Talk:All American Five

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Grammar[edit]

If you are going to correct spelling and grammar, then make sure you know the rules to start with.

The correct version of "1930's" (a correct plural) was replaced with "1930s". There are a few examples where the plural has an apostrophie - 1930's (as in the decade 1930 -1939) is one of them.

This plural has been 'corrected' wrongly twice.

And now wrongly corrected a third time.

The page it links to is wrong.

Rightly or wrongly, Wiki doesn't use apostrophes with years.
Atlant 23:16, 11 May 2006 (UTC)
It's wrong - where does it state this? If satisfactory answer not received, I will revert as most of them is in those parts of the article that I wrote, as I don't want a reputation for not knowing the correct way to use an apostrophie. —The preceding unsigned comment was added by 86.140.80.34 (talkcontribs) .
It says it at Wikipedia:Manual of Style (dates and numbers)#Incorrect date formats:
Do not use an apostrophe to indicate a decade:
Incorrect: 1970's
Correct: 1970s
Then the style guide is wrong. In English, the decade is correctly written with an apostophie. I assume the style guide was written by an American. Americans have not used English for over 2 centuries.
Atlant 20:20, 29 May 2006 (UTC)

About the chassis being "hot"[edit]

The article refers to the Underwriter's Laboratories (UL) requiring a 100k resistor between the mains and chassis. Although I can find several improvements demanded of the UL, mainly to do with proximity of high voltages with low, I can find no reference to a 100k resistor, nor indeed, any schematic that shows one. Such a resistor would be pointless in and AC/DC design as it would drop almost the entire mains voltage across it.

All the AC/DC design radios (and televisions) that I have serviced have had the chassis very much live if the plug was inserted the wrong way round. This practice prevailed towards the end of the 20th century until Switch Mode Power supplies rendered the design obsolete.

The preceding unsigned comment was added by 86.137.52.221 (talk • contribs) .

Every AC/DC radio I worked on had an isolation resistor between the power cord (signal "ground") and chassis. It is clearly shown on their schematic. The power cord was connected to the power supply section at Power "hot" and signal "ground". If plugged in backwards then Power "hot" was neutral and signal "ground" was hot, but the chassis was not hot. None of the circuitry used chassis as a "ground". You got a shock, but it never felt like more than a "tingle".
Right now I don't recall the exact value of the isolation resistor, but it was in the Megohm range. See typical schematic (it is the 220Meg resistor on the left with a 0.1μF cap across it). I will change the value in the article. -- RTC 01:50, 15 February 2006 (UTC

Response:

I had not seen this arrangement before (at least not in this location). 200M seems a better choice of resistor than 100k as it will reduce the current below the threshold of sensation. Exactly what the objective was is not clear. The internal live parts can easily be isolated from the user as they subsequently were. However, the circuitry is nevertheless still live to service personnel even when the set is switched off.

As I said, I have not encountered this arrangement, but I am in the UK. Standard practice here was to operate an AC/DC radio or television from an isolating transformer during servicing, thereby eliminating the danger entirely.

It is interesting to note that this particular UL requirement seems to predate their insistence on rearranging the tube pin-out to move the plate pin away from the heater pins. Quite why they did this is also unclear as the plate voltage is not high by any standard. Safety organisation do come up with some strange directives sometimes.

When I first entered the value of 100K it was from (bad) memory; and I intended to check some schematics and update it with the correct value. However I got busy with other things and didn't get back to it before you did. Luckily I found a schematic on the net that showed it. However I don't recall there being a standard value for the resistor, different sets and different manufacturers used different values, but it had to limit the current to a "safe" value if a person touching hard ground touched the chassis.
The primary objective of the resistor was to prevent repair men from electrocuting themselves by accidentally touching the chassis while working on the radio. In any radio it was possible to get hurt if you touched the wrong thing in the live circuits, but chassis should always be "safe" (even if circuit "ground" isn't). It also made it "safe" if you accidentally touched a hot circuit and the chassis (as long a you were not already grounded elsewhere). One extra resistor and a bypass capaacitor for it was cheap safety – and as you say these sets were cheap.
I never used an isolation transformer. Usually just plugged it in, kept one hand in my pocket and ran a finger against the chassis. If I got a "tingle" I reversed the plug and tried again. I always tried to work on radios and TVs with one hand in my pocket when they were plugged in. -- RTC 20:59, 16 February 2006 (UTC)
I finally dug out my old books. I found schematics showing isolated chassis (also called floating chassis) circuits that had resistors as small as 22K through as large as 330M; even ones that used no resistor, just the 0.1µF or 0.2µF ground bypass capacitor. 220K and 330K were very common values. Some schematics in the book did have a true hot chassis (but I've never actually seen or worked on one myself).
So it turns out my memory wasn't all that bad after all. -- RTC 20:38, 4 March 2006 (UTC)

I note that a contributer modified the article to state that the tube heater chain would limit the current to someone who contacted the chassis. I incorrectly calculated in my head that the resistance would be around 150 ohms or so, which would not provide much limitation in such circumsances. However, consulting tube data, I find that the resistance is much lower at around 60 ohms for the entire heater chain. It rises to 800 ohms when the heaters all reach their working temperature.

Power supply[edit]

I jumped on a change that was made today, as it tried to simpliphy but in the process made the ideas less clear.

1) the filament/heater tap is an option for the dial light, not all radios had them, and a missing burned out light probaly did not have much effect on reliability. It might cause a problem if the curent draw was already high. Many units did not have a dial lamp.

