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[AMPS] Interesting projects -- All Mode KW Transmitter

To: <amps@contesting.com>
Subject: [AMPS] Interesting projects -- All Mode KW Transmitter
From: dcckc@ncn.net (dcckc)
Date: Thu, 14 Sep 2000 00:50:45 -0500
I think Kenwood's calling you they are looking for someone to put the STUFF 
inside their  mock up radio they had at Dayton
Dave / WB0PKK


At 10:30 PM 9/13/00, you wrote:

>Here is my entry into the interesting project category -- A Kilowatt
>transistor SSB/FM/AM/CW/etc. transmitter for 160 through 6 meters.
>
>   The transmit chain consists of:
>
>   1.  A Mike preamp connected to a 16 Bit Analog to Digital converter
>running at a 24 KHz sample rate -- one of the tiny ones with serial data
>output.
>
>   2. A 16 Bit Digital Signal Processor chip good for about 40 mips.  This
>chip can perform  an intelligent VOX function (no missed syllables) by
>delaying the input signal 10 mS.  The same buffer can be used to
>implement a Hilbert transform compressor (similar in function to RF
>clipping).  Transmit bandwidth will be set by mode... or whim.
>
>    SSB will be generated by the Weaver (third) method & the resulting I&Q
>signals will be up sampled by a factor of 32.  These signals will be
>delayed to compensate for the output filter delay in the envelope
>re-modulator filter (part 5 below). A digital representation of the SSB
>envelope will be loaded directly into the modulator at a 96 KHz rate.
>
>    For CW, this critter will also be able to create a variety of envelope
>shapes... from textbook perfect to simulated chirps & clicks.  :-)
>
>    FM is created directly by adding the digitized value of the mike
>audio, 16 bits - up sampled to 192 KHz, scaled for the desired deviation,
>to the nominal carrier setting (32 bits) and updating the DDS registers
>with those results (also at a 192 KHz rate).   This method gives perfect
>FM with ridiculous control over the deviation: 1 LSB = .075 Hz @ 5 KHz
>total deviation.
>
>    AM is made in the old way, by directly modulating the final amp.
>
>    And of course PSK, FSK, etc will be doable.
>
>   3. A combination up-sampler, Direct Digital Synthesizer & I&Q modulator
>(a single IC) that can directly output on frequency up through 6 
>meters.
>  SSB is created by completing the Weaver modulation with the second mix
>directly at the output frequency.
>
>   4. A limiting amp (to make Class D) followed by a two watt stage which
>may operate either Class A for test or Class D for real.
>
>   5. A legal limit Class D amp modulated by a switching amplifier powered
>by a power factor corrected (PFC) input circuit.  Output filtering &
>tuning will be by means a whole bunch of coils & capacitors switched
>by... about 32 relays. An independent SWR protection circuit will
>directly reduce the voltage to the finals, to prevent awful things from
>happening should something screw up in the software.
>
>   The modulator, sampled at 96KHz, will be driven by a digital pulse
>width generator with 11 bit resolution  (ECL parts -- clocked at 200
>MHz).  It will implement the envelope restoration for SSB, envelope
>shaping for CW, direct modulation for AM and power control for FM, CW,
>AM, & SSB.
>
>   The RF amplifier and modulator stages can be line isolated by means of
>RF transformers, plus optoisolators for the control signals, so no big AC
>power transformer will be required.
>
>   6.  and almost forgot  -- An 8 bit microprocessor to handle the mode
>selection, tuning, etc.driving a Vacuum Fluorescent readout for all the
>words & numbers.
>
>    Finally, a 24.576 MHz master clock multiplied (by 8) to 196,608 MHz to
>clock the DDS & ECL stuff; and divided as necessary to run everything
>else.
>
>         ******************************************
>
>   While this sounds like a lot of stuff, it will be rather compact in the
>real world -- except for part 5.  :-)
>
>
>Comments, suggestions... anybody want to help?
>
>
>73,
>   Marv  WC6W
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