KO7M - Ham Radio Blog

So, I have a transformer that has two primary windings that can be typically be hooked up in parallel for 115 VAC operation or in series for...

I managed to find a nice little period (sort-of) speaker for the SW-3 receiver on eBay.  It is a nice little "tombstone" style cab...

So, today I finally sat down to see if the SW-3 is actually functional.  The first order of business is to come up with 2.5 volts at 4 amps ...

After discussing with my buddy Eldon, I have decided not to use the voltage divider approach to power the filaments.  They are all wired in ...

A while back, I posted a note about having found an old 1930's National SW-3 receiver.  The rig came without a power supply.   I need to...

After a couple years of looking, I have located a National SW-3 receiver that is in good shape.  It came with a couple sets of coils, ...