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Re: LF: RE: 500 kHz JT4A

To: [email protected]
Subject: Re: LF: RE: 500 kHz JT4A
From: "Johan H. Bodin" <[email protected]>
Date: Thu, 28 Jan 2010 09:25:53 +0100
In-reply-to: <[email protected]>
References: <[email protected]> <BF4A524700075746A6467658DFC7102C1284D4B328@ICTS-S-EXC2-CA.luna.kuleuven.be> <[email protected]> <[email protected]> <BF4A524700075746A6467658DFC7102C1284D4B32B@ICTS-S-EXC2-CA.luna.kuleuven.be> <[email protected]>
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Andy,

such a doubler will work but the flip-flop is not a guarantee for a
perfect 50/50 square wave in this case. The flip-flop will be clocked by
both edges of *one* of the XOR input signals, which one depends on the
clock polarity (rising or falling edge) at the flip-flop input so the
flip-flop output will have the same duty cycle as one of the XOR input
signals. The traditional C.T. transformer will work equally well (or bad).

73
Johan SM6LKM

----

Andy Talbot wrote:
> I was looking at driving push-pull transmitters from fundamental drive
> signals quite recently.  
>  
> How about a frequency doubler?    The output doesn't have to have 1:1
> mark-space ratio as it only clocks a flip-flop.   And simple doubler can
> consists of a delay line (CR network with around 0.5us time constant)
> followed by a squarer to give a resulting waveform shifted in phase from
> the 500kHz drive signal.  Then apply this one,  along with the original
> to a two input XOR gate whose output will then consists of a 1MHz train
> suitable for dividing by 2 for a perfect 1:1 squarewave drive.
>  
> 
> Andy
> www.g4jnt.com <http://www.g4jnt.com>


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