Mullard ECC83 f91 B8D Long Plate Halo GetterTested good on B&K tester

Mullard ECC83 F91 (2) F91 B8A F91 B81 1.25 / 1.2 amd 1.7 / 1.7 1.2 / 1.25 and 2.1 / 2.1 104%/100% and 106%/106% 100%/104% and 131%/131% (nos/100% = 1.2 and 1.6) Blackburn 1958 Long plate / Halo getter uk onlyuk inlyuk only37

F91 B8F IA 1.2 / 1.2 and GM 1.4 / 1.4 100%/100% and 88%/88% IA 1400 / 1400 and gain 97 / 97 (new is 1.2 and 1.6) Within new range / lightly used.uk onlyuk onlyuk only36

  TUBE HUNTER VACUUM TUBE GEMSTHESE ARE THE SPECIFICS OF THE TUBE/TUBES FOR SALE THESE ARE THE TUBE/TUBES FOR SALE:    MANUFACTURER:                              MULLARD PRODUCTION CITY:                                    ENGLAND TUBE TYPE:   12AX7 COPPER POSTS DESIGNATION:                                              BEST TONE PREAMP YEAR:     1958 MONTH:     SEPTEMBER Date code match    SINGLE SILK SCREEN CONDITION %:                    100% MICA:   2 PLATES:   GREY CURVE TRACER ma: NORMAL = 4.4ma   4.3ma AND 4.2ma AT 200PV AND 0G TRANSCONDUCTANCE: NORMAL=  1600  1560µmhos AND 1530µmhos PERCENTAGE OF BOGEY:                       98% AND 95% SINGLE/PAIR/QUAD/MULTI:   SINGLE GETTER:                                                         O   GETTER DATE CODE                                                    f 9 1    B 8 I THIS TUBE HAS BEEN CURVE TRACER MATCHED. THE CURVES SHOWN IN THE PICTURES ARE OF EACH TRIODE. EXAMINE THE CURVES FOR LINEARITY. THE gm PERCENTAGES IN THE TABLE ARE FROM THE B&K 747B I USED FOR NORMAL TESTING. CURVE TRACER MATCHED!!! TESTING ACCORDING TO DATA SHEETS FOR 12AX7’S ARE AS FOLLOWS: 200 PLATE VOLTS, MARGINAL GOOD 65%: 2.86ma, LOW NOS 85% = 3.74ma, NOS 100% = 4.4ma. THIS TUBE MEASURES: 4.3ma, 4.2ma. Very rare single example of f91 Mullard 12ax7. This tube measures very strong and perfectly matched. This tube will deliver the warmest sound known to man. So sweet and rich, every song in your collection will sound as never before, as you sit right up front. The music surrounds you and you breath it in like a sweet drug. This tube will deliver the goods............I guarantee it ! Normal 0 false false false EN-US X-NONE X-NONE Normal 0 false false false EN-US X-NONE X-NONE I want to see you happy with your purchase. I will never sell a tube that is below standard…… I have sold many tubes here on Ebay, and all my customers have been completely satisfied. I will work with you in good faith if there are any problems, or if you are unsatisfied in any way. I want your business now and in the future, so I assume you are the boss, and I am the employee. All tubes are tested for shorts, continuity, and emissions. I prefer PayPal. ALL CUSTOMERS PLEASE READ ALL NOTES BEFORE BUYING FROM ME !!1.  RETURNS: It is my highest desire that you are completely satisfied with your purchase from me. I will bend over backwards to make sure that you are a happy customer.If anything you buy from me is less than satisfactory, message me BEFORE you either open a case or hit the “item not as described” button.Sound quality is tremendously SUBJECTIVE. For tubes returned for noise or sound quality of any kind you pay for the shipping we refund the purchase. We refund the price of the item NOT THE SHIPPING COST. If we sent the wrong tube we will of course pay for return shipping. For any tubes that are DOA we require that you send a us a picture of the shipping box to show us the damage. We test EVERY tube sent out and none should be DOA unless broken in shipping.2.    PLEASE NOTE:  Tube silkscreen (lettering on the tubes) is VERY fragile. It can be wiped off and destroyed VERY easily. If you wipe off the silkscreen while handling the tube you diminish their value by up to 70%. DO NOT handle the tubes or hold them from the cylinder. ALWAYS hold them from the ENDS. If you are returning tubes and they are not in the same condition cosmetically I cannot give you a full refund. THIS IS VERY IMPORTANT.3.  