VR101 (VR101)
VR101 (VR101)
Dear Radio Friends,
just a few words about this seemingly quite
ordinary octal based double-diode-triode, developed by Marconi-
Osram in U/K, seemingly just prior to WW2, mainly for military
use,- indeed, the only application I'm aware of was as audio o/p,
plus a second one as B.F.O., in the well known R1155 receiver
used by the R.A.F. for many purposes during (and after) that war.
Further investigation reveals, however, that this valve appears to
have no direct equivalent, and was basically known as the type
MHLD6, later given the R.A.F. no. VR101 & later CV1101.
The only characteristics I've discovered (official Air Ministry) are -
Anode volts ------200v. Diode 1 test 0.8 mA.
Anode current----11.5 mA. Diode 2 test 3.5 mA.
Grid bias --------- -5v.
Gm.---------------3mA/v.
Heater ----------- 6.3v. @ 0.65A.
The triode appears to be low impedance, and for some reason one
diode bigger than the other; if anyone has more complete figures
or facts about this valve I'd be grateful to see them.
Regards, John Turrill.
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Jeremy.
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I dont have some characteristics to the VR101/CV1001.
But I have short datas from the MHLD6:
MOV, amplifier triode withs two diodes. common cathode.
Octal: shield, f, p, diode1, diode2, nc., f, c. Cap = grid
filament: 6,3V and 0,65 mA
plate: 200V and 3,8 mA
Grid: -3V
Ra: 18200 Ohms
gm: 2,2 mA/V
amplification factor: 40
cathode resistance: 800 Ohms
From the diodes there are no datas listed.
Source: Babani, International radio tube encyclopedia, last edition 1958, 1. supplement
Best regards, Hans-Thomas
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many thanks for your help, in actual fact, I
should have mentioned I had seen the data in the Babani book,
but the figures don't seem to make sense!
I know the figures I quoted to be correct,- that is, 200v. on the
anode with -5v. bias gives 11.5mA anode current & 3mA/v. - as
this is from an official R.A.F. data sheet; sounds like the same one
Jeremy has, and thanks for that also Jeremy. (if you've looked down
inside the valve - difficult!-, you can just see the 1st. diode, with
the second, smaller one just below that).
As if to prove a point, testing a new valve at -3v. bias yields an
anode current of about 25mA, so I have to assume Babani isn't
correct (unusually).
I've searched the web and all the books I can find, but I'm
beginning to wonder if there is any further information!
Thanks, John.
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here are another datas from the MHLD6 from Osram:
Triode, duodiode
Octal: nc., f, d1, d2, p, nc., f, k
filament: 6,3 V and 0,65 mA
plate: 250 V and 11,5 mA
gm: 3 mA/V
from Prehled Elektronek, 1954
-------------------------------
VR101 = MHLD6
octal same like in my first post
triode-duodiode
f: 6,3 V and 0,65 mA
p: 200 V and 11 mA
g: -5 V
from Röhrencodex 1951
Best regards, Hans-Thomas
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thanks again for this information, which seems
to confirm all my previous data, and that, in this, the Babani is
surely wrong. I find this a little worrying,- makes you wonder if
any other data is wrong, too, in those books - though mostly you
can cross-check with other sources, so far I've not found any
other doubtful figures.
As you mention Osram, am I right in thinking this is an original
German firm? - and if so, I'm wondering how and in what way they
came to be associated with the British Marconi firm?
Regards, John.
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the blue Babani book is one of the best I had ever seen. But it is very difficult to get them. My issue I have found it in Canada and it was not cheap. I have seen it firstly in the library of the Deutsches Museum in munich and it is a must for tube collectors.
The Osram was a light bulb manufacture leaded by Siemens. At beginning of the last century they produced bulbs in several countries, so eg. in England. Osram started at 1906. The name is a abbreviation from Osmium and Wolfram (tungsten), two important metals for bulb manufacturing. In WWI the british Osram was occupied and they start to produce early tubes.
Best regards, Hans-Thomas
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Dear Hans-Thomas,
thanks again; I think I've seen the Babani
book you mean, pretty sure an old friend of mine had one, was
hoping I might persuade him to part with it, but never did!
The ones I have are a "A Comprehensive Radio Valve Guide",
books 1 to 5. (reprints).
Now you've completed my education regarding Osram, I was
never sure of that situation, thanks for the information.
Best regards, John.
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