[time-nuts] HP 117/10509a

Ron Ward n6idlron at comcast.net
Thu Jul 5 07:14:32 UTC 2012


Thanks Charles:
I will consider your ideas as they seem to be excellent!

I wonder if I could just make the whole unit run off of +24VDC or +12
VDC.
I need to look at the schematics and see what would be the best way to
proceed.

I currently do not have an antenna for WWVB and need to get up and
running before I do anything with it.

If successful, would anyone want information on my conversion? I also
have a fluke 207 that needs to be recapped.
Thanks,
Ron


-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Charles P. Steinmetz
Sent: Wednesday, July 04, 2012 11:10 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] HP 117/10509a

Don wrote:

>the fet breakdown voltage has of course got to be high enough.

If the nuvistor is used as a common-cathode or common-grid amplifier, 
you can cascode the fet with a bipolar to extend its drain voltage 
range.  You will need to come up with an appropriate bias source for 
the bipolar.  Generally, you would want at least 10-15 volts across 
the FET channel.

Choose an appropriate JFET (transconductance, drain current, and 
gate-drain voltage similar to the nuvistor at the nuvistor's 
operating point).  You can add degeneration (source resistance) to 
lower the FET's transconductance if it is higher than the nuvistor's.

Best regards,

Charles





_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.





More information about the time-nuts mailing list