The D3a is a special quality frame grid pentode for wideband amplification. The mutual conductance is very high at 35 mA/V. Present day use (2014) is for audio voltage amplification.

Tube D 3a or Röhre D3a ID19218, Vacuum Pentode, Noval, 9 pin miniature (USA pico-9) B9A and RF/IF-Stage shown. Radio tubes are valves.

2009年8月5日 · D3A German Post Office pentode, probably developed in the late 1950s. Good parameters when triode connected. Made by Siemens & Halske as well as by Philips (or might have been a relabel?)

SIEMENS D3a / 7721 Black Plate. High transconductance long-life > 10.000 hours Frame Grid pentode produced for German Post by Siemens. These are triple mica, rare black plate version with gold pins. Can be used in triode connection as a great driver for 2A3 and 300B tubes.

2012年12月20日 · The D3a is a quite modern tube developed for wide band amplifiers for telecommunication applications. It has a nine pin miniature base. The pinout can be seen on the left.

Like the C3m and C3g, the D3a is a relatively modern tube developed for use in telecommunications. Having a nine pin miniature base, the D3A yields linear curves when connected as a triode. Additionally, this tube has a gain factor of 77.

High transconductance long-life > 10.000 hours Frame Grid pentode produced for German Post by Siemens. These are triple mica version with gold pins. Can be used in triode connection as a great driver for 2A3 and 300B tubes.

Siemens D3A goldpin pentode. De D3A van Siemens is een steile indirect verhitte penthode en is ontworpen voor >10.000 branduren in breedband telecommunicatie apparatuur. Een zeer mooie goldpin pentode. NOVAL-voet

1 matched pair) D3a=7721 Siemens Germany NOS 1978 printed in 1980 1 tube) 32.5ma Gm=36,000 1 tube) 33.0ma Gm=36,000 Matched on Amplitrex Vplate=190V Vscreen=160V Vgrid=-1.2V Good NOS Ma = 22-30ma Good NOS Gm = 33,000-35,000

2016年2月8日 · I wonder if there is a equivalent new D3A tube on marked? It´s difficult and expensive to get an original D3A tube. There seemed to be nice NOS 6J52P tubes for which some people say that they are quite near the legendary D3A. I love NOS tubes but it´s not predictable to get them in reliable condition and price.