[AMPS] Re: Surge voltage, HV connectors.

[G0MJW]

> What I wanted to know is: is this voltage surging really a problem? When I
> put the key down, the supply will 'collapse' to its working voltage of 2.1
kV. If
> I tune up the amplifier for steady-state clean output (no flat-topping) at
2.1
> kV, will the initial reduction from 2.8 kV at the start of the
transmission
> cause non-linear distortion?

It should not cause a problem if you sequence properly. Once the standing
bias of the tube is flowing, I expect the supply will drop to a reasonable
level. If you have enough capacitance, the dynamic voltage swing will not be
so bad. You may end up with some 120Hz of ripple on CW.

The 2700v drop is excessive. My 6m 3-500Z runs 2800v off load and 2350v at
400mA and has been reported to be clean. The 70cm amp runs 3.7kV off load
and 3kV at 1A full load, but in this case full load is considerably more
than required.
>
> If the answer is 'yes', what should I limit the surge voltage to?
>
> > >> Ideally I would like an HV connector with a set of extra contacts for
> > >> carrying mains to the amplifier filament transformer as well.
> > >
> > >Never ever do that, unless you have a death wish for you or your
> > >family. Especially in NZ, where the power mains are not grounded.
>
> The mains here is of the Multiple Earthed Neutral type.
>
> Mains and HV are mixed inside the amplifier anyway. I can't see how
> combining mains, interlock and HV in one properly rated cable would make
> things more unsafe. In the case of a short from B+ to mains neutral, the
HV
> supply would be unable to lift the mains supply. The resulting short would
> cause it to blow a fuse.
>
> I can see separate cables would be marginally safer (even though they will
> probably be tied together in one bundle afterwards).
>
> > >Use a decent separate interlocked HV connector
> Any suggestions of what type of connector to use?
>
> > >The HV chassis mount connector should be on the supply ONLY,
> > >not on the RF deck. Then the dangling lead has zero volts, even if
> > >the interlock system fails.
>
> Good point. Also thanks for the suggestion to use grounded, armourd cable
> and a grounded connector shell.
>
> Wilbert, ZL2BSJ
>
>
>
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