[time-nuts] 60 KHz Receiver
sandeenpa at yahoo.com
Mon Oct 4 19:11:58 UTC 2010
Thanks for all the input on the HP 3586B and the Austron Loran C receiver. I’ll try to distill what’s been said.
It appears that using the HP 3586B for a WWVB receiver isn’t a good idea unless I would use my HP 3336B or some other method to phase lock the BFO. Since this seems to be way out of the KISS principle, I will go to plan B.
I appreciate the clever circuit to convert the Austron to a phase detector but the effort required to get just a phase detector alone isn’t cost effective for me.
Opening up the Austron shows that there is a great deal of space. If the three Loran boards are gutted one of my Lucent Rubidium or Xtal standards will just fit in their place. The power supply appears to be robust for the power required. If not, there is space to add on.
So to try to maximize the salvage of my purchase it looks like I should do the following.
1. Gut the Loran boards and get a Lucent unit installed and working.
2. Build a big honkin’ quality 60 KHz loop antenna. I live in the country so I can put up any size I can afford.
3. Convert the Austron RF amp boards to 60 KHz if I can get a schematic and get lucky. Does anyone have one or know where I could download it?
4. If I don’t get lucky, build a TRF receiver in place of the Austron RF boards. 60 KHz crystals are cheap from Mouser. Does anyone have experience building a ladder or similar crystal filter?
5. After I get a good working 60 KHz signal, I‘ll divide it by six and apply it to a Talbot 10 KHz phase detector. The Talbot circuit divides the 10 MHz reference oscillator to 10KHz using 74HC390 decade dividers. It then provides a correction circuit to the reference oscillator from its phase detector. Since the Talbot circuit on uses about six IC’s it will fit nicely in the rear chassis area.
The goal, when completed, is to have a WWVB phase locked oscillator (yes I have to figure out what to do about diurnal shift) a reference frequency output and perhaps add a second Talbot phase detector circuit and meter for calibrating other oscillators.
Yes, the GPS is more accurate more quickly but the issue is to have a second independent source for cross-checking. Though highly unlikely, GPS satellites can be shot down, disabled or turned off or have their outputs modified at any time.
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