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- Q19599367 subject Q7486881.
- Q19599367 abstract "An acorn tube, or acorn valve, refers to any member of a family of VHF/UHF vacuum tubes starting just before World War II. They were named after their resemblance to the acorn, specifically due to the glass cap at one end of the tube that looked similar to the cap on an acorn. The acorn tubes found widespread use in radios and radar systems.High-frequency performance is limited by (1) parasitic lead inductance and capacitance and skin effect, and (2) electron transit time (the time required to travel from cathode to anode). Transit time effects are complicated, but one simple effect is the phase margin; another one is input conductance, also known as grid loading. At extremely high frequencies, electrons arriving at the grid may become out of phase with those departing towards the anode. This imbalance of charge causes the grid to exhibit a reactance that is much less than its low-frequency "open circuit" characteristic. Acorn- as well as Lighthouse tubes and Nuvistors attempt to minimize this effect by arranging cathode, grid(s) and anode as closely spaced together as possible.The original range included about half a dozen tubes, designed to work in the VHF range. The 955 is a triode. The 954 and 956 types are sharp and remote cut-off pentodes, respectively, all with indirect 6.3 V, 150 mA heaters. Types 957, 958 and 959 are for portable equipment and have 1.25 V NiCd battery heaters. The 957 is a medium-μ signal triode, the 958 is a transmitting triode with dual, paralleled filaments for increased emission, and the 959 is a sharp cut-off pentode like the 954. The 957 and 959 draw 50 mA heater current, the 958 twice as much. In 1942, the 958A with tightened emission specs was introduced after it turned out that 958s with excessively high emission kept working after the filament power was turned off, the filament still sufficiently heating on the anode current alone. After the introduction of the miniature 7-pin base, the 954, 955 and 956 were made available with this base as 9001, 9002 and 9003. Other acorn tubes include:American:EIA: 4671, 4672, 4674, 4675, 4676, 4695, 5731RETMA: 6F4, 6L4European:British: AT4Mullard-Philips: D1C, D2C, D1F, D2F, D3F, D11F, D12F, E1C, E1F, E2FRussian: 6С1Ж, 6Ж1Ж, 6К1ЖLarger, higher-power types such as the 316A, 368A, 388A, and 703A triodes and the 713A and 717A pentodes were referred to as Doorknob tubes.The introduction of the EF50 was the first serious competition for the acorn design, and replaced the acorns in many roles, especially post-war when millions of surplus EF50s were dumped on the market.".
- Q19599367 thumbnail 955ACORN.jpg?width=300.
- Q19599367 wikiPageWikiLink Q11695957.
- Q19599367 wikiPageWikiLink Q152466.
- Q19599367 wikiPageWikiLink Q176129.
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- Q19599367 wikiPageWikiLink Q21994628.
- Q19599367 wikiPageWikiLink Q3363655.
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- Q19599367 wikiPageWikiLink Q362.
- Q19599367 wikiPageWikiLink Q3914781.
- Q19599367 wikiPageWikiLink Q4387510.
- Q19599367 wikiPageWikiLink Q4646000.
- Q19599367 wikiPageWikiLink Q47528.
- Q19599367 wikiPageWikiLink Q628096.
- Q19599367 wikiPageWikiLink Q664150.
- Q19599367 wikiPageWikiLink Q687482.
- Q19599367 wikiPageWikiLink Q6934165.
- Q19599367 wikiPageWikiLink Q7180955.
- Q19599367 wikiPageWikiLink Q7276394.
- Q19599367 wikiPageWikiLink Q7486881.
- Q19599367 wikiPageWikiLink Q898377.
- Q19599367 comment "An acorn tube, or acorn valve, refers to any member of a family of VHF/UHF vacuum tubes starting just before World War II. They were named after their resemblance to the acorn, specifically due to the glass cap at one end of the tube that looked similar to the cap on an acorn.".
- Q19599367 label "Acorn tube".
- Q19599367 depiction 955ACORN.jpg.