[Herald1360]

The positive going half of the modulated IF looks compressed, but the AF signal on it doesn't look clipped or seriously distorted. Is the IF asymmetry not simply caused by the asymmetric half wave detector loading?

R16 C41 decouple the anode supply rather than form part of the anode load as such. Depends on whether dc or signal conditions are considered. Lawrence's comment might well be relevant, particularly if an ordinary vs valve voltmeter was used to take the voltage readings, when a lower than expected Va would be seen.

It's also suspicious to say the least that at 10mA anode current and 195V anode voltage Philips would be operating the EBF80 pentode at well over its rated Pa max! The 5mA figure in Philips's own valve datasheet for operation as RF/IF amplifier is much more likely to be where they were intending.