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** FULL TEST RESULTS BELOW AND IN PICS Listed *** **** Quantity ONE TUBE, ONE TUBE, ONE TUBE ***** One(1) UNUSED TV7D/U RE-TESTED Strong 'Bogey' Range DATE MATCHED 1951 '3221-24' Tung-Sol JAN CTL 6SU7GTY with Light Brown Low-Loss Base, Smoked Glass, Two Rounded Plates & Two Rectangular with Round Edged Spiked Mica Wafer/Spacers. In Original Mil-Spec Plain Tan Box each blue inked with Mil-Spec Contract info included. (Please look closely at all 24pics listed) Physical Characteristics: - Two Rectangular with Round Edged Spiked Mica Wafer/Spacers - Smoked dark Glass, Glass etched "6SU7GTY" inside Octangle Stop-sign - Light Brown Micanol/Low-Loss Phenolic base - White ink on base "Tung-Sol" "Made in the USA" "JAN-CTL 6SU7GTY" with White Square Box with 'A' triangle inside ink "S C" "199" =US Military Contract# "3221-24" , "322"=EIA code Tung-Sol, 1=1951 "-24" 24th Week Calibrated TV7D/U tested : Tested at 150VDC Plate Supply : NO Shorts, No Leakage, No Gas, No Apparent Microphonics nor Hum Tube inked '2' : Plate 1: 46.8/30 = 1,170.0 uMhos at 7.3mA Plate Current Emissions Plate 2: 49.3/30 = 1,232.5 uMhos at 7.5 mA Plate Current Emissions Dan Nelson recent Calibrated TV7D/U Test Results : TV7 settings indicate that 30/30 is minimum good = 750/750 uMhos 'Bogey' = Vintage Tung-Sol Data Sheet (ca. 1946) Average Factory Class A1 (lowest THD) characteristics: Plate Supply Volts applied to Tube under Test 150V 250V NOS center average(Gm) 1,250 uMhos 1,600 uMhos NOSTV7 meter reading: 50 64 NOS TV7 average range 46-53 58-66 (from 12 units tested) Reference Link : Tung-Sol Feb 1946 Engineering Data Sheet JAN 6SU7GTY frank dot pocnet dot net/sheets/127/6/6SU7GTY dot pdf All TV7 versions test at 150VDC Plate Supply maximum : Tubes are inked on the top of the Glass "1,2&3" in removable 'Sharpie' easily removed with water/paper towel or napkin if desired. Notes: These Tung-Sol JAN (CTL) 6SU7GTY's are the Best of the Best High-end Pre-Amp audio tube special versions of the 6SL7GT (70/70 Mu) tube which is the predecessor tube of the more common 12AX7. The Tung-Sol JAN (CTL) 6SU7GTY's were specially factory selected for very tight plate matching for Transconductance(Gm)&mA emissions of 3% or less and were burned in at the factory for > 48 hours before pre-selection. At the factory for the Military Contract lots they placed small square sticker indicating Gm&mA on 2 sides of the base, then QA matched them up and removed the stickers before packing. We just finished testing 12 of these dated from 1945-52 and all have small residue on the bases from the stickers that were removed. We are listing closely matched plate singles and also pairs with matched plates of this tube type. If you need more than follow us on eBay as we are listing all 12. Our Test Bench : TV7D/U Restored, Enhanced & Upgraded( Digital Meter and solid state bridge) Dan Nelson Calibrated( 07/24/2023). Calibration re-verified on 01/06/2024 & on 6/03/2024. Our TV7D/U reads Transconductance(Gm) on a scale of 0-120 (push button #3, for rectifiers button #7). This TV7D/U will read mA plate current emissions directly by depressing Gm button and the red button on the digital meter, We use the last published xls spreadsheet by Nolan Lee to transpose actual TV7 digital meter readings 0-120 into actual Transconductance(Gm) #'s in uMhos based upon the selector switch setting A-F. All versions of TV7's and most Hickok designed tube testers will test tubes at a maximum of 150V Plate Volts and Grid #2 at 130V volts and Control Grid #1 (Bias control) at ranges from 0 to -30Volts. WE PACK VERY WELL AND SHIP FAST TO OVER 100 COUNTRIES WORLDWIDE MANY Years of Experience shipping fragile electronics, speakers and Vacuum Tubes. WE COMBINE SHIPPING US Shipping to All 50 States & US Territories + APO/DPO/FPO/ xPO & PO Boxes International via "Improved" eBay International Shipping Center - low cost space available Air-Freight with full Tracking, Insured Guaranteed Delivery. eBay's international ship partners are USPS International, DHL & Asendia. Allow 10-days to up to 6-weeks for delivery depending upon country of destination. IF YOUR COUNTRY IS LISTED IN THE DROP DOWN BOX IN THE 'SHIPPING, HANDELING' TAB THEN WE SHIP TO YOU. Thank you for looking!