Sequencing With Solid-State Power Supplies

[W9ZSL]

I'm getting ready to start my build on the single 813 RF / 811A modulator AM rig.  All my power supplies will be solid-state including 1900V RF, 1400V Mod, RF screen and bias.  I have asked in the past about "soft starts" for the HV and can integrate that in the designs.  For the final and modulator supplies I have two sets of National Electronics SSR-13 diodes...S866A equivalents. The 813 screen and bias supplies are a bit up in the air.  Bias will most likely be provided by a 120 to 120 transformer through a bridge rectifier adjustable for the 813; ditto for the 811A's with their own supply.  Screen voltage will be provided by another adjustable supply through a 15 Hy choke for self-modulation.  Every supply will be separate.

The exciter will have a conventional tube rectifier (5Y3) with the standby/transmit switch on the center tap.

So here is the main question.  I want the amp to be AM/CW so I will use a heavy-duty switch to short the secondary of the Mod Iron.  The modulator will have separate supply and filament/plate switching. I have several 120 volt DPST relays and all the transformers are 120 primary.

When operating AM, I know how important it is to have a load on the secondary of the Mod Iron, in this case a UTC S-22.  So when I transmit, does it matter if HV is applied to both the Modulator and final at the same time?  I know that screen voltage to the 813 should be applied after the plate voltage so a second relay should be able to delay enough.  Antenna change-over is the other consideration.  Logically the sequence should be antenna, plate, screen with the exciter keyed to the antenna relay.  Yes?  No?

Of course, now we have the problem of CW operation!  The schematic I'm considering has a 6Y6 clamp tube which changes everything.

In order to design and lay out the power supplies, I have to nail down how many relays I need.  Everything will work at 120 VAC. The exciter will be a 6AG7/6V6 combo with plug-in coils.

[KA2DZT]

6Y6 clamp tube doesn't work with a separate screen supply and choke.  Clamp tube circuit is used if you don't use any fixed bias on the 813.  You can make life easy if you use a series dropping resistor for the 813 screen.  The screen resistor is about 43K at 100W.

At 1400 volts on the 811s you only need about 4 volts of bias.  This can be done with a Zener diode in the filament xfmr CT to ground.

One set of soft-start relays for both plate supplies with one common fuse.

[K6IC]

   ...   

  I want the amp to be AM/CW so I will use a heavy-duty switch to short the secondary of the Mod Iron. 

By "Heavy-Duty",  hope that you are considering using  a High Voltage switch or perhaps,  a  relay -- with 5 KV or more capability.   A Vacuum relay may do the job well.

FWIW,  GL,    Vic

[W9ZSL]

I won't be using relays on the high-voltage side just the primaries.  I would rather leave the HV supplies on than key them.  I wont be using a rotary inductor as shown substituting an Air Dux and switching.