[time-nuts] Soooo, maybe this makes me a TN??

dlewis6767 dlewis6767 at austin.rr.com
Mon Aug 6 01:26:02 UTC 2012

I finally got my home bench-lab, 10 MHz, GPSDO distribution up and running tonight.

Built it up myself, ...maybe ignorance is bliss, ...it seems to work.  Like Frank said, "Did it my way...."

I set out with only three criteria:  Cheap; 'GPS'-accurate; and tie the bench units to one standard.  That includes servicing eight HP units, at this time. (btw, the external-in references on these HP units varies considerably, generation-to-generation.  It affects loading.)

Armed with what seems miles  of cable-tv cables and splitters, I set out to see if this scheme could be made to work.  It certainly met my price-break criteria (free).
  a.. I set up two distribution splits, each with a subsequent four-way split (the two four-ways are fed by a two way splitter). 
  b.. Built a simple distribution amplifier from an LM7171 high-speed op-amp running at +/-15 volts. 
  c.. Bought an inexpensive DATUM square-wave OCXO for $13 to feed the LM7171.  A little capacitive input rounding and output coupling and it will just hit 5volts PP at all eight units. 
  d.. Bought a $65 Motorola NAVMAN TU60 for the GPS.  Works great and locks in just a few minutes; can monitor it all easily with TAC32. 
  e.. Used a simple 4046 PLL and RC filter to lock the DATUM and GPS.  Locks in about 7 minutes with a VFC of ~2.6 volts from the PLL/GPS. 
  f.. I used left-over bricks to power it all and built a nice box out of 'paint-sticks.'  They sand and stain REALLY nicely - you should try them.!  hihi 
  g.. In the end, ...All eight HP units display 10 MHz when fed the DATUM 'standard', ...even the 3586, ...at least the external-in reference is working in all.
Soooo, for less than ~$80, I have an eight-unit distribution system for the bench.  Cheap and hopefully, accurate.  Not sure this makes me a TN, ...but certainly nuts.

-Don Lewis
Austin, TX

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