This project started from a desire to lock the local oscillator
frequency of various microwave transverters to a 10 MHz reference. It
is based loosely on work done by John Stephenson, KD6OZH, which was
published in NOV/DEC 1999, QEX.
The basic concept is a complete PLL system which doesn't depend on an
existing oscillator. This allows use as a stand alone unit, or as
injection locking.
Much of the original PIC routines were done by Ernie, W7LHL for the
16F84, and rewritten by KD7TS (me) for the 16F630. Magnus, SM4RWI has
taken this a step farther in reworking the code for the LMX2306 and two
examples are linked below.
Since this project started, the MC145170 has become difficult to find
as a DIP part, but this is still supported in a surface mount version.
I would encourage anyone undertaking this type of investigation to
check on availability of the PLL chips before spending huge amounts of
time. The National LMX series appear to be stocked by many vendors, and
might be a better choice than the the Motorola ( now ON Semi).
This is all free stuff.
The schematic and printed circuit board are all done in FREE CAD software from Express PCB. If you don't have the software then this is not too useful. The circuit was originally done on vector board, but that isn't how I wanted this to look. It is pretty easy to use the software and order the boards from Express PCB. If you don't like the way the board is laid out, the PCB CAD program allows you to change it around. Different connectors, no OP-AMP, different OP-AMP, whatever... You get 6 boards for $59.00 including shipping. $10.00 apiece seems to fit my budget.
The schematic software can be linked to the PCB drawing so that you
have a working net list and will also print out a parts list for
ordering.
The following two files are not directly viewable, unless you have
the schematic and board software already installed.
Presently I am using a Motorola MC145170 and programming it with a PIC 16F630. This is really easy to do, and works well. Testing on 10 GHz shows an accuracy of a few cycles. ( we can't measure much better than that) There are no spurs.
The PCB silk screen layer is not printed in a mini-board order, so I use it as a scratch pad to keep track of a few things. You may delete the things you don't want in the silk screen.
If you are interested in PIC's and the MC145170 or LMX2306, drop me
a note and
I'll try to help. If no one is interested, I'll save my time for
experimenting
and building.
Next link is a .GIF screen capture of the schematic from ExpressSCH. This is current,and a good example of the schematic generated in the ExpressPCB program, in case you haven't seen any of this stuff before.
http://members.aceweb.com/kd7ts/html/PLL/VCXO.gif
an
assembly
language file for the 16F630
and the MC145170
A
few
picures.. these are with a 16F84... later boards are very
similar, and have mounting holes !
I have gone to the 16F630 rather than the more popular 16F84a due to the difference in price. $7.00 vs $1.25. The '630 is smaller and lends itself to a more compact layout. The source code is for 106.5 MHz, but can be adapted to any likely transverter scheme below 180 MHz. There are no loop filters to calculate or interconnects to other boards. You will need to bring in 12 volts and 10 MHz. The output is phase locked to the 10 MHz input.
construction notes
updated 07 DEC 2006