I suspect it's a faulty tube in a radio I'm repairing.
Definitely looks like a pentode from what I can tell.
It's got a ux6 base and definitely a 6 volt heater.
I've put it on my tester and it arcs inside when applying the HT and the overload light comes on.
Not sure if it's because the tube is faulty or if it's the wrong type set on the tester.
Definitely looks like a pentode from what I can tell.
It's got a ux6 base and definitely a 6 volt heater.
I've put it on my tester and it arcs inside when applying the HT and the overload light comes on.
Not sure if it's because the tube is faulty or if it's the wrong type set on the tester.
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What does the service sheet state for the valve line up? If I had sight of the make and model, I should be able to check for you.
UK makes of that era had the 41+42+43 all with the same base and 6.3 volt heaters all output types in radios relate to mid 1930,s (approx ) the UK went IO base later in the 30,s .
There is of course others relating to IF stages with the same base but VM like the 6D6 or the 77 and 78 (UK) -screened tetrodes but they have different base connections although the same type base but with a top cap .
So no top cap very likely an output valve -- using an analogue multimeter check each pin against the rest for a short circuit -- common fault in 30,s radios when heated a short appears but there is also the possibility its none of those I can look out my very old/dusty valve radio manuals of the era but the valves I mentioned above are the ones produced in the UK but America has its own as well.
There is of course others relating to IF stages with the same base but VM like the 6D6 or the 77 and 78 (UK) -screened tetrodes but they have different base connections although the same type base but with a top cap .
So no top cap very likely an output valve -- using an analogue multimeter check each pin against the rest for a short circuit -- common fault in 30,s radios when heated a short appears but there is also the possibility its none of those I can look out my very old/dusty valve radio manuals of the era but the valves I mentioned above are the ones produced in the UK but America has its own as well.
Checking out a very early first edition valve tester ( UK ) it turns out that the UK didn't do an UX6 its an American design ours were labelled Br 5/7 --hold on Cosser had a 25RE/35RE but they were American licensed to manufacture in the UK but they are rectifiers so the internals will be different.
I have no idea on the brand or model, so cant even find the service sheet. There is nothing that I can find anywhere on the chassis or cabinet, someone has hand written some of the tube types on the chassis, but no marking for this tube and its all rubbed off the glass, What I can say is that its got a power transformer and he told me its an Australian brand.
I will try and get some photos of the radio for you later. Its not with me at the moment.
I suspect its 1930s and has a magic eye tube.
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Absolutely no doubt its an American import--recognize it right away if its a 6B7 then its a signal level double diode .
The "Miniwatt -274 " is all American rectifier valve and that Rola loudspeaker is an HT + energized coil ( in place of the permanent magnet) and act like an HT+ choke .
I can see the FC (frequency changer) valve connected to the tuning capacitor and the IF valve beside it connected to the IF transformer ,what isn't obvious is the output valve .
As is normal in 1930,s /early 1940,s table radios is that the output transformer is the is in the metal box attached to the loudspeaker frame , all you need to do is trace the wiring back to see which ( and where ) the output valve is.
I hope & pray you are not going to "convert " this VERY collectable US radio into what I dislike ( with a vengeance ) an amplifier.
With the casing polished up and some renovation it will look beautiful in any home --if you are going to "convert it " then please ask somebody else to help you as I refuse to help anybody destroy an old collectable radio.
In some UK books of UK manufactured valves a 6B7 is only mentioned as a "double diode " --looking at a USA tube manual its also an output valve so it amplifies audio --rechecked and yes WW equivalent book lists it as a "DD" -UX7 base --a yes ! they made it in two different bases for the earlier version and a later version had a different base so it can amplify --not very loudly -sorry about the confusion .
The "Miniwatt -274 " is all American rectifier valve and that Rola loudspeaker is an HT + energized coil ( in place of the permanent magnet) and act like an HT+ choke .
I can see the FC (frequency changer) valve connected to the tuning capacitor and the IF valve beside it connected to the IF transformer ,what isn't obvious is the output valve .
As is normal in 1930,s /early 1940,s table radios is that the output transformer is the is in the metal box attached to the loudspeaker frame , all you need to do is trace the wiring back to see which ( and where ) the output valve is.
I hope & pray you are not going to "convert " this VERY collectable US radio into what I dislike ( with a vengeance ) an amplifier.
With the casing polished up and some renovation it will look beautiful in any home --if you are going to "convert it " then please ask somebody else to help you as I refuse to help anybody destroy an old collectable radio.
In some UK books of UK manufactured valves a 6B7 is only mentioned as a "double diode " --looking at a USA tube manual its also an output valve so it amplifies audio --rechecked and yes WW equivalent book lists it as a "DD" -UX7 base --a yes ! they made it in two different bases for the earlier version and a later version had a different base so it can amplify --not very loudly -sorry about the confusion .
