Hello All

Im new to collecting and will probably only collect 2 or 3 sets to compliment our 1940's house in Perth (well if I keep telling my wife this she'll atleast let me start collecting!)

I have my eye on a nice white AWA 433MC but im a little concerned about the power supply it will use as in my searching Ive found it uses a 90/1.5 volt supply - I understand this and feel confident I could build a suitable supply (TV/Radio Tech by trade) but on the back of the set I only see two terminals - One marked "A" and the other "E" I assume these are for the A battery?

Would/should there be a fly lead or similar hanging out for the "B" battery?

Any advice you can offer will be much appreciated.

Mike

Over at http://www.kevinchant.com/model-numbers-401---500.html there's the schematic and service notes for this radio http://www.kevinchant.com/uploads/7/1/0/8/7108231/433mc.pdf. Looks like there was a cable that plugged into the radio to feed the battery power into the chassis. Looks like you need to provide -4V or so bias for the audio output tube's grid, along with 90V and the filament power. Be sure to replace all the wax paper caps in the radio. Wires A and E are the antenna connections.
Kevin has a good website http://www.kevinchant.com/.

MikePerth said: on the back of the set I only see two terminals - One marked "A" and the other "E" I assume these are for the A battery?

Welcome to the forum.

A is for aerial and E is for earth.

On mains powered sets, there usually is no need to provide a separate earth as the chassis is either earthed via the earth pin on mains plug, or there is sufficient capacitive coupling through the mains transformer to provide an earth return for the broadcast signal.

However, in battery sets without the benefit of a mains earth, a separate earth via a water pipe, rod driven into the ground, etc, combined with a good aerial may be required in order to get a strong signal into the front end of the set.

Al of the above also depends on your proximity to the transmitters. City folks can often get away with no aerial or a short piece of wire for an aerial.

Looking at the schematic for the 433MC, it shows that it's either a vibrator set which means that it generates its own high voltage from a single battery supply, or it can be operated via separate A and B batteries.

The notes state that a 3 volt cycle battery (no longer made these days) is required to power the dial lights such as the double-barreled looking battery to the bottom right in this picture:

http://us1.webpublications.com.au/static/images/articles/i1101/110151_12mg.jpg.

Any 3 volt supply will do for that.

Note that there are two vibrator types specified, one needing 1-4 volts DC and the other type needing 1-6 volts DC.

Be aware that vibrators can be "dead on arrival" in such sets. Depending on the type, some are repairable while others can be replaced with a modern vibrator eliminator.

Note also from the specs that the vibrators have a pretty heavy battery consumption rate so they were really designed to be operated from accumulator (rechargeable) batteries.