# Turning the clock back



## Shipbuilder (Jun 30, 2005)

A couple of weeks ago, I decided to design and build a three valve radio in the style of the 1930s. After a lot of thinking, experimenting, building it rough and finally re-building it neat, it was completed earlier today, and works a treat. The three valves are each between 80 and 90 years old!(EEK) A lot of the components are modern ones made up to look like vintage types. Most of the circuit was done in shiny brass strips or brass rod, on a French-polished baseboard.
Was glad to complete it , as I was beginning to get a bit fed up of it! The coil cans are stainless steel salt-sellers
Bob


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## hughesy (Dec 18, 2007)

lovely job mate all the best Hughesy


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## GW3OQK (Jun 10, 2010)

Well done indeed Bob. Give us a circuit description please. I can't resist a guess. Freq changer, IF with reaction and audio amp. 

How about taking some turns off so it will go to 1.85 MHz and making a 1 or 2 valve CW transmitter. Hint. Google for antique wireless tube transmitter
All the best
Andrew


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## Shipbuilder (Jun 30, 2005)

Thanks for replies. It is not a superhet, just a three-valve TRF. RF amplifier followed by detector and audio amplifier. The coils are just tiny 47uH RF chokes in the bottom of the salt sellers that are just for show. It may go up to 1.85mHz, but I haven't checked its coverage yet! Haven't got a HAM licence, so can't go transmitting!
Bob


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## Mad Landsman (Dec 1, 2005)

Very nice project - Just needs a case, with windows, to keep the dust and fingers off the works. 
(and maybe polish up the variable caps......(Thumb))

What kind of power supply are you using?


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## Shipbuilder (Jun 30, 2005)

It isn't very dangerous! The High Tension is 100 Volts, and the Low Tension is 2 Volts from a sealed lead acid battery. The 100 Volts comes from a variable power supply that I made some time ago, but it will work from 10 small 9 Volt batteries clipped back to back. The total current consumption on the HT is only 6mA, so it is not going to run the batteries flat in a hurry! The capacitors were the cleanest I could find, and my first priority was getting it working. I may clean them up at a later date, but it is 100 F oustide today (In Lanacashire(EEK), so couldn't summon up much energy!
Bob


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## BobClay (Dec 14, 2007)

Very neat job (Thumb)

Now that's what I call a real radio, none of yer pansy southern jessie low tension voltages. Something that'll make your teeth rattle if you touch the wrong thing.

(Jester)


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## Basil (Feb 4, 2006)

Beautiful!
A few years ago, I was in someone's house and they had a factory-made modern but retro audio amp with thermionic valves on display.


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## gwzm (Nov 7, 2005)

Nice job and pure nostalgia for me! It was receivers built like that by my dad that got me interested in radio and later on becoming an R/O. Designs by John Scott-Taggart and published as blueprints in Practical Wireless with never a soldered joint in sight. We didn't have electricity at home in those days so the HT came from an Ever-Ready 120V dry battery made up from individual 1.5V cells connected in series and resembling a small breeze block and grid bias supplied by a 9V dry battery with taps every 1.5V. LT for the heaters was supplied by "ac***ulators". There were two of them so that one went to the local radio shop to be charged each week whilst the other was in use.
Happy days


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## Duncan112 (Dec 28, 2006)

Beautiful Bob, you are a true craftsman, now I can see it - no photos on the version on my phone!!

Basil, here are the valve amps - not cheap and I'd imagine require frequent dusting to prevent the smell of burning fluff but a real conversation piece http://www.fatman-audio.co.uk/


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## Bill Greig (Jul 4, 2006)

Beautiful, nice job Bob.


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## Varley (Oct 1, 2006)

A good job must always look to be a good job or it doesn't qualify.

This one certainly qualifies.


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## Shipbuilder (Jun 30, 2005)

Thanks. Funny thing about museums, their official job is to show the present generation what things were like in the past. But more and more, I see old and well-loved exhibits disposed of, to be replaced with modern "touchy/feely" items to keep the modern public amused!(Jester)
This is very common with maritime museums as well!
Actually, I don't do a lot of radio, but the urge surges up from time to time, and I probably will not touch it again for months and months!
Bob


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## Varley (Oct 1, 2006)

Shipbuilder said:


> Thanks. Funny thing about museums, their official job is to show the present generation what things were like in the past. But more and more, I see old and well-loved exhibits disposed of, to be replaced with modern "touchy/feely" items to keep the modern public amused!(Jester)
> This is very common with maritime museums as well!
> Actually, I don't do a lot of radio, but the urge surges up from time to time, and I probably will not touch it again for months and months!
> Bob


How true. Collections should, if possible, grow but that doesn't mean that the earlier history should be jettisoned. I don't think that you have many months left to see the fabulous Measurement of Time Gallery at the Kensington Science museum. It might well be said that the Worshipful Company of Clockmakers museum which effectively replaces it (on the floor above) does encompass the entire and developing clock and watch history but is compressed. Somehow a paperback version.


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## Shipbuilder (Jun 30, 2005)

I finally got round to drawing the circuit diagram, and producing it as a blueprint. As the set was built by trial and error, the circuit developed as it went along with lots of adjustments and alterations along the way. The rather unusual wiring of L1 and L2 was initially a mistake, but it worked very well. When I spotted it, I corrected it by connecting the grid of V1 to where I had intended it to go, the right hand side of L2. But, although it worked, it was nowhere near as good as with the "incorrect" wiring, so I reverted to the "wrong" wiring as shown. I have no idea why it should be so, maybe somone with more knowledge on theory can explain it!
Bob


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