DescriptionThis is a single-stage amplified OTL amplifier with class A single operation using a Darlington connection (so-called Tamarrington connection) between a 421A and a 2SC3857.The circuit is simple enough to memorize and is based on a tamarrington or super three-connection circuit on the Internet with a choke load instead of a transformer. In principle, it is a choke-loaded capacitor output OTL amplifier with 421A as 80 paras! The 421A operates at an RMS plate voltage of 20 V and current of 12 mA, which is about the same as if it were sleeping. The 421A heater is igniting at about 5.8V, the lower rated limit. Maximum output power: 4.9W/10? at the point where the waveform begins to be disturbed, increasing to around 7W as it is.Frequency response: 20 to 20kHz flat 10Hz -1.5db 100kHz -3dbGain: 3.5x VR position usually around 10 oclock becomes around 12 oclockNoise: Not detectable by oscilloscope, silent from SPShipping Fedex,DHL,Japan Post *For FedEx / DHL shipping items, a person residing in the remote area will have to pay an additional shipping fee.International Buyers - Please Note:Import duties, taxes, and charges are not included in the item price or shipping cost. These charges are the buyers responsibility. Please check with your countrys customs office to determine what these additional costs will be prior to bidding or buying. Thank you for your understanding.Read more... Conditions shown here are based on our standard.Please understand that the conditions of used items that have been stored in our warehouse changes by time.Listings that shows Working means that it confirmed working when we stored items in our warehouse, some items might stop working during the shipment or after delivery to you.(We double check if they are working before shipping them out) Pre-owned(used) items are used items, so please purchase if you acknowledge it.