Re: CW coil top terminals?/Modulation

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Steve Cook by way of Terry Fritz <twftesla-at-uswest-dot-net>" <Steve-at-g8cyerichmond.freeserve.co.uk>

In my early days as a radio amateur I used series modulation with a
transistor in the cathode of the output valve (QQVO-640A). it only needs to
handle the cathode current. Then output was rated at 40W contiuous duty.
----- Original Message -----
From: Tesla list <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Wednesday, January 31, 2001 7:07 PM
Subject: Re: CW coil top terminals?/Modulation


> Original poster: "Stefan Richter by way of Terry Fritz
<twftesla-at-uswest-dot-net>" <Stefan.Mac.Richter-at-t-online.de>
>
> Hello to all,
> I found a schematic of an old military shortwave transmitter and there
> they used grid 1 modulation of the output tube. Audio coupling was done
> with a little modulation transformer, no big one for output stages.
> Another way of modulation I found in other old books was grid 2
> modulation using a second power tube for controlling grid 2 voltage.
> There are many variations: grid 2 resistor replaced by an audio selenoid
> or a small PA transformer or a power tube controlling directly the grid
> 2 voltage as a variable resistor (depending on the audio signal to this
> tube).
> I hope I could help with that little information.
>
> Kind regards
> Stefan Richter
>
>
>
>