I am the original owner of a lk500zc I bought brand new from AMP Supply back in 1987. The only thing I have had to do to the amp all these years is replace the original Eimac tubes with a new pair of Taylor graphite's and when a couple of the original HV caps went I dropped a Harbach replacement board in its place.
For those familiar with the amp there is ALO circuitry on the meter and ALO board to drop the amp in standby for a few seconds if a high SWR or too high drive etc is sensed. Well something has gone whacky with the ALO. When flipping the switch from standby to operate it takes the usual second or so for the green ready LED to come on but even without applying any RF drive the green ready LED goes off and the red ALO LED comes on for a couple of seconds and this just repeats endlessly until the switch is flipped back to standby. I found a reference on the web from someone that bypassed the ALO or that had it bypassed when they got the amp but no details on how to do the actual bypass without losing the metering. After all of these years I don't particularly care if the ALO functions work or not. I am always careful with SWR and always drive it with less than 100w so I don't need the ALO stuff to protect me from myself. I do however always monitor both grid and plate current while operating so whatever I end up doing I want the metering to work. Are any of you familiar with this amp and have any suggestions before I spend lots of time trying to decrypt from the schematics how to go about bypassing only the ALO functions while keeping the metering intact? Tnx es 73 de Rich WA3WLH _______________________________________________ Boatanchors mailing list [email protected] https://puck.nether.net/mailman/listinfo/boatanchors
