Hello all:
Richard escribió:
> >It's also somewhat common for solid-state PAs are unstable running
> >into narrow filters. Did you try removing the filter between the amp
> >and the radio?
> >
> >It's virtually impossible to be in the amp,
>
> ? 813s don't need a VHF suppressor because they have virtually no VHF
> gain. However, this is undoubtedly not the case for the 8877. The last
I'll ask something not directly related with the main thread. I've seen
a a friend who made his own amplifier with one 813 (don't laugh, may be
qrp for you, but for one that is new to this...), getting nearly 450
watts out in GG. Perhaps a bit high input for this tube.
But mainly at 80 or 40, and not so frequently in the remaining bands,
20, 15 and 10, he have had heavy oscillations, traced to be in the
45..55 MHz region. He used a parasitic suppressor at plate (ferrite
bead, partial fix because an R-L with too many turns made R being burnt
quickly, specially at 21..28 MHz), and later in the cathode input
(parallel of R-L). Now it's quiet, at least for those parasitics.
Could these be called parasitics (low freq), or he was directly building
an oscillator?.
Best regards
Guillermo - LU8EYW.
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