Good comments from everyone. FETs are interesting. But as luck would have it and strange as this is I had the tube. Working quite well now
On Sun, May 2, 2010 at 11:07 PM, Burt I. Weiner <[email protected]> wrote: > For what it may be worth, I've swapped Nuvistors out with FETS. I see from > the schematic that the Nuvistors are running on 35 Volts. It would be > simple to drop the 35 Volts to 12 or 8 Volts with a 3 terminal regulator in > the receiver. If desperation sets in, try stuffing N-Channel FETs in place > of the Nuvistors. The gate is the grid, the drain is the plate, and the > source is the cathouse. Since the FETs are usually pretty low in > capacitance you may need to shunt the tuned circuit/s with a small piston > type capacitor. In one low Voltage preamp circuit I used a National U-310. > In another one, a Nems Clark receiver, I replaced the two RF front end > ceramic triodes stages that ran on 150 Volts with two U-310's and rewired > the plate supply to run off of the 12 Volts already in the receiver. This > made for a low noise, very sensitive front end. All I needed to do was add > a small quartz piston capacitor to bring the tracking in at the high end and > the bottom end fell right end. If you can make that work, you'll never have > to replace those pesky wittle Nuvistors again. > > Burt, K6OQK > > > From: paul swed <[email protected]> >> Subject: Re: [time-nuts] 6CW4 Nuvistors on eBay... >> >> >> Indeed there are. >> And even 7587s thats the TRF frontend. In one of the units V3 appears bad >> all Rs are good voltage high on plate, 0 cathode current. But oddly when I >> swap v1 into position same effect so somethings odd. Or my methods not >> correct. >> The other units working. Had to replace a shorted 6.2 V zener. >> The 100 kc vco /lock osc is awful touchy. >> Pretty amazing the units pretty hot sensitivity wise -80 dbm. >> Interesting afternoon. Way in the deep corner of the basement I think I >> may >> have a nuvistor or two. Time to see what they are. >> >> On Sun, May 2, 2010 at 4:14 PM, Burt I. Weiner <[email protected]> wrote: >> >> > >> > For what it's worth, I just took a look and found a bunch of 6CW4's on >> > eBay. See: >> > > Burt I. Weiner Associates > Broadcast Technical Services > Glendale, California U.S.A. > [email protected] > K6OQK > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
