Hi Guy's,

Does anyone have a diagram of an AM Radio that uses tubes that are easily available? maybe a 4 or 5 valve and dare I say it a solid state rectifier?


Steve

Well, the tubes for an All American 5ive are easy to come by (at least in the USA).

Oh, I'd sub a 6AQ5 for the 50C5, 6v tubes for the 12V ones, and a 6X4 and a power transformer.
AWA Radiola B15 is essentially that.

http://www.kevinchant.com/uploads/7/1/0/8/7108231/b15.pdf.

Thanks Wa2ise,

Where can you get hold of stuff like the oscillator coils etc for a build like this?

Steve

Hi Steve

No Idea on IF coils lest wise in Oz, Best source is junked radios I suppose and you can repair them if the coil its self isn't kaput

EDIT 2The linked PDF Circuit would be the go to play around with the idea Steve

I didnt realise that wasn't that radios circuit My Apologies Wa2ise (I just zeroed in on the Circuits lack of transformer)

EDIT I just notice something I am not now Sure if I can call it a Live Chassis per say... But I'll let my comment stand for the moment As Is

(The only was this could be considered safe or safer is if the mains in no way contacted the Chassis..and any caps between the circuit and Chassis were mains certified safety caps)

I'll check this later.... very late now......I have and the links may best explain it

=====
Edit 3 Just on what I am talking about in the post a few links say it far better then me ...its just a point for beginners to watch out for thats all (of which I thought you were one Steve but seems not the case if you been building valve amps)

thought bear in mind in Ref to US power system, same basically still applies, thought we have (for the most part that I know of) always use a polarized plug top but as Marc points out below a lot of the time these old radios were feed from light sockets which weren't with *connection polarized or even earthed in the early days
(* meaning they could go in either way like a light bulb, even if a standard was followed, which probably would really be only that the Active be switched to the Lt fitting in those days...but thats getting into the realms of lic electricians not really for this forum)

most all device works perfectly well with Active Neutral transposition and that is what make them so dangerous
(also US colour coding can easily be mistaken for a neutral wire here Black as neutral or white as a switched Active...were as US wiring black=Active white=Neutral, thought that applies more so to electrical wiring but does carry over to device mains wiring)

Anyway Links

http://www.antiqueradio.org/safety.htm

http://www.geojohn.org/Radios/MyRadios/Safety.html

Another 2 links that maybe an interesting read, thought I haven't read them all fully yet..and as I said its a worth studying the circuit, as a lot applies to other radios and circuits

http://www.angelfire.com/electronic/funwithtubes/AA5-1.html


http://www.wa2ise.com/radios/12ba7.html

Thought the opinions are those of the Author and I am not educated enough on valve radio to offer advice for or against..any idea put forward

Just use your own grey matter and research or even post to draw your own conclusions

=====

Original post (comments in regard to the Schematic only)
---

On that Set above Id highly recommend you NOT attempt something like that

That whats known as a LIVE Chassis job (or potentially)...these days if not illegal defiantly frowned upon though its one very common Radio I believe

if you were to attempt something like that you could get a 240 to 120 Volt step down transformer

I mean one that * ISOLATES you from our 240 Mains but the thing is still a death trap
(* has 2 separate windings not an Auto step down transformer...)

For any set like this Id advise (if not legally required) a 1:1 transformer, if it was an OZ radio (240/240...ok we are now suppose to be 230Vac...I measure here 245 Vac last night)

whats actually happening there is Direct Rectification of the Mains Voltage...this was done by manufacturers to save cost on transformers and make things cheaper but the down side... its dangerous

In The US there power system is less voltage then ours (and people assumed safer, its not) and unlike now where they have finally woken up to the Fact Active & Neutral should be on a polarized plug and they should earth things in the bad old days that wasn't the case.(and you had a lot of people electroplated )

Not that the DC voltages in any Valve equipment wont kill you and always be aware that you are playing with a red belly black snake...if you want to stay alive...one hand in pocket at all times
always make a serious point to make sure its disconnected and the power caps are discharged before sticking your hand in there to do anything while trouble shooting

