In article
,
raypsi wrote:

. =A0Misfortunately a Q of 5 is
not quite low enough to reduce VHF gain enough so that oscillation can no=
t
be sustained =A0It apparently takes a Q of =A02 at 100MHz to achieve
acceptable VHF stability. =A0One way to decrease Q involves exchanging th=
e
highly-conductive Cu wire for highly-resistive Ni-Cr wire =A0 This simple
change results in a Q of c. 2 at 100MHz as measured on a HP 4191A
Z-analyzer. =A0 =A0By using =A0two Ni-Cr =A0VHF suppressors per 2-500z, Q=
can be
further reduced to c. 1.5.
- =A0end

--
Richard L. Measures. 805-386-3734,AG6K,www.somis.org

Hey OM:

When I made a living selling tubes, my fav best method of stopping VHF
parasitic oscillations was when the transconductance went kaput from
the little grid wire overheating and burning out. I made a living off
of parasitics.

** chortle. And apparently so was Eimac since the Eimac markeing
rep,,Reid Brandon, reportedly complained to QST that I should never have
been told by Eimac engineer Willis B. Foote that 8877s can be damaged by
gold plating evaporating off the 8877's grid during an "oscillation
condition".

sum gr8 articles on your website too OM.

** Tnx Ray. 73



73,
de n8zu.

--
Richard L. Measures. AG6K, 805-386-3734, www.somis.org