I would like to build a superhetrodyne with normal tube s in space-charge mode audio output
tube will be a 12k5 and the rest of the tubes are 12av6 12ba6 12be6 I have large style I.F transfomers and a junker aa5 chassis
i dont want to wind coils

The following and the links within it might provide some useful informations: http://www.junkbox.com/electronics/lowv ... ubes.shtml

There was even a link to an AA5 style space-charge design, but it is all in Japanese

Curtis Eickerman

ok i will look at the Japanese site in google translate

Actually the low voltage car radio tubes are just that, low voltage... Except for the tetrodes that were generally used as drivers for audio or power tuning, none operate in space charge mode...

You can use AA5 types on low voltage, but the types designed to operate at 12v will perform better...

http://www.wa2ise.com/radios/12ba7.html#aa5




Tom

what about using battery radio tubes (eg 1r5 1u5 3v4)

if not I will get the space charge tubes and I have 12k5 tubes

Due to their somewhat delicate filament, I'm not a fan of the battery tubes for experimentation(at least in multiples)... They could be no doubt be used, I'd guess B+ should be in the 25-30v range for best performance, probably same for AA5 types...

A 25v CT transformer would supply the higher B+ & each leg could be used for 12v to operate the heaters...

Tom

I will go with the 12v tubes on a all 12v circut

Every portable Superhet using batteries that I've collected so far requires either a 45 or 67.5 volt B supply.

Heaters light with but one C or D cell. I've even used an AA in a Koyo Parrot with the submini "peanut" tubes.

Even a three tube earphone-only set requires a 45 volt battery.

Built a lot of radios using 1 1/2 volt tubes. They are best for battery use (portable) but require two voltages.

Tom posted an interesting circuit that I've never seen. Car radios used an additional transistor stage. This one only requires 12 volts @ 1 amp. Easy to make power supply.

I am using the 12v car radio tube tubes so they only require 12vdc on the plate

They'll no doubt operate on much less than 45v, mostly it's the audio output that looses performance first... I've used AA5 tubes in 12v car radios, all I ever tried worked but performance on RF/IF circuits was down somewhat...




It's in the link but there is even a hot rod version...

I have two 12K5s, a few other low B+ tubed from junk car radios and AA5 that's built on plexiglass... Hasn't worked in years just needs a little TLC, ummm five sockets ready to go... Wonder how much out that PP setup would make at 25-30v??? The 12K5 is rated 30v and the others probably are as well...

I built a 12k5 push pull amp before and it plenty of output

Have you looked at this site:

http://cool386.tripod.com/12vsuperhet/12vsuperhet.html

Rob

yes I saw the site

I have built a radio but don't know if it works

Wouldn't that be like if you can tune and receive stations then it works but if you can't then it doesn't?

it is not finished

If it isn't finished then how can it work?

I have a feeling English may be MrE12AX7s second language & just possibly past tense was used for present...

it isn't finished I am using a 6as5 for the output tube and 6ba6 6be6 6av6 for the rest of the tube