>
>On Tue, 21 Oct 97 10:38:54 -0800 Rich Measures <measures@vc.net> writes:
>>>Does anyone have the first release Eimac sheet? The one that shows
>>the
>>>HV above 2250V max and 600 ma Ip.
>>>I have the 8/89 specs which references 4/87 but I believe there is an
>>>earlier version which was quickly pulled back due to FCC
>>intervention.
>>>
>>>I wonder just how much this tube was really "designed for" ?
>>>
>>>Tnx Carl KM1H
>>
>>Rumour has it that it will do 800mA in SSB service. However, I would
>>be
>>reluctant to go with a brick on the key test at more than 600mA.
>>Rumour
>>also has it that the rated warmup is a bit on the low side. An extra
>>half minute might be worth the wait.
>
>Rich, the sheet FAXed to me (dated March 1983) lists the 3CX800A7 at
>2500VDC, 800ma and 1370W out in "typical SSB" service.
>Dunno about the FCC thing; that was something mentioned on this list
>several months ago.
800mA SSB/ 600mA keydown sounds reasonable, Carl. The 8874 is rated at
350mA in continuous service, or 500mA in SSB service. However, if one
looks at the appropriate curve in the 8874 spec. sheets, one finds out
that going key-down for more than 50 milli-seconds at 500mA is a no-no.
In my opinion, one should tune up at the SSB service rating by using a
tuning-pulser. A keyer sending 50wpm dits is also ok. OTOH, those with
a free supply of new tubes can tune up any way they like.
PUBLIC NOTICE: If one of you has a kaput 3CX800A7 that is out of
warranty, I would like to purchase it. My intention is to disassemble
the tube, and publish photographs of the innards on the Internet.
Rich---
R. L. Measures, 805-386-3734, AG6K
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