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Pieces of a Puzzle Print E-mail
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At the moment it's really fun to work on the project as it has such a lot of variety. What I did yesterday evening:
* some calculus: I designed a band pass filter for 20MHz and run a sim in PSpice to check it with real world component values
* some solder smoke: I built the clock amplifier between the BPF and the DDS chip and did some matching and optimization on the current drain
* some bits and bytes: I adopted the NMEA protocol routines and attached the Navsync RS232 to my existing beacon to see if it works - and it does.

Now the Navsync module is completely integrated. I get a nice 20MHz master clock with low jitter, everything is running on 3.3V now
and the old serial GPS mouse is gone and replaced by the CW25-TIM.Tonight I will play with analog switches. I have some ADG736
here on my desk. I want one in between the DDS chip and the balun transformer, to be able to route the RF signal either to
the balun and ahead to the preamp and PA for 160m to 6m, or switch it to the pin head connector for the option module.

This free slot could host e.g. a 500kHz amplifier, or a frequency multiplier and a PA for 4m or 2m .... Another analog switch will be placed
at the output of the GPS module. In "beacon mode" the 20MHz are routed from the GPS trough a band pass and an amplifier to the
DDS chip and the 1pps signal is routed to the CPU. There will be a "reference source mode" where these two signals are routed to
connectors on the back plane to be used in the shack as a reference source. Once this is accomplished I will look into power management
and sleep mode for the CPU. This will be the last piece of the puzzle before I can draw the PCB.


Find out more about the BeaconTNG procect here!

Stay tuned on the project.
73
Gernot