[time-nuts] HP 117/10509a

paul paulswedb at gmail.com
Thu Jul 5 14:54:05 UTC 2012


Yes they will still work well for that and the 207 does much better then 
the 117 by about 10 X
Regards
Paul
On 7/5/2012 10:52 AM, Ron Ward wrote:
> Hi again:
> Well I guess I will just use the Fluke 207 and HP117 for local standard
> comparisons.
> Ron
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of J. Forster
> Sent: Thursday, July 05, 2012 6:31 AM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] HP 117/10509a
>
> You do know that neither a 117A or a 207 will work when WWVB changes to
> BPSK fairy soon?
>
> -John
>
> ===============
>
>
>> 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
>>
>>
>>
>>
>>
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>
>
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