Actually, a burned out dial light had a huge effect on reliability as it caused that section of the heater to carry the current that was not diverted through the dial light. This in turn heated the cathode to a temperature far higher that it was designed for and more or less stripped off the oxide coating. The rectifier tube could literally fail after a few hours of such use. 20.133.0.14 14:15, 5 September 2006 (UTC)
A 35W4 or a 35Z5 has a heater rating of 150ma. If you put a dial lamp that nominaly draws 100ma, the section of the tube heater taps will see LESS than the normal curent, if the dial lamp pops it will see "normal curent"..NOW if their is say a leaky filter (you use the term smoothing) that incresed the draw, both will pop. Their is probaly only 50ma of dc draw on a heathy radio.
You have overlooked the fact that the B+ supply current is routed via the part of the heater that has the dial light connected across it. The Dial light current rating was designed to be the same as the B+ current. The failure of the dial light caused the heater current plus the B+ current to be routed through that part of the heater. The B+ current can be observd in a real radio. At switch on, the heaters are cold and pass a large current. The dial light light to more or less full brightness, but as the heaters warm up and the current falls, the dial light dims considerably. As the rectifier and the other tubes start to conduct, the B+ current starts to flow through the dial light and the parallel heater section and the light resumes to full brightness. 86.132.200.242 17:36, 13 July 2007 (UTC)
when tubes are made, they are run at 200% of heater rating to activate the cathodes, so any slight variation will have little effect.
But that is only while the cathodes are being activated. It is a process that has to be carefully monitored because once the cathode is activated it will destroy itself very soon after. Regardless of this, it is a matter of record that a failed dial light would cause the rectifier tube to fail far quicker than it would normally do so. 86.132.200.242 17:36, 13 July 2007 (UTC)

cmacd 14:54, 5 September 2006 (UTC)

2) the norm was to use the tap as a fuse, thus the plate curent went through that section and the Dial lamp. You could actually see the lamp brighten as the radio started to play. If a short happened, the lamp filament would blow at the same time as the tube heater.

I have not been able to find any reference to this part of the circuit acting as a fuse.
Look in any RCA tube manual, the circut is clearly described in every edition from RC-12 to RC-25

cmacd 14:54, 5 September 2006 (UTC)

Tube rectifier circuits are rarely fitted with fuses, and even if they were, the relatively high resistance of the rectifier tube itself, would render the fuse pretty ineffective.
There is always SOMTHING that will act as a fuse, even if it is the power transformer. :) Many appliances (and vehicles)use a length of small guage wire as a fuse. cmacd 14:54, 5 September 2006 (UTC)
I have never seen a fuse in the plate circuits of small tube rectifier sytems (I have in larger systems). Every domestic radio or whatever that I have serviced with a short on the power supply, the inherent tube resistance has limited the current (the glowing plates are a bit of a give away though). 86.132.200.242 17:36, 13 July 2007 (UTC)
It is this resistance that severely limits the size of the reservoir capacitor. Too large a capacitor and the surge currents can damage the cathode. 20.133.0.14 14:15, 5 September 2006 (UTC)
Their is an optmum size for the filter cap, and yes too big a capaitor will overdraw the circuit and blow the fuse. in the 1930 the cap was 8 MFD, and later ones got up to 80.cmacd 14:54, 5 September 2006 (UTC)

3 Edison wired NY and other areas with DC power, and it was the 50's before everyone had ac. The Niagra falls area had 25 Cycle power until the war. A transformer set would not work in a dc area, and a 25 cycle set would need a special transformer.

So what? Although the All American Five would operate on DC (as long as you put the plug in the right way round), as the article states, this was a side effect not a design objective. A different version of the set would probably have been required for a 25 Hz supply as larger reservoir and smoothing capacitors would be required. The former would have been limited in size by the rectifier tube characteristics. 20.133.0.14 14:15, 5 September 2006 (UTC)
The use of a larger second stage filter can also be considered, as well as the value of the resistor between the two (or more) caps, (where the ripple is dropped)

cmacd 14:54, 5 September 2006 (UTC)

Atwater Kent[edit]

Note: Atwater-Kent did not go bankrupt because they refused to make an AC/DC set. Atwater-Kent refused to unionize.Dfoley51 00:30, 7 October 2006 (UTC) RESPONSE: Not true. Unionization issues may have been one added reason for the owner's decision to get out of the radio business, but did NOT cause Atwater Kent's precipitous fall in market share as a radio manufacturer. Atwater Kent was the #1 manufacturer of radios in the country from 1926 through 1929. In 1929 they were producing almost a million receivers a year. However, during the Depression, where the cost of the average purchased radio dropped 75% or more, it was Atwater-Kent's refusal to produce cheap AAF table radio designs and concentrate on upper-end console models that first caused its business troubles. By 1931 the engineering department had already closed, meaning that the company was simply mass-producing existing designs until they ran out of steam. Sales continued in a downward spiral. In the last years the company's workforce was only 800 employees (down from a high of 12,000!), mostly on-call workers, and unionizing would have resulted in little leverage anyway. By 1936 Arthur Atwater Kent was tired of the radio business, and made the decision to close the factory for good..[1] -AK 6 MAR 2007

I can buy that version, I can't imagine AK even CONSIDERING building less than a high end unit. The old version made it sound like he was forced to pick between making a stock RCA design or going out of business. I can imagine more than a few makers were caught by the combination of the depression, and the technological change represented by the AA5. cmacd 12:49, 22 March 2007 (UTC)

References

  1. ^ Douglas, Alan, Radio Manufacturers of the 1920s ( Vol. 1) Vestal, New York: Vestal Press, Ltd. (1988); Schiffer, Michael, The Portable Radio In American Life, Tucson: Univ. of Ariz. Press (1991)

DC voltage[edit]

"The radio used a simple half wave rectifier to produce about 160-170 volts of plate voltage."

This would be true for a perfect rectifier fed 120VAC (120VAC*1.414= 169VDC).

With low-cost vacuum rectifiers like 35Z5, the actual voltage was more like 125VDC. See 35Z5 data-sheet: http://www.mif.pg.gda.pl/homepages/frank/sheets/127/3/35Z5GT.pdf which shows 122V-127V at 60mA current

You need to find out what data sheets are trying to tell you. The 125 volts quoted is merely the plate voltage at which those characteristics apply. It also quotes them at 235 volts, but I would not even try to use that as evience that the half wave rectifier produced 235 volts.

