Building a tube radio

JECalvert · 16th July 2011, 07:14 PM

I'm a musician and I have alot of 6L6 and 12AX7 tube's lying around and would love to build a tube radio. Is it possible with these tubes?

Pano · 16th July 2011, 07:27 PM

There was just a link to a 12AX7 radio. Let's see if we can find it.

EDIT: Nope, it was 12AT7. But here it is anyway.
http://cool386.tripod.com/12at7/12at7.html

Eli Duttman · 16th July 2011, 11:20 PM

It might be possible to build an AM radio with a 12AX7, but its performance would be very poor. You would need a long wire antenna to get any kind of reception and selectivity is not good.

The single "bottle" FM circuit Pano linked is quite sophisticated and will do nicely on strong stations. For table radio use, a power amp in addition is necessary. The power amp could be built from a 'X7 and a 6L6.

kevinkr · 16th July 2011, 11:58 PM

Quote:

Originally Posted by Pano

There was just a link to a 12AX7 radio. Let's see if we can find it.

EDIT: Nope, it was 12AT7. But here it is anyway.
12AT7 super regen FM receiver

Very cool FM super regen, think I might want to build something based on this design..

Eli Duttman · 17th July 2011, 01:39 AM

Quote:

Originally Posted by kevinkr

Very cool FM super regen, think I might want to build something based on this design..

Technically, it's an AM setup used to slope detect FM. It is not immune to AM noise, but it is signal seeking.

The use of a single 'T7 section as both a grounded grid RF amp and a reflex common cathode AF amp is elegant. That triode isolates the oscillating detector from the antenna, provides some RF gain, and provides a fair amount of AF gain.

Miles Prower · 17th July 2011, 05:49 AM

Quote:

Originally Posted by JECalvert

I'm a musician and I have alot of 6L6 and 12AX7 tube's lying around and would love to build a tube radio. Is it possible with these tubes?

Need more information. What kind of radio? (TRF? Regen? Superhet?) What frequencies did you have in mind? (ELF, VLF, LF, MF, HF, VHF, UHF+) What are you intending to receive? (AM, SSB, FM, digital?) Depending on what you have in mind, may be going solid state might be the better solution?

It all depends.

kevinkr · 17th July 2011, 07:10 PM

Quote:

Originally Posted by Eli Duttman

Technically, it's an AM setup used to slope detect FM. It is not immune to AM noise, but it is signal seeking.

The use of a single 'T7 section as both a grounded grid RF amp and a reflex common cathode AF amp is elegant. That triode isolates the oscillating detector from the antenna, provides some RF gain, and provides a fair amount of AF gain.

True, and in my case it would be only used for strong local signal reception since I live very close to downtown Boston.

Sal Brisindi · 01:54 AM

A little off topic but a few years back I built a 5 tube AM radio for a homebrew contest. Its not based on the tubes you mentioned, I used the standard All America Five tubes, 12AV6 12BE6 12BA6 35W4 and 50C5. I named it..... Salerola...

Sal

Wavebourn · 18th July 2011, 01:59 AM

This Salerola can be renamed to Salekila. Power transformer today is THE MUST.

Sal Brisindi · 18th July 2011, 02:04 AM

Duly noted....I plugged the radio to a isolation transformer at the contest.

16th July 2011, 07:14 PM	#1
JECalvert diyAudio Member Join Date: Jul 2011	Building a tube radio I'm a musician and I have alot of 6L6 and 12AX7 tube's lying around and would love to build a tube radio. Is it possible with these tubes?

16th July 2011, 11:20 PM	#3
Eli Duttman diyAudio Member Join Date: Apr 2004 Location: Plainsboro, NJ	It might be possible to build an AM radio with a 12AX7, but its performance would be very poor. You would need a long wire antenna to get any kind of reception and selectivity is not good. The single "bottle" FM circuit Pano linked is quite sophisticated and will do nicely on strong stations. For table radio use, a power amp in addition is necessary. The power amp could be built from a 'X7 and a 6L6. __________________ Eli D.

18th July 2011, 01:52 AM	#8
Sal Brisindi diyAudio Member Join Date: Nov 2006	A little off topic but a few years back I built a 5 tube AM radio for a homebrew contest. Its not based on the tubes you mentioned, I used the standard All America Five tubes, 12AV6 12BE6 12BA6 35W4 and 50C5. I named it..... Salerola... Sal Last edited by Sal Brisindi; 18th July 2011 at 01:54 AM.

18th July 2011, 01:59 AM	#9
Wavebourn diyAudio Member Join Date: Sep 2006 Location: Pleasant Hill, CA	This Salerola can be renamed to Salekila. Power transformer today is THE MUST. __________________ If I disappear suddenly, that means I finally created a time machine and pushed wrong button that brought me to Stalin's Russia. In any experiment any result is the result. Even if it is negative.

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16th July 2011, 07:27 PM	#2
Pano diyAudio Moderator Join Date: Oct 2004 Location: North Carolina Blog Entries: 4	There was just a link to a 12AX7 radio. Let's see if we can find it. EDIT: Nope, it was 12AT7. But here it is anyway. http://cool386.tripod.com/12at7/12at7.html

18th July 2011, 02:04 AM	#10
Sal Brisindi diyAudio Member Join Date: Nov 2006	Duly noted....I plugged the radio to a isolation transformer at the contest.

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