[time-nuts] HP 117/10509a

[Randy D. Hunt]

On 7/5/2012 3:57 PM, bill wrote:
> On 7/5/2012 9:49 AM, Randy D. Hunt wrote:
>> On 7/4/2012 11:09 PM, Charles P. Steinmetz wrote:
>>> 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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>> I have a PDF document that covers this for Fetrons. This is from 
>> Teledyne.  It shows some of the more common tube replacements with 
>> the circuit and actual device number. Let me know if you would like a 
>> copy and I will sent it to you.  Or, maybe a better option would be 
>> to upload it to something like Didiers site. . .
>>
>> Randy
>>
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> Yes do upload it. I have some Fetrons and want to know what they 
> replace. And in my other life, I ordered some custom Fetrons
> to replace some WE tubes that was used in WE K carrier. If you don't 
> upload it, send a copy.
>
> Bill K7NOM
>
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>
I uploaded the PDF to Didiers' site. Hope this helps some of you out 
there. . .

Randy, KI6WAS