See also 50L6 data: http://www.mif.pg.gda.pl/homepages/frank/sheets/127/5/50L6GT.pdf which shows operation at 110V across the tube (add ~7V bias and ~7V drop in output transformer= 125VDC).

Yes, 50L6 is allowed higher voltages, but never got it with AC/DC construction and vacuum rectifiers; and later "5-tube" tube-sets often used a 150V-max output tube.

The low voltage limited such designs to 1 or 2 Watts power.

PRR 68.239.136.129 08:22, 11 February 2007 (UTC)

All the All American Five service sheets and diagrams that I have seen all refer to the B+ voltage being around 160-170 volts. Most of the cited links do as well.

86.132.200.242 17:36, 13 July 2007 (UTC)


> You need to find out what data sheets are trying to tell you.

Avoid personal attacks http://en.wikipedia.org/wiki/Wikipedia:No_personal_attacks

> All the All American Five service sheets and diagrams that I have seen all refer to the B+ voltage being around 160-170 volts.

"I have seen" is not valid support for an article.

> Most of the cited links do as well.

The few links are to self-published blogs or websites, created long after the 5-tube radio era, without deep roots or supporting material. Some are good, some are light-weight, all seem to be lacking meaningful editorial oversight.

Reliable sources http://en.wikipedia.org/wiki/Wikipedia:Identifying_reliable_sources

Verifiability http://en.wikipedia.org/wiki/Wikipedia:Verifiability

Here are scans of ten service manuals for specific models printed when these radios were new.
I picked the models semi-randomly to cover a spread of years and brands.

Schematic link URL raw DC Plate
http://www.nostalgiaair.org/PagesByModel/990/M0016990.pdf - (pg3)  ?? 110V
http://www.nostalgiaair.org/PagesByModel/243/M0017243.pdf - (pg3) 120V 115V
http://www.nostalgiaair.org/PagesByModel/946/M0015946.pdf -  ?? 114V
http://www.nostalgiaair.org/PagesByModel/948/M0015948.pdf - (pg3) 122V 115V
http://www.nostalgiaair.org/PagesByModel/760/M0014760.pdf - 115V 115V
http://www.nostalgiaair.org/PagesByModel/738/M0013738.pdf - (pg3) 130V 108V
http://www.nostalgiaair.org/PagesByModel/671/M0013671.pdf - (pg5) 124V 104V
http://www.nostalgiaair.org/PagesByModel/726/M0003726.pdf - (pg4) 117V 100V
http://www.nostalgiaair.org/PagesByModel/160/M0002160.pdf - 118V 110V
http://www.nostalgiaair.org/PagesByModel/232/M0003232.pdf - (pg3) 115V 100V
Averages 120V 109V

Yes, it is probable that some typos exist, we must survey many such sheets and discount notes which seem exceptional. It is unlikely, for instance, that M0014760 has the same voltage raw B+ and at plate (implies zero loss in output transformer; good economics lead to 5%-20% loss). However these manuals were published in good faith by the manufacturers' designers for field support of their product, and would be as correct as possible ("meaningful editorial oversight") so that a manufacturer would not get a bad reputation with repair shops who dealt directly with customers.

I believe that classic "5-tube" (vacuum rectifier) radios DO NOT have 140V-160V DC B+ levels. That the B+ was more often 110V-130V (100V-115V at power amp plate). That this mis-statement may confuse persons working on old radios ("Why is my voltage low?"). That the article _should_ be edited to remove the too-high voltage numbers (now in several places), and perhaps some more typical numbers given.

PRR (talk) 05:29, 30 April 2011 (UTC)

How could the circuit operate at peak AC voltage? AC power is a function of the RMS [[1]] voltage, not the peak. I'm not going to change it, since I am not knowledgeable about tube circuits, but I can't see how this is correct. Can somebody prove it mathematically?Yak99 (talk) 15:16, 12 May 2012 (UTC)

The quoted AC voltage is the Root Mean Square (RMS) of the instantaneous voltage taken over a complete cycle. The peak voltage is equal to the RMS voltage multiplied by the square root of two. If a rectifier is used to power (say) a resistive load, the voltage across that load will be a little less than that RMS voltage. But when a rectifier circuit is used to charge a capacitor, that capacitor charges to the peak voltage as current will flow whenever the supply voltage exceeds the voltage on the capacitor. In the case of a 120 volt supply, the capacitor will charge to 169.7 volts. In practice, the load on the power supply provides a discharge path for the accumulated charge, and the actual voltage will be somewhat less than that peak value, but often more than the RMS value. 86.159.159.194 (talk) 19:00, 14 November 2012 (UTC)

Can't find if Five not spelled out[edit]

I tried finding this article today and searched "all american 5" No such article, nothing relevant in the first page of search results. I tried it in Google and the first hit got me here. Can there be some sort of redirect set up? 151.204.233.138 (talk) 16:00, 18 May 2009 (UTC)

Done. --Wtshymanski (talk) 17:24, 19 September 2009 (UTC)

AGC in AA5[edit]

I don't think you can really build a consumer radio that *doesn't* have AGC to some degree. Check out [[2]] which gives a schematic of a 5-tube set that looks very similar to the schematic in one of the external links. (Can't look at the other external links because our firewall says they've got malware on them.) Notice the network on Pin 5 of the 12SQ7 with a bypass cap and connection back to the antenna coil - which is the smae conection marked "AVC" in the book above. Even the Popular Science article on "build your own 5 tube radio" says it has AGC. It doesn't cost a lot especially as the second diode is already in the tube envelope - which is what it was put there to do! (You strictly don't need a second diode, either.). There's lots of non-linearities to exploit for gain control, it doesn't cost anything extra. I have yet again removed the assertion that AA5s didn't have AGC. --Wtshymanski (talk)

