On Wed, Sep 20, 2023 at 01:28 PM, Da Amazin' man G0FTD wrote:
Only BS170's ?
Nice try, I never said that.
Not 2N2222's, BC108's, MPF102's ?
Those are fragile, too.
Erm, ANY? semiconductor is more fragile than a lump of metal elements
inserted in a vacuum tube
because EVERY semiconductor relies upon a fragile atomic bond.
Semiconductors 101.
Be careful making a categorical statement like that. GaN RF transistors are very durable and many of them may be more durable than 6146, although there probably won't be a fair ground to make that comparison objectively. LDMOS is also pretty robust.
Pointing the finger only at BS170's plain daft, and only shows a lack of basic
semiconductor
knowledge and safe operating params, like EVERY other semiconductor on the
planet.
Again, that's a straw man attack as I never made statements you criticize.
Just take a look at how Yaesu / Icom yada yada use PA parts.
They don't (ab)use general purpose switching transistors to squeeze RF power for sure. We are slightly abusing those cheap devices in a way.
They barely use them at 25-40% of their rated values to ensure that stupid
users don't keep
sending their rigs back for repair, have low power tune modes when you hit the
auto ATU function
and complicated foldback mechanisms.
That's only a part of the reason. All mode transceivers must have decent linearity to limit IMD and that requires device headroom at the expense of cost and power efficiency. RF engineering 101 that is, by the way.
These BS170 discussions really do make the amateur community look like a real
bunch of amateurish
amateurs, and reflects badly upon the technical training and competencies
within our hobby.
Absolutely. Professionals wouldn't use a general purpose switching transistor to squeeze RF power. They probably spend a few bucks to go straight to LDMOS. (That's what I plan to do in my QMX, by the way, so that I can avoid "stupid discussion" altogether in the future.)
Time to upskill if we want to be taken seriously.
I'm probably more likely criticized being too serious, so thanks for a fresh concept.
Ryuji Suzuki AB1WX