Wow!!! I heard of a runner's hi but never a mosfet hi! LOL Just sit the fet down and step away! LOL
Ok so we have had some time now to get used to non-rf rated fet's in rf production. What are your thoughts now?
Other than the insane cost difference are you still hi as a kite on mosfets??? The only thing I can see is better profit margins from the top to the bottom of the food chain.
The pep power is sometimes better than the bjt parts but not always. The rms power is seldom any better at all. Often we are talking a insignificant improvement. By insignificant I mean it will not change our ability to communicate over using the same setup but with bjt parts from the past.
So far the only real argument for them is as follows: 1) The older bjt transistors are no longer made and expensive! 2) They produce more power but not enough to be meaningful in the real world. Not exactly wowing me with those as Pro's!!!
1)As I see it. You can still get the older parts you just have to pay more for them.
2)The non-rf specific fet's have terrible vswr mismatch survivability!!!
3) They lack durability almost as a design feature and even with decent swr's are failure prone when used in rf production when not designed for it. No one is talking about using actual rf-specific fet's in CB radio's or export radio's. Why? Because they are not cheap!
4) 99% of fet's do not make much power or have much gain at the voltages we operate at. Modifying the radio to step up the voltage to the fet's to 28V, 48V, 100V would defeat the cost savings so no one is doing that.
5) Did I mention the lack of GAIN at 12V-16V for these fet's??? If you do not understand how important gain is hfe to optimum 2 way radio operation I suggest you read up on it. The Bird 43 watt meter is not the end all be all tool for rf communication validation!
When I see a NXP or Freescale Fet in a CB or Export radio I will change my mind! LOL Seriously though we should at the very least demand rf-specific fet's in our rf-radio's. At the very least we should have a gain of at least 10 minimum for AM/FM/SSB/CW radio's and even higher for AM only which traditionally had hfe's of 50-60 minimum for the driver and final. They need to be rated for rf in linear mode with gain at the voltages we operate the mostly mobile gear at. Watt's with out gain is like horsepower without torque looks good on a dearlership brochure might even work on race track that is set up for high sustained speeds but in the real world will be almost useless! We do not drive around on a dyno and we do not talk to a Bird 43 meter.
I am thinking about trying some RD16HHF1's I can get real ones fairly cheap much cheaper than the MP 2SC1969's and 2166's I just got. I should be able to get 10 of them for the same price as a single MP or the two parts above. It should produce about the same power as a 2SC1969 and even more gain at out voltages!
