electronic gear is way more expensive and it does not run the lamp as well.

So far I have been running UK popular pack PP220
And SRS 240 volt ballast on 60 Hz it runs them fine
And it use a odd value cap to run American 5 foot HO tubes.  And I got a big surprise coming up next.

So far I have been running UK popular pack PP220
And SRS 240 volt ballast on 60 Hz it runs them fine
And it use a odd value cap to run American 5 foot HO tubes.  And I got a big surprise coming up next.

The SRS is not operating even close to resonance, the capacitor is connected so, the ballast inductance is cancelled out.
It is rather an exemption: The higher inductive reactance causes the arc current to be 20% lower, but the lower capacitor reactance cause the auxiliary heating current to be 20% higher than on 50Hz. That mean the lamp run 20% underpowered, but still with proper filament heating.
But the SRS won't work with SOX any better than just simple series choke.

The main "warning" was aimed mainly at the near-resonance ballasts, so CWA or similar, mainly used for SOX.

The series choke only ballast could be used with elevated voltage

And for the electronic: If it is designed for a particular SOX lamp, it should run it properly and yet be insensitive for different mains frequency.

Ahh ok Medved talking about the CWA  leak type sox ballast. We do have sox ballast in the USA but being expensive.  The two American sox ballast I own
Between advance and Jefferson is dual rated 35/55 watt
Sox, the Caps was just PFC caps on mains here. The
Way it was set up was PFC on 240 volt mains
And 120 volt HX normal power factor  that I kind of find
Odd.

@funkybulb: I know, but what I want to say is, the CWA designed for 50Hz really won't operate at all on 60Hz and vice verse, the one designed for 60Hz won't operate at 50Hz. And that is not a slight parametric change, as it is the case for series choke or HX, the CWA would be really fried...