You just dont want to up the ante By having mains potential in there as well by having the switch in the neutral side and the chassis running HOT at 120 Vac

This still could be the Case with Oz sets but most all of ours do use a beefy transformer so it will only be the primary side that might still be alive, That to me is risky enough
----
its probably a good circuit to delve into in theory and you will find heaps of info on them to be sure
it just something personally I wouldn't want to cut my teeth on

The US is probably a place you may find IF cans but I dont know ...it would be nice to know if someone actually makes them...but it wont be any manufacture of the present day I dont think (or know of anyway)

you can get power transformers and output transformers (at expensive prices here) but other things
Ebay, used or if your lucky unused is probably your best bet

But others here may know of sources and chime in to help....

It would be nice to have source of parts to roll your own for sure Agree

Also you might want to look at the later circuits that use thing like 6AN7 etc they will probably be more plentiful
later valves I mean not the Octals..still there a few of them around too (also more junk with the later sets Id imagine)


Anyway mate not much help just some warnings and hows life in Dirty old Stanmore....all around the inner city was my old stomping ground...many years ago ...but its all changed drastically since I was there...

Cheers mate

PS there's still a lot of valves around but no one makes radio valves anymore...there are people that can supply without having to jump on to Ebay Auctions..in fact quite a few world wide

Thanks DJ Oz,

Yes live chassis is a dodgy thing to be sure. I did find this one: http://ad7zj.net/kd7lmo/ground_am_tube_radio_hardware.html. Although I looks like it's not really sorted. I do have some Nixie tubes though!

What I wanted was a circuit using maybe Hammond transformers for the mains and maybe the output and (all available from Evatco) using valves that are available for guitar amps for the audio circuit, not sure what I could use for the IF stage etc and as I mentioned the oscillator coils.

Stanmore is going fine. Their building too many home units though. Cramming in as many as they can on tiny blocks.

Steve

Hot chassis radios, in the later years of production, were installed in plastic or wooden cabinets, with plastic knobs designed to not be removable. Idea being that the radio circuits are completely isolated from the user. Cold chassis sets still have some hot wiring inside anyway. Thus you still need the cabinet.

PC power supplies are partially "hot chassis" (the primary side rectifier and switching transistor).

The circuit posted is a reminder that there are instruments, with transformers that have managed to slip into this country with metal cases,wired in a similar manner to the one posted. which actually (the way it is drawn) suggests its a later type with the mains "floating".

These and the metal case are not intrinsically safe as they have capacitors going from mains to the metal case, chassis, or both. Rarely are the capacitors rated, or "approved" for use on the mains & as most of us know paper caps leak and can fail short.

The "X" type "approved type that are normally plastered with symbols like UL are designed to fail open an have high punch through voltages and normally have an AC rating not DC on them.

The metal cased instruments with transformers I normally ground, by getting rid of the two wire cable & grounding the cabinet. One great danger, as pointed out with "hot chasses" is that there was no guarantee that either the plug or socket was wired to any convention (as we have) and many two pin plugs, especially 110V ones, and don't forged many radios here were on lighting bayonets, could be inverted and you never knew where Active (Line) was lurking. This meant that the cap, resistor & wire put mains voltage onto the chassis.

The Transformer valve equipment needs to be understood, especially Professional audio. I have a Philips Line amp irrespective of what is shunts out, 100V line. This particular one has variants with two, to six, 6CM5's in Push Pull, massive transformers, and around 100mA per valve and the plate on top.

Not the sort of thing for a novice to be playing with.

Marc

Hi Steve

I'll look at your link soon (I just did)

EDIT oh I see now that interesting

I'll read it properly later but I see your interest there ..

Could be Fun

(I'll fix any typos later..late way late)

but yeah I didnt mean to scare you or anything its just a trap for the unwary thats all...a lot of portables seem to be done this way too and I think theres a few here that fall into that Category

Have a look at this Video by AllAmericanFiveRadio

https://www.youtube.com/watch?v=FT41gCPEEic.