And check out the data sheet for the 6SQ7/12SQ7 at [3]] - guess what it recommends using the second diode for? --Wtshymanski (talk) 17:55, 7 October 2009 (UTC)
See also [[4]]. --Wtshymanski (talk) 18:11, 7 October 2009 (UTC)
Paul J. Nahin says essentially all consumer receivers had AVC (AGC) by 1932, see [[5]].He also says AVC was invented by Harold Wheeler, working at Hazletine, in 1926 and it was in commercial use by 1929. --Wtshymanski (talk) 18:22, 7 October 2009 (UTC)
You most certainly can build a practical radio without AGC. In fact all radios built before AGC was invented didn't feature it. Granted, it does make the radio more stable in operation. Most All American Fives did not feature AGC. Almost any schematic shows the diode plate that would be used for AGC either paralleled to the detector diode plate or just connected to the cathode. A typical schematic is shown here. In this one the AGC diode plate is connected to the cathode rendering it ineffective. 20.133.0.13 (talk) 10:59, 9 October 2009 (UTC)
So tell me, what is the purpose of the 2.2 meg resistor at 3, and the 0.05 uf capacitor at 13, on the referenced schematic? As noted above, you don't need a second diode, though it does make it possible to have so-called "delayed" AVC. Why is this "fed back" all the way to the antenna coil? Sure *looks* like a filter and some kind of feedback control...could it be AVC? And recall that there's *two* components resolved by the audio detector diode - the 0.01 uF capacitor at 11 blocks the *dc* average component proportional to carrier strength that had been detected by the diode connected to pin 4 of the 12SQ7. This dc is fed back to the earlieer stages to reduce their gain on strong signals. Also please note the phrase "Stage gains measured with AVC made inoperative.." at the bottom left corner of this very schematic! Three references and two schematics, including the one you yourself cite, show AVC ( or AGC) was commonplace in All American Five radios. ( I really want the Nahin book now, it looks very interesting on the Google preview.) --Wtshymanski (talk) 14:08, 9 October 2009 (UTC)
The 4th edition of the "Radiotron Designer's Handbook" says that sometimes one of the dual diodes had its anode grounded to prevent leak-through of the IF into the audio stage; it could be detected in the audio amplifier and produce a low level of sound even with the volume control turned all the way down. This meant that delayed AGC wasn't too practical since the only remaining source of AGC voltage was the detector diode only. This is probably too obscure to include in the article but does explain why it's common to see one diode grounded in 5-tube schematics. --Wtshymanski (talk) 21:06, 29 October 2009 (UTC)

AVC?

AVC was in general use by 1934 according to a contemporary source (closer to the events than some recent book):
Procedings of the Institute of Radio Engineers, Volume 22 Number 10 page 1151-
http://louise.hallikainen.org/BroadcastHistory/uploads/Wlw500kw.pdf
"With present receivers... ...with the general use of automatic volume control in receiving sets..."

The concept is older, implementation is inexpensive, convenience is much higher. Whether it was "essentially all" in 1932 or "general use" in 1934 is not critical; this Wikipedia article says it covers a type manufactured "from the mid 1930s...."

PRR (talk) —Preceding undated comment added 04:21, 2 May 2011 (UTC).

"I don't think you can really build a consumer radio that *doesn't* have AGC"

AVC had been described in the early 1920s but not much used. Broadcasters still used 100-1,000 Watt transmitters with lame antennas. Receivers used 0.2 Watt (type '71) audio output.

By 1930 there was money in radio. Broadcasters went to 10,000 and 50,000 Watt transmitters with near-ideal towers. Receiver power was often over 1 Watt. If the set were adjusted for ambient atmospheric noise level and the level of smaller transmitters, tuning onto a 50KW station was frightening.

To really handle this dynamic range new RF/IF tubes were needed, the SuperControl remote-cutoff tubes. Also improved detectors. An improved converter (6A7) took AVC and reduced cost by not needing an RF stage for AVC action. By 1933 these improvements were common even on low-price radios. Competition was fierce.

So while there were cheap radios, and 5-tube radios, without AVC, the "All American Five" radios developed in the period when AVC was generally used.

http://www.americanradiohistory.com/Archive-Radio-Enginering/30s/1933/Radio-Engineering-1933-08.pdf page 7.

PRR (talk) —Preceding undated comment added 01:49, 17 December 2013 (UTC)

Vandalism on All American Five.[edit]

Please do not continue to vandalise the article on All American Five. You continue to remove the [citation needed] flag without supplying a valid citation. Your opinion, even if you do claim it's 'common sense' is not a valid citation.

The manufacturer's data sheet for the type 48 tetrode shows that it is capable of as much as 3 watts of audio output when operated at a plate voltage of 30 volts. A paralleled pair should easily be capable of more than this (but I doubt double). Even the characteristics for the 35L6 shows that it can muster more than a watt at 32 volts on the plate.

