MOSFETs vs PILLS

[Ranier1315]

Ok I'm probably stepping on a bee's nest but here goes.

I'm really looking for an amp. for my Jeep Wrangler. With that said it doesn't have the best electrical system and pulling 70 amps on the battery/alternator for an extended time would probably fry things.

MOSFET amps seem to alleviate some of the amp draw but do they do as good a job?

What are the draw backs?

Thanks for the input.

73s from the big peach.

176

 

[9C1Driver]

Mosfet amplifiers still must follow ohms law. As a general rule you plan for 10 amps of draw for every 100 watts. A 250 watt amplifier will draw about the same regardless of what finals it has. If your concerned about too much amp draw choose a smaller amplifier.

 

[Shockwave]

Spend the money the first time and buy one with real RF transistors. It takes twice as many power supply MOSFET's to make the same watts as the older bipolar transistors and the durability is not even close. They draw less amps because they make less watts. Not because they are more efficient.

 

[Captain Kilowatt]

When some folks think about MOSFETS drawing less current they may be confusing the 50 volt MOSFET's with the 12 volt devices. The higher voltage devices draw less current because they operate at a higher voltage.

 

[GnG8d]

When some folks think about MOSFETS drawing less current they may be confusing the 50 volt MOSFET's with the 12 volt devices. The higher voltage devices draw less current because they operate at a higher voltage.

I don't think so, most people aren't even familiar with the 50v devices. It just gets passed around on the forums for some reason.

 

[Ranier1315]

The only thing I'm basing my info on is xforce's web site. 500W MOSFET pulls fewer amps than the 500W pill unit. I'm just starting to look for an amp so that's why I came to You guys. Thanks for the input. I will keep researching.

 

[Captain Kilowatt]

I don't think so, most people aren't even familiar with the 50v devices. It just gets passed around on the forums for some reason.

Maybe so, maybe no.You know how it is. A little bit of fact thrown into a forum that adds a lot of misinformation and conjecture and before you know it someone has an amp that makes more power out than it consumes in DC power input. :laugh: Lately there has been a lot of talk about higher powered devices hitting the market that draw far fewer amps thus making power supplies smaller and lighter. These devices from Freecell output over a kilowatt and only require 40 amps but at 50 volts.

 

[9C1Driver]

The only thing I'm basing my info on is xforce's web site. 500W MOSFET pulls fewer amps than the 500W pill unit. I'm just starting to look for an amp so that's why I came to You guys. Thanks for the input. I will keep researching.

I gave an X-Force mosfet amp a test drive about 2 years ago. It did draw less amperage............ but it also only did maybe 60% of it's "advertised" wattage. I concluded that less peak watts = less draw.

 

[TonyV225]

When some folks think about MOSFETS drawing less current they may be confusing the 50 volt MOSFET's with the 12 volt devices. The higher voltage devices draw less current because they operate at a higher voltage.

Thank You C.K., Im glad that Im not the only one that seeing or realizing this as an asnwer to peoples misconception of the Mosfet tranisitors.

 

[Shockwave]

Yes, when the cheap new power supply MOSFET's can't come close to handling the same current as the old bipolar transistors, the end result is it will draw less current. You can be sure it will have less output too. The two go hand in hand. The only way to get the same output for the same amount of amps is to increase efficiency.

The problem there is when you use a power supply transistor for high frequency RF, it's impossible to increase efficiency. It actually goes down and is why these cheap devices tend to run even hotter than the old transistors. Unfortunately most 11 meter operators have never even seen a real RF MOSFET. Take a new 12 volt HF Kenwood, Yaesu, Motorola, or Icom apart and you'll see a modern push-pull 12 volt 100 watt RF stage.

 

[ND88]

Well, looks like I won't be buying a mosfet midnight special after reading this discussion. I'll get the 250 with tubes!

 

[Ranier1315]

Well, looks like I won't be buying a mosfet midnight special after reading this discussion. I'll get the 250 with tubes!

Yup. That's what I got from the conversation. LOL

 

[Nick23]

Well, looks like I won't be buying a mosfet midnight special after reading this discussion. I'll get the 250 with tubes!

Hey ND88 did you get my PMs? Been having trouble with it, just want to make sure. Haha

 

[The Jerk]

I don't get the mosfet thing...most new radios are mosfet, my 100 watt radio is mosfets. I would have no issues running a mosfet amp...just need to umderstand you can't run them like a transistor amp.

Sent from my SAMSUNG-SM-G730A using Tapatalk

 

[222DBFL]

Hey ND88, might want to go with the 350HD TNT. They are a little more expensive than the 250, JMO, the 350HD has the 2879's and will handle more drive as well. Guess I am biased as I have a magnaforce 350HD, basically the same amp as the TNT 350hd minus pre-amp, and I can use most any radio I want with it as it will take up to 120 watts pep input. Again this is JMO. But at least this way you won't ever overdrive the amp and it should last for years.