Note the schematic and what he says about tieing the B -(return or floating ground if you like) to chassis

Yeah the same happening up here mate building everywhere ..seems the done thing now are Granny Flats that are more Mac mansions... apart from 2 houses go and 5 town houses appear..I am going down that way with luck next week I'll be in Newtown/ St peters area

Wa2ise
your absolutely right and I agree its just from some of steve's post I think he's is more on the beginner scale of things thats all

Yes and very True AT ATx etc switchmodes do directly rectify the mains for starters so its not a not done thing today just with radio's a real trap and I think in the UK its actually illegal now and they do need to have an isolation transformer fitted but not sure on that point..it is I believe a recommended thing these days but you 'd probably know more if your states side based as I think that is an often done type of circuit

The thing with switchers and I guess this is what you mean by "partial" is that they do use a High Frequency transformer for isolation of the secondaries.....these days too they have been brought into line with regulations on "power factor correction" etc and so now a computer psu is a safer beast then in the past but as you said Marc on capacitors... how the hell some of these 30 dollar old AT type even got into Oz is a wonder and its sad that our regulations arn't being up held these days with so much potentially unsafe gear getting in

Still with regard to my EDIT in bold and I've yet to check, but I wasn't sure on that point of it being a floating supply with no actual ties to ground but thats probably cause all I have been working on of late use the chassis as a return path for the heaters and as common ground but as marc said in those days they weren't in them selfs ties physically to the ground safety wire but sure may well have been by the Antenna

Anyway Steve it just I rather you become an expert in time not worm food thats all mate & why my warnings, but radio like that configuration are fairly common in the world so it is a point to bear in mind with what lands in your lap as a project or repair

Yes there are high voltage power transformers you can use and the outputs too (apart from the ridiculous prices we pay for them..but I once read a break down on taxes etc and it made sense of why we do

The 6V6 is probably the best Audio tube to grab as they are plentiful just dont go looking for RCA Black plates or you'll pay through the Nose all the guitarists want them...in new tubes grab a tung sol reissue dont pony up for the new mullard you'll be buying the same tube as far as I am concerned ...maybe they cherry pick them but doubt it...still theres heaps of NOS 6V6 tubes
to be had and from what I understand they are a robust tube..lots of Radios use that as an audio tube

IF cans, coils tunning gangs etc and even variable capacitor mate well I think you back to junk box parts really thought you can source NOS RF IF/Det tubes

What you might want to try is the over seas places like Just Radio or Radio Daze etc they might have some parts....but as I said I dont think anybody makes these parts.... at best maybe you'll find a a person that does but I haven't as yet and if so I cant imagine they be all that cheap)

Some parts you could if you get you skills up make your self I suppose like coils etc but I think thats kinda an art in its self too...still I was looking into it

I suggest you get you hands on a copy of the "Radiotron designers Handbook" ( a 50's edition) another if you can is "wireless coils, Chokes and transformers By F J Camm"...also not so cheap but see if you can buy the "Radio & Hobbies" CD from Silicon Chip ...it has all the old issues on the disc from the Days of Valves so I am sure there many useful Articles on it and probably a few projects on building radios thought the part these days are long gone

There is a massive (or was) book shop up on King Street that deals in second hand books just before you go down City rd I think it is pass the uni...not far after the road that goes down to the hospital (the name escapes me now)

Anyway there heaps of infor out on the net too and many books in PDF...if you want some links let me know...

With valves mate we probably should have been born 50~ 70 years ago ...there day is done but they are still beautiful things...

PS the Article on that Valve Amp part 1 is in the November 2014 issue of Silicon Chip.

Nobody much uses old TV tubes & you can normally get these by the bucket load. 6BL8 was a universal widget valve that was used all over the place. It is actually a frequency converter that can go to several hundred MHz. So several could be used all the way to the output where valves like 6BM8 can be used.

There are a few of these in an old 2.5 MHzHeathkit CRO I have. Where a new SS one dies at just over its 10MHz. The valve one just looses resolution as it continues well out of the spec. as the valves can handle it.

Marc

Hi DJOz,

I know the book shop, it's still there if that's the one.

Have a look at this Variable cap. Does it have enough range?

http://www.ebay.com/itm/High-Voltage-Air-Variable-Capacitors-22-360pF-1KV-Amplifier-Tuner-REPAIR-DIY-/151216034189.