I would challenge the claim of low output, but I don't know what the actual output of the subject radio was and in any case the original [citation needed] was not mine. 20.133.0.13 (talk) 12:54, 4 November 2009 (UTC)

Note that the farm radio conversion is not talking about a set purpose-built with selected tubes to operate on a 32 V B+ but instead is discussing a conversion of a set meant to operate on 115 V with the same tube line up. It stands to reason that operating with a fraction of the B+ will produce a fraction of the audio volume.
There's no obligation to abandon common sense when editing a Wikipedia article. --Wtshymanski (talk) 14:10, 4 November 2009 (UTC)
All wikipedia content requires a valid citation. There is no validity in the 'common sense' claim because things don't always follow common sense. All of the tubes listed in the paragraph claiming low output were specifically designed to give reasonable output at low voltages. One, the 35L6 is capable of managing 1.5 watts with a plate voltage of just 35 volts when the bias is properly adjusted. Oddly, and because of the tetrode characteristics, it actually rises to 2.5 watts at 25 volts. You cannot claim that is significantly lower than its maximum rated output of 3 watts (the difference is barely audible anyway). None of the tubes listed will turn in less than 1.5 watts at 32 volts. Article ammended accordingly. I B Wright (talk) 18:41, 4 November 2009 (UTC)
Where can I read about the power output of a 35L6 with 32 volts on the plate? The data sheet reference listed isn't any help here because it just lists "puisance modulee" and doesn't give any characterstics at other plate voltages. It does say maximum of 110 volts on the plate (though it would be good to find an English-language data sheet). --Wtshymanski (talk) 19:56, 4 November 2009 (UTC)
Looking for references:

--Wtshymanski (talk) 20:18, 4 November 2009 (UTC)

I don't think the 35L6 is physically capable of producing 1.5 watts audio at 32 volts on the plate. There's not enough plate current available. Supposing we have 32 volts on the plate, the biggest RMS voltage we can generate there is 32 V peak to-peak = 11.3 volts RMS. The data sheet says the tube maximum current is 44 mA. So, maximum power output can't exceed 11.3 * 44 = 0.497 watts. And I don't think you can make a tube amp go rail-to-rail. I don't think you can compensate by running up the plate current, because you're limited by how much emission you have from the cathode. So, less than half a watt is an audible reduction from the 3.3 watts at full voltage. Oh, and why does a pentode have a tetrode characteristic? I thought the whole point of pentodes was to get rid of tetrode characteristics.
What I'd like to find is an old Popular Mechanics article that describes the conversion - so far the Google archive has not given up such a treasure. --Wtshymanski (talk) 20:57, 4 November 2009 (UTC)
And on the 25th of September of this year, we have an anon editor observing "Also, if run from a DC supply the radio had a substantially reduced performance because the B+ voltage would only be 120 volts compared with 160-170 volts when operated from AC. " No reference supplied. From 160 V to 120 V gives substantially reduced performance, but 160 V down to 32 V gives a barely audible difference. Must be the tetrode characteristic or something. --Wtshymanski (talk) 21:46, 4 November 2009 (UTC)
Looking at page 342 of the RCA receiving tube manual RC 20, available from the excellent Peter Millet web site, we find the characteristic curves of the 35L6 vacuum tube (well, really the 35C5 which the manual says has the same curves). Picking a plate voltage of 30 volts, we can put a control grid voltage of -6 volts, which gives us a plate current of , oh, say 2.5 mA. Set the grid voltage back to 0 volts and we hit the space charge line at about 45 mA and 20 volts on the plate. So, using the formula out of the manual, power = change in current * change in volts /8, or 42.5 * 10 = 425 mW. Less than half a watt, and close to what I calculated above. No sign of a tetrode kink in these curves, by the way. So, I am unconvinced that a 35L6 could deliver 2.5 watts to the speaker with 25 volts on the plate - there just aren't enough milliamps available. All this original research is inadmissable in the article, of course - but it does rather strongly suggest that the original comment about 32-volt conversions of otherwise 117 V designs would be rather quiet. From what little I've read of farm radio restorations on the Web, it looks like the audio transformer is not changed for these conversions, so I suspect the optimum load line is not achieved - which would further reduce power delivered to the speaker. I wish the original IP editor who added this paragraph had put in some reference, but that address doesn't seem to have edited in quite a while. --Wtshymanski (talk) 02:39, 5 November 2009 (UTC)
I have access to many data sheets on obsolete tubes. The data sheet that I have for the 35L6 is published by Sylvania and is in French, but it gives the operating characteristics for 'Amplificatéur Classe A' (Class A amplifier to you). It specifically gives the operation at a Plate voltage of 35 volts. At this voltage the Output Power is quoted as 1.5 watts. We have to assume that Sylvania know a thing or to about their products. I have been in the electronics business long enough to know that devices don't always follow what would appear to be the obvious. In the light of this, if you (or indeed anyone) wishes to put an assertion into the article that a farm radio conversion has barely audible output, then a citation is required to support this. However, I agree that it is probably best deleted until a valid citation one way or the other is found.
Wrong. Unbelievably wrong, though consistent with earlier discussions. Au Canada, nous parlons en Anglais et aussi en Francais. My French 300 was many decades ago but "tension de chauffage" is plainly "heater voltage" - another clue would be "CA ou CC" - French for AC or DC. "Tension plaque" is what we would call "plate voltage" and again that's a perfectly ordinary 110 V (DC). Mistaking the heater voltage for the plate voltage is not consistent with being in the electronics business more than a short time. With a myriad of English-language data sheets available on the net, it's curious that one would cite a reference in a language one does not speak or read. --Wtshymanski (talk) 14:20, 5 November 2009 (UTC)
