> The schematics for both the Ameritron AL-82 and Heathkit > SB-200 amplifiers show that no neutral is used, regardless > of primary voltage setting.
Unfortunately, the AL-82 and SB-200 both create a pseudo-neutral by placing high voltage bypass capacitors from each line to the chassis/ground. Unless the chassis is properly grounded to the station common point ground along with every other piece of equipment in the shack, the noise (hum) s still going to appear in common mode on the shields/cases. 73, ... Joe, W4TV > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of Paul > Christensen > Sent: Thursday, June 04, 2009 3:06 PM > To: [email protected] > Subject: Re: [Elecraft] K3 Ground Loop Issues using Ameritron ARB-704 > > > > "First, to be code compliant, any amplifier that has a neutral > REQUIRES a four wire power cord (hot-Neutral-hot plus > ground). The neutral must be isolated from the chassis > (safety ground) and must be returned to the source (breaker > panel) separately. The neutral may not be tied to the > amplifier chassis." > > The schematics for both the Ameritron AL-82 and Heathkit > SB-200 amplifiers > show that no neutral is used, regardless of primary voltage > setting. Amps > that utilize a neutral (e.g., ETO/Alpha 77 series & older > Henry) make use of > a neutral only to power the 120 VAC blower. These amps > require 4-wire > electrical service as W4TV states. They were designed and > manufactured at a > time when little attention was paid to the ground v. neutral wiring > structure. A fault as a result of a neutral loss between > the amp and > service panel causes the chassis to carry the full blower > current. Anything > on the amp chassis that's grounded (e.g., SO-239, BNC, RCA) > including a > grounded operator touching the amp will complete the current path. > > Most amps do not utilize a neutral and use a jumpered > center-tap transformer > primary to ensure that the amp's blower or fan works > correctly on both 120 > VAC and 240 VAC circuits. > > Paul, W9AC > > > > > > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
