>The Product Reviews of the Alpha 91b and the QRO 2500DX merit reading
>since these are the first with the Svetlana 4CX800/GU-74B tetrodes.
>To be honest, I am amazed at the IMD performance of both amps; the Alpha
>is 45/49 dB and the QRO is 43/40 db for 3rd/5th orders. This sure beats
>the old 25/28 dB typical of 4CX250's.
>
That's probably better IMD performance than any transceiver, Carl.
However, a 4CX250B with 10 ohms of cathode RF negative feedback R, loaded
to 5mA of screen current, has IMD performance that is comparable to the
typical transceiver.
...snip....
>
>Of particular interest is that all 3 amps experienced failures during
>testing which IMO is a bit bizarre.
Bizarre by far. What was the reported nature of the failures, Carl?
Did anyone perform the Funderberg gold-sputter test on the tubes after
the failures?
Rich---
R. L. Measures, 805-386-3734, AG6K
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