two stages or three?

[N0BST]

I was thinking of building a sortof PW class AM transmitter with an old CVM-0 mod transformer I acquired.  It'll be about 20W with an 807 output.  For the RF chain I was wondering if it would be best to use a buffer to drive the 807 or if there is enough isolation to just drive the 807 directly with the oscillator?  I'm wanting to avoid any incidental FM-ing or phase modulation.

As they say in Brooklyn when the Fifth Armored Division rolls through,

Tanks,

Scott Todd

[Bacon, WA3WDR]

I would put a buffer in - a tetrode or pentode.

[WD8BIL]

No doubt... Bacon is right... put a buffer stage in there.
It'll help the stability of the osc.

[W1FRM]

I agree ......... use a buffer.  The rig shown in my avatar ("Baby T.") uses
a single 807 final at either 10 or 20 watts (variable plate voltage).  A driver
stage is almost mandatory for most VFO's.

I used a 6V6 and it also is a doubler on 80 and 40 meters.  Take care in
shielding the stages from the VFO and each other to avoid pulling and
"wobulation" (FM'ing).

Good Luck!

[K1JJ]

Yes, a buffer is needed unless you desire the SBE effect.

For a circuit that is DESIGNED to wobulate somewhat, check out my VXO xtal controlled power oscillator PW rig . It would wobble much more if it didn't use a xtal.  This rig was designed to be as simple as possible. 5W out, fully self contained. Still used today.

http://www.amwindow.org/tech/htm/series.htm

Guy - is that Baby-T in your avatar? If so, I didn't know it had a digital readout. Neat looking rig, OM.

T