I'm not confusing anything so there is no 'apparent confusion' to resolve. What makes you think that we are even looking at the same data sheet (highly unlikely)? What also makes you think that I can't read a French language data sheet? Assuming that you are looking at the same data sheet that I am, try page 2 where three operating options are offered, one of which has a 'Tension Plaque' (that's plate voltage to you) of 35 volts. The tension chauffage is shown in each case as 50 volts, but then I am actually looking at the sheet for a 50L6. The 6L6, 12L6, 25L6, 35L6 and 50L6 are all electrically identical apart from the heater voltage and current and maximum heater to cathode voltage. 20.133.0.13 (talk) 10:12, 6 November 2009 (UTC)
As for the claim that a substantially reduced performance would occur if the (mains version) of the radio was run from DC instead of AC: the characteristics suggest that a 35L6 (or 50L6 - same thing) would deliver 3.1 watts with a plate voltage of 160 volts, falling to 2.4 watts with a 120 volt plate voltage. This, of course, assumes biasing conditions are optimised which would not be the case in a standard radio run from DC. The output would therefore be lower, and the characteristic curves suggest to me an output of around 1.7 to 1.8 watts. This is not quite half the power at 160 volts and thus I have to conclude that the audible difference would be imperceptible. However, my interpretations are probably not acceptable as a citation on wikipedia (OR), so although I cannot correct the article on this basis, a [citation needed] tag would seem to be perfectly in order. 20.133.0.13 (talk) 07:57, 5 November 2009 (UTC)
Uncited. Extrapolate your reading of the characteristic curves to 30 volts - if one is really reading the curves, one will find even lower output at 30 V plate than at 110 V plate. You can't quote the curves for ONE voltage and ignore them for the next. Given the confusion between heater voltage and plate voltage, and the inability to recognize a dirt-common AVC circuit even when it is described on the schematic said to prove the lack of AVC, I'm sticking to my position. Common sense trumps delibrately misquoting or misreading references. WP:AGF and all, but one must speculate where the limit is on the assumption. --Wtshymanski (talk) 14:20, 5 November 2009 (UTC)
As I said, I haven't confused anything with anything. Nor am I misreading anything. It's there in Black and White on the spec sheet - no interpretation required. Common sense still isn't a citation and rarely reliable. 20.133.0.13 (talk) 10:12, 6 November 2009 (UTC)
Looking at this spec sheet again, I'm starting to wonder if it contains a misprint, because the power output is exactly the same as in the adjacent column for a plate voltage of 110 volts as indeed are most of the other parameters. It wouldn't be the only misprint in the history of data sheets and they were surprisingly common. The Spec sheet for the Sylvania 6BN6 famously goes into a lot of detail describing the characteristics of an entirely different device. The Tung-Sol spec sheet for the same tube does exactly the same thing. 20.133.0.13 (talk) 12:23, 6 November 2009 (UTC)
Oh yes - I have restored the [citation needed] tag against the claim that 120 volts DC provides a 'substantially reduced' performance compared with AC operation. I know you put the [citation needed] tag there, but it is clear that the reduced output is a barely audible reduction rather than substantial one. The claim remains uncited and the [citation needed] tag is therefore valid. 20.133.0.13 (talk) 10:31, 6 November 2009 (UTC)
Outdent - let me get this straight. That needs a citation now, but didn't when someone using your IP address put it in back in September. Fine, be inconsistent. The data sheet linked at http://frank.pocnet.net/sheets/121/3/35L6G.pdf has one page, does not list a plate voltage of 35 volts nor performance at that plate voltage. The data in the RCA manual does give curves which are not cosistent with 1.5 watts out at 32 V plate. --Wtshymanski (talk) 13:10, 6 November 2009 (UTC)
This IP address is used by a very large IT company as a gateway to serve many PCs around the globe. It is not known how many but, it is believed to be in the hundreds of thousands.
The data sheet I am looking at was published by Sylvania and on page 2 it has operating conditions for plate voltages of 35, 110 and 200 volts (Did they have the farm radio in mind?). However, the bottom part of the 35 volt conditions look to have been reproduced from the 110 volt column. It was the grid 2 current being the same, despite the much lower grid 2 voltage that aroused my suspicions. It certainly doesn't square with the graph on page 4. 20.133.0.13 (talk) 13:47, 12 November 2009 (UTC)
Intersting. What is the date on that data sheet? None of the data sheets that I have seen on the Internet list a 35 V plate voltage. (I've been looking at the 1951 Sylvania manual at http://www.pmillett.com/tube.htm - that spans two sheets, says the curves are the same as the 35A5, and the 35A5 data does not give any data for a 35 V plate). A different IP address did supply a link to a French language Sylvania data sheet but that did not give a 35 V plate voltage or any curves and was a single sheet. I would appreciate a link to a viewable edition of a data sheet that shows power output with 35 volts on the plate of a 35L6 or any data sheet that shows a 35 V plate voltage on tubes normally operated with 100 or more volts on the plate. --Wtshymanski (talk) 14:55, 12 November 2009 (UTC)
The data sheet is a paper one in a book (remember those?) and is in French (and the terminology suggests a Canadian publication). It isn't actally for a 35L6 but for a 50L6 (same thing). It's dated 1957 and is a data book listing low voltage tubes and presumably tubes that can be used at lower than normal votages (the lowest voltage ones operate with a plate (and filament) voltage of just 1.4 volts). I haven't found an on line version of it so far.
A colleague has just pointed out that the 1.4 volt tubes are a special type of tube known as an electrometer which are designed to operate with positive grid bias and are in fact designed to amplify tiny grid currents (which explains why the data sheet shows the curves with grid one current rather than voltage - actually down to 3fA (that's femtoAmps or 0.00000000000003 Amps!)). But I digress. 20.133.0.13 (talk) 12:40, 13 November 2009 (UTC)

