PACKAGE PART NUMBER

SOWTER TYPE 9100
100 % MUMETAL
PP INTERSTAGE TRANSFORMER

HIGH IMPEDANCE TRANSFORMER WITH FULL GEOMETRIC BALANCE FOR PRE-AMPLIFIER USE

U-Clamp 9100-A
Mumetal Can 9100-J
9100 connections 9100a
APPLICATION Exceptionally high impedance, high bandwidth interstage transformer for small signal use in a push-pull pre-amplifier. Suitable as replacement for original transformer in many vintage recording studio units. Normaly used with the primary and secondary windings in series as a push-pull interstage transformer with a balanced drive. It may also be used as a phase splitter with an unbalanced drive. The two secondary windings permit separate bias supplies to the grids of the stage fed by the transformer. As the Mumetal core is very sensitive to unbalanced dc a balancing pot is recommended to adjust equalize the two anode currents. As the windings are accurately resistance balanced the currents can easily be adjusted by measuring the quiescent dc voltage between the anodes.
FEATURES Unusually large Mumetal laminated core for minimal distortion even at relatively high levels. Two chamber bobbin provides 100% geometric balance to ensure near perfect phase splitting and absence of distortion caused by unbalance of resistance or capacitance. The primary windings may be used in parallel to obtain a 1:2 step up ratio. Low copper resistance for low insertion loss. Optional heavy Mumetal screening can to ensure immunity from hum fields. Can dimensions 73x 63x 45mm high. Similar to picture above but with colour coded leads.
Voltage ratio 1+1 : 1+1
Bandwidth (-0.5 dB points, typical) 5k0 source 20k0 +10 pF load 8 Hz to 60 kHz
Total DC resistance ref. primary 850 ohms
Maximum balanced dc current per side. 40 mA
Max. input level at 50 Hz for 0.5%THD (Zero unbal dc) 60 V rms
Max. input level at 50 Hz for 0.5%THD (Unbal dc = 0.25 mA) 6 V rms
Max. input level at 50 Hz for 0.5%THD (Unbal dc = 0.125 mA) 24 V rms

9100 response

FREQUENCY RESPONSE
Measured with 5k0 ohm source and 20k0 ohm + 100 pF load
9100 phase response PHASE RESPONSE measured using 5k0 ohm source and 20k0 ohm + 100 pF load
9100 Zin INPUT IMPEDANCE measured with 20k0 ohm load
9100 THD TOTAL HARMONIC DISTORTION measured with 5k0 ohm source and 20k0 ohm load. Input Level +24 dBu.
E A Sowter Ltd, The Boatyard
Cullingham Road
IPSWICH IP1 2EG England
Tel: +44(0)1473 252794
Fax: +44(0)1473 236188
E-Mail sales@sowter.co.uk