early
seventies for $50.
I believe I also still have a UHF Motrac Consolette Base Station
which is no longer in service - in case anyone is interested. I
bought it from a guy named Wayne M. in Burbank, California for $50
about 30 years ago ... before Wayne discovered the 440 MHz band ...
then he groaned. ;)
> The low power UHF Motrans will work intermittent duty.
By low power, Mike means 15 watts output.
> The Mocom 70s I never played with much.
I have tried duplexing a UHF Mocom-70 about 30 years ago or so,
there is too much densense to allow good performance as a repeater.
I have a number of Mocom-70's here in case someone has a question.
BTW, am looking for a high-band Mocom-70 receive crystal on 161.10
MHz. I want to listen to the BNSF road channel.
> The low power UHF Mitreks will work - and a Mitrek radio can be
> fitted into a Mocom 70 consolette but with a very necessary
> electrical mod to the box...
I found a high-band 110 Watt Mitrek Consolette Base station at a
swapmeet 3-4 years ago for $25. It is now in my garage.
If you are planning to use a Mitrek in a designed for Mocom-70
environment, please be careful. The Mocom-70 Audio output
transformer secondary is grounded on one side of the winding.
Not so with the Mitrek as both sides of the speaker audio are hot.
The Mitrek Audio output is fed from a pair of push-pull IC's then
fed through a pair of capacitors for DC decoupling. In the Consolette
Station package, Motorola installed a 1:1 transformer to isolate the
push-pull IC's from the chassis. The 1:1 transformer comes with the
stock Mitrek Consolette Base Station chassis.
> Note that the Motran, Mocom 70 and Mitrek consolettes came
> with a couple of different power supply options. Watch out
> if you swap radio chassis... you can physically bolt a high power
> radio into a low power consolette chassis, but the radio will not
> be happy.
Nor will the power supply. :(
> Note that the Motracs, Motrans, and Mocom70s are all over
> 20 years old, and some are over 30. If you want to do a
> table-top-base, I'd get a Mitrek model and convert that.
It would be simpler. As I mentioned above, the UHF Mocom-70
doesn't take too well to duplexing.
> Look at the repeater-builder web site on the Mitrek page.
> The interfacing document I wrote has been used to build
> over thirty repeaters, and at least three were in consolette
> housings.
>
> Or get a Desktrac repeater and over half the work is done. Note
> that a Desktrac is a single radio chassis and a Desktrac repeater
> has two radio chassis inside.
>
> Any other questions?
>
> Mike
I certainly agree here. Any other questions?
Neil - WA6KLA
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