Lethal How to advice[edit]

'How to' advice is not permitted on Wikipedia.

The advice purports to advise the lay reader to touch a potentially live conductor. While an experienced engineer such as myself (and possibly the provider of that advice) may safely undertake such an obviously hazardous procedure, a person without such knowledge and experience should never consider even thinking about trying it.

As for the crack about open heart surgery not coming with a health warning - well actually: it does. No surgeon would carry out open heart surgery (or indeed any surgery) without a signed approval from the patient or his next of kin. Such an approval contains all the necessary notification of risks and potential hazards. 81.157.217.225 (talk) 08:18, 1 March 2010 (UTC)

For some inexpicable reason, the contributor seems hell bent on including a procedure likely to result in fatal consequences to the lay reader following his foolhardy advice. If he insists on reverting it, I will refere the matter to an administrator.
REPEAT: 'How to's are not permitted. Lethal how tos, I would be very surprised is the admins would allow in any form. —Preceding unsigned comment added by 86.141.192.254 (talk) 08:01, 2 March 2010 (UTC)
Oh my. A repeat. YOu know, I refuse to believe that a minor observation in a Wikipedia article is going to have slaughterous effect amongst the populace. Perhaps my learned annonymous correspondent has never had the opportunity to *use* a televison set equipped with rabbit ears. (Perhaps he's been raised in a cable-TV household, or perhaps he's a disembodied brain in a bottle, or perhaps a naive AI.) As someone who gets all his broadcast TV in this fashion, I can assure you that the consumer may occassionally, nay, is expected and required, to grasp said rabbit ears with a bare and ungloved hand, and manipulate them so as to minimize the snow and ghosts. Directions for this lethal practice are included in the operating manual for the set. The authorities seem powerless to act in such cases; or mayhap it's a vast conspiracy to increase the sales of funeral wreathes.
Thank Jimbo the ever-vigilant administrators watch every one of 3+ million articles for the least hint of practices that might endanger, embarrass or inconvenience us. There's certainly no descriptions of how to inhale heroin, how a meth lab works, or other practices that could leave you permanently crippled, for example...no, not here on the Wikipedia. But please, E-mail "the administrators" and let them know that peril lurks.
(Extra points to anyone who can tell which one is the fool in this argument.)--Wtshymanski (talk) 15:27, 2 March 2010 (UTC)
I'll claim those extra points. The antenna of a TV set should be isolated from the mains supply, by a filter circuit that blocks 50 or 60 Hz but allows the RF to freely pass. If you do get a tingle from 'running your finger' against an antenna connected to an AC/DC chassis, then that fitering is faulty and the antenna most likely live. Your advice is to come in contact with a live circuit and (as far as I can count) two other contributors have pointed out is potentially dangerous. I would go further and also brand it irresponsible and stupid.
Since you raised the subject: the fool in the argument is yourself who just will not accept the obvious that others have pointed out. Your pathetic attempts to belittle their point is childish and pointless. I B Wright (talk) 19:00, 2 March 2010 (UTC)
What a delightful alias. Wrong answer, of course. It's too bad Wikipedia editors don't work for UL, or CSA, otherwise there wouldn't be approval stickers on the backs of so many portable TV sets - many of which display this *exact* behavior. The consumer is *expected* and *required* to come in contact with the TV rabbit-ears antenna during normal operation of the set and the listed Wikipedia paragraph only explains the "buzz" you get from the antenna. Sure it's live, but it's harmless - so says CSA and UL and whatever local inspection authority approves appliances in your part of the world. --Wtshymanski (talk) 19:07, 2 March 2010 (UTC)
Read my point about the isolation circuit again. Have a look at the schematic for any AC/DC TV set, and you will find it in the antenna circuit. Also for any radio which has an external antenna connection. Since you are so determined to have your stupid advice in the article, you will doubtless be able to provide a valid citation for the technique (a citation is compulsory for anything that is added to an article). In the event that you do not do so, then it will be deleted as Original Research (prohibited by wikipedia policy WP:OR). Edits are also required to be by consencus, and so far you are alone -v- 3 contributors who have stated that your edit should not be there (WP:CONCENSUS) thus is is entirely correct for anyone to delete it and wrong for you to keep reverting it. Also, as stated, Wikipedia should not contain 'How to' information (WP:NOTHOWTO), though your advice would have been far more appropriate in this article. I B Wright (talk) 12:50, 3 March 2010 (UTC)
I remember you. You're the kinky tetrode guy.
This is ludicrous. Are you saying "'Tis death to touch the bunny ears!" - plainly not true. Why, just last night I twice manipulated the rabbit ears antenna on a TV set. You're a Nobel Prize winning electrical engineer, how many picofarads are there between the antenna terminals and the hot chassis? What is the reactance of that many pf at 60 Hz? Measuring on my own set with a 10 megohm meter, I found last night about 40 V on the rabbit ears - that gives 1/3 the line voltage across the meter, so 80 volts or 20 megohms reactance on the coupling capacitor. This is the reactance of 8 nanofarads. It's actually a bit less C than that, because I see about 5 megohoms of resistance when I check from bunny ears to plug.
There is no consensus for errors. --Wtshymanski (talk) 16:06, 3 March 2010 (UTC)
Who do you believe you are replying to? - certainly not I B Wright.
You have clarified your edit. BUT you failed to supply the citation requested by I B Wright in accordance with Wikipedia policy and consequently had no right to remove the [citation needed] tag. I don't know where you live, but where I live such a leakage would never have been tolerated and any TV set exhibiting that degree of leakage would fail type approval testing. I strongly suspect that the effect you describe is something that you yourself have experienced (and your description and discussion strongly suggests this) in which case it is still original research. You must now provide a valid citation that this is a real world phenomenon that is both known and documented - I certainly don't know of any. If you can't provide a valid citation within a reasonble period then the material will be deleted as original research - in accordance with Wikipedia policy. 86.140.82.123 (talk) 18:14, 4 March 2010 (UTC)
How's this? Even a citation from the same country as your Intenet provider. All our toys have some leakage and it looks like my set would still even pass UK regulations for leakage. --Wtshymanski (talk) 18:48, 4 March 2010 (UTC)
Check out Slippery nipple for how-to information. --Wtshymanski (talk) 02:28, 5 March 2010 (UTC)
It's clear that the guy who put that site together knows as little about TV design as you do. No TV design that has been made in the last 25 years (and probably longer) has had a live chassis design. Since the introduction of all transistor TV sets, they have been equipped with flyback type switch mode power supplies. One of the essential features of such a supply is the inclusion of a transformer which isolates the outputs of the supply from the input. Even the regulation feedback from the output to the control circuit goes via an opto-isolator to preserve the isolation. The site that you cited runs on the incorrect assumption that there is some sort of direct connection. No modern TV set (at least here) will give any detectable leakage from any externally accessible input or output. No modern TV set provides any additional isolation for aerial or other inputs or outputs beyond the isolation transformer. Indeed in most parts of Europe an earth connection is obligatory. The transformer that provides the isolation is a fraction of the size of an equivalent powered mains transformer because if its far more efficient operation.
Your citation doesn't even support the material as you wrote it claiming that a full electric shock will be obtained from an antenna connector - that has no connection to the mains. I B Wright (talk) 08:48, 5 March 2010 (UTC)
(outdent) What is the relevance to this article? Do you have a point or (judging by your contributions history) are you here only to argue? --Wtshymanski (talk) 14:18, 5 March 2010 (UTC)
I have no idea what the relevance of open heart surgery is. But then you were the one who introduced it. 81.157.217.144 (talk) 12:21, 10 March 2010 (UTC)
I believe Wtshymanski was responding to my last point above, and demonstrated perfectly why attributions should be made correctly. When the next contribution is not correctly indented from the previous one, it becomes unclear which point is being responded to.
The point above is not relevant to the article, but was very relevant to the point being made. But since the subject has been brought up: both 'rabbit ears' antennae and the original esearch of 'tingling' from such antannae are totally irrelevant to an article on the All American Five which never featured such antennae. I B Wright (talk) 16:26, 20 March 2010 (UTC)