UNLESS YOU MAKE ARRANGEMENTS WITH US BEFORE YOU PURCHASE, YOU MUST PAY FOR ITEMS PURCHASED WITHIN 2 DAYS OR A CASE WILL BE OPENED FOR AN UNPAID ITEM!!!4. TESTING: I test all tubes that I sell in one way or another, or I will state untested. I have a B&K 747 tube tester. This is a mutual conductance tester. It give a percentage value of gm for the tube under test and checks for shorts and grid emissions. I also use a Tektronix curve tracer for testing triodes. I give a number of evaluations for tubes. One evaluation is a screen shot of the tube with a high voltage applied to the plate. This helps the buyer see the linearity of the tube in question at the highest voltage the tube will see in a real circuit. The Curve tracer steps the triode through 10 gate/grid voltages starting with -10 volts and going to 0 volts. The lines show how the tube conducts throughout that range. At 0 volt the tube is at max conduction and is the top line on the display. It is easy at that point to take where that top line intersects the plate voltage, find the milliamp level and compare it to the datasheet. I give those numbers for you in the Item condition box. To further help the buyer I also include the Design values, for gm and ma readings in the table. This can then be compared to other tube sellers using inferior test methods such as Hickok,  Amplitrex, and other testers. The Tektronix curve tracer gives values within 3% of the actual value. The very best portable testers only can approach 10% accuracy.5.    Please note: The numbers given for gm are what I see on my tester. I DO NOT guarantee that you will see those numbers on your tester. I only guarantee that these tubes will test good, with no shorts, or gas, on a decent calibrated tester. I dont guarantee or imply anything else.6. VERY IMPORTANT!!! Vintage tube testers almost always, due to age, have VERY LOW HEATER VOLTAGES!!!  Every tester I have ever bought is below 6 volts when selecting 6.3 volts. They average 5.8 volts. The voltage NEEDS to be 6.3 and 12.6. You can calibrate a vintage tube tester all you want. If the heater voltage is not right, you will NEVER get the right gm value. I have customers complain that their tubes are not the same as what I see on my tester. They say they have a calibrated tube tester. I have 40 tube testers. On all of them I have an outside regulated DC power supply that feeds the tube tester the correct heater voltage.7. I dont check each and every tube for noise or tone. This is SUBJECTIVE and it is too time consuming. If you dont like the noise level or the tone we offer a hassle free refund policy.  International customers note:1. Please wait for us to invoice you for the correct amount. If you have purchased more than one item, we must calculate how much the shipping will be. Shipping will be HIGHER due to insurance and shipping methods needed for expensive item totals. If you are buying only one item this will not be an issue. 2. Under no circumstances will we state on a US customs a declared value of less than the sale price. This is an honesty issue. We are honest with everyone to the best of our ability to do so. We want you to trust that what we say is true. There cannot be that trust, if we make false statements knowingly to anyone. If your country has tariffs/taxes so high that they cause large numbers of normally honest folks to make false statements, we urge you to work for change of those laws.3 International buyers if you bought more than one item and want combined shipping it will ship in 2 days.4. And all the Angels sang because the heavenly music was playing and it was turned all the way up.    Listing and template services provided by inkFrog

Mullard12AX7/ECC83Long PlateSquare GetterMade in England. Date Code: f91 B7FMade in June 1957 in Blackburn England. Fully tested by calibrated Hickok 539C tube testerwith no shorts, leakage or gas. Measurement: 1300/1680where minimum good value is 875 Tested in my preamplifier to make sure working as intended with no issues at all. I will gladly combine shipping upon request. __________ The tube(s) in this sale include a 30-day satisfaction guarantee.I strive to ensure you have a completely satisfactory purchase experience.If you are unhappy with your purchase for any reason,you can return the item for a full refund. Please contact me directly prior to opening a return or leaving feedback.I will almost always reply at least within 24 hours to remedy the situation for you with direct communication.