[time-nuts] AN/URQ-10A

[Bob kb8tq]

Hi

As temperature shifts up and down, the phase will change. If you have something
with bandwidth measured in KHz, it’s a good bet it’s going to have a change dimensioned as
tens if not hundreds of microseconds. That probably going to get you multiple cycles at 10 MHz 
over maybe a  thousand seconds. One cycle is 0.1 ppm …..

Yes there is a lot of handwaving in all that. There (obviously) are a lot of ways to make 
a filter. You can be at various points in the passband of the filter. It can have a lot of poles
or not quite so many. Your room may swing a lot and do it quickly or you may live in a cave
deep in a mountain. KHz could mean 1 KHz or it could mean 200 KHz …..

If you are doing something that ultimately gets back to time (this is Time Nuts …) the drift
from a narrow filter will probably bug you. 

Bob

> On Jul 18, 2019, at 4:07 AM, Hal Murray <hmurray at megapathdsl.net> wrote:
> 
> 
> kb8tq at n1k.org said:
>> The thing to avoid is a lot of bandpass  filters. They will be temperature
>> sensitive and “modulate” the output as temperature changes. 
> 
> What does "modulate" mean in that context?  Are you talking about minor phase 
> shifts which would be very very low frequency phase modulation or is there 
> something more complicated going on?
> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
> 
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