Garey, Thanks for the reply. I still don't get why the resistor is needed. The ammeter is in series with the flow of the current, so what does the resistor do? What would happen if B- went directly to ground? I'm sure the answer is simple but for some reason it is evading me. 73, Bill ******************************** Bill -
It's just a relatively safer way (low voltage) to measure current of a high voltage supply. Any current that goes OUT of the supply on the positive end MUST come IN via the negative end, or vice-versa depending upon whether you learned your electronics in the military or civilian schools! Anyway, the resistor is near ground, (unless it opens!,) and so connecting it to a panel meter is much safer than having the meter connect across a shunt resistor somewhere up in the HV area of the supply. 73, Garey - K4OAH --- On Sat, 5/29/10, Bill Dzurilla <[email protected]> wrote: > From: Bill Dzurilla <[email protected]> > Subject: L-4B and L-7 power supply question > To: [email protected] > Date: Saturday, May 29, 2010, 9:56 AM > Hi, > > The B- of the power supply for the Drake L-4B and L-7 goes > to pin 6 of the Cinch connector. Inside the amp, the > B- is floated above ground by a one ohm resistor. The > one ohm resistor that floats B- above ground is said to be > for the purpose of plate current metering. I do not > quite understand how this resistor is needed for plate > current meter accuracy. Could someone please tell me > how that works? > > I have an L-7 and a homebrew amp that uses a similar power > supply. However, in the homebrew amp the B- goes > directly to ground. I'm trying to understand the > difference in the configurations. > > Thanks and 73, > Bill NZ5N > > > > _______________________________________________ Drakelist mailing list [email protected] http://mailman.zerobeat.net/mailman/listinfo/drakelist
