6V6 / 6F6 /6L6 Exciter

[W9ZSL]

Hello again!  This relates to my "Bare Minimum" project.  This time I'm concentrating on the Exciter for the 813.  The rig will be 75-40 and maybe 20.

I've run two different diagrams past you with one PA of a classical MOPA and two oscillators.  I picked one oscillator and have most of the parts I need.  Note the 100 pf on the output of the 6AG7.  It is the same as the one on the input of the 6V6.  Comments on the combination?

I think I'll use plug-in coils.

The last parts needed for the separate 6V6 Speech Amp / Driver for the 813 are on the way.  Ever hear of the word "antsy"?   

[VE3LYX]

Looks like an interesting project. Myself I prefer a Hartley but that is just me. My own bare minimum uses a 6l6 (just one) and is AM. Stuff like this is a lot of fun and the results can be surprisingly good. There is something almost magical about building the old circuits and putting them on the air. Mine also has plug in coils. When conditions are right such a rig will reach out pretty good on 40M. 80m on AM can be a different story. Truth is it doesn't matter. You wait till conditions are good and go for it. While many operators live in a different world I have met several who actually appreciate hearing the old rig and the fun of an unusual contact. I have never had any luck on 20M and have built a few rigs for that. Just simply not enough AM activity on 20M to give it a reasonable chance of success. That is an opinion I recently formed. I had thought previously that 20M would have been a piece of cake but it turned out not to be so. 40M though has worked well.
Go for it. You wont be sorry and let me know when it is up and running. I will be listening for a Contact!
don

[W3RSW]

Looks nice.  
If your contemplating any CW work (since I see you have a key line into the cathode of
your 6ag7/6cl6 ECO ) make the 47pf in the grid a variable padder.  

The lower 220pf cap should be silver mica of good quality.  Proper setting of the 47 when keying will eliminate chirp.  I almost recommend putting a front panel knob on it   because adjustment of it goes a long way between getting lazy crystals to oscillate and getting a nice sweet note.  I've found that it does need to be variable and the setting you choose will be a compromise between crystal activation and a sweet note from most of your crystals.

I know you want minimum components but I'd put an OB2 in screen of 6ag7 to regulate to 108, with proper dropping resistor off B+ of course.  Do this too if wanting to work CW.

Even if you only want AM, I'd still make the 47pf variable. Stability and drive will be affected into the following stages.

[W9ZSL]

  OK Rick.  I'm on the fence with making this exciter CW because I have a DX-20 so the exciter would be strictly for the 813.  If I did QRP with the exciter bare-foot, I'd use a 6L6 PA, AM only.  I just happen to have a cherry Merit 10 watt modulation transformer and a P/P 6V6 modulator to go with it.  Golly.  Just solved a problem.  I'm going to go with a 200 ma supply and put on a tap for a modulator.  HaChaCha!

On the other hand, I've toured a few circuits using a single 813.  If I build a "multi-purpose" PA, it could be used for CW when and if I get my code speed up.  My first rig was a DX-20.  Going full circle.  Yes, got a nice Gonset rcvr in the shop to match my first "real" station!  The Ranger replaced the DX-20.  Not bad for a high-school Junior!

Remember, the final goal is a 375 watt HB AM station.  If I can run 400 watts CW, I'm not sure what I'd do with it!!!

[W9ZSL]

How would you tune up the oscillator properly if the 47 pf was replaced with a variable mica?  Next.

THERE WILL BE NO TUNED CIRCUIT IN BETWEEN THE OSCILLATOR AND THE PA because........this is going to be 75 / 40 only and I have a 3885 crystal, and the two 40 meter calling frequency crystals for 40.  Got it covered.

I already have the 80 meter coil.  Single tuning control.  Wind a 40 output switched and this would be.  Oscillator feeds the 6V6 / 6F6 / 6Y6 / 6L6 direct.  Should have a solid 300 VDC @ 200 ma to work with.

50 Year Class Reunion this weekend.  My LAST DJ gig ever.  Pray for me!