SZIKLAI complimentary-symmetry modulator , ammended

[KD6VXI]

As a class a series mod, you're going to get 50 pct voltage swing on the device being modulated....  Using a standard darlington that's the best I could do.

Maybe this configuration will do better, but..   

--Shane
KD6VXI

[km6sn]

Shane,
Not sure I am following what you are saying. Take a look at the files associated with post #22..
getting full swing on the load.

Rod

[KD6VXI]

What I am saying is:

With an non / non darlington pair, I can only get 1/2 Vcc swing under real world conditions.  As has been discussed elsewhere (recently) in the qso section. 

If the non / pnp darlington pair gets actual near full Vcc swing then this is amazing!

I don't always trust modeling.  Not saying it won't work, I really hope you get near full Vcc swing.

In a series mod with 2N2222 and MJE3055 I see half Vcc swing.

Because of this inefficiency I went PWM.

--Shane
KD6VXI

[W4AMV]

Excellent point Shane.

Rod,

One item I believe is missing from the simulation is associated with the AC source.
There is no source R attached. Or I do not see one in the screen shot. Rs is zero. It is set up as an ideal source. Although the input R for the device pair is high, there will be an input signal voltage divider. The consequence is reduced output swing. Re check that aspect.

Attached with sweeps on Rs from 1 to 100 ohms with a step through 50 ohms. You can see the consequence.

Alan

[km6sn]

Yes, Alan, I agree. One needs to adjust the driving voltage to compensate for driving source resistance.

I believe Shane is talking about something else.

Shane, could you post your 2n2222/MJE circuit, showing the RF deck equivalent resistance (Vdd/Idd)?

Thanks,
Rod

[W4AMV]

Cool....

I built the experiment. All total, 5 minutes. See attached.

No curve tracer matching but required careful setting of bias control.
The Vcc is set at 24 V, the swing is 24 V. Now I confess, I do not have a fancy 6 digit readout scope... So counting scales on my Tek scope. But indeed, careful set the bias and supply is swung, 0-to 24 V. I'll try to post an ugly board pix and scope shot.

Initially setup was no bias tweak. In that case, I lost 4 V in swing. So yes, careful device selection or bias adjustment would be required to get complete swing. The voltage gain for this arrangement is 0.89.

The scope at 5 V/major div. The channel 2 set to 24 V top line. Bottom gnd.
The ugly card is it at 1 kHz. Yep... ugly.

Alan

[km6sn]

Alan, good job! Ugly is the way to fly!
Rod

[km6sn]

Here is the final version, showing circuit, Vswing, Vfft.  See attached files.