Amusing story:
Back in high school, Ewa Beach Hawaii, I used to notice that the second hand
on the clocks would sometimes slow significantly. This turned out to be caused
by the man who would later become my father in law.
He ran the steel mill, melting old cars into rebar, which was
Hi
What may well have happened is a part aged quite a bit or failed outright in
all of them. Without
tearing into the circuit, and analyzing it, there is no way to really know.
Bob
> On Jun 20, 2016, at 2:28 PM, Iwa2008 via time-nuts wrote:
>
>
>
> was messing around
Hi
Yes, indeed doppler is problem. It is not a un-solvable problem. That’s why
you need the long audio records to look at. That’s why you go a bit crazy
looking at giant long FFT’s. The next layer to it is that your receiver has to
stay
on that signal for the entire duration of the test. If
On 6/20/16 1:44 PM, Graham / KE9H wrote:
The ionospheric Doppler will spread the signal a few tenths of a Hz, YES.
so getting millihertz is more random luck of the draw. NO,
it is all about how good your averaging method/strategy is, over the period
of the test measurement.
A lot of the
http://www.cliftonlaboratories.com/off-the-air_frequency_measurement.htm
If you peruse http://www.b4h.net/fmt/fmtresults201204.php you will see that
HP3336A's also feature regularly.
On Jun 21, 2016, at 4:52 AM, Pete Lancashire wrote:
> Never tried it but a Selective Level Meter aka HP
was messing around with one of theocxo's last night. The most easily way to
guarantee an instantincorrect frequency turn on is to either start it at an
under voltagecondition(ex. initial power on at 10V, with full current), or
tostart it with a current limited power supply, that delivers
On 6/20/2016 11:18 AM, Mark Spencer wrote:
I am quite convinced that HF Doppler shift is a real issue at times.
Absolutely true Mark. I spent some time looking at this way back when
and it is quite possible to observe (in Southern Calfornia) transitory
phase shifts on the 10 MHz signal
I also added the HP10811 double oven board to Dirty PCB's shared projects. 10
boards will cost you a whopping $25 (They usually send you couple of extras if
they had good yields).
http://dirtypcbs.com/view.php?share=22492=f5a69b7619ce8f139bb9d1ea789ad45e
t...@electrictime.com said:
> In the suburb of Boston where we are located - you never have to correct an
> electrical clock between the daylight saving time changes. This of course
> assumes you haven't lost power - due to major snow storms etc
I agree with the spirit of your comment, but
Most of the folks doing the FMT these days use some sort of audio
spectrum analyzer program and estimate the frequency using that.
Or use the audio spectrum analyzer to measure the difference between
the frequency being measured and the precision reference. You are
correct, it is usually not a
> On Jun 20, 2016, at 12:52 PM, Bob Camp wrote:
>
> Hi
>
> The cheaters way is to simply use a fully synthesized radio tied to a known
> reference frequency.
Yeah, that’s what I’ve got in mind. Both the synthesized tuning LO and the
second LO would be derived from an external
Hi
The cheaters way is to simply use a fully synthesized radio tied to a known
reference frequency. Feed the output into one channel of a sound card. Feed
the other channel of the sound card with a known frequency tone. Post process
it to death with your choice of FFT programs.
Another
To echo the point that Jim Lux made in another post...
I'm not sure how those of us who live an appreciable distance from the
transmitters can expect to get mili hertz accuracy in light of the HF Doppler
shift over long distance paths with restorting to tactics such as
simultaneously
On 6/20/16 10:10 AM, Graham / KE9H wrote:
You need to be able to measure frequency accurately in the milli-Hertz
range to be competitive in the frequency measuring contests.
I doubt the Selective Voltmeters have that level of resolution. I think
they 'only' read to 0.1 Hz.
--- Gr
And
You need to be able to measure frequency accurately in the milli-Hertz
range to be competitive in the frequency measuring contests.
I doubt the Selective Voltmeters have that level of resolution. I think
they 'only' read to 0.1 Hz.
--- Graham
On Mon, Jun 20, 2016 at 11:52 AM, Pete Lancashire
On 6/20/16 7:51 AM, Nick Sayer via time-nuts wrote:
I'm considering taking a shot at the next ARRL frequency measurement
contest.
The assumption going in is that the signal is CW, with at least a
half minute or so of just solid "on" at one point or another and that
reception is reasonably good.
Nick:
You can do it this way, but it requires you to totally understand the
mathematics and granularity of ALL of the frequency sources and
synthesizers in the superhet receiver.
And if there are any audio soundcards or sampling devices involved, the
specifications and origin of the sampling
Never tried it but a Selective Level Meter aka HP 3586A/B/C ?
On Mon, Jun 20, 2016 at 7:51 AM, Nick Sayer via time-nuts
wrote:
> I'm considering taking a shot at the next ARRL frequency measurement contest.
>
> The assumption going in is that the signal is CW, with at least a
Line frequency in the USA is actually very accurate over the long term - not
with respect to atomic clocks - but the power companies do correct the line
frequency.
In the suburb of Boston where we are located - you never have to correct an
electrical clock between the daylight saving time
I'm considering taking a shot at the next ARRL frequency measurement contest.
The assumption going in is that the signal is CW, with at least a half minute
or so of just solid "on" at one point or another and that reception is
reasonably good.
I've got a good TIA and excellent references, but
-pete
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I got a couple of requests for the schematic... apparently the old link is
dead. Here is Warren's original drawing. Buy the man a beer... The only
change that I made was using a single high-beta (say 1000) transistor to drive
the heater. Warren used two transistors. All the part numbers
Attila wrote:
Having put the circuit through Spice, I see that the current through
the tail fluctates violently during the time when the current switches
from one transistor of the pair to the other. The reason for this seems
to be that the f_t of the current source transistor is too low to
Did finally complete my lab at the new location all instruments survived
the move. As a result of downsizing found, that I have quite a few of the old
oval shaped 3 pin power cords used by HP and Wavetek. Noticed them on ebay
for $ 25 plus shipping. I will charge time nuts $ 15 shipping
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