[time-nuts] AN/URQ-10A - on frequency doublers

[Glen English VK1XX]

Roy,

The passive frequency doubler is essentially perfect. It will add some 
flicker noise. (There are documented methods like using CB connected 
transistors etc however I suggest just build it unless you are after 
doing better than the best labs in the world).

For all passive freq doublers, depending on where it is going, you might 
want some selectivity to reject 4f, 6f etc , and also duty cycle affects 
you might need to take notice of.The sort of input level you have 
available, 3 to 10dBm is fairly suitable.

Expect conversion loss of 10 to 12dB , start with +10 is a good place.

You will most likely need some amplification post doubling to get back 
where you want to be.

...could buy off the shelf :  I would suggest this one : The balance is 
good ensuring low odd harmonics :

https://www.minicircuits.com/WebStore/dashboard.html?model=RK-3%2B

For easy construction , for your 5 MHz doubler, I would suggest two RF 
transformers and a bridge

like this: (schematic at the page) - see figure 4.

https://www.qsl.net/4f5aww/module5k.htm

you can use a centre tapped transformer, or 3 wire transformer.

OR, you could use a bridge frequency doubler .... has a little better 
non even harmonic rejection...
page 13:
https://www.qsl.net/va3iul/Frequency_Multipliers/Frequency_Multipliers.pdf



glen




On 18/07/2019 8:07 AM, Roy Thistle wrote:
> Hi All:
>
> I tried to search for this, in the forum, but, I didn't find much.
>
> I'm interested in getting a AN/URQ-10A... I have the manual. It's an old on ship, frequency standard.
>
> Does anyone have recommendations, or issues, concerning these units?
>
> The one I am thinking of is a little bit high (about +10 Hz, I think) and can't be "tuned" back to 5 MHz, without... I am guessing calibration. But, I am wondering if... because of the positive drift, if the crystal is damaged.
>
> By the way, how and why 5MHz... because its not that useful! … at least today.
>
> Does a frequency doubler… assuming a lock on the standard... cause errors in the 10 MHz signal obtained?
>
> Best regards and wishes
>
> Roy
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