[time-nuts] Modern signal generators

[Dr. Ulrich L. Rohde]

My feeling is
A Because of the low sunspot cycle the large signal performance of the RX is less a topic, the ICOM 7851 dynamic range, synthesizer and frequency concept is winning but expensive 
B The power amplifier from 100 W to 1500 Watt need to be catching up to the old Collins tube Amps with negative feedback, producing - 45 dB or better IMD products.

The military amplifier are fast on , reliable , durable and expensive... initially.

The noisy blower may be a bad thing.

I “only “ run 1 KW, and I am happy with it

73 de N1UL 

Sent from my iPhone

> On Dec 12, 2018, at 10:47 AM, Bob kb8tq <kb8tq at n1k.org> wrote:
> 
> 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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