Sidebar Sidebar
  • You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.

Are mosfets

lords said:
...ken white WROTE: MOSFET's are less durable than a BJT. They are easily damaged when over voltaged

Now thats funny:LOL:
I wouldn't say that unless you work with them and I do alot!

...ken white WROTE: "Lords, do me a favor since you are such an expert"

...i said that,wow i think your a word changer ,making something up out of the new guys word!
i said i do this stuff almost every day.
i didn't just say CB's now did I...

...remember before the internet(which i do update that to) there was a thing called HANDS on!!
remember this...
Click to expand...

Experience normally equates to expertize...

In linear operation, a MOSFET and BJT will dissipate nearly the same power. A MOSFET used as a switch can dissipate less power when the resistance of the channel (drain-to-source) is minimized. This does not mean that ALL MOSFETs will be better than ALL BJTs for power.

MOSFETs will also not make a board have smoother current or run cooler than a BJT when applied in the same manner.

As for hands on, I'll bet that there are quite a few forum members who have worked in the electronics industry and have experience too...

:p

Just busting your balls...

:D
 
lol:
In linear operation, a MOSFET and BJT will dissipate nearly the same power. A MOSFET used as a switch can dissipate less power when the resistance of the channel (drain-to-source) is minimized. This does not mean that ALL MOSFETs will be better than ALL BJTs for power.

Now thats good to know. i know mosfets can switch fast and take turns..but ya as in shuting down i see that can be a problem in amps for the future compaired to BJT's.
would this be because of the frequency???
Example: 2987's are upto 30MHz
i mean because i get some regular stereo amps that just sound like pure crap that are mosfet driven...and not blown..I thought in parallel they devide the voltage? and take turns and are calm to Frequency?? I may be wrong on this or not..
Any ways thanks for busting my balls...man i hate typing :LOL:
funny i can code php,asm and sql like a mofo but typing sucks:p

oh btw as i was running through your posts to see what i was up against..which was a lot:)
i noticed you saying that coax cut don't change the swr's
Man i am 45 now and have been saying this for years
all it does is trick the damm swr Meter..but back then when your running a 102" whip what can you do but cut the coax or just make a 12 or 18 foot section and take it from there!
 
lords said:
Good Lord lords what's with all the ! marks? Lay off the coffee man. Laughing What is really funny is that you work with MOSFETS all the time yet you erroneously call them CMOS. Now THAT is funny.
QRN.......!!!!!!!!!
sorry to see you don't like the !!!!!!!!!!!
i love coffee, maybe to much!
you work with pc's? or you just one of them dudes that debate with it??? or wait, i know a simple board changer:p
CMOS overclocking..Pc..Stereo amps, course this won't ring a bell to you..I wasn't only talking about CB's,or ham i was saying in general.
you need to lay off something and break that old door down and update!
Click to expand...

Man you do need to lighten up a bit. You have absolutely NO idea what my electronics background is.Overclocking and stereo amps? :roll: Wow! I guess that sure beats my qualifications of being a COMMERCIAL BROADCAST ENGINEER OF 22 YEARS. All I ever had to do was plan new radio station installations,actually do the grunt work of aquiring the gear and assembling it all into a working radio station right from studio microphone to seeing that the clearance light was installed at the top of the friggin towers and everything else in between.AM or FM take your pick. I have done them both. I have also had to install VHF and UHF STL (that's Studio-Transmitter Link) repeater sites and maintain all the equipment needed to keep six,yes six, radio stations on the air and all networked together for common or split programming,replacing older tube transmitters with MOSFET types and maintaining them.We won't even talk about the satellite integration and computer networking necessary to keep MY six stations integrated with the other nineteen stations in the network operated by MBS Radio Yep your overclocking experiance and stereo amp knowledge has me beat. :roll:
 
Man you do need to lighten up a bit. You have absolutely NO idea what my electronics background is.Overclocking and stereo amps?
that was for why i call them CMOS not to degrade or say this is a big field...hell i make more money painting and and doing flux finishes to lake front properties.
the electronics is just side work now days but i did have 2 shops in chicago and wisconsin at one time and was doing good:)
but the Eyes arnt like they use to be now days,thank god for cheap reading glasses and parts arnt getting any cheaper.
lol...i was a messing with ya..but as you see i bring out the big guys at the least! <ops sorry .
All that stuff makes me money,you have to admit that:)

And wow i am impressed ,for real.I mean your satellite integration and computer networking....that does take some doing I know this as 1 wrong slip of a movement and you could be shutting down a bank or some major company,as you know many company's share satellites now days.
well as you know your set for life because that is future stuff too.
May i ask how many watts are standard for tis.. I do know some are 5000 watts ,well the rock stations Ilisten to..I can see if there
more as i don't think 5000 watts is nothing now days, or is it?

anyway, I am backing down and going 10-7 for a while
as all my parts came in and need time to do this mod off the internet and MY mods to this Galaxy DX959...
Just one more question before I go.....



Do you have one of them cool DJ voices too???
;)
 
If I remember correctly, in the U.S., the FCC allocates power limits based on local market share. So if your station has big market share, you can run more power. It's kind've strange actually because some of the smaller stations always feel like that if they had a bigger footprint, they would have more market share. Kind've a catch-22.....

Anyway, I know some pretty popular FM stations around SoCal run around 10KW, and that's considered pretty low for here. The bigger stations run upwards of 100KW.
 
