[AMRadio] 813 Final Problem

Jim Tonne Tonne at Comcast.net
Thu Mar 19 15:28:47 EDT 2015


Yes indeed I understood the situation as you described.

Turn on the high voltage and THEN key the RF amplifier
on and off and all hell will break loose.

Short the modulation transformer (temporarily) and the
rig will be quite calm when you key the RF on and off.

This same situation will occur when you have the same
rig used for AM phone and CW.   When in CW short out
the modulation transformer.

Even when the modulator tubes are installed be sure
they have considerable standing (idling) current when the
RF is keyed on and off or when you key the B+ on and
off.   Best to short the modulation transformer when you
do that.

- JimT W4ENE

On 3/19/2015 2:16 PM, Paul Baldock wrote:
> Are you suggesting the problem I am seeing is normal, and that it will 
> go away once I connect the modulator tubes to the transformer primary?
> Did I make it clear that the arc is on the HV connector to the RF PA, 
> not the HV connector to the (yet to be built) modulator? That side of 
> the transformer is currently completely disconnected from everything.
> Thanks
> - Paul

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