[Boatanchors] Please review & comment on my Heath Warrior HA-10 amplifier design changes

[Gary Schafer]

The gas tubes will hold the filaments down but a single one across the
center tap to ground would do the same thing. However the voltage will go
much higher than a diode would and not protect the meter as well.

73
Gary K4FMX

> -----Original Message-----
> From: Boatanchors [mailto:boatanchors-bounces at mailman.qth.net] On Behalf
> Of Rick Poole WA1RKT
> Sent: Sunday, November 23, 2014 7:33 AM
> To: boatanchors at mailman.qth.net
> Subject: Re: [Boatanchors] Please review & comment on my Heath Warrior
> HA-10 amplifier design changes
> 
> 
> From: "Gary Schafer" <garyschafer at largeriver.net>
> Sent: Sunday, November 23, 2014 12:16:43 AM
> >>
> >> Don't forget to place the safety diode from the junction of the
> >> plate meter shunt and HV choke with the cathode to the choke and
> >> the other side of the diode to ground. This keeps the negative
> >> side of the HV close to ground in case a tube or something should
> short.
> 
> I planned on adding two voltage clamps to the filament lines per
> http://www.w8ji.com/al811_important_modifications_changes.htm (Tom
> W8JI).  Wouldn't that do more or less the same thing?  It would clamp
> the negative side to around 150-170 volts which is a lot higher than
> doing it your way but would it not provide sufficient protection?
> 
> The other alternative would be a zener diode of nominally 10-12 volts
> from the junction of the plate meter shunt and HV choke to ground.  That
> should do it without having to install a dozen diodes and associated
> 0.01-uf caps, right?
> 
> Rick WA1RKT
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