[time-nuts] OT: xtal osc PN
lists at rtty.us
Sun Sep 19 13:38:33 UTC 2010
Ok, you have just ruled out all of the silicon oscillators and by similarity ruled out a DDS. That narrows things down quite a bit.
You will indeed need to shop around for low noise VHF crystals. Since you are in Europe, talking to KVG probably is your best bet.
On Sep 19, 2010, at 3:35 AM, francesco messineo wrote:
> On 9/19/10, Bob Camp <lists at rtty.us> wrote:
>> Is -195 dbc/Hz floor good enough or is it overkill?
> I'd say this is obviously overkill, -160 dBc/Hz could be a good compromise.
>> Is -155 dbc/Hz at 100 Hz offset a requirement or is -40 dbc ok?
> -40 dBc/Hz at 100 Hz is about useless, -150 dBc/Hz at 100 Hz is again
> a good compromise, the lower (practically) the better.
> It's hard to explain why to ones not familiar with weak signal
> operation between broadcasting signals, but really the noise floor
> raise a lot when you have some 5 or 6 broadcasts signals in 500 KHz of
> band (all with power levels of at least 10 dB more than the levels
> used in amateur radio, often +20 dB more)
>> You need to quantify what you are after before deciding on an approach. Low
>> noise means many different things to each of us.
> it's a compromise, of course I can't spend years or thousand dollars
> on the LO part of the setup. In the first case I'd not use it very
> much (so would be useless) and in the second case I could probably pay
> me a trip at the other side of the world far away from broadcasts :-)
> As good as it can gets within few months and a hundred dollars (maybe
> more if for useful test equipment). The rest of the parts are going to
> cost less than $300 total.
> Best regards
> Frank IZ8DWF
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