# SY4307A > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/SY4307A > Markdown URL: https://mediated.wiki/source/SY4307A.md > Source: https://en.wikipedia.org/wiki/SY4307A > Source revision: 1354512663 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) {{more references|date=January 2013}} {{Infobox vacuum tube |image = SY4307AFace.jpg |image_size = 150px |caption = [Standard Telephones and Cables](/source/Standard_Telephones_and_Cables)/Brimar brand Australian Pentode, type SY4307A, c1940 |classification = Power Output Pentode |service = [Class C amplifier](/source/Class_C_amplifier), (Radio Frequency) |height_in = |diameter_in = |weight_lbs = |cathode_type = Directly heated |heater_voltage = |heater_current = |filament_voltage = 5v |filament_current = 1A |max_dissipation = 6W |max_voltage = 500v |pinout = American 5 Pin, (UX5)
with side locating pin between pis 1 and 2.
Pin 1, Heater/Cathode
Pin 2, Screen Grid, g2
Pin-3, Control Grid, g1
Pin-4, Suppressor Grid
Pin-5, Heater/Cathode
Top Cap, Anode/Plate |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_power_output = |class_c_anode_voltage = |class_c_anode_current = |class_c_screen_voltage = |class_c_bias_voltage = |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 [Western Electric](/source/Western_Electric) 307A,[https://frank.pocnet.net/sheets/136/3/307A.pdf WE307A datasheet] a power output [pentode](/source/pentode) possessing a similar power rating, but significantly different characteristics to the far more common type [807](/source/807_(vacuum_tube)) 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[http://www.environment.nsw.gov.au/heritageapp/ViewHeritageItemDetails.aspx?ID=5062416 N.S.W. Office of Environment and Heritage] in the suburb of Alexandria and existed under that corporate entity from 1937 to 1970.[http://www.eoas.info/biogs/A001445b.htm Encyclopedia of Australian Science]{{Cite web |last=Centre for Transformative Innovation |first=Swinburne University of Technology |title=Standard Telephones and Cables Pty Ltd - Corporate Body - Encyclopedia of Australian Science and Innovation |url=https://www.eoas.info/biogs/A001445b.htm |access-date=2026-05-16 |website=www.eoas.info |language=en-gb}} 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](/source/class_AB)), and radio frequency amplification in the 1-30 MHz range, (usually [class C](/source/Amplifier)), this type was usually used for the latter.
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 [807](/source/807_(vacuum_tube)) 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 [floating](/source/Floating_ground) (not connected to other heaters). If the heater is supplied from an [A.C.](/source/Alternating_current) source, linking pin 4 to the centre of that source and the cathode [bootstrap](/source/Bootstrapping) 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 [Bakelite](/source/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.{{Cite web |title=Radio transceiver, 'Winnie The War Winner': Signaller Max Lyndon Loveless, 2nd Australian Independent Company |url=https://www.awm.gov.au/collection/C137997 |access-date=2026-05-16 |website=www.awm.gov.au |language=en}} This transmitter became known affectionately as "[http://www.ww2australia.gov.au/japadvance/boots.html Winnie the War Winner] {{Webarchive|url=https://web.archive.org/web/20090516043757/http://www.ww2australia.gov.au/japadvance/boots.html |date=2009-05-16 }}", named after the British wartime Prime Minister, [Winston Churchill](/source/Winston_Churchill). 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 ==See also== * [List of vacuum tubes](/source/List_of_vacuum_tubes) ==References== {{DEFAULTSORT:4307a}} Category:Vacuum tubes --- Adapted from the Wikipedia article [SY4307A](https://en.wikipedia.org/wiki/SY4307A) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/SY4307A?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.