Don K4KYV said: > > > > I ran the VF-1 off a CVT. It too, drifted with > slight > > changes in fil. > > voltage. I think both the VF-1 and Collins PTO's > use a 6AU6 > > as oscillator > > tube. My "silent" Sola beats fooling around > swapping tubes. > > I suspect even > > a good tube would eventually become drifty with > age. > > > > Don k4kyv
Don, I'm wondering about those 6AU6's. Not all of us have a Sola CVT, so I have another idea. Change the tube for a 5AU6, and then take the 6.3 vac (usually unbalanced), and 1/2 wave rectify with a low drop Schotcky diode (about 0.3 volt forward drop), filter, and then run through a 3 terminal low drop 5 volt regulator. I'll do some book searching for some suitable part numbers. I think it will work with minimal fuss. Some of the available low drop regulators (use pnp output transistor)only need about 1/2 volt minimum in/out differential to maintain regulation, so the trick will be to keep the regulator Vin at the 60 hz ripple minimum value at > 5.5 volts. This will require a big filter capacitor in value, but 5,000 mfd at 10 volts is still real small in size. Jim JKO
