[Milsurplus] [Boatanchors] Calling Smart People: Class D Transmitter

[hwhall at compuserve.com]

>
You will need a more complex arrangement 
to divide an 8 MHz oscillator output to get 7 to 7.3 MHz, perhaps even 
choose a different chip that works at 30 MHz, and divide by 4. The RF 
amplifier is being fed essentially square-wave pulses.
>

Seems like you could use nearly any sort of oscillator if you passed the output through some sort of solid state switch IC to square up the output.

Wayne
WB4OGM


-----Original Message-----
From: Brian <brianclarke01 at optusnet.com.au>
To: David Stinson <arc5 at ix.netcom.com>; milsurplus <milsurplus at mailman.qth.net>; boatanchors <boatanchors at mailman.qth.net>
Sent: Sat, Jan 31, 2015 6:41 pm
Subject: Re: [Boatanchors] Calling Smart People: Class D Transmitter


Hello Dave,

The chip is providing divide by 16. You will need a more complex arrangement 
to divide an 8 MHz oscillator output to get 7 to 7.3 MHz, perhaps even 
choose a different chip that works at 30 MHz, and divide by 4. The RF 
amplifier is being fed essentially square-wave pulses. So, it relies on high 
Q in the PA to attenuate the predictable output from square waves - all the 
odd harmonics. I have no idea whether the active devices there will work at 
7 MHz; you'ld need to check that.

73 de Brian, VK2GCE.

On Sunday, February 01, 2015 9:49 AM , you said:

Yes, this is boatanchor related.  I promise.

Hello Smarter-Than-Me-People:
Take a look at this Class D 630 Meter transmitter:

http://njdtechnologies.net/wp-content/uploads/2014/08/Schematic-for-25-watt.jpg

If I scale all the parts at RF in the Drain circuit
by matching reactances (assuming IR factors are not
material), can I make this transmitter work on 40 Meters?

Thanks,
Dave S. 

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