I've used the 6N1P with some success - it's not exactly a drop-in replacement but as a driver or phase splitter I've had success with it. It does need 600mA of 6.3 volt though, and of course with the Russian twin triodes, the usual caveat about the filament pinout applies. Also pin 9 (centre filament tap on 12AU7) connects to a shield between the internal triodes, ground it, else you can get some parasitic oscillations (so I was told once, though I've never seen it myself)
Yeah. In 1967 an Irakian MiG-21 pilot deserted and flew his plane to Israel where it was examined thoroughly. Mossad found out that the whole onboard electronics was based on hundreds of rod tubes.
Best regards!
Still, it was an urban legend. New Mig-25 in 1976 were already with solid state electronics.
Viktor Belenko - Wikipedia
"Western intelligence and the MiG-25:
MiG-25RBSh with markings of 2nd Sqn/47th GvORAP (Guards independent recce Regiment)
Inaccurate intelligence analysis caused the West initially to believe the MiG-25 was an agile air-combat fighter rather than an interceptor. In response, the United States started a new program which resulted in the McDonnell Douglas F-15 Eagle.[29] NATO obtained a better understanding of the MiG-25's capabilities on 6 September 1976, when a Soviet Air Defence Forces pilot, Lt. Viktor Belenko, defected, landing his MiG-25P at Hakodate Airport in Japan.[30][31] The pilot overshot the runway on landing and damaged the front landing gear. Despite Soviet protests, the Japanese invited U.S. Air Force personnel to investigate the aircraft.[32] On 25 September, it was moved by a C-5A transport to a base in central Japan, where it was carefully dismantled and analyzed.[33] After 67 days, the aircraft was returned by ship to the Soviets, in pieces.[34][35] The aircraft was reassembled and is now on display at the Sokol plant in Nizhny Novgorod.
The analysis, based on technical manuals and ground tests of its engines and avionics, revealed unusual technical information:
Belenko's particular aircraft was brand new, representing the latest Soviet technology.
The aircraft was assembled quickly and was essentially built around its massive Tumansky R-15(B) turbojets.
Welding was done by hand. Rivets with non-flush heads were used in areas that would not cause adverse aerodynamic drag.[36]
The aircraft was built of a nickel-steel alloy and not titanium as was assumed (although some titanium was used in heat-critical areas). The steel construction contributed to the craft's high 29,000 kg (64,000 lb) unarmed weight.
Maximum acceleration (g-load) rating was just 2.2 g (21.6 m/s²) with full fuel tanks, with an absolute limit of 4.5 g (44.1 m/s²). One MiG-25 withstood an inadvertent 11.5 g (112.8 m/s²) pull during low-altitude dogfight training, but the resulting deformation damaged the airframe beyond repair.[37]
Combat radius was 299 kilometres (186 mi), and maximum range on internal fuel (at subsonic speeds) was only 1,197 kilometres (744 mi) at low altitude (< 1000 metres).[11]
The airspeed indicator was redlined at Mach 2.8, with typical intercept speeds near Mach 2.5 in order to extend the service life of the engines.[30] A MiG-25 was tracked flying over Sinai at Mach 3.2 in the early 1970s, but the flight led to the engines being damaged beyond repair.[36]
The majority of the on-board avionics were based on vacuum-tube technology, not solid-state electronics. Although they represented aging technology, vacuum tubes were more tolerant of temperature extremes, thereby removing the need for environmental controls in the avionics bays. With the use of vacuum tubes, the MiG-25P's original Smerch-A (Tornado, NATO reporting name "Foxfire") radar had enormous power – about 600 kilowatts. As with most Soviet aircraft, the MiG-25 was designed to be as robust as possible. The use of vacuum tubes also made the aircraft's systems resistant to an electromagnetic pulse, for example after a nuclear blast.[38]
Later versions:
RP-25 (Smerch A-4) radar based on vacuum tube electronics, for early MiG-25P. RP-25MN (Saphir-25) radar based on semiconductor electronics, for later MiG-25PD
As the result of Belenko's defection and the compromise of the MiG-25P's radar and missile systems, beginning in 1976, the Soviets started to develop an advanced version, the MiG-25PD ("Foxbat-E").[11]
Plans for a new aircraft to develop the MiG-25's potential to go faster than the in-service limit of Mach 2.8 were designed as a flying prototype. Unofficially designated MiG-25M, it had new powerful engines R15BF2-300, improved radar, and missiles. This work never resulted in a machine for series production, as the coming MiG-31 showed more promise.[11]"
Mikoyan-Gurevich MiG-25 - Wikipedia
MiG-25RBSh with markings of 2nd Sqn/47th GvORAP (Guards independent recce Regiment)
Inaccurate intelligence analysis caused the West initially to believe the MiG-25 was an agile air-combat fighter rather than an interceptor. In response, the United States started a new program which resulted in the McDonnell Douglas F-15 Eagle.[29] NATO obtained a better understanding of the MiG-25's capabilities on 6 September 1976, when a Soviet Air Defence Forces pilot, Lt. Viktor Belenko, defected, landing his MiG-25P at Hakodate Airport in Japan.[30][31] The pilot overshot the runway on landing and damaged the front landing gear. Despite Soviet protests, the Japanese invited U.S. Air Force personnel to investigate the aircraft.[32] On 25 September, it was moved by a C-5A transport to a base in central Japan, where it was carefully dismantled and analyzed.[33] After 67 days, the aircraft was returned by ship to the Soviets, in pieces.[34][35] The aircraft was reassembled and is now on display at the Sokol plant in Nizhny Novgorod.
