Yesterday ended with two almost identical exchanges in different threads
of the debate. I am pulling both back together here.
R L Measures wrote:
>>> On Jul 20, 2006, at 4:42 AM, Harold Mandel wrote:
>>>
>>>> The GM3SEK and WD7S Triode and Tetrode Controller boards,
>>>> when suitably integrated, when properly adjusted, serve to
>>>> protect tubes and power supplies in a much faster time frame
>>>> than fuses.
>>>
>>> Hal --- Does the GM3SEK / WD7S Triode Controller board for an 8877
>>> use a grid protect transistor rated at >50A?
I had replied:
>>
>> Despite requests in the past, you have never provided a specific
>>example
>> of a circuit that needs a "grid protect transistor rated at >50A".
>
>An example is any amplifier that uses an 8877.
>
The question is about the control circuit, not the type of tube. PLEASE
name a specific amplifier that has schematic we can all look at, showing
a "grid protect transistor" in the configuration you're talking about.
>>
>> The schematic of my grid-protection circuit is in the Triode Board
>>user
>> manual which is downloadable from the website. The only transistor in
>> this circuit is a 2N2222 that senses a small fraction of the grid
>> current, and can handle even extreme fault conditions.
>
>Does the 2N2222 interrupt the flow of grid current if the limit is
>exceeded?
Have you looked at the schematic yet? If you have, you can see that the
answer is "No, the 2N2222 is not located in the direct path of the grid
current".
In a parallel thread of the debate, Rich had also replied:
>On Jul 20, 2006, at 3:40 PM, Ian White GM3SEK wrote:
>> I don't know of any electronic protection circuit that actually works
>> that way. Despite requests in the past, Rich has never shown an
>>example
>> of what he claims.
>
>An 8877 cathode can emit 50A. If 50A is flowing into the grid, how
>does your electronic circuitry stop it?...
I already posted the shorter version yesterday. The longer version
(which is easier to understand because it includes diagrams) is in the
downloadable user manual for the Triode Board. Here is a direct link:
http://www.ifwtech.co.uk/g3sek/boards/triode/triode-manual.pdf
My own circuit does not contain anything that could be correctly
described as a "grid protect transistor" requiring a rating of >50A.
Neither do I know of any other amplifier control circuit containing a
transistor that fits that description.
Unless Rich can provide a specific example of some other amplifier
control circuit that does contain such a transistor, we may have to
conclude that no such circuit actually exists.
--
73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|