Here is a Mullard GZ34 tube; old production, produced in the Blackburn factory in the UK.The GZ34 is a full wave rectifier. This tube bears the brand name Philips (hardly visible). The tube has a top halo-getter, a red plate rim and an f32 etch code.
The Mullard GZ34 is famous for its contribution to the tonal quality of tube amplifiers and their extreme long life. They are highly regarded also for application in guitar amplifiers. And deliver superior performance compared to the Chinese and Russian new production.
Anode current, gas and shorts tested with: AVO CT-160 (Dutch army tester), Utracer3+, AVO Valve Data Manual 23rd edition 1981, Philips 1532, RFT stabilised power supply and 2x Keithley 2700. Test condition: Ua (plate voltage) = 10 Volts.
The measurement data below show that the GZ34 tube is in super condition and surpasses the factory requirements for a new tube.
|Ia (anode current):
Gas test, Shorts test:
|124 / 127 mA
*The rated emission value for a new GZ34 valve at the used test conditions is: 120 Milliamperes (mA). (Factory data sheet)
* Specified measurement data
Test results on other testing devices may supply different values. Just in case of mismatch of “standard” values of the different tube testers “standards”. My test results refer to tube data sheets provided by the original tube producers. (You’ll find them easily on the web.) And are obtained with the specified test equipment.
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|Quantity of Tubes||One|
|Manufactured in||Mullard, Blackburn, UK|
|Date code||f32 B 2B3 1962|
|Plate Construction||red rim plate|
|Getter Construction||round halo getter|
|Print Condition||mediocre; see pictures|
|Box included||generic white box|
|General test results||NOS|