[time-nuts] MV89A / MTI-260 / HP10811 carrier board
Gerhard Hoffmann
dk4xp at arcor.de
Thu Feb 25 15:25:20 UTC 2016
HI,
I have made some progress on my crystal oven carrier board.
It will offer a home for one of these:
- MTI-260
- Morion MV89A
- HP 10811-611
It provides regulated voltages for either of them, and the needed
electronics.
It will be possible to lock the resident oscillator to an external
reference frequency,
tune it a few Hz using a 10-turn-pot or an external tuning voltage from
0 to 5 volts.
The 10811 oscillator does not have a stable tuning reference voltage
output, it will be
provided.
There is a Xilinx Coolrunner 2C64 CPLD that generates a 1pps output from
the
resident oscillator with the usual 20 us pulsewidth.
The squarer that feeds the CPLD is either a LT6759-4 or my
implementation of
C.Steinmetz's interpretation of C.Wenzel's version of the standard
differential limiter.
The 1PPS can drive 3V3 CMOS, terminated with 50 Ohms. The output of the CPLD
is re-clocked in a 74LVC74 Flipflop directly from the limiting amplifier.
There is a 1 stage common base isolation amplifier between the output of
the oscillator
and the output of the board. It can be configured to work as a push-pull
active frequency
doubler without attenuation instead. There are 2 or 3 crystal notches to
remove the
closest (sub-)harmonics without affecting carrier phase stability.
Board size is abt. 100 * 110 square mm.
The design is modular from predefined macros. You can cut it into pieces
and get:
3 positive voltage regulators, LM317 style
1 negative voltage regulator, LM337 style
2 current feedback amplifiers using LMH6702 / AD8009 etc
1 ring mixer using a low 1/f noise Avago diode ring
1 PLL-regulator
1 isolation or frequency doubler amplifier
1 LT6759-4 limiter
1 Wenzel limiter
1 Xilinx 2C64 Coolrunner with pins on 100 mil grid
1 3V3-CMOS reclocked driver for 50 Ohm load.
1 input power meter
Connections to the modules are on a 100 mil grid, so one can
rearrange/recycle everything on Vector board or such.
This is open source hardware under BSD rules.
I do not intend to sell boards on a commercial base,
maybe there will be some samples to get things started.
All parts are available from Digikey/Mouser.
I'm currently doing the layout and will be trough with it in a week or so.
proposals, spotted errors, what to do with the empty space etc. are welcome.
(but not on parts values, that will be taken care of later)
circuits can be found under
<
http://www.hoffmann-hochfrequenz.de/downloads/CrystalOvenCarrierBoard.pdf >
This is no product documentation but a quick snapshot as of this afternoon.
One thing that is missing is sync'ing on a 1PPs instead of the external
frequency reference.
regards, Gerhard, DK4XP
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