Actually Mole you have to have a power level determined when you actually submit the application so all you have is what you think your market share may possibly be. The question was about TIS which I take to be Traveller Information Services.To be honest I have no idea. The system is not used here in my area but I do know that in the USA it was only permitted a few watts on the AM band with some stations now appearing on the FM band but again I have no idea what the power level is.it would certainly be no more than a couple watts anyway. It is interesting to note that although these systems only run a couple watts and a very short antenna,typically 4 feet long, I once heard a station on 1610.I was using my Kenwood R-1000 receiver and was trying to hear a really weak station.Then I realised it was a TIS station and was broadcasting info about the New Jersey Turnpike. Not a bad catch for such a low power station to be heard up here in nova Scotia.

Yeah the satellite integration was mostey for RX of various programs but we did send stuff via the old ISDN connection to head office for uplink.That was pretty much phased out due to the internet and the use of T1 or T3 lines and VPN's tying all stations together.I got out of the business almost 2 years ago now.Being the only engineer for 6 stations plus being on call 24/7/365 for the last 7 years burned me out. Not to mention the direction the money hungary *rick that owned the company was taking with the staff.In the end I looked after three 1 Kw AM stations,an 18 Kw FM station,a 3 Kw FM station,a 100 Kw FM station and was called upon occassionally to look after another 10 Kw AM station and a 100 Kw FM station in another market area of the company.FAR too much for one person.I'll stop right there but lets just say that I know that everyone I worked with has a job application in somewhere else. I used to be proud to say where I worked but the last few years I was embarrassed because of the reputation the company as a whole had obtained due to management.Life is good now however even if I am no longer in the broadcast biz.I work four minutes from home, there is no on call crap, the money is better and I work four days and have four days off.I can still play radio if I want and it has been VERY tempting to put my RCA 1 Kw broadcast TX on the air on 720 KHz. :twisted: Yep that is my project,convert a commercial AM broadcast transmitter I aquired to work on the 80m ham band.Some people bring their work home at night,well I brought some home with me after I quit. :LOL: As for the "cool DJ voice", well no but then again most of the DJ's just put on that voice and the audio processing helps too. ;)
 
2 years ago now.Being the only engineer for 6 stations plus being on call 24/7/365 for the last 7 years burned me out. Not to mention the direction the money hungary *rick that owned the company was taking with the staff.In the end I looked after three 1 Kw AM stations,an 18 Kw FM station,a 3 Kw FM station,a 100 Kw FM station and was called upon occassionally to look after another 10 Kw AM station and a 100 Kw FM station in another market area of the company.FAR too much for one person


Jesus, sounded like you needed 4 of you,at the time.
I seen this a lot, in close fields! boses want you to kiss ass over promises and better futures..and for what well there pocket books,of Course .
but some when they make a great profit do share .
that what sucks sometimes you gather the great background
but then the bigger ones look at it like its easy because your good at what your doing and not knowing the reason why you can't be faster for the same amount of money:)

when i was doing tv's stereos and such, I had more business fixing the older tube tv's and stereos and old vacuum cleaners
I couldn't believe...and for just 11 meter beefing up cb's back then i had more business with local cops (off duty) wanting theres done up..
I finally said i need to get out of here, Chicago that was.
had 6 kids all young and needed a better place for them
and got sick of roaches in everything i got in!
Point was i made great money but the work just kept getting
more and more and people wanted better prices for bringing in more stuff,thinking hay i let you fix 3 of my items,what no deal of this one:p
 
Hey, I just have an off topic/on topic question about MOSFETS.

If they are so sensitive to ESD, how are we getting away with connecting them to antennas?
 
MOSFETS have an inherently high input impedance and that allows static to build up on the pins.When installed into a circuit the components offer a path for that static to bleed off. Once installed in a circuit a MOSFET is not really any more susceptable to ESD than a bipolar transistor. It is only while handling the device with the pins connected to nothing they are in danger.
 
QRN said:
MOSFETS have an inherently high input impedance and that allows static to build up on the pins.When installed into a circuit the components offer a path for that static to bleed off. Once installed in a circuit a MOSFET is not really any more susceptable to ESD than a bipolar transistor. It is only while handling the device with the pins connected to nothing they are in danger.
Click to expand...

X2...
 
OK, well that kind of blows DTB's colledge lab experiment.

I still find it suspicious, however. I know my company builds some equipment with esd sensitive components in the RF path, and users have a big problem with zapping them when they touch the RF input/output connector center pin.
 
ESD damage depend on a lot of things like temp/humidity and even what material your clothes are made of. Some materials like nylon will build up static like crazy.The circuit design has a lot to do with how they function with static once installed as well. Usually in an RF input there is some sort of low resistance to ground,low as compared to the very high impedance of the MOSFET.
 
C2 said:
Oh, you mean an inductor.
Click to expand...

It could be an inductor or a resistor or even an input transformer.Anything that will pass DC.Sometimes the path is back through the power supply. Some MOSFET's have built in protection diodes that have a breakdown voltage higher than the supply voltage the device is rated for but lower than the voltage that will destroy the device. Often these diodes are not even shown on the schematic of the MOSFET device itself but are mentioned in the data sheet.
 

dxChat
Help Users
  • No one is chatting at the moment.


      Top Bottom
      Back