[time-nuts] Thunderbolt versus Home made

[Didier Juges]

Richard W. Solomon wrote:
> I looked at the ACE-III on Trimble and do not see mention of a 10 KHz output.
> Maybe I miised it, but without it, the N1JEZ board will not do unless you modify
> it for 1 pps.
> I am trying to find more info, but since it reached EOL, Trimble may have deleted
> it.
>
> 73, Dick, W1KSZ
Dick,

You are correct, you need to patch another set of dividers in the chain. 
Keep in mind that the only benefit of a 10 kHz output on the Jupiter is 
to save 4 decade dividers. You should not use the fact that the Jupiter 
outputs 10 kHz to speed up the loop in a GPSDO. The loop bandwidth is a 
function of the crossover point between the VCXO and the GPS, which in 
most cases will be between many minutes (cheap VCXO) and a few hours (HP 
10811). Whether you use 1 Hz or 10 kHz comparison frequency into the 
phase detector will not affect the filter.

One advantage of the ACE-III over the Jupiter is the 90 mA power 
consumption, versus 250 mA for the Jupiter. That is significant in a 
portable, battery operated application.

The point I am trying to make is that if you are not sure how good a 
GPSDO is, you might as well make your own, and it is not that difficult 
or expensive if you are only looking for average performance 
(considering that even an average GPSDO you made yourself will be a 
better, cheaper frequency reference than anything else you might come up 
with in your home lab).

A typical use for a home made GPSDO would be to synchronize test 
equipment such as frequency synthesizers and frequency counters to a 
known good 10 MHz, or to obtain accurate operating frequency on the 
microwave bands.

The ACE-III is still accessible on the Trimble page:

http://www.trimble.com/ace3.shtml

Didier KO4BB