[time-nuts] A Highly-Accurate and Stable SDR-IQ Using GPS-DO and DFS

paul swed paulswedb at gmail.com
Sat Jul 24 10:08:40 EDT 2010


Indeed the do. I believe its actually a HP3586b a selective level voltmeter.
One heck of a reciever measures signals to 100th of a db. As a heads up they
have a very good xtal oven in them. I have 5 of these units. Just can not
resist them.
Often you find these quite cheap. Last one was $20 because it did not work.
Well the oven had been taken. Ext ref did just fine. Mine are locked to a Rb
standard.
Another big caution these have a nicad in them with a resistor for charging.
They leak.
You need to pull the board and look at it and remove it before powering up.
If the leakage has hit the traces, normal. It will raise holy heck and
damage the regulators.
Clean all the gook and repair any traces and you should be fine.

On Fri, Jul 23, 2010 at 11:05 PM, J. Forster <jfor at quik.com> wrote:

> If you want an HF radio that reads to a Hz, ready made, get a used HP
> (Agilent) 3486 Selective Level Meter. It covers essentially DC to either
> 20 or 30 MHz. It has a good internal ovenized oscillator, and can be
> locked to an external standard.
>
> A virtually unique feature is that it will lock onto a carrier and read
> that carrier frequency to a Hz or better.
>
> They are often abailable for a few hundred. The 3486A & B are similar.
>
> FWIW,
>
> -John
>
> =====================
>
>
>
>
>
> > I have been involved with many kinds of radio receivers for over fifty
> > years -- amateur, military, and commercial. This modified SDR-IQ is a
> > dream come true. When I was a young ham, I dreamed of the day when I
> might
> > have a receiver that would read out to one kilocycle (before we used the
> > term Hertz). Now I have assembled one that reads out to one Hertz and is
> > accurate to a few millihertz -- and thanks to GPS -- it will maintain
> this
> > accuracy as long as the GPS satellites keep working.
> >
> > I well remember the early radios that I used. I had to be very careful to
> > not bump the table where the radio was or it would jump completely off
> > frequency. Whatever frequency it indicated was only approximate. It made
> > me nervous to operate near a band edge.
> >
> > Dave Powis, G4HUP designed and built a 66.66666 MHz DFS for me. I really
> > appreciate his help on this project, especially since several hams told
> me
> > it couldn't or shouldn't be done. Some said that the frequency read-out
> on
> > the SDR-IQ would not be accurate because the time-base in the computer's
> > sound card would be a variable factor, but this is not true. The
> frequency
> > accuracy and stability of this radio ONLY depends on the 10 MHz
> oscillator
> > in the Trimble Thunderbolt and that oscillator is locked to the GPS
> > constellation.
> >
> > Dave and I worked together on this project for about one year. The DFS
> box
> > travelled across the Atlantic Ocean five times before we finished.
> >
> > Dave has written an article "Precise Frequency Locking for the RFSpace
> SDR
> > radios" and I have a web page showing how I connected all of this
> > equipment together. Here are the links:
> >
> > http://www.braddye.com/g4hup_dfs.html
> > http://www.braddye.com/gps_do.html
> >
> > 73s
> >
> > Brad Dye, K9IQY
> > ex KN9IQY, KN4BK, KM5NK, WB4JCF, ZP5TQ, WA4VXU, WA9RVL, HH2FJ /TI2, /9Y4,
> > /6Y5, /KP4
> > 53 years as a FCC licensed amateur radio operator
> > 37 years as a FCC licensed first class commercial radio operator
> >
> >
> > _______________________________________________
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> >
> >
>
>
>
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