UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

m0cemdave · 15th May 2020, 7:43 pm

One thing that will need to be dealt with is the question of determining the Tx frequency.

A small simple transmitter would require crystal control, and crystals were understandably almost impossible to obtain. Anyone caught trying to source one, or worse still in possession, would be assumed to be an enemy spy. The death penalty might be applicable, it certainly was on the other side of La Manche...

A sufficiently stable VFO would most likely be beyond the skills of a casual builder and add too much to the cost, size, and complexity of the set.

The search for a suitable crystal could make for quite a sub-plot. Maybe something could turn up eventually and have to be re-ground as necessary?

The classic pre-WW2 British transmitter valve was the KT8, nowhere near as good as an 807 but a lot smaller in size. But like a crystal it would be shouting *TRANSMITTER!* and a dead giveaway. Better to stick with a standard audio output valve like a 6L6 as suggested above.

15th May 2020, 7:43 pm	#25
m0cemdave Octode Join Date: Feb 2009 Location: Bletchley, Buckinghamshire, UK. Posts: 1,219	Re: Home made Wartime transmitter /receiver One thing that will need to be dealt with is the question of determining the Tx frequency. A small simple transmitter would require crystal control, and crystals were understandably almost impossible to obtain. Anyone caught trying to source one, or worse still in possession, would be assumed to be an enemy spy. The death penalty might be applicable, it certainly was on the other side of La Manche... A sufficiently stable VFO would most likely be beyond the skills of a casual builder and add too much to the cost, size, and complexity of the set. The search for a suitable crystal could make for quite a sub-plot. Maybe something could turn up eventually and have to be re-ground as necessary? The classic pre-WW2 British transmitter valve was the KT8, nowhere near as good as an 807 but a lot smaller in size. But like a crystal it would be shouting TRANSMITTER! and a dead giveaway. Better to stick with a standard audio output valve like a 6L6 as suggested above.