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Yes your right, it does look like this has an electromagnet on the speaker, apparently this was quite common in early sets because they didnt have very good permanent magnets.
Didnt realise 274 was the type, I couldnt come up with anything when i googled it.
Its definitely the output valve, im pretty sure. None of the other valves inside appear to be output tubes and all have grid caps from what I can tell.
I see this tube has F8 marked on the base, could this be the tube type?
Nothing shows on my testers data, and I couldnt find any info on this either, so assumed it was a factory code of little relevance.
No chances of this set being converted into an amp, im fixing it for a friend 😉
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I am looking at a Raytheon 6B7 and its got a top cap in a UX6 base , Raytheon,s own tube book of the 30,s shows the 41 and 42 in UX6 base , there is also a type 75 DDTriode with a UX6 base and 85 same type .
The problem again is during the same era they changed the bases to IO and quote the both of them so if its definite that its a UX6 base then that radio is the earlier ( more valuable ) version .
The valve you post the pictures of is possibly a DD-Triode not unusual in a small compact radio of that era rather than a DD-Pentode so it could be as I said a type 75 or type 85.
To help you here is Raytheon,s original 1930,s tube book with circuits/descriptions and lists of tubes and their bases to check out.
http://www.tubebooks.org/Books/Atwood/Raytheon 1937 Radio Receiving Tubes.pdf
If you have a problem with Google search engine getting this technical data then use a much more private and open search engine like DDG-Duck-Duck-Go its US but its 90 % private which is a world different from Google .
The problem again is during the same era they changed the bases to IO and quote the both of them so if its definite that its a UX6 base then that radio is the earlier ( more valuable ) version .
The valve you post the pictures of is possibly a DD-Triode not unusual in a small compact radio of that era rather than a DD-Pentode so it could be as I said a type 75 or type 85.
To help you here is Raytheon,s original 1930,s tube book with circuits/descriptions and lists of tubes and their bases to check out.
http://www.tubebooks.org/Books/Atwood/Raytheon 1937 Radio Receiving Tubes.pdf
If you have a problem with Google search engine getting this technical data then use a much more private and open search engine like DDG-Duck-Duck-Go its US but its 90 % private which is a world different from Google .
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The label on the speaker seems to indicate Australian origin. There is enough text left to read it. "Rola Company (Aust.) Pty Ltd elbourne"
There is a company named Rola that made speakers in the US, The UK, and Australia, among other places.
The US 274 rectifier is a large tube similar to a 5U4 with a different base. In the 30's Western Electric was the only large supplier. It's too big to be found in a table radio.
Miniwatt is the name Philips put on some of their tubes. It would not be found on a US tube in the 30's. That tube appears to be from the 50's or 60's. The number 274 on the tube is the EIA (RETMA) vendor code for RCA, not the type number. If it's an octal tube it's likely a 5Y3. If it's a 4 pin then its probably an 80.
I'm not an expert on old radios, but I would guess it is of Australian origin, possibly made with US sourced tubes, or some tubes have been replaced with US tubes.
The F8 on your mystery tube is not the type number, it is the date code, or other manufacturing code.
If you have a power supply feed the heater pins (likely 1 and 6) 6.3 volts and measure the current draw. That can narrow down the list of possibilities. A 41 will draw 400 mA, while a 42 will draw 700 mA.
It may also help if you can see which pins some of the electrodes are connected to.
The casing is typical Art-Deco American the UK imported many of them the OP says the bases are UX6.
The rectifier is made in the USA and Western Electric made 274 rectifiers, what you are thinking of is the 274B, not the same size or shape equivalent 5U4 is high current so I say unequivocally it is NOT a 5U4 --I will stick with a US import and a good reason having had many of the same through my hands is the tuning dial -- typical USA as is the unusual positioning of the "magic eye " .
I have Wireless World yearly hard cover books from 1915 up to 1948 and that design is not typical European a bit later the very small coloured Bakelite radios were exported to the UK .
The rectifier is made in the USA and Western Electric made 274 rectifiers, what you are thinking of is the 274B, not the same size or shape equivalent 5U4 is high current so I say unequivocally it is NOT a 5U4 --I will stick with a US import and a good reason having had many of the same through my hands is the tuning dial -- typical USA as is the unusual positioning of the "magic eye " .
I have Wireless World yearly hard cover books from 1915 up to 1948 and that design is not typical European a bit later the very small coloured Bakelite radios were exported to the UK .
I agree that it does look a lot like US made radios from the 30's. I still have a few myself. I sold or gave away most of my collection before moving several years ago.
