Taylor Model 60 signal generator

[Mike Watterson]

Two feedback wires to grid of audio triode (one wire will be earthed?), two for audio triode anode (HT to anode) and one for RF triode HT feed = 5 wires. The RF Triode HT modulation might not share the same HT point as the Audio Triode "primary" winding.

So you need five connections and six isn't extraordinary. My replacement transformer actually has two 0-115 primaries for 230V rather than a centre tap, so they can be in parallel on 110-120 mains.