[time-nuts] 5 Mhz to 10 Mhz and 25 Mhz

Bob kb8tq kb8tq at n1k.org
Thu Sep 12 22:19:14 UTC 2019


Hi

If that’s the objective then the correct answer is: “none of the above” :) 

For a low noise microwave chain, you want to go as high as you can with a 
crystal oscillator in the first step. That gets you into the 100 to 200 MHz range
as the first step up from your low frequency standard. 

There are a lot of reasons why. Bottom line is that it’s how you get the best noise
out of the chain. Depending on the offset involved, and what you are comparing to,
it may be better by as much as 20 to 40 db.

Bob

> On Sep 10, 2019, at 11:19 AM, Paul Bicknell <paul at bicknells.f2s.com> wrote:
> 
> Hi Dave  I posted the question as I am not up to speed with the latest
> solutions 
> But I want the lowest phase noise that is easily possible so you might be
> correct as it is to lock up a 10 Ghz receiver but later for a 120 Ghz
> receiver 
> 
> Regards Paul 
> 
> 
> 
> -----Original Message-----
> From: time-nuts [mailto:time-nuts-bounces at lists.febo.com] On Behalf Of Dave
> B via time-nuts
> Sent: 10 September 2019 17:40
> To: time-nuts at lists.febo.com
> Cc: Dave B
> Subject: Re: [time-nuts] 5 Mhz to 10 Mhz and 25 Mhz
> 
> On 10/09/2019 17:00, time-nuts-request at lists.febo.com wrote:
>> Re: [time-nuts] 5 Mhz to 10 Mhz and 25 Mhz
> 
> Why not just create a comb of frequencies based on the 5 MHz input, then
> filter and extract the 10 and 25 MHz signals you want, amplify and
> distribute as needed?  Going the PLL route seems like a large hammer to
> crack a small nut.
> 
> Unless you want a free-running signal if the incoming 5 MHz vanishes...
> 
> Dave G0WBX.
> 
> 
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