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

Chris Wilson chris at chriswilson.tv
Sat May 18 18:11:05 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).

> Ed

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18/05/2013 23:05

Thanks Ed, some good info there. I was going to see if it was easier
to multiply my TB output to add a 500 MHz oscillator to an HP8444A
tracking generator to give it a poor man's Option 059. This option was
an in built 500 MHz oscillator to work with spectrum analysers like my
HP8568B, which does not have this LO available internally. It looks
like I am overcomplicating things so have built a cheap Mini Kits xtal
controlled oscillator with thermistor heater, and it seems to work
fine for my pretty basic tracking generator needs. I have the HP8568B
locked to the Thunderbolt, so I was just musing if that could also
give the 500MHz, but I guess the answer is yes, but at some cost and
fuss :)

Thank you Ed, and those that have replied, I have learnt a lot from
the info.

       Best Regards,
                   Chris Wilson.

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