Valves, alternative sources, an example radio with low HT (12v)

[G0CWA]

Hi I am still posting my designs for you to look at and hopefully build your own versions.

The set I am presenting here is based on a common TV valve, the PCF80 triode pentode.
I haven't seen this particular valve family used in many homebrew projects. TV valves such as this are widely available and more importantly cheap.

This set, The Minuet, is small and compact and will run on 12v to around 30v HT, using no matching transformers,



The set details are available on Peebles Origionals site in his visitors projects section at the link below

http://www.peeblesoriginals.com/visi...ick-minuet.php

The idea behind this set was to show it is not neccessary to just use the accepted valves in homebrew radios, alternatives are available.
As in most of my sets it is designed to accept different plug in coils for different bands.

Enjoy your hobby, enjoy building, it should be a pleasure not a chore.

73 for now Nick G0CWA

More designs to follow

[AB9LZ]

I've just started a little mopa transmitter project, going to see how well back to back 12v 3 a ( the ones that are available at rat shack) transformers will work in a voltage doubler configuration. Should give me somewhere around 250v at the plate and hopefully with enough oomph to give me 15w input and a clean note. The last bit (clean note) will probably be the hard part.

73 m/4

[K9STH]

Back during the late 1960s and into the 1970s, there were "starved amplifier" tube circuits using "normal" tubes but with only 13.8 volts on the "plates". Tubes like the 12AX7, 12AU7, 12AT7 were very popular in those circuits. Of course, RCA, and other tube manufacturers, developed tubes designed for 13.8 volts on the plates for use in automobile receivers.

Glen, K9STH

[W4HAY]

I've just started a little mopa transmitter project, going to see how well back to back 12v 3 a ( the ones that are available at rat shack) transformers will work in a voltage doubler configuration. Should give me somewhere around 250v at the plate and hopefully with enough oomph to give me 15w input and a clean note. The last bit (clean note) will probably be the hard part.

73 m/4

I get a very clean note with modern crystals using a 6AH6 as a Colpitts oscillator. With 150 volts regulated on the screen and 250 on the plate, it easily drives a 5763. The filament draws 0.45 Amps.