Dave VanHorn wrote:
>I have a pair of amps here, that I would like to get into service.
>
>The first is a UHF amp, TLE 1713A-3
>
>
It's a 450 to 470 MHz, 75 Watt, continuous duty amplifier. *However*
the rating of 75 watts is after the Antenna Network (circulator) which
you won't likely use, so 100 watts is more the correct rating for the
amplifier output itself. More on this later....
>The second is a VHF amp, TLD 1693E-PR
>
>
It's a 150.8 to 162 MHz, 110 watt intermittent, 100 watt continuous duty
amplifier.
>I've not had any luck finding any information on them.
>
>
Motorola Manuals are not down loadable like the GE manuals are, so go to
eBay and simply look for Micor Station manuals. Just about any UHF and
VHF manual (one of each) will cover the amplifiers you have.
>My understanding is that they are very low power input (2W) and
>relatively high power out (75-100W) which would make them pretty much
>what the Dr ordered.
>
>
The VHF amp requires 400 mW of drive.
The UHF requires 1.5 to 2 watts of drive. (2W is Motorola's spec.)
Do not under drive the amplifiers or spurious output will result. By
the same token, don't go over 3 dB of overdrive. I don't know what you
will be driving the amplifiers with, but do try to come up with the
right drive level. Transmitter (exciter) output level can be safely
dropped by using a power pad or inline power attenuator. This allows
the exciter to run at its specified output and remain stable. Power
Pads come in different dB and power dissipation values. Online
calculators will help determine the right one for your inputted power.
>There are some connections that aren't clear in the intent, like plugs
>for "power control", and a connection on the side marked "SWA" on the
>UHF and "CTRL" on the VHF.
>
>
The VHF amplifier utilizes an onboard power sampler (directional
coupler) and Power Set Control Board; which sets the power level of the
amplifier and keeps it constant over several variables, like slight drop
in input voltage or drive. It also provides some protection from high
VSWR. The connection to SWA is simply a switched A- (switched ground)
that simply enables the amplifier only when there is a valid PTT
signal. In fact, if your controller has a beefy enough PTT driver, it
can simply be used to enable the amplifier. If not, a relay or FET or
other transistor switch will also work.
The UHF amplifier utilizes an Antenna Network in association with the
amplifier for power control. The Antenna Network provides feedback to
the Power Set Control board located on the Station itself. Realize this
is not an integral part of the amplifier like on the VHF. The Power Set
Control on the UHF is slightly more complicated, but does basically the
same thing, sets the output power of the amp, and provides some protection.
With all that said, the CTRL input is basically a variable voltage to
the controlled stage. Voltage at this point ranges from about 7 to 14
volts depending on what you have the Power level set to and what the
Antenna Network will allow. It is possible to run this amplifier
without the antenna network and power set control board (which I have
done). You must understand that running the amplifier from simple
circuitry that will control the UHF amplifiers power output level and
bypass the Antenna Network and Power Set Control, will take away the
protection afforded by it.
I have replaced the Power Set circuitry and delivered a variable voltage
to the CTRL pin using a LM-317T three terminal device, and a pot. The
loss in the circulator is bypassed when it isn't used and you can safely
run the UHF amplifier at 100 Watts, or so.
>I am told that these won't run on less than 15V, and yet I seem to
>remember Matthew in northern indiana running one of these on his system
>at 12VDC.
>
The Micor amplifiers are stable with an input voltage 11 to 16 volts.
Run them on 13.8 like everyone else (or 15 with the Micor supply) and
all will be well.
Hope this helps...
Kevin Custer
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