If the arc was one of Ameritrons EID events the plate choke may have opened, a fairly common occurance as the tube is prone to parasitics. Also check the safety choke on the back of the Tune cap. Car
Carl and all, if the plate choke opened, there would be no plate voltage or current alright. But, with drive, the grid current would be there in abundance. 73, Gerald K5GW In a message dated 10/19/20
Both comments below are true if they were singular events. This amp seems to have had a singular IED leading to multiple failures which is pretty common when an Ameritron lets loose. Carl KM1H Carl a
Gerald, Wouldn't that cause the grid to fail rather quickly? Hal W5GHZ Carl and all, if the plate choke opened, there would be no plate voltage or current alright. But, with drive, the grid curre
Fortunately that tube has a fairly robust grid so short periods of drive without plate voltage probably will not damage the tube. Prolonged operation most certainly would damage the tube. We are talk
Boye posted from a search "Zeners was replaced too to a 50W type and 2A fuse insert to cathode DC connection" This is interesting because I was also looking at the 50W zeners and wondering if the 10W
With say 1.3A cathode current (plate + grid) and 5.8v, that will be 7.54W dissipation. So, the 10W rating seems ok but not a lot of headroom. Considering the diode is using the chassis as a heatsink,
With a shorted and open zener there will be some conduction depending if its CW or SSB position. You already stated there was a very low bias earlier which should mean the tube is conducting. By mult
ORIGINAL MESSAGE: REPLY: I don't have an AL-1200 in front of me to see if this is feasible, but here's a thought: Install the two new zeners (50 watt) on a small piece of aluminum sheet and mount the
Kevin, Don't forget to clean up the mark left by the arc (remember the sizzle you heard?). Then replace the diodes with the 50 watters and turn on the amp. Let us know how it works. Hal W5GHZ O