Don't forget that the whole '7xxx' series are 6.3-volt filament tubes with "loctal" bases, and that the '14xxx' series is similar with
12.6-volt filaments.
Confused a bit by metal tube nomenclature, where the can (the shield) was grounded through a pin, which was counted as an electron -- so a
6SK7 is a pentode with heater, cathode, three grids, plate, and shield.
So the 6V6 is a beam tetrode (heater, cathode, two grids, plate and shield), while the 6AQ5 is the _exact same innards_ put into a glass envelope, with the loss of the shield 'electrode'.
I read somewhere that the designer was often free to pick unclaimed letter pairs, so initials would sometimes creep in there. Where it made marketing sense (for instance the whole '6S' line of metal-can octal pin tubes with special shielded bases) the company involved would push a system.
Some heptodes for HF service were pentagrid mixers, designed with the intent that you would use an external mixer (to help prevent mixer pulling with a strong received signal close to the local oscillator frequency).
--
Tim Wescott
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Why? They are 6.3 volts, just like the 6 series. The 7 & 14 were chosen to signify that they were Loctal based, which was expected to replace the Octal series. They cost more, and soon displayed problems with the smaller pins and the problems of some tubes seizing the locking pin so tightly that they couldn't be removed without damaging the tube & the socket. Spare locatal tubes are easy to find. Unused sockets are rare.
--
For the last time: I am not a mad scientist, I'm just a very ticked off
scientist!!!
I don't think that's it. 6V6 has no shield, nor a need of one. The EIA basing diagram 7AC shows pin 1 is "S/NC", which I've never seen used as anything but a tie point. The pin is usually missing from the tube base.
I guess octals often had plus one. Example: 6X4, a dual indirectly heated power rectifier for radios. 7 pin miniature. The octal was 6X5. Or 6C4, which is a lone 12AU7 triode in 7 pin mini. Octal 6C5.
Supposedly, the letters were assigned more-or-less sequentially. As you go through TV history, you'll see deflection tubes like 6BG6, then 6BQ6, then 6DQ6, then 6LZ6, then...
Rectifiers seem to go the opposite direction sometimes. There's a bunch towards the alphabetical end of the series, like 6X4, 5Y3, 1X2, etc. But there's also 3A3, 6AX4, etc.
There were also numbered designations (e.g., 7199), which I don't know if they had any rules at all. I wouldn't be surprised if ranges were reserved by manufacturers, or by series.
Finally, a new system was invented, the electrode number - letter type - identifier number scheme, from which we have tubes like 2C53 and 2E26, and semiconductors like 1N60, 2N3904 and 4N25.
Tim
--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms
The "RCA Receiving Tube Manual: Technical Series RC-19", RCA 1959, clearly denotes pin 1 of a 6V6 as a shield.
Whether the shield was necessary or not, the folks that came up with the metal octal tubes were publicly quite proud of the "shielding" provided. So I wouldn't be at all surprised if that's not why it seems to be called out.
Supposedly -- but how does that explain the whole "6Sxx" metal tube series, which are functional replacements for the "6xx" series of top-cap metal tubes except for RCA's much-ballyhoo'd special base shielding? The fact that RCA got those "6Sxx" numbers (and the apparent violation of the "number of elements" rule for metal tubes) certainly seems to indicate that the manufacturers had quite a bit of latitude in choosing what numbers they could use.
I know that originally there were no rules at all. In fact, the _really_ old tubes like RCA's 201, 210, 224, etc. were quickly copied by other tube manufacturers -- so one company's "UT-10" would be another company's "310" would be RCA's "210". I know that amateur radio operators (and probably the industry) started referring to them as "type
10", "type 45", "type 24", etc. Certainly by the time my 1940 RCA tube manual came out that's how they were referenced.
I think by the time the four-digit numbers were coming out, there was some sort of a system where you could reserve numbers either from the EIA or from JAN.
I know the semiconductor numbers are JAN (Joint Army-Navy) specifications. I don't know if they were shadowed by the EIA, or not.
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at http://www.wescottdesign.com/actfes/actfes.html
The 6AQ5 is in a 7-pin miniature envelope and has lower ratings than the
6V6. The glass envelope equivalent of the 6V6 is the 6V6G.
My RCA Tube Handbook, May 1, 1942, shows: Pin1-6V6 Shell, 6V6-GT-G No. Con. The 6L6 is the same except there's no
6L6-GT.
I built my first oscilloscope in 1942 using a 913. This is a one inch electrostatic deflection CRT. It looks like a 6V6 with a glass screen at the end. The data sheet is dated Jan. 30, 1942, and shows a schematic for an elementary scope.
According to the 1953 ARRL Handbook, the _innards_ of the 6AQ5 are the same as the _innards_ of the 6L6. I didn't say they had the same rating, I didn't say the 6AQ5 was the glass equivalent tube, I didn't say you could plug either of them into the same place, I didn't make _any_ of the statements that you are imagining that I made so that you could contradict them. I said that the _inner assembly_ was the same. Not the _outer assembly_. Not the pins. Not the envelope. Etc.
The earlier tube references to the 6AQ5 says "all ratings the same except power dissipation and maximum voltage", both of which are functions of the smaller envelope, but not necessarily a function of what's inside it. To me, that's certainly consistent with the 6AQ5 being the same mechanical assembly as the 6V6 _on the inside_, only put into a 7-pin miniature (yes, I know the 6AQ5 is a 7-pin miniature tube) envelope instead of a metal octal (yes, I know that the 6V6 is a metal octal tube) or a glass octal (yes, I know that both the 6V6-G and 6V6-GT were glass octal tubes).
So, do you know for sure that the early references that I'm going on were incorrect about the _inside part_ of the tubes being the same?
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at http://www.wescottdesign.com/actfes/actfes.html
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