[600MRG] Class E Keying

[Jim Miller]

I've printed it out and am studying. It perhaps could use some updating for
newer parts but I think it's a start.

jim

On Thu, Feb 11, 2016 at 9:14 PM, Jim Miller <jim at jtmiller.com> wrote:

> http://www.its.caltech.edu/~mmic/reshpubindex/papers/buckwalter.pdf
>
> I think our emails crossed but here's a link to one I found. Published in
> QEX!
>
> 73
> jim ab3cv
>
> On Thu, Feb 11, 2016 at 9:04 PM, Frank Lotito <k3dz at live.com> wrote:
>
>> Jim AB3CV- Can you refer me to one or more "pulse width modulation"
>> designs for keying the power supply voltage?  I assume someone has tried
>> this  approach and wrote it up for publication in the popular press or
>> Internet?
>>
>>
>> 73 Frank K3DZ / WH2XHA
>>
>>
>> ------------------------------
>> *From:* jtmiller47 at gmail.com <jtmiller47 at gmail.com> on behalf of Jim
>> Miller <jim at jtmiller.com>
>> *Sent:* Thursday, February 11, 2016 5:48 PM
>> *To:* John Langridge
>> *Cc:* Frank Lotito; 600 / 630 Meter Group
>> *Subject:* Re: [600MRG] Class E Keying
>>
>> I would think at the 5-10ms rise/fall time needed for good shaping that a
>> PWM approach would work on the drain supply line.
>>
>> 73
>>
>> jim ab3cv
>>
>> On Thu, Feb 11, 2016 at 4:12 PM, John Langridge <kb5njd at gmail.com> wrote:
>>
>>> Hi Frank,
>>>
>>> I can't really comment much on what you have provided above but...
>>>
>>> There is option for what you are using now that will work well.
>>>
>>> I will be referencing the GW3UEP shaped keying circuit on his basic
>>> IRF540
>>> amp and have placed a copy of the schematic on my website as it was not
>>> explicitly linked on Rog's parent site:
>>> http://njdtechnologies.net/wp-content/uploads/2016/02/GW3EUP-keyed-pa.gif
>>>
>>> So lets say you wanted to key the base GW3UEP amp, which you already own,
>>> in order to achieve improved harmonic performance on CW. In your case,
>>> you
>>> would implement the portion of the circuit at the top right of the
>>> schematic built around the IRF9530 on the positive power lead input to
>>> the
>>> amp.  Your driver could be any signal source and you simply key the
>>> positive lead with a signal applied to the input.  The rise and fall
>>> times
>>> are controlled and lead to a really nicely shaped waveform.
>>>
>>> I have this particular keying method in my arsenal of 630-meter CW
>>> transmitters, using Rog's homebrew VFO design based around a binary
>>> counter
>>> feeding the input of the amp and I just key the power lead.  It works
>>> very
>>> well and its very clean.  You might get better stability from a
>>> commercial
>>> signal generator.  My VFO does tend to drift around a little but is often
>>> pretty stable within a CW session.
>>>
>>> That's one option.  I am sure you will get other recommendations.
>>>
>>> 73!
>>>
>>> John KB5NJD / WG2XIQ..
>>>
>>> On Thu, Feb 11, 2016 at 2:56 PM, Frank Lotito <k3dz at live.com> wrote:
>>>
>>> > I am looking for suggestions on methods to key Class E RF Power
>>> Amplifiers
>>> > for ON / OFF keying, be it at regular CW speeds, or QRSS speeds.  I
>>> assume
>>> > this topic has been discussed in the popular literature, or special
>>> > interest bulletin boards such at the 600mrg bulletin board.  Improper
>>> > keying may generate key clicks with its resulting plethora of
>>> emissions on
>>> > either side of the carrier.  This may be a moot point point for the
>>> QRSS
>>> > mode, maybe not.
>>> >
>>> > ..........
>>> >
>>> > I found the 1997 May / June QST 2-Part article by Lau, et. al.  The
>>> > article presents a drain (B+) keying circuit for the Class E
>>> amplifier's
>>> > 120 VDC drain supply voltage.  For a specified power level a little
>>> simple
>>> > theory gives the relationship that the (approximate) equivalent
>>> resistive
>>> > load on the DC power supply at key down varies as the square of the
>>> ratio
>>> > of drain voltage.  For example, double the design's drain voltage, the
>>> > equivalent power supply resistance is 4 times that of the lower voltage
>>> > design. Higher drain voltage designs may have an advantage as in the
>>> 1997
>>> > QST article's power supply keying design if higher voltage components
>>> and
>>> > semiconductors are available.
>>> >
>>> > ...................
>>> >
>>> > Besides voltage and current concerns, including the problem of
>>> obtaining
>>> > appropriate RF current rated amplifier tuning capacitors, there is the
>>> > matter of controlling the shape (rise and fall) of the keying waveform.
>>> > This is mandatory to minimize key clicks.  Not easily done when the
>>> > equivalent DC load resistance is only a few ohms.  The Lau design
>>> presents
>>> > a method to shape the rise and fall times of the keyed power supply
>>> drain
>>> > voltage.
>>> >
>>> > ...................
>>> >
>>> > Anything else out there published on keying Class E RF Power Amplifiers
>>> > (the popular literature, or on an individual's or company's web
>>> site?)  I
>>> > am assuming other designs might be more suitable for the more common
>>> 24 VDC
>>> > systems. Your suggestions are welcome.
>>> >
>>> > .................
>>> >
>>> > 73 Frank Lotito  K3DZ / WH2XHA
>>> > _______________________________________________
>>> > 600MRG mailing list
>>> > 600MRG at w7ekb.com
>>> > http://w7ekb.com/mailman/listinfo/600mrg_w7ekb.com
>>> >
>>> _______________________________________________
>>> 600MRG mailing list
>>> 600MRG at w7ekb.com
>>> http://w7ekb.com/mailman/listinfo/600mrg_w7ekb.com
>>>
>>
>>
>