[AMRadio] Plate modulating a 807


Brett Gazdzinski brett.gazdzinski at mci.com
Wed Apr 7 08:29:42 EDT 2004


Well, yes, for cw you have to short the mod transformer out,
but you would also have to short the screen choke if you used one.
You don't want the inductance in circuit when keying the cw on and off....

Brett
N2DTS


> -----Original Message-----
> From: amradio-admin at mailman.qth.net
> [mailto:amradio-admin at mailman.qth.net]On Behalf Of Geoff/W5OMR
> Sent: Wednesday, April 07, 2004 8:20 AM
> To: amradio at mailman.qth.net
> Subject: Re: [AMRadio] Plate modulating a 807
> 
> 
> 
> 
> > Best thing to do is insert a choke in the screen circuit.
> > 
> > A small choke, 15 henrys or more will work.
> > Otherwise, you have to run the screen off a voltage divider,
> > some from the unmodulated B+, and some from the modulated B+.
> > 
> > The choke setup MAY hose you up on cw if you run cw, so a switch
> > or some quick way to remove the choke might be needed.
> > 
> > Brett
> > N2DTS
> 
> Why not just turn the audio off, and short the secondary of 
> the modulation
> transformer?  Or, is using a reactor in the Final BE+ line, 
> switch from the 
> modulator, to the final.
> 
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