[time-nuts] Inside a CTS 1960017 OCXO

Pete Lancashire pete at petelancashire.com
Sun Feb 28 10:53:38 EST 2016


... I was using an HP lab supply>>>

Model ? Age ?

My bench has some pretty old HP's even Harrison Lab branded supplies. I
have had to re-cap a few of them.
In a way it is almost a curse how reliable their supplies were. You always
got the V and I you wanted so one
never thought about the filtering getting worse over the years.

Also HP had two variations of their bench supplies. The basic ones and the
low noise versions. When I need
to make measurement like this, I make sure I'm using one of the low
noise/ripple models.

Another thing that is pretty easy to eliminate is radiated 60 Hz. Build a
cell (box). A very simple disposable one
can be from a corrugated box, aluminum foil, and a few feed through
connections.

Any lighting not based on piece of tungsten wire ?

On Sat, Feb 27, 2016 at 1:07 PM, Rob Sherwood. <rob at nc0b.com> wrote:

> I cannot say exactly, as I measured it as 59 Hz.  VA7OJ measured it as 60
> Hz.  I was using an HP lab supply, and Adam was using some other lab
> supply.  I put a 500 uF capacitor across the Vcc pin and it had no effect.
> I don't think it has anything to do with the power supply since both of us
> saw the same thing.  If an attachment will go through this reflector, I can
> post a spectrum analyzer screen shot.
>
> -----Original Message-----
> From: time-nuts [mailto:time-nuts-bounces at febo.com] On Behalf Of jimlux
> Sent: Saturday, February 27, 2016 12:07 PM
> To: time-nuts at febo.com
> Subject: Re: [time-nuts] Inside a CTS 1960017 OCXO
>
>
>
> On 2/27/16 9:35 AM, Rob Sherwood. wrote:
> > Hi Dan,
> >
> > I purchased two of these, and VA7OJ one.  One of mine is defective, and
> the seller is going to replace it.  What was disappointing was all the
> spurious at 60 Hz intervals relatively close-in to the 10 MHz carrier.  I
> suppose if all one wants is a reasonably accurate 10 MHz, then they work
> OK.  My good one and Adam's unit were 1x10^7 low in frequency once warmed
> up, and there are pins for frequency adjustment and sync to another
> standard.  However if one wanted it for an oscillator with good close-in
> phase noise, the spurs ruin that hope.
> >
> > Do you know if there is a chopper at 60 Hz that runs the proportional
> oven that is the source of all the spurious?
> >
>
>
> Is it right at line frequency, or is it "close" to 60 Hz?
>
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