[Boatanchors] Heath Warrior bias supply (was WTB: 6.3VAC/20A and 10VAC/low current transformer)

[Ian Wilson]

Hi Rick,

I took a quick look at the schematic. There does indeed seem to be about
400mA of quiescent current in the bias supply (6.3V / 16 ohms). You may
be able to arrange your circuit so that the current draw in cutoff (-150V or
whatever, when the antenna relay is open) is much smaller, however.

73, ian K3IMW


On Fri, Nov 21, 2014 at 9:29 AM, Rick Poole WA1RKT <wa1rkt at comcast.net>
wrote:

>
> From: "Ian Wilson" <ianmwilson73 at gmail.com>
> Sent: Friday, November 21, 2014 11:32:31 AM
> >>
> >> ...run a 120V/6.3V transformer backwards.
>
> Good afternoon, Ian (and others who have made the same suggestion in this
> thread).
>
> Heathkit claims that the bias circuit needs to provide 400 ma (?!?!?) so
> that it is "stiff" enough to handle the "large amounts of grid current
> drawn by the amplifier" (their words).  Seems rather bizarre for a bias
> circuit but that's their story and they're stickin' to it... maybe it's a
> characteristic of class B rather than class AB2.  So, using a
> reverse-connected 6.3VAC transformer would require that the 6.3 volt side
> be capable of 8 amps or better to provide enough current on the 120 volt
> side.
>
> So yeah, that's a good thought if the bias circuit were more like what one
> might expect.
>
> Rick WA1RKT
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