Hi all,
Seems that the subject "parasitics" is endless...
Ofcourse you can put as much hypotetical theories as ever into that tiny
little choke, but my general advice is: Dont try to fix what already works! ;)
In my homecooked amp built around Philips QBL 5/3500 I´ve never encountered
any stability problems. The parasitics choke is made by "trial and error" in
order to find a good balance between VHF supression and as little as possible
at 28MHz. Use conventional copperwire and resistors. Works great!
Have used the amp for four years in G2DAF configuration. In my opinion
a very clever design wich also contributes to the stability.
Read in the archive that some of you "wiseguys" stated that the G2DAF
design was as close to class C as you could get. Bullshit!
During the period I`ve used my amp I have`nt got a single complaint abt
beeing "to broad".
As I also want to collect more sientific proofs, I`ve have started
to do a series of linearity measurements using professional equipment.
So far the amp shows very good linearity, but I will do several more
measurements in different operating conditions before I`m finished.
Then I will share what I`ve found, here on the reflector.
It is my beleive though, that the G2DAF design is NOT suitable with
cheramic tubes, wich are far "to wild" and handles only small grid-
currents.
As a very good friend of mine (SM3PXO) says: "measuring is knowing -
But how the hell do you know what you just measured...." ;)
73 de Lars /SM3BDZ
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