[GPS_Standard] Ovenaire OSC 49-61C

[Bert, VE2ZAZ]

Hi (again) Geoff,

It may not be visible on the GPS_Standard article pictures, but I use the
same Ovenaire OSC 49-61C OCXO in my system. I don't have the specs. So I did
a bit of experimenting to find out the pinout, the voltages, the tuning,
etc. This unit has no electronic tuning pin so I added one. The final unit
works well and meets the my GPS_Standard system specs. That being said, The
HP 10811 and HP10544 series are probably better units. I have not personally
tried to compare; just a gut feeling. Note that the Ovenaire is a
single-oven unit.

I had to crack open the unit in order to figure out what the pinout was. I
also added a EFC (electronic tuning) line to the unused pin. I basically
connected that line to the center wiper of the fine tuning potentiometer. I
then adjusted the pot for a 1Hz end to end tuning range with 0-5Vdc applied.

I found what the supply voltages were by slowly increasing the voltage until
the unit worked solid. This is how I wired it:

Pin1: GND
Pin2: GND
Pin3: +8V DC (oscillator)
Pin4: No Connect, re-wired for EFC, 0 to +5V DC
Pin 5: +15V DC (oven)
Pin 6: GND (oven)

By the way, when I opened the unit the insulation fell off in powder,
completely dried out. I replaced it with some pink bubble pad, the ESD-free
pink type. I cut several pieces and enveloped the electronics. I re-inserted
everything in the case.

There you have it. Have fun experimenting!

Bert, VE2ZAZ


----- Original Message -----
From: "Geoff Blake" <geoff at palaemon.demon.co.uk>
To: <gps_standard at mailman.qth.net>
Sent: Wednesday, January 23, 2008 5:56 PM
Subject: [GPS_Standard] Ovenaire OSC 49-61C


Hi,

Firstly apologies to those who may have already read this
elsewhere.

Has anybody the specs on an Ovenaire OSC 49-61C 10MHz standard as
sometimes used in a HP 8568A.

I probably can work out the connections from the HP manual, and
the frequency spec is rather similar to the HP 10811. What I would
like is the oven voltage, the oscillator voltage and particularly
the EFT voltage range and configuration.

Thanks in advance.

73 de Geoff
--
    Geoff Blake G8GNZ      located  near  Chelmsford,  Essex,  U.K.
    Please reply to:      geoff(at)palaemon(dot)demon(dot)co(dot)uk
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