One Hickok Tested NOS 12D4 12D4A 12D4GT Vacuum Tube

You are purchasing ONE of our tested NOS 12D4 vacuum tubes. Tubes are in their original boxes, which are in fair to good condition. The picture is of one of our available tubes and may not be the tube you receive. This is our new Test on Demand sm tube service. What does this mean? Once you buy one of these NOS vacuum tubes, we will pull it from our extensive inventory. We will test the tube to our normal, exacting standards. We will be able to make available to you many more types and quantities of our NOS tube inventory at one time, and test each tube before we ship it, keeping costs to a minimum. You receive our quality NOS tubes as quickly and at the best price possible. The Item Description describes what brands we have in stock for this tube type. You can specify a preference; however, sometimes we may not have your brand preference available due to previous purchases. In this case we will email you to let you know. We have a large buffer stock on hand, but on very rare occasions we may not be able to find a tube in our remaining NOS stock that meets our critical tests. If this happens we will refund you the total purchase price including shipping costs. We provide test results with each Test on Demand sm NOS vacuum tube we ship, including Hickok 539 minimum value/s as well as the manufacturer’s range/s where possible. If this tube is not what you are looking for, please look at the other tubes we have in our store you can search on the type number. When searching our store please do not use the tube type suffix. For example 6SN7 instead of 6SN7GT due to limitations on eBay’s search engine. How we test our tubes: Before we ship a Test on Demand sm NOS vacuum tube, each tube is fully tested on our calibrated Hickok 539C tube tester. Every tube is tested for shorts using our Hickok 539C Ohm-meter. We don’t neon test for shorts, as it isn’t a sensitive enough test. We test the tubes for shorts hot and cold to 50MOhms. All tubes are gas leak tested to ensure the reliable performance of the tube. We test all tubes for mutual conductance (sometimes referred to as trans-conductance) including each section, if applicable. Hickok 539C provides a minimum acceptable mutual conductance. We will not sell tubes that meet these minimums. Most tube manufacturers provide new tube mutual conductance range(s), and we test to these range(s). We also life test every tube. This is a test where the filament voltage is reduced by 10%, which gives an indication of the future performance of the tube. We discard any tube that does not meet the life test. If any test results in failure for shorts, leaks or open filaments, we discard the tube, and will never ship it. Tube and box condition: Some of our tubes come with original boxes. If a Test on Demand sm NOS tube description does not indicate the tube is packed in its original box, it will be packed in a new, standard white box. If a Test on Demand sm NOS tube has an original box, we will also describe its condition, as often the box is just as interesting and collectable as the tube itself. If any Test on Demand sm NOS tube has an original box in poor condition and we pack it in a new standard white box, we will give you the original box as well. Since we open all boxes to test them, sometimes the box flaps or tabs are damaged and we will note this in the description of the tube. All Test on Demand sm NOS tubes will include the tube’s test results. Our simple warranty: We believe each tube should have an appropriate warranty, regardless if it is used, NOS or NIB, we do not sell as-is. If you are not delighted with your purchase, let us know and we will authorize the return of the tube. We may be able to provide another tube from our large inventory – your choice. To improve our quality, we would like to understand the reason for the return, but it is not a requirement. Returns must include the original box in the same condition (if applicable), and be packed in the original packaging. Purchaser must pay return shipping fees. When we receive the return, we will refund your purchase price (excluding original shipping fees) within 72 hours. We want you to be happy with your purchase, and will work with you if you have any concerns or problems. Please contact us to work out a mutually beneficial solution before writing negative feedback. About us: We have a collective 40+ years of experience in electronics and vacuum tubes. We have professional credentials and qualification in electronics and testing. Our staff has designed a significant number of vacuum tube-based equipment. It is not only our business, but also our hobby to design and refurbish vacuum tube equipment. Our supply of tubes: We buy all of our tubes from reliable sources and are always on the look out for quality tubes and tube suppliers. Special thanks to Frank Philipse (whose web site is tubedata.org) and other host sites of vacuum tube data. These are wonderful sites full of PDF specifications of vacuum tubes, we get our data from them.