KY6R Spy Radio – Part 1

The Wheatstone Bridge has very high quality components on a thick Bakelite front panel

The front panel with most components removed

As it turns out, the IN OUT control at the bottom center will be PERFECT as the SPOT control for the QRPGuys Para40Set rig. The BA+ and – are perfect for the battery – although I will also mount an internal battery using 8 rechargeable “D” batteries – or an external battery. X1 and X2 will be used for an external key. B and G happen to be momentary contact switches – so they could be used as a built in key. I think this means I won’t mount that cool WWII British key on this rig – but use it connected to X1 and X2. GA + and minus will be used for an End Fed antenna and counterpoise. I will use the two switches for the crystal control positions.

If the headphone out were High Z for old cannonball headphones – I’d probably configure the terminals differently, but I will use a jack most likely – not sure. Three of the big holes will be used for the controls that have knobs, and I will try to use the meter that came with the Wheatstone Bridge – else it looks easy enough to make one of the holes a little bit larger for an NOS S meter of some sort, maybe this one:

Harris Radio RF 301 S Meter

Or something like this:

An interesting old meter – not sure if it would work

I will need to see what kind of circuit I will need to make a meter move. The QRPGuys kit doesn’t have a meter circuit, but all I care about is to see some kind of meter movement – it doesn’t have to be accurate at all. Maybe – just maybe I can use the cool meter that came with the Wheatstone Bridge – but its a strange beast for sure. It was wrapped with a big horseshoe magnet – so I think its a pretty special kind of meter. I’ll apply some low voltage and see what happens.



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