[AMPS] Re: 8877

[Rich Measures]

>From:          Rich Measures <measures@vc.net>
>Date:          Fri, 25 Jul 97 00:25:27 +0000
>
>>From:          Rich Measures <measures@vc.net>
>>Date:          Thu, 24 Jul 97 02:15:00 +0000
>>
>>>>Why do you continue to make such a big deal over driving voltages? 
>>
>>The grid has C.  Developing 1000V or so across the typical grid's C
>>at 28MHz is not a piece of cake.  Another complication is that 
>>when you are trying to drive a triode's grid in the positive-going 
>>direction, the anode is headed in the opposite direction.  Since the 
>>anode/grid C in a 3cx3000 is about 20pF, it is a big deal at 28MHz.  
>
>Of course youn forgot to mention when the tube is neutralized, the 
>anode grid capacitance effectively goes to zero.
>
Good point, Mr. Rauch.  Nevertheless 1000v of grid drive across a 100pF 
grid takes a bit of doing.

>>Yes indeed, and the total IMD level was probably -20db.  The 
>>all-time record that I measured was -11db.  
>
>Interesting you know the IMD level of amps from the 60's and 
>earlier, yet when you discuss your big grid driven 13 kW PA you 
>quantify IMD via over the air reports
>
I measured the total IMD of the 8171 Class AB1 amplifier with the 
step-attentuator method, using H-P 355 step-attentuators.  
Rich---

R. L. Measures, 805-386-3734, AG6K   


--
FAQ on WWW:               http://www.contesting.com/ampfaq.html
Submissions:              amps@contesting.com
Administrative requests:  amps-REQUEST@contesting.com
Problems:                 owner-amps@contesting.com
Search:                   http://www.contesting.com/km9p/search.htm