Greetings!!!


I plan on building a 500 KC transmitter, 200 watts output. I have
never worked with power FETS before.

What is the selection method used in determining which FET to use??
I see some great FETS
cheap.

Example: IRFP254

250 volt Vdss

RDS on .14

Amps 32 amps

Rise time : 51 NS

Cost; 2.50 each

The data sheet does not spec any freq's ( Ft) like bipolar
transistors?? How do I select the right FET??? freq range

Thanks!!!

The 500 KC transmitter will run at 28 VDC

I can hardly imagine just about any device like this having an Ft so low
that it wouldn't work at 500 KHz. What ham band do we have at 500 KHz?

wrote:
Greetings!!!


I plan on building a 500 KC transmitter, 200 watts output. I have
never worked with power FETS before.

What is the selection method used in determining which FET to use??
I see some great FETS
cheap.

Example: IRFP254

250 volt Vdss

RDS on .14

Amps 32 amps

Rise time : 51 NS

Cost; 2.50 each

The data sheet does not spec any freq's ( Ft) like bipolar
transistors?? How do I select the right FET??? freq range

Thanks!!!

The 500 KC transmitter will run at 28 VDC

--
Scott
http://corbenflyer.tripod.com/
Gotta Fly or Gonna Die
Building RV-4 (Super Slow Build Version)

--
Scotthttp://corbenflyer.tripod.com/
Gotta Fly or Gonna Die
Building RV-4 (Super Slow Build Version)- Hide quoted text -

- Show quoted text -

There are Part 5 licenses recently issued for a 2 year duration 505 to
515 KC to WD2XSH for 20 watts ERP...
I doubt that even 200 watts will get you there with any normal ham
antenna...



denny / k8do

RV7 - even super SLOWER build....

Scott wrote:
I can hardly imagine just about any device like this having an Ft so low
that it wouldn't work at 500 KHz. What ham band do we have at 500 KHz?

wrote:
Greetings!!!


I plan on building a 500 KC transmitter, 200 watts output. I have
never worked with power FETS before.

What is the selection method used in determining which FET to use??
I see some great FETS
cheap.

Example: IRFP254

250 volt Vdss

RDS on .14

Amps 32 amps

Rise time : 51 NS

Cost; 2.50 each

The data sheet does not spec any freq's ( Ft) like bipolar
transistors?? How do I select the right FET??? freq range

Thanks!!!

The 500 KC transmitter will run at 28 VDC

Well a friend of mine once wanted to build a mobile transmitter for
455khz AM and 10.7mhz FM so he could tell the bozo in the car ahead of
him where to go after he cut him off.....

"ken scharf" wrote in message
. ..
Well a friend of mine once wanted to build a mobile transmitter for
455khz AM and 10.7mhz FM so he could tell the bozo in the car ahead of him
where to go after he cut him off.....

I hope you clued him in.. (re. 262 kHz...)

Pete

It is a temporary authorization to specific hams or is it for something
completely different and it just happens to be a ham who asked the
original question??

Scott
N0EDV

Denny wrote:
--
Scotthttp://corbenflyer.tripod.com/
Gotta Fly or Gonna Die
Building RV-4 (Super Slow Build Version)- Hide quoted text -

- Show quoted text -


There are Part 5 licenses recently issued for a 2 year duration 505 to
515 KC to WD2XSH for 20 watts ERP...
I doubt that even 200 watts will get you there with any normal ham
antenna...



denny / k8do

RV7 - even super SLOWER build....

--
Scott
http://corbenflyer.tripod.com/
Gotta Fly or Gonna Die
Building RV-4 (Super Slow Build Version)

LOL!! That might be more fun then using "the finger"

Scott


ken scharf wrote:

Scott wrote:

I can hardly imagine just about any device like this having an Ft so
low that it wouldn't work at 500 KHz. What ham band do we have at 500
KHz?

wrote:

Greetings!!!


I plan on building a 500 KC transmitter, 200 watts output. I have
never worked with power FETS before.

What is the selection method used in determining which FET to use??
I see some great FETS
cheap.

Example: IRFP254

250 volt Vdss

RDS on .14

Amps 32 amps

Rise time : 51 NS

Cost; 2.50 each

The data sheet does not spec any freq's ( Ft) like bipolar
transistors?? How do I select the right FET??? freq range

Thanks!!!

The 500 KC transmitter will run at 28 VDC


Well a friend of mine once wanted to build a mobile transmitter for
455khz AM and 10.7mhz FM so he could tell the bozo in the car ahead of
him where to go after he cut him off.....

--
Scott
http://corbenflyer.tripod.com/
Gotta Fly or Gonna Die
Building RV-4 (Super Slow Build Version)

ken scharf wrote:
Well a friend of mine once wanted to build a mobile transmitter for
455khz AM and 10.7mhz FM so he could tell the bozo in the car ahead of
him where to go after he cut him off.....

"This is God. You don't even want to know what I'm going to do to you for
cutting that poor beloved gentleman off. Just don't make any long-term
plans."

--
Dec. 6 (Bloomberg) -- Government officials and activists flying to Bali,
Indonesia, for the United Nations meeting on climate change will cause
as much pollution as 20,000 cars in a year.

On Thu, 27 Dec 2007 20:52:20 -0800 (PST), wrote:

Greetings!!!


I plan on building a 500 KC transmitter, 200 watts output. I have
never worked with power FETS before.

What is the selection method used in determining which FET to use??
I see some great FETS
cheap.

Example: IRFP254

250 volt Vdss

RDS on .14

Amps 32 amps

Rise time : 51 NS

Cost; 2.50 each

The data sheet does not spec any freq's ( Ft) like bipolar
transistors?? How do I select the right FET??? freq range

Thanks!!!

The 500 KC transmitter will run at 28 VDC

Those FETs have usually quite large gate capacitances (nanofarads), so
in order to rapidly change the gate voltage (and hence the
drain-source current) rapidly, the driver stage may have to supply a
significant current to charge and discharge this gate capacitance. In
many cases, the driver current limit may limit the operating speed of
the circuit.

Paul OH3LWR

On Dec 28, 7:03*pm, Scott wrote:
It is a temporary authorization to specific hams or is it for something
completely different and it just happens to be a ham who asked the
original question??

Scott
N0EDV





Denny wrote:
--
Scotthttp://corbenflyer.tripod.com/
Gotta Fly or Gonna Die
Building RV-4 (Super Slow Build Version)- Hide quoted text -

- Show quoted text -

There are Part 5 licenses recently issued for a 2 year duration 505 to
515 KC to WD2XSH for 20 watts ERP...
I doubt that even 200 watts will get you there with any normal ham
antenna...

denny / k8do

RV7 - even super SLOWER build....

--
Scotthttp://corbenflyer.tripod.com/
Gotta Fly or Gonna Die
Building RV-4 (Super Slow Build Version)- Hide quoted text -

- Show quoted text -

It's temporary (for now) and there are 23 licensees authorized... DO a
search on the 500 kc and the call and you should come up with it...

denny