New Multimode MEPT with WSPR

I was going to hang up my soldering iron for the summer but with friends like ZL1BPU a boy like me will get no rest.

Why only 5 tones he insisted, well I took a short cut I used another bit to enable/disable the original 2 bits of WSPR, when the 4 Units were high impedance I set another tone frequency. I then squeezed S/MT Hellschriber into 5 Units, clever aye.

I know you are trying to keep the bandwidth down but with 3 bits you can have 8 tones said Murray. Yes but, no but, well I may do something in the future.

Then I spotted 8 Unit Multiplexers at £0.17 each, well just one more project before the summer.

An 8 unit De-Multiplexer was produced.


I re timed the Software for a 4MHz Crystal for the Microprocessor Chip. The original 3.648MHz Crystal was a cheap one and not too thermally stable. Added to which the the frequency was not a direct multiple of the data timing. The 4MHz unit has proven to be very stable needing very rare compensation for thermal drift.

I included the reset push button for manual timing. However the Grubby Finger has been superseded by technology.

We know how to use GPS time signals, we know how to use MSF/DFS time signal Modules to set lock frequency and time. Despite the new stability I decided that a 20 or 40 minute MSF time re-set would be good.

Using this the shack temperatures can rise and fall without any time sync problems.
I decided upon a KISS and Junk Box solution.

There is one segment that is used only once every 20 and 40 Minutes (twice an Hour) on an LCD MSF Clock. I shine a Bright Blue LED at the Clock Face and detect whether this segment is Black or Reflective. Thus with just 2 chips from the Junk Box, an LM392 Comparator and LM555 used as a one Shot I am provided with a precision pulse.
What is more it works reliably in Daylight, Artificial Light and Darkness.MSFlock

This photo does not show the segment used.

ZL1BPU extols the virtues of Castle Morse, I described a version which re uses the steps and thus saves bandwidth. Step Morse is now in its second simpler version. It uses a Center Line Dashes are Above the Line Dots are Below. Steps are re used in that they go up 2 and then down again this can cary on above or below the line ad infinitum. Thus all Morse Characters can be catered for using 5 tones.

Does it work? Pierre ON5SL copied my Call Sign and said he found it easy. This is his Grab of my signal.


What about S/MT Hell using the new MEPT. It certainly has a less squashed appearance.


Signals from me and G6AVK into Italy.


The Netherlands PA1SBD. Right click and select View Image for full size.8unitpa1sbd


Finally for now again with G6AVK into Nova Scotia VE1VDM all on 40mWatts of RF. Naturally G6AVK is stronger with his 200mW.



This is all on test and will need housing, one of these days.