>
>
>On Fri, 11 Sep 98 13:23:18 -0800 Rich Measures <measures@vc.net> writes:
>>
>>>
>>>
>>>On Fri, 11 Sep 98 08:20:52 -0800 Rich Measures <measures@vc.net>
>>writes:
>>>>
>>>>
>>>>The designers rather obviously did not bother to read the RCA
>>>>Transmitting Tube Manual. In stock config., the amp. is potentially
>>
>>>>an
>>>>8122-screen-assassinator.
>>>
>>>
>>>No argument...what was designed was not what Mike Ferber ( National
>>>Marketing VP) forced on the market.
>>>
>>>
>>>
>>> > If you are interested, I can mail you a copy
>>>> of a schematic with needed changes.
>>>
>>>I tried them...they dont work.
>>
>>You tried the RCA Transmitting Tube Manual recommended cathode
>>feedback
>>resistors and they don't work?
>
>
>That is correct....they do not work in the NCL2000's I tried and the amp
>goes wild on 10/15M. The problem can be traced to the marginal screen
>bypassing that is used, only 500pf per pin coupled with the 2W cathode
>resistor lead lengths.
Are you saying that was with resistors supplied by us?
>Those tests were done about 10 years ago.
>The amp can be made completely stable by using Johnson, Eimac, etc.,
>4CX250 screen bypass rings but those items are becoming very hard to
>find. If you note...RCA specifies those rings in their literature and the
>early NCL prototypes used them. Marketing nixed the idea as too
>expensive.
A mistake. So is using a too-inductive resistor. So is using too much
lead length. .So is not using at least one resistor per filament pin.
-
Rich...
R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
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