Variations, 12AU6[edit]

To reduce costs further sometimes a pair of 12AU6 pentodes was used, one as an autodyne converter (instead of a pentagrid converter) and the other as an audio preamplifier.

How did this reduce costs? Were the 12AU6s that much cheaper, or did they take the place of more than 2 tubes? This statement needs clarification.

They would have had to have been less than half the price of the two tubes that they replaced (that is: the tubes; the tube holders; all the extra components required and the extra labour required to install them). All highly unlikely and as the claim is unsourced, I have deleted it. 109.156.49.202 (talk) 15:25, 19 October 2011 (UTC)

Tube heater voltages[edit]

Our resident self proclaimed owner of Wikipedia Wtshymanski keeps editing the article to say that the total heater voltage is less than the supply voltage. Since the radio has no series dropper resistor, perhaps Wtshymanski would care to tell us where the difference between the supply voltage and that which he thinks appears across the heater string dissappears to?

The total voltage of the series tubes (with the standard line ups) is rated at 121 volts (12+12+12+50+35), deliberately designed to be slightly greater than the mains supply voltage. The series connected heaters are connected directly across the incomming mains supply (have a look at a schematic - there's one referenced from the article). There is no series resistor to drop extra volts - a deliberate design goal. The only complication to the series heater circuit is the dial light connected across part of the rectifier heater, plus the B+ current being routed through that small parallel circuit.

Any discussion about a dropper resistor being required for the European market is superfluous as that particular set design was never marketed in Europe. Although other AC/DC designs were marketed, this article is specifically about the All American five and not AC/DC sets in general. 86.159.159.194 (talk) 17:23, 12 November 2012 (UTC)

questions[edit]

1.) Computer power supplies had 115/220 switches for use in Europe. Hasn't European power been 220 volt 50 Hertz for quite some time? Wouldn't a 117 volt filament string be inappropriate? 2.) Schematics listed give "T47" or type 47 bulb for dial light, it is 6.3V .15A; not listed in the article but part of the AA5 set. 3.) '4 tube set has no IF' doesn't make sense with TRF sets at the time that used IF or RF stage as an audio amplifier also. In fact using a smaller bypass capacitor on the AGC allows amplified audio to be captured and negating need for IF amp. 4.) Mark of AA5 was capacitive coupling (not noted) but interstage audio transformers cost less than vacuum tubes. 5.) 1N21 diodes came out in early 40's and 1N34 diode was introduced in 1946. The audio triode was a low gain stage. The IF stage, the second IF transformer was for improved selectivity, usually unecessary by FCC regional frequency allocation. 6.) Later AA5 sets used ferrite rods which were higher Q (more selective) and acted as a much better antenna (stronger signal). 7.) The "shock hazard" of the hot chasis is overblown. One would need to be touching a ground at the same time as touching the radio, not impossible but unlikely. I looked at some of the schematics and didn't see a resistor and honestly cannot fathom a need for one. There are capacitors from the chassis to the line cord presumeably to improve RF reception from a long wire antenna, I saw .05 which would give a fairly high impedance to 60 Hertz AC, definitely a timgle. The .1 microfarad 200 Volt capacitor mentioned would have bee rare and more expensive that the usually cheap parts used in the AA5. Shjacks45 (talk) 02:48, 18 January 2014 (UTC)

"Hasn't European power been 220 volt 50 Hertz for quite some time? Wouldn't a 117 volt filament string be inappropriate?"

Note that the article is "All American Five". It was very common in the US and Canada. This specific design was NOT used in Europe.

"shock hazard" of the hot chasis is overblown

I grew up with these things, often in kitchens or basement "rec rooms". They were also found in bathrooms (though never in my house). The shock hazard is real.

Your other points seem to be a general discussion of the topic, not the article. Two IF transformers are generally needed, despite channel allocations, and AGC does not eliminate that. True the 1N34 diode is very old, but was a specialized radar part, and in some ways not as good as an extra wire near an existing cathode. Your point about capacitive/transformer coupling is unclear here.

PRR (talk) 21:59, 19 February 2014 (UTC)

"Manufactured until the early 60s" needs verification?[edit]

There has to be a line drawn somewhere on verification of statements. Some statements are quite important; in that the credibility of the article can hinge on the validity of certain sources, and only if those sources can confer truth to those statements. However, the above-mentioned statement is not that critical, nor is it easily verifiable from any source, therefore the use of the "unreliable source" tag is over-used and inappropriate in this case.Landroo (talk) 15:21, 13 May 2017 (UTC)

Untagged, found another reference. People love tagging. --Wtshymanski (talk) 17:49, 14 May 2017 (UTC)