[AMPS] Blown TL922A... What to do?

[measures]

>
>measures wrote:
>>
>>>
>>>measures wrote:
>>>>
>>>>>The correct unedited conclusions are on N7WS's web page.
>>>>>
>>>>
>>>>Who needs conclusions when we have the numbers Wes measured?
>>>>
>>>
>>>For the benefit of anyone who joined AMPS since the N7WS Incident,
>>>here's a short run-down.
>>>
>>>Wes Stewart, N7WS, tried to help resolve the disagreements about the
>>>relative virtues of conventional R-L parasitic suppressors and Rich's
>>>designs using nichrome. He obtained an R-L suppressor from Tom and a
>>>suppressor from Rich, 
>>
>>€  Not quite.  I supplied Wes with the materials and he constructed a 
>>suppressor that was similiar to the W8JI suppressor.  Both had c. 100nH 
>>and 100-ohms. 
>>
>Thanks for the correction. 
>
you are welcome, Ian. 

>>> measured the R-X properties of both types on an
>>>impedance analyser, and published the results.
>>>
>>>The AMPS archives show that:
>>>
>>>* Wes strongly disagreed with Rich's interpretation of the measurement
>>>data. To see how Wes himself felt about this, go to his own web page, if
>>>it's still there - http://www.azstarnet.com/~n7ws
>>>
>>>* Rich's own interpretation was based on a total 
>>
>>€  (key word)
>>
>>>misunderstanding about
>>>what "Rs" means. 
>>
>>€  I originally designated the suppressor resistor as Rs.  This 
>>apparently confused some people, so now I call it R-supp.  
>>
>People were confused because you were unaware that "Rs" always means
>"series equivalent resistance". You actually
>believed that the Rs 

€ (Wes uses "Rp"). 


>values quoted by Wes *were* what you now call R-supp.
>
The suppressor resistor was 100-ohms.    I supplied it.  I did not 
confuse R-supp with Wes' parallel equivalent resistance measurements.  

>> Wes measured the Q of the two suppressors at various frequencies.   At 
>>100 MHz, the copper-wire (W8JI) suppressor had a Q of 2.2, and the 
>>resistance-wire suppressor had a Q of 1.5.  The difference is 46%.   
>>What's to interpret, Ian.?  
>>
>Everything! 

[chortle]  
>
>That difference simply meant that Wes hadn't made the two networks as
>"similar" as he had hoped for. 

The copper-wire suppressor had more inductance than the resistance-wire 
suppressor.  This gave the copper-wire suppressor the advantage.  

> From his measurements, it was easy to see
>how he could have made a conventional suppressor with identical Q to
>yours at 100MHz. 

To do this, L-supp wouId need to be increased.  Therein is the 
''gotcha''.  

> If he had done so, it would have had *lower* loss at
>28MHz than your design. 

Increasing L-supp increases 10m dissipation exponentially.  Have you 
perused the March 1989 QST article on suppressor resistor dissipation?

end

-  Rich..., 805.386.3734, www.vcnet.com/measures.  
end


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