Pi-Network

[w1vtp]

<snip>

...The G-G configuration wastes driving power by passing a large portion of it on through the amplifier stage to the antenna.  This also prevents 100% modulation in the negative direction, since this feed-through is always present, no matter how negative the modulation voltage drives the plate.

<snip>

I believe this is why Stu AB2EZ modulates the exciter as well as his 2 X GS-35 linear - it resolves the issue of feed through RF from the exciter since it is modulated as well

Al

[k4kyv]

That would work.  But even in grounded grid configuration, the amplifier still should be run in fully saturated class C mode if it is to be plate modulated, not linear.

[w5omr]

That would work.  But even in grounded grid configuration, the amplifier still should be run in fully saturated class C mode if it is to be plate modulated, not linear.

Agreed.

Well, the input has been wonderful and I thank each and every one of your for your input.  I think I'll just run the 450T deck in it's constructed configuration for the SSB rig.  In the process of building a universal power supply, complete with meters and a Vari-Ac, and use it to power either the SSB amp, or the 250TH x 450TL rig.
The final is near complete - just a few minor repairs.  The power supply and modulator are being built from scratch.  The big transformer I discussed in another post, a pair of 872A's, 30H @ 500mA choke to meet L_(crit) and somewhere around 25uF @ 5kVDC (total) should filter any hum out.  Critical reactance calculates out to somewhere between 20~40Hy - make have to string a pair of chokes together to get there.

That said, anyone have any 5kV oil-filled caps they wish to part with? 

[w1vtp]

That would work.  But even in grounded grid configuration, the amplifier still should be run in fully saturated class C mode if it is to be plate modulated, not linear.

Don

I think this would be a good topic of discussion / documentation.  There are a lot of linears out there that might lend themselves to this application.  Your point of still running the final in saturation while applying some modulation to the linear is an interesting one.

[KM1H]

Most commercial ham linears dont have the Tune cap spacing to handle Class C AM and barely make it on SSB.

On top of that some tubes in use likely wouldnt even hi pot high enough.

[w5omr]

Ok... here's some pics of the 450T amp...

[w5omr]

two more...

[Opcom]

That's a good-looking layout there.

[w5omr]

That's a good-looking layout there.

yeah, I think it'll work.  I just need to get some time to do it. 

I wish there was a way to bank time... ~sigh~

[WA1GFZ]

You might want to run those nice caps through the dish washer.
You can also take them apart and clean them one part at a time. Just be careful with the ceramic and make sure the soft washers get reinstalled.