[time-nuts] Trimble Thunderbolt, any easy way to create 500 MHz reference from one?

ed breya eb at telight.com
Sat May 18 09:23:28 EDT 2013

I sent this Friday morning, but it didn't seem to get through, so I 
am repeating. Please excuse if both copies eventually show up:

I assume the question is about going from 10 Mhz to 500 MHz. The 
possible solutions depend on how clean the result has to be. For 
"counting" grade use, this has been done in a number of test 
instruments like the HP5345A and HP5370A that I'm familiar with, and 
certainly others. If you look at the multiplier or PLL systems in 
equipment that does this, you can get an idea of what's involved. It 
takes quite a bit of circuitry to provide a really clean output.

If you already have such an instrument in service, you can modify it 
to tap off the 500 MHz, buffer it up, and provide an external 
connection for it. This won't be enough if you need a dedicated or 
more compact built-in source, but if you can find a carcass of one of 
these instruments, or just the appropriate boards, you can build up a 
unit that should be quite good.

Of course, any synthesizer that covers that frequency could do the 
job directly. One of my favorite oldies is the Wavetek 3000 or 3001 
that reaches 520 MHz - I have acquired a couple over the years for 
very cheap. These are tall, half-rack width, so not very compact, but 
could be cheap enough to dedicate to an application.

If it must be very small and modern, you should be able to find 
off-shelf a complete phase-locked fixed 500 MHz or programmable 
module, ready to go, but it will be quite expensive new. If you want 
to start from scratch, I'd recommend looking for an off-shelf 
SAW-resonator based VCSO from an RF vendor (expensive new, but maybe 
can be found surplus), and a PLL IC such as those available from 
Analog Devices and National (now p/o Texas Instruments).


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