PARTRIDGE TG6556
Hiwatt 50
As its "great brother", the TG5479, this transformer was wounded to the original "MULLARD" winding patterns, which was used in early HIFI output transformers.

Over the years, this winding pattern was changed for making the transformers faster, the 0.35 mm hi-grade lamination was replaced by a lower grade material with a thickness of 0.5 mm too.

Contrary to other British transformer companies, all Partridge transformers were wound on SRBP bobbins with flanges. Characteristically for the TG6556 was its open framed mounting.

Above I would like to give you some results of measurements of this transformer. Please keep in mind, that these measurements are time-intensively.
I don´t mind using these results on other sites, but I think it would be more than fair to ask before copy and paiste, thank you very much.

PARTRIDGE TG6556
Raa
3400 Ohms
Inductance@50Hz
self-inductance@8H
230 Volts@332H
Leakage Inductance @1,6kHz
P1+P2/S 4,1mH
P1/P2 2,2mH
Frequency-Respond
DC-resistance (primary)
(black-yellow) 44.5 Ohms
(brown-grey) 50.7 Ohms
DC-resistance (secondary)
8 Ohms@0,41 Ohm
16 Ohms@0,50 Ohm
self capacity of primary, CT and one side of secondary connected to core
ca. 200 pF
Frequency-Respond
This very wide frequency respond isn´t characteristically for an output-transformer of a guitar amplifier. The -3dB points are at 3.8Hz and at 181kHz, which shows, that this transformer was developed for HiFi-amplifiers. Another point for that are the above shown square-wave and phase-shift pictures. A very slight ringing at a 10kHz square-wave signal and minimum phase shifts at 20Hz and 20kHz.
Square Waves/Phase Shift Pictures
(resitive primary load 2*1500 Ohm)
enlarge
100Hz/8Ohm (3,6 mW)
1kHz/8Ohm (3,6 mW)
10kHz/8Ohm (3,6 mW)
Phase Shift 20Hz/8Ohm (3,6 mW)
Settings
Phase Shift 20kHz/8Ohm (3,6 mW)
All square-waves and phase-shift pictures were taken at an output voltage of 170 mV (3,6mW).
The lower beam is the original signal, the upper is showing the output signal, taken from the 8 Ohms tap.