The Future of Radio :)

Discussion in 'Wireless & RF Design' started by Art, Oct 20, 2013.

  1. Art

    Thread Starter Distinguished Member

    Sep 10, 2007
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    Doesn't leave much room for this :)

    Got the amp today:

    [​IMG]

    (AM & SW)

    [​IMG]

    I do need to replace a valve, and all electrolytic capacitors I imagine.

    Can anyone recommend any good radio serials?
     
  2. bertus

    Administrator

    Apr 5, 2008
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  3. MaxHeadRoom

    Expert

    Jul 18, 2013
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    It is usually recommended you replace ALL caps with the exception of the mica type, maybe.
    Some of the carbon resistors may also be suspect!
    Max.
     
  4. #12

    Expert

    Nov 30, 2010
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    All electrolytic caps need replacing and all resistors over 100K will be out of range (on the high resistance side). All pots will need spray cleaner or replacing.

    Watch out for the glass part of the tubes breaking off where they are glued to the plastic base. Lift them by the plastic base.
     
  5. MaxHeadRoom

    Expert

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    If you search for early superhet receiver you should get many hits.
    http://oldradios.co.za/features/38-informative/142-example-superhet-circuits.html
    I assume you are in UK or one of the 'Colonies'?
    I would replace the waxed paper caps also, they have a habit of changing value or leakage over time.
    Max.
     
  6. Art

    Thread Starter Distinguished Member

    Sep 10, 2007
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    I'm in Australia.
    This is actually a piece of glass:
    [​IMG]

    Unfortunately I don't have it's cabinet, but still worth the effort I think.
    I've already joined a vintage radio forum, I will need help identifying components.
    Full schematics are out there, so that's a good thing.

    I would prefer it were AM only. That's another whole radio in it to worry about.
     
  7. WBahn

    Moderator

    Mar 31, 2012
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    That's actually pretty amazing. A time when radios came with the station identifiers on the dial face. It seems really amazing given that there are 46 stations on the dial, so presumably by this time it would/should have been apparent, at the very least, that new stations were almost certainly going to be added. It provides a hint of a glimpse into the mindset of the time, though just what the glimpse means is very hazy.

    I wonder what cultural anthropologists would have to say about it? Knowing them, I'm sure they'd deduce all kinds of things about our diet, our life expectancy, our clan structures, and our mating habits -- at least that's what they seem to do anytime they find a bone fragment in a prehistoric campfire.
     
  8. Art

    Thread Starter Distinguished Member

    Sep 10, 2007
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    Well 4IP, first on the third line, I remember, It's my local station 4 "Ipswich".
    By the time I listened, I think it was called Radio 10 by then.
    The "4" prefix is my state (Queensland), it has always been that way.

    Out pocket transistor radios stopped with that, and just printed AM frequency,
    but this is very common in valve/console radios at least around here.

    I have found out it was made in a factory an hour drive distance from me.
    I know where to take it for servicing now.

    What are the rectangular metal cans on top, and if they are Capacitors,
    why do they have four leads?
    In the pic in first post there are four of them on top.


    I could get it to come up as good as I want to...
    just depends how far I'm prepared to pull it apart:

    [​IMG]

    The pots are just props in this pic... I'm keeping the knobs, but it needs new pots.
    (these are just the wrong values, but otherwise close.

     
  9. MaxHeadRoom

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    The four cans are the Intermediate (IF) Transformers these are used as it is more efficient to amplify a known fixed frequency, something around 475Khz, rather than one that varies with station tuned to as forerunner radio's did.
    Search for Superhetrodyne receiver and it will come clear.
    Max.
     
    Last edited: Oct 21, 2013
  10. #12

    Expert

    Nov 30, 2010
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    Don't forget religion. Anthropologists thing that anything people gather around is a God being worshiped. Problem is, they should wait until they find a television.:D
     
  11. KL7AJ

    AAC Fanatic!

    Nov 4, 2008
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    I used to do complete "capacitectomy" operations on radios of this vintage, but it isn't always necessary. Generally only the main power supply filter capacitors need if. If you do that and it still acts flaky, replace the electrolytic coupling caps. (I've never seen a MICA cap go bad in 50 years of radio fixin' :)

    Eric
     
    Art likes this.
  12. Art

    Thread Starter Distinguished Member

    Sep 10, 2007
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    Thanks Eric, Yes, they are telling me on links from the radio forum,
    what caps to replace, and what is best to stay away from.

    I'm likely going capacitor shopping today.
    I could get started while waiting for the valve.

    Why was it never Earthed?
    The original cable is only two strand, but it has a metal chassis.
    I'm pretty sure that makes it illegal to plug in to mains in my country.
    But even in the 50's metal cased appliances were earthed I would have thought?

    I hope you will check in every now and then.
    The radio forum seems to be helpful, but very slow.
    I'm learning as I go here... I don't want to make a mistake with a
    replacement, so I'd rather take shots if need be, and be real sure.

    I'm very committed to physically cleaning it up as well.


     
  13. Art

    Thread Starter Distinguished Member

    Sep 10, 2007
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    This certainly looks genuine to me:

    [​IMG]

    It just leads me to suspect there's a reason for not Earthing it,
    I mean how easy was it to connect the third wire to the chassis?

    You'd be surprised how nice the original cable came up (not the plug),
    and would have been nice to use it, but I don't think I get to use a two conductor mains cable.
     
  14. MrChips

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    Oct 2, 2009
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    Most likely the original plug was a 2-pin plug.
    Someone changed the plug to fit the 3-pin outlet.
     
  15. Art

    Thread Starter Distinguished Member

    Sep 10, 2007
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    But then why not Earthed in the first place by the manufacturer?

    There is an antenna and Earth connection at the rear, and the Earth is direct to chassis.
    If that is what's happening, it still seems poor standard at the manufacturer's end.
    I don't know if we are allowed to provide our own Earth today, but suspect it wouldn't fly ;)

    I guess the answer is I earth the chassis, but the cord is another part that has to go :(
     
  16. MrChips

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    Original household AC mains wiring was 2-pin conductor and 2-pin outlets. There was no means of earthing the chassis via the AC mains wiring. The manufacturer had no alternative but to leave it up to the consumer to earth the chassis via a separate connection to a grounding rod.

    Replace the 2-conductor cable with a 3-conductor cable and 3-pin plug. Connect the chassis to the earth conductor.
     
  17. Art

    Thread Starter Distinguished Member

    Sep 10, 2007
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    There is one more thing that came to mind.
    The dial is glass, the case and knobs are bakelite, and there's nothing else to touch.

    It's no worse than our light and power point switches :D
    but unfortunately I don't have that case. Otherwise it might be ok.



     
  18. MaxHeadRoom

    Expert

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    As MrChips said, both early UK and N.A. installations did not have an appliance grounding system in place for outlets etc, the Radio in question is isolated from the mains AC via the input transformer.
    Max.
     
  19. KL7AJ

    AAC Fanatic!

    Nov 4, 2008
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    Many radios of the era, especially AC/DC sets were known as "widow-makers" for that very reason. The National Electric code came later. :)
     
  20. WBahn

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    Mar 31, 2012
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    Holy Rabbit Ears!

    Many religions encourage/require people to have some kind of a shrine/alter in their homes. But I'm not aware of any in which you routinely see multiple shrines in the home which virtually every chair always turned toward it.
     
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