[time-nuts] GPSDO Question

JOS Earthlink jsternmd at earthlink.net
Sat Sep 1 23:01:57 EDT 2007

73 de  K1JOS (Jerry)
CCA #11906
CRA #1777

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From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
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Sent: Saturday, September 01, 2007 12:00 PM
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Subject: time-nuts Digest, Vol 38, Issue 1

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Hi Group,

I just recently completed a GPSDO inside a HP5328A.  I was going to use the
Schera board but opted for the VE2ZAZ.  At first I tried to cannibalize the
HP5328A's internal power supply for either the +/-15VDC or +5/-5.2VDC supply
but I discovered the hard way that they would not supply enough current
(burnt out CR1 and Q7) or the supplies would not be well regulated.  I opted
therefore to include inside the case a +/-12VDC swtiching supply powered
externally by a 24VDC wall wart.  From the +/-12VDC dual supply I cleaned up
the rails with an L7805 and L7905.  I was able to bring out to the the rear
panel the 10Mhz and 5Mhz references plus the SMA GPS antenna connector.  On
the side panel I put in a momentary pushbutton switch to reset the GPS if
needed plus a DB9 RS232 for serial communicatiosn with either the GPS using
software like VisualGPS) or to monitor the VE2ZAZ board status.  A simple
DPDT switch next to the DB9 connector controls the serial selection.  I have
complete pictures if anyone is interested and it works very nicely.


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