I won't guess what the H may signify, but possibly comparing your set with the X754 at the end of this thread may yield a clue:
https://www.vintage-radio.net/forum/show...p?t=116302
RM.org has an entry (no photo) for the Pilot 754, subject of Trader sheet 1126, which may be a relative but its valve complement if correct indicates series heaters -
https://www.radiomuseum.org/r/pilot_754.html
Paul
(Ah - just noticed the valve position diagram among the X754 photos, and it too has series heaters...)
https://www.vintage-radio.net/forum/show...p?t=116302
RM.org has an entry (no photo) for the Pilot 754, subject of Trader sheet 1126, which may be a relative but its valve complement if correct indicates series heaters -
https://www.radiomuseum.org/r/pilot_754.html
Paul
(Ah - just noticed the valve position diagram among the X754 photos, and it too has series heaters...)