I used to build guitar amps. Mostly for Bass guitar. Copies of the Hiwatt 100. These are pretty simple. no tuning stage!! I play the bass but I use a amp that it solid state ;) the valve jobs are way too heavy to cart around. Got interested in radio when the Mrs got me a Kriesler for a wedding anniversary so she can't say too much about all the old radio's.......it's her fault!!

Steve

Got interested in radio when the Mrs got me a Kriesler for a wedding anniversary so she can't say too much about all the old radio's.......it's her fault!!

You lucky, lucky man. Don't lose that one, she's a keeper!

Hi Steve Sorry was in old Sydney town on another mission LOL, So only just got back

I didnt realise you had been building your own Valve Amps so thats a plus

One point as noted above to watch out for is heater wiring..valve amps tend to float the whole heater line and use twisted wire to feed the tubes ..the Valve jobies I looked as so far...every one uses the Chassis as a Return Wire, this as I understand it may lead to issues with the 6X5 valves in regard to H~K leakage but thats another discussion..again just a point to note in the grey matter

Well mate sadly I am not well versed enough to say if that tuning gang is of use...I would expect what you use depends on the design of the circuit and what values you can change if need be to accommodate a tuning gang

Sadly these things aren't cheap really and you have to watch out that the plates arn't damaged, meaning they dont short when meshed

There is a circuit for an RF Generator That I looked at the parts list for and the tunning gang was available as NOS item here at $70 AU needless to say I was going at that price thought I guess since they are not longer made it was probably worth it, if you needed one desperately

http://www.vintage-radio.com/projects/signal-generator.html.

heres a build of it ..rolled his own version & used with a frequency counter (which is the more ideal way to go)

https://yo4hhp.wordpress.com/2011/10/31/simple-rf-generator/.

There is someone on Ebay that tends to sell second hand ones from radios... Tested, cheaper but UK based so you have shipping as well...its pot luck what they have at the time thought

So pillaging old stuff is the cheapest option...Be the "Dumpster Diver" for sure I think with old tube stuff is the way to go..put the word out to family and friends

I did track down a supplier of old IF's in the states ..they are a bit anal in there ordering process and you have to buy $30 US plus shipping from them...so that kinda expensive with out nose diving dollar
(link not handy at the moment but will find it and add it later)

As Marc has pointed out above with TV valves...just cause there are certain Valves that are used for certain purposes doesnt mean another Valve cant do the same job as you need ..you just need to know the characteristics of and adapt or design to meet the Valve requirements for your purpose

So you'll probably find circuits in home brew jobs that use valve like this

Basically "Junk is Good"

Your Missus is a good Lady not to many would even think of that or put up with it lol.

I do have to agree thought Valves are addictive stuff & understand your enthusiasm for Rolling one of your own.

I dont have the Article but I believe Silicon Chip did post a design or at lest info on a design for a 3 tube Radio in the Jan 2008 issue..I dont have it but you can buy that issue via on line access at the lest (just found the opening page).

Aussie 3 (yeah and the name a direct dig at the All American five).

http://archive.siliconchip.com.au/cms/A_109837/article.html.

If you interested, and maybe theres some discussion here but I never searched for any here so dont know.

I am sure there are a few here that have looked at it and it design and probably have comment on it in their opinions...anyway...I was just looking on my phone while I wasn't here so I do have a few more links if I can find them on the phone.

Hope some of this helps you anyway

Hi Guys, thanks for the links etc. I think I'll have a go at building the Aussie 3. Looks OK. Not sure about getting some of the parts but I'm looking into it.

Steve

Hi Steve
Haven't actually looked at it yet but finding heaps of stuff on building you own on YT.

There is a Video By All American five that gives a running description of a variation of the Circuit posted... That maybe interesting in understanding it, also the general Idea

https://www.youtube.com/watch?v=zknp0FOkPXU.

(oh he keeps says 455 Hz he means kHz)

but with radio there more then one way to do things too and different types of receivers.

Anyway find some junked sets and build your own frankien~radio

Cheers