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JECalvert 16th July 2011 07:14 PM

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?

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 (Post 2641149)
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.. :D

Eli Duttman 17th July 2011 01:39 AM

Quote:

Originally Posted by kevinkr (Post 2641349)
Very cool FM super regen, think I might want to build something based on this design.. :D

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 (Post 2641140)
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 (Post 2641411)
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 18th July 2011 01:52 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

http://www.tuberadios.com/temp/homebrew.jpg

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.


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