[time-nuts] Modern signal generators

[Bob kb8tq]

Hi

Usually on HF, the issue is large signal rejection. Phase noise very definitely 
gets into that part of things. Other components in the signal chain do as well.
Once the synthesizer is no longer the weak link in the chain, spending more
to improve it (vs spending on the other components) probably does not make 
a lot of sense. Since the synthesizer is *far* from ideal, that sort of begs the
question of just how troublesome the other parts are and how much better a 
device *could* be built.

This does seem to be wandering a bit from a Time related topic …..

It does illustrate the point that “good enough” may be way far  away from 
“pretty good” and yet even more distant from “as good as it gets”.  The 
question on any system is always “how good do you need / what are you 
doing?” …. 

Bob

> On Dec 12, 2018, at 8:49 AM, jimlux <jimlux at earthlink.net> wrote:
> 
> On 12/11/18 3:26 PM, Bob kb8tq wrote:
>> Hi
>> As I said, just how rational using these parts in a radio …. not at all clear to me.
>> Back when I went to school, stuff that was this noisy was not in the “greatest” category.
>> That was a *very* long time ago.
>> Oddly enough best performance synthesizers have gotten better. (as the posted
>> presentations very clearly show). Just why a “high end” radio uses a less than
>> ideal synthesizer likely relates more to cost (even at a price of thousands of dollars)
>> than to anything else.
> 
> Or "good enough" performance - driving to a 3 dB NF for a HF receiver while maintaining good strong signal performance is probably not worth it
> 
> 
>> Indeed cost also drives things like GPSDO’s and GPS modules. We often are not
>> very eager to acknowledge that fact.
>> Bob
> 
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