Posted by
P.B. Christensen on
Apr 05, 2011; 7:36pm
URL: http://elecraft.85.s1.nabble.com/K3EXREF-and-Trimble-Thunderbolts-tp6242158p6243572.html
> 1. Any reference oscillator operating at 10 MHz would work with the
> K3XREF?
The 10 MHz source should have a signal level between +4 dBm and +16 dBm. For
square wave sources, 2VDC to 3.3VDC peak is optimum. If the source is a 5V
logic level, use a 50-ohm resistor in series with the input.
> 2. All that's needed for this to work is the K3XREF, updated
firmware, an accurate 10 MHz clock/oscillator, and a BNC cable?
Yes.
> 3. Trimble Thunderbolt seems to be a good, cheap product to try. Any
others that are > $100?
Many. For those not affraid of getting a soldering iron hot, I think the
Trimble units are pretty tough to beat. Requires making a power cable to a
triple-output power supply of your choice. For a while, the HP Z3801A units
were very popular. These use noisy DC-DC internal converters, are power
hungry, but offer some of the best phase noise peformance of all the GPS-DO
units. The Trimble units have been documented to pretty much meet the phase
noise performance of the Z3801A. Rubidium is another choice in the USD
$100 range but these too will require some creative power connections.
> What are the additional advantages of doing this other than knowing
you've pretty much eliminated any frequency drift?
Really none I can think of, but as the weak-signal V/UHF ops have said,
that's reason enough!
Paul, W9AC
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