That does not explain the label on the speaker with the reference to Melbourne Australia. There is also a nearly obliterated label on the chassis itself that has some text on the second line that looks like "Australian Radio Tecxxxx."
That does not explain the label on the speaker with the reference to Melbourne Australia. There is also a nearly obliterated label on the chassis itself that has some text on the second line that looks like "Australian Radio Tecxxxx."
Philips had a base in Australia but guess what--- they imported a lot of the parts and even manufactured Mullard radios there although that was not the case in the UK .
While large tube manufacturing plant(s) of Mullard existed in the UK actual radios were imported, in my Radio & Television Servicing hardbacks from the 40,s into the 70,s only one Mullard radio schematic is shown.
You are right about the manufacturer -Australian Radio Technical Services took over the patent rights
to Philips radios ( Australia ) in 1934 so the company was licensed to make radios by many patent holders and yes several of those designs were American -Stromberg-Carlson-Radiola-Philco etc so you do have a point they were built to American designs parts imported but "made " in Australia .
They originally had labels on the rear up to 1936 they were plastic then a decal.
While large tube manufacturing plant(s) of Mullard existed in the UK actual radios were imported, in my Radio & Television Servicing hardbacks from the 40,s into the 70,s only one Mullard radio schematic is shown.
You are right about the manufacturer -Australian Radio Technical Services took over the patent rights
to Philips radios ( Australia ) in 1934 so the company was licensed to make radios by many patent holders and yes several of those designs were American -Stromberg-Carlson-Radiola-Philco etc so you do have a point they were built to American designs parts imported but "made " in Australia .
They originally had labels on the rear up to 1936 they were plastic then a decal.
The 6K6GT has a very similar plate structure. The 41 is a 6K6 with a 6 pin base, so the mystery tube could be either a 41 or 42, hence my suggestion to measure the heater current.
Nothing to add regarding the 41 tube, do as Tubelab says. Or look at the top of the valve, the number is not always on the side or base.
But the label is the licence for the manufacture of the radio. It reads 'Australian Radio Technical Services & Patents Co. Ltd'
More detail here half way down the page: The NZ Vintage Radio Project - Tech Info
I wonder if the name is under the dirty dial?
But the label is the licence for the manufacture of the radio. It reads 'Australian Radio Technical Services & Patents Co. Ltd'
More detail here half way down the page: The NZ Vintage Radio Project - Tech Info
I wonder if the name is under the dirty dial?
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A common lineup was 6A7, 6B7 & 41. The rectifier was a 1V in that one but some had an 80. The receiver is a Reflex Type, the 6B7 doubles as both IF & 1st AF. A flaky compromise, but it works.🙂
That sounds feasible --is it John ? but my problem ---where is the OP to verify it all -Nzoomed ?
I did mention in my post it could be a 41 --post #3 but your line up sounds realistic and proper to the era , if he had pulled all the tubes and named them it would have saved time .
Yes small radio --space saving circuit I like your comment sounds right .
That 1V is ancient would date to the late 20,s or very early 30,s .
I did mention in my post it could be a 41 --post #3 but your line up sounds realistic and proper to the era , if he had pulled all the tubes and named them it would have saved time .
Yes small radio --space saving circuit I like your comment sounds right .
That 1V is ancient would date to the late 20,s or very early 30,s .
Its definitely not a type 75 or 85, since those have a grid cap for a start, and i can see there is only one valve in the envelope, not 2.
I will grab another photo to show inside, it looks identical to a type 41 or 41 inside from photos ive seen, there are a couple of other types too that look similar but have 2.5V heaters.
Yes its definitely an Australian model that likely was exported to New Zealand.
My friend who it belongs to said he thinks its a "Universal" radio. Im going to see if i can identify the model.
Your right about the 274 rectifier, the photos on a google search show something much bigger, this has 4 pins, so is probably a type 80 as you say.
Yes Miniwatt was found on later philips tubes, ive seen it on the odd US tube, but usually from the 50s or 60s as you say, its obvious this tube has been replaced at some point id say.
I should get an idea on its heater current if i connect it to my benchtop power supply.
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I have an old RCA radio. It's one of their very first superhet designs. It has a 1V rectifier tube. When I first got it, probably 30 years ago, the 1V red plated on power up. This was due to a shorted cap. I changed it and a couple others that were real ugly looking, and the radio played. It still did the last time I tried it.
That radio has very little selectivity ahead of the mixer, and the local oscillator obviously has some harmonics, because I can pick up some strong shortwave broadcasting stations even though the radio is AM BCB only.
There is no stickers, model number, or other identification on the radio. I have not found an exact matching picture online, but there are some similar looking RCA superhets in the 1929 to 1931 time period.