AM Valve Radio - schamatic and valve information needed!

TiagoSilva · Mar 25, 2011

Hi,

suddenly I had a vintage outbreak and I decided to build a simple AM valve radio, I already bought an air variable capacitor from ebay (lol) and I'm currently looking for some schematics.

My main idea is to build an experimental AM valve radio with a very selective coil and a gang (2) air variable capacitor.

I expect to had switches to select the capacitance and the inductance, giving a huge selection range, it need not to be perfect, I just want to make it like they made them in the old days, including, no p.c.b., just wires and connectors!

If the end result gets very good I might also ponder using it to test SDR Dream But thats not a requisite.

I just want a easy to make AM Valve radio

Cheers!

Nigel Goodwin · Mar 25, 2011

Why don't you just try google?

Dave's Homemade Tube Radios

Reloadron · Mar 25, 2011

Pretty cool site Nigel.

Ron

TiagoSilva · Mar 25, 2011

Nigel Goodwin said:
Why don't you just try google?

Dave's Homemade Tube Radios

Thanks Nigel,
I did and thats why I posted here... Because I didn't find anything good, like 6,3v heater valves... I have a Elektor article that uses an ECC88 (if I'm not mistaken), that will be my primary design guide, if I don't find a another one... I just want to cross schematics and get the basics for building a simple AM radio...

High voltage heater valves are a huge risk when using for DRM decoding on a PC sound card.

Nigel Goodwin · Mar 25, 2011

TiagoSilva said:
Thanks Nigel,
I did and thats why I posted here... Because I didn't find anything good, like 6,3v heater valves... I have a Elektor article that uses an ECC88 (if I'm not mistaken), that will be my primary design guide, if I don't find a another one... I just want to cross schematics and get the basics for building a simple AM radio...

ECC88 is (or was) a double triode intended for VHF tuner frontends.

High voltage heater valves are a huge risk when using for DRM decoding on a PC sound card.

Why on earth would you want to do that?, and the heater voltage makes no difference at all to any risk anyway.

TiagoSilva · Mar 25, 2011

Nigel, true, my bad, it was not an ECC88 but an ECC86...

DRM was intended to be used with SDR... But, if you tune and stabilize the signal well enough (think of something like... solving a Rubik Cube lol) you can decode it like any SDR DRM Radio.

My main idea is to listen from VLF to HF...

TiagoSilva · Mar 25, 2011

And forgive my ignorance on valves, but the only times I used valves, was when I was a kid... On target practicing lol

Reloadron · Mar 25, 2011

Finding good tube (valve) receivers on Google sometimes takes a little finesse. Google terms like Two Tube Superheterodyne Receiver or Three Tube Superheterodyne Receiver and you will get circuits like this one. The B+ is 150 volts and the tubes are 6.3 volt heaters. Tubes in most of these older circuits do indeed run high plate voltages with the referenced circuit at 150 volts actually being low. The ECC88 / 6DJ8 is a dual triode valve and I may be wrong but would likely serve better in the amplification stages of audio than in the front end and detector stages of a simple AM radio. I may be way off on that note.

Building the power supplies for some of these classic radios also involves a little work. The parts can be found, just need some effort.

A really great and old book I still cling to is the Radio Handbook Ninth Edition which was the original printing in 1942. Great books like this can be had on Ebay relatively inexpensive loaded with the theory, circuits and how to information. Additionally old ARRL (American Radio Relay League) and other old ham radio publications are a gold mine.

Ron

Reloadron · Mar 25, 2011

TiagoSilva said:
And forgive my ignorance on valves, but the only times I used valves, was when I was a kid... On target practicing lol

I wish I had half of the valves I gave away or used for target practice.

Ron

TiagoSilva · Mar 25, 2011

Reloadron said:
Finding good tube (valve) receivers on Google sometimes takes a little finesse. Google terms like Two Tube Superheterodyne Receiver or Three Tube Superheterodyne Receiver and you will get circuits like this one. The B+ is 150 volts and the tubes are 6.3 volt heaters. Tubes in most of these older circuits do indeed run high plate voltages with the referenced circuit at 150 volts actually being low. The ECC88 / 6DJ8 is a dual triode valve and I may be wrong but would likely serve better in the amplification stages of audio than in the front end and detector stages of a simple AM radio. I may be way off on that note.

Building the power supplies for some of these classic radios also involves a little work. The parts can be found, just need some effort.

A really great and old book I still cling to is the Radio Handbook Ninth Edition which was the original printing in 1942. Great books like this can be had on Ebay relatively inexpensive loaded with the theory, circuits and how to information. Additionally old ARRL (American Radio Relay League) and other old ham radio publications are a gold mine.

Ron

Ron, Thanks a lot too The terms I used in Google were "AM, Radio, Valves, Triodes" thats why I kept getting modern valve amplifiers and some strange results...

I will try to find the books

I am living in a friend's house and he also likes electronics, he has a store room full of old stuff and... a shoe box full of valves lol now its all about testing them lol...

TiagoSilva · Mar 25, 2011

I should share my Elektor article... Its not fair ihihih

Reloadron · Mar 25, 2011

I am living in a friend's house and he also likes electronics, he has a store room full of old stuff and... a shoe box full of valves lol now its all about testing them lol...

Testing them is easy. You just take them to the corner drug store and use the tube tester and if the needle on the meter shows bad they sell you new ones.

The scary part is I remember doing just that.

Remember that Google is your friend but with stuff like this can be fussy about the phrases.

<EDIT> Nice little circuit worth building and no HV which is sweet. If you can't find the tube a 6DJ8 will work. </EDIT>

Ron

AM Valve Radio - schamatic and valve information needed!

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