[NLRS] 10GHz LO Query

[Zack Widup]

Hi Jack,

Anything made by Isotemp should be adequate. They publish or supply their
phase noise figures. From my observation, any company that actually
supplies phase noise figures has good phase noise characteristics.

For over a decade I have been using three Isotemp OCXO's with no GPS
disciplining for all bands through 47 GHz. They have been accurate, stable
and low phase noise. I calibrate them at home with a rubidium standard
every month or so.

I have been using the KD6OZH low-noise phase-locked VHF VCXO circuit in all
microwave transverters through 47 GHz. In the 10 GHz transverter I use a
106.500 MHz crystal and one of Paul's "10 GHz personal beacon" multipliers
to get 10224.0 MHz. On the higher bands I use Frequency West bricks to lock
the ~100 MHz KD6OZH circuit to the brick.

I would stay away from the ApolLO or DIGILO circuits for 10 GHz and above.
Their phase noise is far worse than the KD6OZH circuit. Tom WA1MBA has put
together a page about this circuit, including files to have ExpressPCB make
the boards for you.

http://www.wa1mba.org/PLLVCXO.htm

73, Zack W9SZ

On Mon, Aug 17, 2020 at 11:00 AM Jack Parker <vhfplus at gmail.com> wrote:

> I would like a bit of input on the subject of a local oscillator for a
> 10GHz transverter.
>
> I am going to attempt to build one of W1GHZ's 10GHz transverters and
> will start with the LO chain. My system will use a 144MHz IF and I have
> Paul's LO board to generate the 1136MHz signal the transverter board
> requires. I realize the best route to take would be a high stability
> 10MHz reference source or a GPS locking system but prefer to avoid that
> complexity initially. It appears the next option is an OCXO and therein
> lies my question.
>
> What would folks in the group suggest as a place to acquire a
> sufficiently stable OCXO? The 144MHz IF would require a source at
> 94.666667MHz to drive the LO multiplier board I have presently but that
> seems an odd frequency for readily available off the shelf components. I
> had considered the Q5 Signal digiLO but they told me even with the high
> stability option it would not be stable enough to support digital modes
> at 10GHz.
>
> It may well be that digital modes at 3cm will mandate an externally
> referenced LO source. If that is the case then I will have to be
> satisfied with analog modes initially.
>
> I look forward to hearing the group's thoughts on this.
>
> Jack, K0JP/VE3RUA
>
>
>
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