Re: [time-nuts] Z3801A OCXO manual trimming
Thank you, Hal, for these links and to others for your comments.
Setting the oven temperature on a turning point appears tedious. Perhaps there
is enough range in the frequency adjustment to put the oscillator back on
frequency - or close enough for the EFC to be effective. If not, I may have to
adjust the temperature, but time is limited.
Some measurements with the EFC disconnected and a calibrated frequency counter:
9999.815 KHz at Z3801A turn on
9999.9984 KHz highest frequency seen (temperature overshoot)
9999.9947 KHz approximate final frequency
The EFC does have wide range; it can almost pull the 5.3 Hz offset onto frequency.
Thanks again,
Joe, W7LUX
Does the oscillator have an adjustment? If so, is this somewhat accessible
without destroying the assembly? Are there pictures of the oscillator
assembly?
Crazy thought.Could you just force a DC offset into the EFC assuming the
internal varicap is not out of range.
It would be simply adding a resistor to pull up or down to see if you can
get a bit of pull and allow the dac to move back in range a bit. Its a band
aid.
I know its sort of crazy. But ripping the oven apart really is no fun at
all.
Regards
Paul
WB8TSL
On Mon, Mar 5, 2018 at 11:21 AM, Joe Hobart nova@npgcable.com wrote:
Thank you, Hal, for these links and to others for your comments.
Setting the oven temperature on a turning point appears tedious. Perhaps
there
is enough range in the frequency adjustment to put the oscillator back on
frequency - or close enough for the EFC to be effective. If not, I may
have to
adjust the temperature, but time is limited.
Some measurements with the EFC disconnected and a calibrated frequency
counter:
9999.815 KHz at Z3801A turn on
9999.9984 KHz highest frequency seen (temperature overshoot)
9999.9947 KHz approximate final frequency
The EFC does have wide range; it can almost pull the 5.3 Hz offset onto
frequency.
Thanks again,
Joe, W7LUX
Does the oscillator have an adjustment? If so, is this somewhat
accessible
without destroying the assembly? Are there pictures of the oscillator
assembly?
https://www.realhamradio.com/GPS-oven-journey.htm
https://www.realhamradio.com/z3801a-turning-point.htm
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Hi
Either tear into the OCXO or go shopping for a new(er) GPSDO. The
Z38xx devices all had a lot more in common with each other than they
did differences. The OCXO design changed from the 10811 to various
more modern designs. The disciplining process seems to have remained
pretty much the same over the years.
Bob
On Mar 5, 2018, at 11:21 AM, Joe Hobart nova@npgcable.com wrote:
Thank you, Hal, for these links and to others for your comments.
Setting the oven temperature on a turning point appears tedious. Perhaps there
is enough range in the frequency adjustment to put the oscillator back on
frequency - or close enough for the EFC to be effective. If not, I may have to
adjust the temperature, but time is limited.
Some measurements with the EFC disconnected and a calibrated frequency counter:
9999.815 KHz at Z3801A turn on
9999.9984 KHz highest frequency seen (temperature overshoot)
9999.9947 KHz approximate final frequency
The EFC does have wide range; it can almost pull the 5.3 Hz offset onto frequency.
Thanks again,
Joe, W7LUX
Does the oscillator have an adjustment? If so, is this somewhat accessible
without destroying the assembly? Are there pictures of the oscillator
assembly?
https://www.realhamradio.com/GPS-oven-journey.htm
https://www.realhamradio.com/z3801a-turning-point.htm
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.