[time-nuts] RFTG-m-XO disassembly photos

[Dr Bruce Griffiths]

Rex wrote:
> On Tue, 26 Dec 2006 22:06:28 -0600, "Bill Hawkins" <bill at iaxs.net>
> wrote:
>
>   
>> What's all this about 15 MHz out?
>>
>> Bill Hawkins
>>     
>
> I have an FRS-C rubidium (10 MHz) that I bought a couple years ago. It
> came in a metal box that also contained a circuit board that provided 3
> TNC output connectors. Two of those had 10 MHz square wave output. One
> provided a strong (24.3 dBm into 50 ohms) 15 MHz sine wave output.
>
> The board somehow used the 10 MHz from the rubidium to generate a 15 MHz
> sine. I never figured out exactly how they were doing this; the board
> had an an Altera EP610PC-25T PLD doing most of the interesting stuff. I
> now suspect my box must have been for a similar setup to the Lucent
> application.
>
> In the FRS box I noticed a 15 MHz filter on the board. If you look at
> John's picture rftg-m-xo-7.jpg, the metal can in the top-center (not the
> Efratom oscillator) is a 15 MHz filter.
>
>
>
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>   
Rex, Bill

The simplest way of generating a 15MHz output signal from a 10MHz input 
signal, is to divide the 10MHz by 2 using a flipflop and then extract 
the 15MHz 3rd harmonic component of the 5MHz square wave output of the 
flipflop with an analog bandpass filter.

Bruce