|[AMRadio] Ranger... good news, bad news|
manualman at juno.com
Fri Nov 3 23:33:42 EST 2006
Why not just make the screen voltage adjustable by using either a
variable pot or some solid-state circuitry with a variable pot. Pot can
be mounted behind the xtal socket with a small knob or shaft protruding
through the center hole of the xtal socket. Electric Radio, not to long
ago, had a simple circuit for this that worked very well. And the plate
current meter still worked and no diddling behind the Ranger with the
On Fri, 03 Nov 2006 21:02:54 -0500 Larry Szendrei <ne1s at neandertech.com>
> Jack Schmidling wrote:
> > I have read page after page of mods and changes to the Ranger to
> make it
> > suitable to drive an am and wonder why I can't just reduce the
> drive to
> > get about 15 watts out and be done with it.
> > What am I missing?
> > js
> The problem is that in a Class C amplifier the grid is driven well
> beyond "saturation" (no additional power output with increasing
> If this wasn't the case, you would have no increase in output with
> increasing plate voltage on positive modulation peaks - so there
> be no positive peaks in your "AM" RF output! Also, reducing drive
> reduce your plate efficiency greatly and you may exceed your plate
> dissipation in the 6146 PA tube (in case you wanted to try this for
> IMHO the best way to reduce the output from a Ranger to drive an amp
> to use the LV power supply (~300V) for the PA plate supply instead
> the HV plate supply. This can be done right at the accessory plug in
> back of the rig, but you'll lose your plate current indication on
> panel meter. You can either rewire the Ranger internally so that it
> read Ip no matter whether you use the LV or HV plate supply (as I
> on mine), or use an external plate current meter wired to the
> plug. Of you choose the latter you can leave the Ranger stock and
> even take it out of the cabinet!
> You can still use the HV supply on the modulator plates for lots of
> audio headroom, but turn the audio gain pot will be way down from
> it is when running the rig at full output.
> With this approach you'll get about 12-15W out, perfect for driving
> linear amp.
> This is the Timtron-approved way of doing it, and I can vouch for
> it, as
> it has worked well for me.
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