[AMRadio] New Project

[Brett Gazdzinski]

Why bother?
Because its fun.

The only problem using octal tubes is the plate and grids are close and all 
under the chassis.
That is not as much of a problem with push pull since you can neutralize 
them brute force.

A pair of 2E26's would be fun.

I always used to joke on the air I was going to build a water cooled 6aq5 
rig...

Brett
N2DTS

----- Original Message ----- 
From: "John Coleman" <jc at pctechref.com>
To: "'Discussion of AM Radio in the Amateur Service'" 
<amradio at mailman.qth.net>
Sent: Saturday, October 15, 2011 1:58 PM
Subject: [AMRadio] New Project


> Well there will be many folks that will say "why bother", but I have a
> little project in mind that I have been discussing with Geoff, W5OMR.  It 
> is
> just a little fun and learning project.
> I want to build a push pull class C rig using a single 6SN7.
>
> Max Plate Dissipation is 7.5 watts for both sections or 5 watts for each
> So I plan to dissipate about 3 watts per section
>
> Peak voltage rating is very high on the 6SN7 as is the peak current -
> something like 1200 volts and 300mils.
>
> I think I will run each section it at 400V on the plate and 30mils of 
> plate
> current.  That's 12 watts input per section or 24 watts input total.  This
> should yield about 18 watts output.
>
> The load reflection from the Tank is calculated
> Lz = Eb/2Ib = 400/.06 = 6666 ohms
>
> I'll figure the tank circuit from that later.
>
> At 400 Volts Eb, the charts show cutoff at about -30 to -40 volts grid 
> bias
>
> Class C is usually biased about 3 X cutoff so I will apply -100 to -120
> volts regulated to the grid RF choke and drive it till I get max output at
> 60 mils plate current and then about 1.2 times more drive from my
> experience. And then measure the grid current.  I'm expecting it to be 
> about
> 5 mils of grid current, but that is just a guess.  I'll calculate a grid
> leak from these findings for later use.
>
> Anyone got any other ideas or experience with these little triodes as 
> class
> C devices.
>
> John, WA5BXO
>
>
>
>
>
>
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