Class C Wavemeter

[Chris Suslowicz]

Originally Posted by Mike Kelly

I picked up this Class C wavemeter at the hamfest , it was 20 bucks . I have had a few of these .

I am not sure if this unit is based on a UK design ? Anyway all of them Ive seen are dated 1941 and they were made by AWA Sydney .

Each set came with a spare valve , the spare valve and its box are marked the same serial nr. as the set is .

The power plugs are the same pattern as the AWA 101 set .

Each set came with a calibration chart - the chart slides into a thin pocket next to the PSU . These sets are next to useless as a wavemeter, you would be lucky to get within 20 khz of an assigned frequency .

They were a British designed (and originally manufactured and shipped around the Commonwealth) unit from the days when radio communication was from Battalion level upwards, so there were not many sets required.

20kHz accuracy was initially perfectly adequate, as they were intended for use with Wireless Set No.1 (and later 11), to allow the initial frequency setting to be reasonably close and thus make the net findable.

The calibration chart was intended to be user updatable - all the wavemeters for a net would be collected up and recalibrated against a master unit when possible.

The unit could be operated from dry batteries (and an accumulator for the valve heater) using a supplied socket/terminal block to connect to the set it was being used with, or using the vibrator pack.

Later on, there was a crystal calibrator issued, which fitted into the space previously occupied by the spare valve tin. (I assume they moved the spare valve to the wireless set spares case.) That allowed for calibration checking in the field, and rather more accuracy.

Chris.
(I'm looking for a vibrator unit for this wavemeter, I've got the other parts (though the calibrator is in horrible condition and needs restoring).)