View source for Engineering:SY4307A

{{more references|date=January 2013}}
{{Infobox vacuum tube
|image = SY4307AFace.jpg
|image_size = 150px
|caption = [[Company:Standard Telephones and Cables|Standard Telephones and Cables]]/Brimar brand Australian Pentode, type SY4307A, c1940
|classification = Power Output Pentode <!-- Mandatory -->
|service = Class C amplifier, (Radio Frequency)
|height_in = <!-- inches -->
|diameter_in = <!-- inches -->
|weight_lbs = <!-- pounds -->

<!-- Cathode -->
|cathode_type = Directly heated <!-- Mandatory -->
|heater_voltage =
|heater_current =
|filament_voltage = 5v
|filament_current = 1A

<!-- Anode -->
|max_dissipation = 6W <!-- Mandatory -->
|max_voltage = 500v

<!-- Socket Connections -->
|pinout =  American 5 Pin, (UX5)<br />
with side locating pin between pis 1 and 2.<br />
Pin 1, Heater/Cathode<br />
Pin 2, Screen Grid, g2<br />
Pin-3, Control Grid, g1<br />
Pin-4, Suppressor Grid<br />
Pin-5, Heater/Cathode<br />
Top Cap, Anode/Plate

<!-- Class A amplifier ops -->
|class_a_amplification_factor =
|class_a_anode_voltage =
|class_a_anode_current =
|class_a_screen_voltage =
|class_a_screen_current =
|class_a_bias_voltage =
|class_a_anode_resistance =
|transconductance_gm =

<!-- Class C amplifier ops -->
<!-- Recommend the use of highest rated CCS specification -->
|class_c_power_output =
|class_c_anode_voltage =
|class_c_anode_current =
|class_c_screen_voltage =
|class_c_bias_voltage =

<!-- Class AB amplifier ops -->
<!-- Recommend the use of highest rated CCS specification -->
|class_ab_power_output =
|class_ab_anode_resistance =
|class_ab_load_resistance =
|class_ab_anode_voltage =
|class_ab_anode_current =
|class_ab_screen_voltage =
|class_ab_screen_current =
|class_ab_bias_voltage =
|reference =[https://frank.pocnet.net/sheets/125/4/4307A.pdf 4307A datasheet]
}}

The type '''SY4307A''' is the STC version of the [[Company:Western Electric|Western Electric]] 307A,<ref>[https://frank.pocnet.net/sheets/136/3/307A.pdf WE307A datasheet]</ref> a power output [[Engineering:Pentode|pentode]] possessing a similar power rating, but significantly different characteristics to the far more common type [[Engineering:807 (vacuum tube)|807]] thermionic valve/vacuum tube. The "SY" prefix denotes the site of manufacture as being Sydney. The plant, operated by Standard Telephones and Cables Pty. Ltd. was located on Mandible Street<ref>[http://www.environment.nsw.gov.au/heritageapp/ViewHeritageItemDetails.aspx?ID=5062416 N.S.W. Office of Environment and Heritage]</ref> in the suburb of Alexandria and existed under that corporate entity from 1937 to 1970<ref>[http://www.eoas.info/biogs/A001445b.htm Encyclopedia of Australian Science]</ref>.. Although the remaining structure postdates the depicted device, this device was likely assembled on an adjoining property upon which the structures have been demolished and site re-purposed.

Electrically equivalent devices marked "307A" were manufactured in North America by Western Electric and these possibly predate the Australian version.

==Uses==

Although the 807 is used for both audio amplification, (usually class AB), and radio frequency amplification in the 1-30&nbsp;MHz range, (usually [[Engineering:Amplifier#Class C|class C]]), this type was usually used for the latter.<br />
This tube/valve is a pentode with a 'directly heated cathode', meaning that the cathode consists of an emissive oxide coated filament. These features suggest the 4307A could predate and is contemporary with, the 807 which is a beam power tetrode, a more advanced design with a more linear transfer characteristic and a more complex 'indirectly heated cathode'.

==Similarity to 807==

If the pinout of the 4307A is compared to that of the [[Engineering:807 (vacuum tube)|807]] the similarity is striking. All pins are assigned equivalent electrodes with the exception of pin 4, which is the suppressor grid, g3, in this type but in the 807 pin 4 is connected to the equivalent of a suppressor grid, the 'beam plates' and also the separate indirectly heated cathode.
It is possible to interchange the two with the relatively minor alteration involving the linking of pins 4 and 5 and ensuring the heater supply is [[Engineering:Floating ground|floating]] (not connected to other heaters). If the heater is supplied from an [[Physics:Alternating current|A.C.]] source, linking pin 4 to the centre of that source and the cathode bootstrap minimizes hum pickup.

==Historical significance==

The STC/Brimar-made '''SY4307A''' was used extensively during World War II by the Australian armed forces and the example depicted is marked on the [[Chemistry:Bakelite|Bakelite]] collar of its base with the "D broad arrow D" commonwealth department of defense mark.

Two SY4307As were used, wired in parallel, as the output stage, or "final", in a transmitter constructed clandestinely by the Australian soldiers of Sparrow Force in Japanese occupied Portuguese Timor in 1942. This transmitter became known affectionately as "[http://www.ww2australia.gov.au/japadvance/boots.html Winnie the War Winner]", named after the British wartime Prime Minister, Winston Churchill.

<gallery>
Image:SY4307ASide.jpg|Side view of SY4307A
Image:SY4307AHtr01.jpg|View of directly heated cathode of the SY4307A
Image:SY4307ABase.jpg|View of UX5 Base of the SY4307A
</gallery>


==See also==
* [[Engineering:List of vacuum tubes|List of vacuum tubes]]

==References==
<references />

{{DEFAULTSORT:4307a}}
[[Category:Vacuum tubes]]

{{Sourceattribution|SY4307A}}