S, T, O
APPLICATION: For experimenters who wish to try valves such as 5881, EL34, 6550, 6L6, KT66 in various push-pull configurations such as triode, tetrode or pentode mode with a pair of valves or two pairs in parallel with or without cathode feedback. The primary may be connected to give an RLa-a of approximately 10K or 5k0 ohms and the secondary may be configured to give 16/8/4 ohms. If an 8 ohm speaker is used with the secondary configured to 16 ohms the primary reflected load will be 5k0 or 2k5 ohms. May be used for a range of high quality designs without any performance compromise or for experiments to study the effects of different circuit configurations. Please note the reflected impedances do not take account of the dc resistance of the windings.
FEATURES: High grade low loss grain oriented silicon iron core for minimal distortion. 14 winding sections which can be configured so that all the sections are always in use to ensure minimal leakage inductance so the transformer has exceptional bandwidth and transient response.

There are 4 separate identical secondary windings which can be configured for 4/8/16 ohms speakers. Please note the actual secondary impreances are 4/9/16 ohms). 

Cathode winding for "super ultra linear" connection as described by Williamson and Walker AES Journal April 1954 Volume 2 Number 2. Screen taps or even a separate screen feedback winding allowing the screen to be returned to a different voltage may be configured for experiments.
BANDWIDTH: Depends on configuration but typically - 3dB at 10Hz and 40KHz. Best response is obtained with triode connection and/or with cathode feedback.
POWER at 25 Hz 20 Watts minimum
ANODE CURRENT max per side 150 mA
8774 connections   RLa-a = 10K RLa-a = 5K
ANODES 1,13 3,11
CATHODES (optional) 6,8 6,8
HT+ 5 5
JOIN 5+9, 2+3, 11+12 5+9, 1+3, 2+4, 11+13, 10+12
33% SCREEN TAPS 4,10  
66% SCREEN TAPS 2,.12  
50% SCREEN TAPS   4,10
Primary inductance (typical) 70H 30H
Ratio Tertiary/Primary  6% 12%
Primary resistance (typical) 160 ohms 120 Ohms
E A Sowter Ltd The Boatyard, Cullingham Road IPSWICH IP1 2EG England Tel: +44(0)1473 252794
Fax: +44(0)1473 236188