[Johnson] Viking Valiant Modulation

[Paul Baldock]

I'm renovating a Valiant. I've made the usual audio chain mods to improve 
the frequency response.

However, when I monitor the modulated wave form on a scope I notice that as 
you take the audio lower in frequency that the modulation gets distorted. 
Its OK down to about 500Hz, but below that gets progressively worse. The 
drive to the 6146 modulators is reasonably distortion free.

Is this a feature of the original modulation transformer? Is a better 
transformer available?

Thanks

Paul - KW7Y