19-Set Dummy Load

[Chris Suslowicz]

Originally Posted by David Dunlop

When one uses this item with the standard Aerial base No. 8, the ground strap is long enough for the alligator clip to be attached to one of the bolt assemblies attaching the Aerial assembly to whatever vehicle, so essentially the Dummy Load is grounded to the vehicle.

What do you attach the ground strap to if the Dummy Load is being used with the Carriers No. 23 System?

Was a set of instructions ever issued for use of the 19-Set Dummy Load?

David

It's not actually a dummy load, but a dummy aerial (it's a co-axial capacitor formed from the central rod, two insulating bushes, and the outer metal tube). This behaves like the standard rod aerial (30 picofarad capacitance) as far as the set is concerned and allows the operator(s) to tune up and (more importantly) net all the sets to the frequency selected by the net controller without radiating much signal. After that's been done, the standard aerial can be put back in the base and you're ready to go.

It was mainly used for "netting in harbour" with tanks, since if the rod aerial was used, the signal strength would be so great as to make it difficult to net accurately to it, which could be fatal once you were in action. (If the signal is strong enough you will get multiple possible "nulls" - the wanted signal, the receiver local oscillator (465 kc/s away from where you're supposed to be), or a multiple of the 465 kc/s BFO that is close enough to frequency to pass through the transmitter mixer tuned circuits and be broadcast.)

The dummy aerial wouldn't be used with the truck & ground station as they would not normally be netting in close proximity to control (and it won't fit anyway).

I don't recall seeing any instructions on its usage, but it's possibly in one of the sets of training notes somewhere. (Which have faded enough to be impossible to scan, and in some cases difficult to decipher with the Mk.1 eyeball.)

Chris.