More complete evaluation of the BG7TBL from eBay:
One week continuously powered up.
19-23 degrees ambient temperature, 55-65% humidity.
Output 10 MHz at 4 volts p-p.
Frequency measured by phase drift rate when compared to a Thunderbolt GPSDO 10
MHz standard using a scope.
Precision --
+/-
Regarding Dana's remarks on VLBI, consider the recent black hole image released
by the Event Horizon Telescope.Measurements were taken at 230 GHz, and they
would like to begin measurements at 345 GHz.Hydrogen masers were used at
each telescope.I am no expert, but I strongly
Harmonics from a Si5351A is not a problem. As pointed out a LPF will do what it
takes to get the fundamental frequency "extracted". The Si5351A is designed to
clock/feed other digital circuits so that shouldn't be a problem in this
particular case either.
In the digital clock domain spurs are,
Chris, better to set your SA to 5 MHz span with 2.5MHz center. Adjust the input
attenuator (start with lots of attenuation) until the 995 kHz peak is just
less than the always present peak at zero frequency. (Namely always keep zero
Hz at the left side of the screen, or to the left of that so
"Some people build giant laser interferometers, other people build large-scale
particle accelerators, still other people build elaborate clocks. They are all
looking for the same thing: a conversation with Mother Nature that begins with,
"Hmm, that's funny," and ends in a Nobel acceptance
In my personal lab, I have many oscillators that I consider "standards". They
have varying long term and short term stability. I have:
1: HP11811-6011 double oven
2: Nortel GPSTM GPSDO (I have two)
3: Efratom PRFS1024: Efratom PRFS2025: PRS-10 disciplined by Trimble
Resolution-T GPS
5:
Hi
Not quite sure what this has to do with time and frequency but ok ……
A spectrum analyzer has a “zero frequency” response. You can see this when you
do not have any input. It is clearly present on both of your plots. I suspect
you are
confusing it with an actual signal.
Analyzers are
That's what a square wave is ! A LPF will work on anything. I'm not sure why
you are using a class D amplifier though ?
Dave G4IUG
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Chris,
In general I'd say that the rather high level sidebands on your
signal are not reasonable at all, but I think I see what's *really*
wrong: your SA settings. It looks to me like the tall signal
is the DC spur, (a.k.a. "start spur") of you analyzer, and
the signal very near center screen is
This thread reminds me of a few things, firstly, nuclear fusion:
On Wed, Jun 5, 2019 at 1:00 AM jimlux wrote:
>
> 30 odd years ago, I heard a speech from a guy at AT who said that by
> definition, you cannot predict technology that will result in a
> revolution ahead of time.
>The cost of a
This topic reminds me of my first job at NPL Teddington back in the late
60's when Prof Essen was my boss's boss.
Frequency standards, length standards, etc, etc.
Happy days, an amazing place to work, an amazing library, and one hell
of a start for a 16yo for a career in electronic and
05/06/2019 16:24
I am using a small transmitter called a U3S by QRP Labs as an exciter
for a high power Class D amp. I take the output at circa 951kHz direct
from CLK0 (it has no output stage built, I go direct from CLK0 on the
Si5351A and input it to a level converter based on a
Being thoughtfully non-dismissive.
Personally, I subscribe to the school of "We don't don't need it yet, but ..."
in the belief that things like insanely accurate clocks will lead to greater sources of
excitement later on.
And I am reminded that :
1. A guy with one clock knows what time it
Will Kimber wrote:
>
> The thing with TIME is that its measurement is a abstract concept. Most
> other "standards" have a physical representation.
The metre is derived from the second and the speed of light using
interferometry. The kg is derived from the metre and the second and the
planck
> As to your analogy, it is valid only if and to the extent that NIST-F2 has
> practical applications. That is what I am asking about.
The important thing about devices like NIST-F2 is not that they are better
than any other clocks, it's that they are still imperfect. The researchers
are
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