Absolutely not!
I am referring to the RF cycle itself, not the envelope. During one dit, you
send a few millions of them!
Since the FET has no storage effects, a high frequency signal is seen as a
train of pulses, so that actually what the transistor puts through is a long
string of square pulses. Those are the 50% pulses I was talking about.
Alex 4Z5KS
-----Original Message-----
From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
Behalf Of Joe Subich, W4TV
Sent: Wednesday, August 24, 2011 6:50 PM
To: amps@contesting.com
Subject: Re: [Amps] MRFE6VP Datasheet
> On the other hand a CW wave is actually a 50% square wave, producing
> in effect a 50% duty cycle.
CW is only a 50% duty cycle if one is transmitting a string of dits.
For alternating dits and dahs, the duty cycle is 66% (on for four dot
periods and off for two dot periods). When one moves to text the duty
cycle will reduce due to the addition of letter and word spaces but
since the number of dits and dahs in text are generally similar, the
duty cycle will be about 60% (assuming a "typical" five character per
word average).
73,
... Joe, W4TV
On 8/24/2011 11:27 AM, alexeban wrote:
> Hi everybody:
> FET's , per se, don't have any intrinsic time related effects.
> On the other hand a CW wave is actually a 50% square wave, producing in
> effect a 50% duty cycle.
> This might indicate that some duty cycle limitation can exist for greater
> than 50% situations. It was usually present on IRF switching power supply
> devices, years back. you could actually melt the internal bonds when
> operating them at maximum current for prolonged periods, especially the
> source bonds.
> Alex 4Z5KS
>
> -----Original Message-----
> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
> Behalf Of Fuqua, Bill L
> Sent: Monday, August 22, 2011 6:35 AM
> To: jeff millar; amps@contesting.com
> Subject: Re: [Amps] MRFE6VP Datasheet
>
> I have not looked very close at the data sheet but it did occur to me that
> in some applications some devices require time to thermally or
electrically
> stabalize.
> But, you may be right. I'll look closer.
> 73
> bill wa4lav
>
> ________________________________________
> From: amps-bounces@contesting.com [amps-bounces@contesting.com] On Behalf
Of
> jeff millar [wa1hco@wa1hco.net]
> Sent: Sunday, August 21, 2011 9:24 PM
> To: amps@contesting.com
> Subject: Re: [Amps] MRFE6VP Datasheet
>
> I think the pulse operation applies to the 60:1 VSWR specification.
> Effectively, that gives a specification on how fast the control circuit
need
> to
> operate.
>
> jeff, wa1hco
>
> On 08/21/2011 08:06 PM, Fuqua, Bill L wrote:
>> If it will do 1200W average power CW it should do the same in pulsed
> mode.
>> The question is, why list both unless some application requires that
> particular
>> pulse specification. It could be that the product was targeted for that
> application.
>> And others (CW).
>> 73
>> Bill wa4lav
>
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