The analysis, based on technical manuals and ground tests of its engines and avionics, revealed unusual technical information:
Belenko's particular aircraft was brand new, representing the latest Soviet technology.
The aircraft was assembled quickly and was essentially built around its massive Tumansky R-15(B) turbojets.
Welding was done by hand. Rivets with non-flush heads were used in areas that would not cause adverse aerodynamic drag.[36]
The aircraft was built of a nickel-steel alloy and not titanium as was assumed (although some titanium was used in heat-critical areas). The steel construction contributed to the craft's high 29,000 kg (64,000 lb) unarmed weight.
Maximum acceleration (g-load) rating was just 2.2 g (21.6 m/s²) with full fuel tanks, with an absolute limit of 4.5 g (44.1 m/s²). One MiG-25 withstood an inadvertent 11.5 g (112.8 m/s²) pull during low-altitude dogfight training, but the resulting deformation damaged the airframe beyond repair.[37]
Combat radius was 299 kilometres (186 mi), and maximum range on internal fuel (at subsonic speeds) was only 1,197 kilometres (744 mi) at low altitude (< 1000 metres).[11]
The airspeed indicator was redlined at Mach 2.8, with typical intercept speeds near Mach 2.5 in order to extend the service life of the engines.[30] A MiG-25 was tracked flying over Sinai at Mach 3.2 in the early 1970s, but the flight led to the engines being damaged beyond repair.[36]
The majority of the on-board avionics were based on vacuum-tube technology, not solid-state electronics. Although they represented aging technology, vacuum tubes were more tolerant of temperature extremes, thereby removing the need for environmental controls in the avionics bays. With the use of vacuum tubes, the MiG-25P's original Smerch-A (Tornado, NATO reporting name "Foxfire") radar had enormous power – about 600 kilowatts. As with most Soviet aircraft, the MiG-25 was designed to be as robust as possible. The use of vacuum tubes also made the aircraft's systems resistant to an electromagnetic pulse, for example after a nuclear blast.[38]
Later versions:
RP-25 (Smerch A-4) radar based on vacuum tube electronics, for early MiG-25P. RP-25MN (Saphir-25) radar based on semiconductor electronics, for later MiG-25PD
As the result of Belenko's defection and the compromise of the MiG-25P's radar and missile systems, beginning in 1976, the Soviets started to develop an advanced version, the MiG-25PD ("Foxbat-E").[11]
Plans for a new aircraft to develop the MiG-25's potential to go faster than the in-service limit of Mach 2.8 were designed as a flying prototype. Unofficially designated MiG-25M, it had new powerful engines R15BF2-300, improved radar, and missiles. This work never resulted in a machine for series production, as the coming MiG-31 showed more promise.[11]"
Mikoyan-Gurevich MiG-25 - Wikipedia
We were told by one officer in our university (we had parallel military education) that the machine that Belekno stole was new and supposed to contain new state of the art solid state electronics, but the plant was out of schedule so some old vacuum tube equipment was installed. Not all of it, but some.
However, the legend about "Withstand nuclear blast" sounds nice, but what do you think of a plane that contain a mix of solid state and vacuum tube electronics, does it sound right about "withstanding nuclear blast"?
Last edited:
So, this would support the statement that the onboard electronics was completely based on tubes, wouldn't it?
Best regards!
In Mig-21 it was all based on tubes. In later Mig-25 it was all solid state. Mixed between that. Slow steady upgrade. The main obstacle was not to design new electronics. The main obstacle was to get all needed approvals to do that. It was real PITA in USSR. The system of approvals kept electronics in USSR behind.
6N2P is the only tube that replaces a 12AX7 as far as I know.
Same reason I use them - 12AX7 isn't as good IMHO.
Tube Tester Files - 6N2P - 6H2P
Tube Tester Files - 12AX7WB Sovtek
Same reason I use them - 12AX7 isn't as good IMHO.
Tube Tester Files - 6N2P - 6H2P
Tube Tester Files - 12AX7WB Sovtek
Attachments
Last edited:
TBH I don't know. 6N5P and 6N1P work the same in the same circuit though but I heard the 6N5P was designed for RF.
Tube Tester Files - 6N1P - 6H1?
Tube Tester Files - 6N5P
On the other hand, 6N5S and 6N13S appears to be a 6AG7G and I can't find a difference in the datasheets for 6N13S / 6N5S.
I am using a pair of 6N5P as the output buffers in my phono stage (along with a pair of 6N2P and 2 pair of 6N1P (6N3 in a different version)).
Tube Tester Files - 6N1P - 6H1?
Tube Tester Files - 6N5P
On the other hand, 6N5S and 6N13S appears to be a 6AG7G and I can't find a difference in the datasheets for 6N13S / 6N5S.
I am using a pair of 6N5P as the output buffers in my phono stage (along with a pair of 6N2P and 2 pair of 6N1P (6N3 in a different version)).
Last edited: