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 Post subject: Subminiature 8-pin tubes - any use?
PostPosted: May Thu 09, 2019 7:34 pm 
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There are a number of 8-pin subminiature tubes in the RCA tube manual, mostly for 1.4-volt battery operation. The dawn of the transistor radio put these tubes into obsolescence soon after they were released, I am sure. Is there any use for any of these types for replacing 7-pin miniature tubes for experimental purposes? I was just wondering... These are types 1AC5, 1AD4, 1C8, 1D3, 1E8, 1Q6, 1S6, 1T6, 1V5, and 1W5, just for reference...


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 Post subject: Re: Subminiature 8-pin tubes - any use?
PostPosted: May Thu 09, 2019 10:24 pm 
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Being they are one volt tubes, you might cross some of them to use in something like a tube portable that uses DC filament tubes. Well maybe except for the audio output. See this site: http://www.wa2ise.com/netcom/WA2ISE%20s ... 0page.html As far as I know, they are good for projects. Can be used in alot of projects like simple regen radios, audio preamps, stuff like that. I am sure you could build a sophisticated superhet radio with them, too. I think I have seen plans for basic AA5 type stuff, but not for fancier radios. As far as direct cross reference, I doubt it due to the drastically different physical specs but maybe you could compare and get close enough to allow use with some circuit tweeking. Then there are tons of Russian subminis for really cheap. Good luck with those. Some sites have the specs but who knows how accurate? I am sure they must have been a Soviet secret at one time. Some of the tube manual entries give basic info like audio amplifier stages with component values. I have a box full of subminis here. I have a half dozen of the 6112 dual hi mu triodes and the manual entry shows basic voltage audio amp configurations for that tube.

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 Post subject: Re: Subminiature 8-pin tubes - any use?
PostPosted: May Fri 10, 2019 2:12 pm 
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Well, okay, it seems like these could be interesting. I was thinking about building portable AM transmitters and AF signal tracing amps just for fun. Maybe installing some below the chassis deck on 1.5-volt battery parts sets, just for kicks. I have used 5676's to sub for the WD-11 tube in my RCA Radiola X "Regenoflex", and they work well there. We'll see what happens. I don't imagine these tubes are common, since most of them went into industrial/military gear; only a few home radios used them, some alongside the newcomer transistor...


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 Post subject: Re: Subminiature 8-pin tubes - any use?
PostPosted: May Fri 10, 2019 5:43 pm 
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Zenith introduced some subminis around 1939, I think, for use first in hearing aids.

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 Post subject: Re: Subminiature 8-pin tubes - any use?
PostPosted: May Fri 10, 2019 6:46 pm 
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Motorola, Emerson, and probably a few other companies made battery and "3-Way" portable radios which used subminiature tubes, so those tubes do have some small value for replacements. RCA made a series of receivers for the Navy--the SRR and FRR-11, 12, and 13 which used six-volt versions of those tubes. They were nice receivers but no match for the R-390 or R-390A. Subminiature tubes also went into various other kinds of communications equipment such as RTTY converters, computer logic boards and even some things like HV rectifiers in certain oscilloscopes.

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 Post subject: Re: Subminiature 8-pin tubes - any use?
PostPosted: May Fri 10, 2019 9:57 pm 
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I've seen a number of simple radio projects using subminiature tubes. Here's one for example:
http://makearadio.com/tube/6418.php


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 Post subject: Re: Subminiature 8-pin tubes - any use?
PostPosted: May Wed 15, 2019 5:09 pm 
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I do not recall the types used, but PRI used them in some Geiger counters.


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 Post subject: Re: Subminiature 8-pin tubes - any use?
PostPosted: May Wed 15, 2019 5:14 pm 
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They make good targets for the pellet rifle.

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 Post subject: Re: Subminiature 8-pin tubes - any use?
PostPosted: May Tue 21, 2019 12:05 am 
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You could build a headphone amp with tubes. This kit looks like a lot of fun using 6418s albeit shipping from Down Under is a bit steep for one. Price + shipping on 3 kits is much better per unit, I’d just have to find a couple of kit buddies.

http://oatleyelectronics.com//product_info.php?products_id=1168&osCsid=rpbqknopkn2j4g2v80agrvopo6

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Paul

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 Post subject: Re: Subminiature 8-pin tubes - any use?
PostPosted: Jun Fri 28, 2019 2:56 am 
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The most commonly used subminis for commercial use were the 1V6 converter, 1AH4 IF (and sometimes RF) amp, 1AJ5 detector/AVC/AF amp, and 1AG4 output.

Example: Emerson 747 (schematic also in Sams 234-8) :arrow: https://www.radiomuseum.org/r/emerson_747.html


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 Post subject: Re: Subminiature 8-pin tubes - any use?
PostPosted: Jun Fri 28, 2019 5:24 am 
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Almost all of the subminiature tubes ever manufactured were made to be shot up in the air. The quantities were so large as to swamp all other applications.

Ted


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 Post subject: Re: Subminiature 8-pin tubes - any use?
PostPosted: Jun Fri 28, 2019 12:00 pm 
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Yes, they were used for proximity fuses in artillery projectiles. Also used in weather balloons for data transmission. Lots of uses for them, although they were short lived, and went the way of the flint lock, when transistors hit the market.

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 Post subject: Re: Subminiature 8-pin tubes - any use?
PostPosted: Jun Sat 29, 2019 3:29 am 
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I always wondered what I am gonna do with the ones I have accumulated. The smallest ones I think, are some tiny tetrodes that might be Russian. I have not seen any ham radio projects with them like receivers, although I would have thought that someone would have made a project for a portable receiver or transceiver before transistors took hold real well. I thought that some of the prox fuses showed up in surplus or for sale but I suspect that being militaria collectibles the prices might be outrageous. Would be fun to have one.

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 Post subject: Re: Subminiature 8-pin tubes - any use?
PostPosted: Jun Sat 29, 2019 4:11 am 
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While everybody seems to be aware of their use in proximity fuses they were originally developed by Raytheon for hearing aids.


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 Post subject: Re: Subminiature 8-pin tubes - any use?
PostPosted: Jun Sat 29, 2019 10:19 am 
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Greetings to Chuck and the Forum:

Both Motorola and GE used these tubes in their "draggie-talkies".... brief case sized portable 2 way FM VHF radios from the 1950's and early 1960's. If you are into restoring any of these critters, a supply of those tubes would be good to have.

Regards,

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 Post subject: Re: Subminiature 8-pin tubes - any use?
PostPosted: Jun Sat 29, 2019 1:20 pm 
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Location: St. Louis, MO, USA
Back in my B-52 navigator days, we had a radar set that used a rack of discrete amplifiers about the size of a beer can. They had these subminiture tubes in them-6volters as I recall. These amps ran so hot they caused blisters if removed without gloves. There were spares in case of failures. I remember replacing them while flying low level missions while being thrown about the cabin.

Dennis


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 Post subject: Re: Subminiature 8-pin tubes - any use?
PostPosted: Jun Sat 29, 2019 1:45 pm 
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My nephew got a commission and is now training to be a buff nav and weapons officer. He does not seem to be shocked by the age of the airframes. I have sent him links to old 50s movies about the plane. But he seems to like the atmosphere and morale of the crews that are flying them. I guess it is probably different from when they were purely strategic.

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 Post subject: Re: Subminiature 8-pin tubes - any use?
PostPosted: Jun Sat 29, 2019 2:27 pm 
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Location: Pennsville, NJ 08070
Motorola made a neat little battery powered radio called the "Pixie," about the size of the early transistor radios that came after. They're hot little sets, I own two and love them. The Pixie (Motorola's model designation for them was 45P1 and mine is presumably the later 45P2) uses one standard miniature tube, a 1R5, as the local oscillator/converter tube, the rest are all subminiatures. I can still get the 45 volt "B" batteries, though many I have heard make their own.

They have good sound and perform quite well in spite their small size.

Another use, is the 5678 subminiature tube, which with a couple additional discrete parts can be made to be a near perfect sub for the 1U4. See http://www.walkingitaly.com/radio/RADIO ... BMINI.HTML

I have followed the directions, and for portables with lower B voltage (that use 67.5 volt "B" batteries instead of 90V), I found the design works just fine if you omit the 47K ohm resistor in their plans. True we have plenty of 1U4 tubes, but the 5678 mod works just as well and does seem to have a little more gain than the 1U4 does. I have them in a couple of my lunchbox portables and after a couple years' regular use, I have seen no evidence these subminiature tubes are short lived.



My $0.02,
Joe


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 Post subject: Re: Subminiature 8-pin tubes - any use?
PostPosted: Jul Fri 12, 2019 5:01 am 
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I suppose peanuts are another "twilight" tube, along with Nuvistors. I have a General Radio 1551-B DB meter that uses two CK6418 and four CK512AX peanut tubes plus one transistor.

I have one Nuvistor knocking around in my parts drawers.

jdivito, I'd love to see a pic of your 45P1 Pixies. When it's said subminiatures were short-lived, that refers to the brief time they were made and used.

-Ed


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 Post subject: Re: Subminiature 8-pin tubes - any use?
PostPosted: Jul Sun 14, 2019 2:13 pm 
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Location: St. Louis, MO, USA
Is there a subminiature tube that would sub for a 1L6?

Dennis


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