> I have gone back thru some old e-mails and re-read some concerning
> "Parasitics" and "parasites" and ETC.
> what is most interesting to me is not so much how to control and?or
> eliminate them , but the fact that they were recognized "Way back" in the
> twenties and such, and yet there are those folks today who seem to believe
> that such things don't exist.!!!! I don't have the books from those days ,
> so i'm having to assume that the info does in fact exist., but believe me,
> I'm following the thread all the time.
> It's very interesting !!!!!
Any "doubting Thomases" can do an easy experiment. Just breadboard up
a circuit with a glass tube sans suppressors, and observe the results. I don't
think anyone could possibly deny the existence of VHF parasitics. We have
been living with them since at least the 1920's. The argument is how to
identify them and prevent further oscillations. As ceramic tubes became
popular, with their shorter leads and compact designs, it was found some
could be tamed sans suppressor, or with only an inductor (3CX3000A7, etc.)
or with any old suppressor laying in the junque box. In other words, with the
advances in tube technology, suppressor design had room for error.
There now seem to be four camps out there.
1. Those who believe ALL tubes and layouts will have VHF parasitics.
2. Those who believe that a suppressor of a certain makeup and design
is better than anyone else's design.
3. Those who start out from scratch on a new amp design, and tackle each
problem as it comes up, installing only the preventative devices necessary
(if any) then quitting when the beast is tamed.
4. Those who will bet with you either way that the Sun will rise in the East
tomorrow
morning.
In the early days of amp engineering I suspect a lot more trial-and-error went
on than slide rule sliding. Those less experienced in this art need to give
the math and computer programs a rest every once in a while, and get out
the drill and soldering iron.
This opinion is worth what it cost you!
(((73)))
Phil, K5PC
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