[time-nuts] yet more RFTG thoughts
Robert E. Martinson
REMartinson at rcn.com
Tue Feb 20 23:32:28 EST 2007
All 3 voltages are present as marked at XO-TP400. The jumper W11-W12
measures 2.394 volts. I'm running the pair, XO & RB, but having
intermittent "NO GPS" LEDs on, on both units.
With the Ref input/output & the J5 jumper cables disconnected the above 4
voltages do not change.
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Rich and Marcia Putz
Sent: Tuesday, February 20, 2007 6:33 PM
To: time-nuts at febo.com
Subject: [time-nuts] yet more RFTG thoughts
To answer a question first. I believe PLDENB likely means programmable logic
device enable. Right next to that header is an Altera Max7000 series device.
What we dont know is, when enabled does that mean the device just wakes up,
or does it mean the device is opened to be reprogrammed.
I am still interested if anyone else has measured the voltages on TP400 to
see if anything is present other than +5 volts. I have not found any mode
that makes my RFTG produce any voltages other than the 5volts. The DAC
appears to be dormant. You can roughly follow the traces from the DAC near
TP400 over to the EFC line to the oscillator. The jumpers W11-W12 is the EFC
line to the osc, I measure much less than 1 volt, I would imagine with the
unit working, it would be somewhere around 3-4 volts!
Again I have to say I am running the RFTG-m stand alone, as I have no
RFTG-RB to go with it.
So as was mentioned earlier , when a 10 Mhz signal appears at the input do
things start happening, I applied 10 Mhz from my HP5334, but perhaps I
didn't have enough level, and thats begs a second question; if 10Mhz is
present there then why would the GPS side be needed at all, unless the
RFTG-m is somehow comparing the two signals and picking the one in closest
agreement to GPS. Who knows?
On a side note, I did a google search on RFTG and one hit was a guys resume
describing how he designed RFTGs for HP. I'll let a younger and more daring
person search the guy out and contact him, hi-hi!
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