Amp Supply Company LK 500-ZB
I just purchased an LK 500-ZB from the estate of an SK. This is my first amp, and from what I can tell online, it's a pretty solid unit. Right now it's wired for 220, and I have to get inside and switch it to 110, which I'm told is a pretty straightforward process.
So while I've heard a lot of good things about these units, is there anything I should be aware of, as I'm setting it up and using it?
Tom, W8JI has basic HF amplifier usage / operation DOs and DON'ts on his web iste.
Bill Edwards, K4BWC(sk) who passed away in 2008 provided service (Omega Electronics) for this Amp Supply model.
Al Link, K4ICL currently provides service for the Amp Supply HF amplifiers
Due to the age of these units (> 30 years), perform regular maintenance (clean the inside)/remove dust
and perform a close visual inspection for bulged or burnt components.
Some radio amateurs (DX contesters, daily amplifier usage) will update the HV section (change/replace electrolytic capacitors).
Last edited by W9GB; 02-20-2011 at 03:51 PM.
We keep moving forward, opening new doors, and doing new things, because we're curious and curiosity keeps leading us down new paths. -- Walt Disney
Do not switch that amp to 120V!
You are in the big leagues now.
If you can't swing a dedicated 240V line to run an amp then sell it and get one that will run well on 120V like an AL-811 or such.
CW is a manually controlled, message asynchronous, simplex chat mode used without FEC.
"The democracy will cease to exist when you take away from those who are willing to work and give to those who would not." -- Thomas Jefferson
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I'd be really careful running that amp on 120V. At full power it will draw about 22A from a 120V circuit, and most household circuits are 15A.
If you run it on 120V, I'd suggest either a dedicated 20A circuit (12 AWG wire and a 20A breaker, with a 20A outlet) or never trying to drive it to full power.
In general from what I have read about that amplifier, it is held in pretty high regard.
I found a lot of interesting commentary about it in the eham reviews of it.
Some of the reviews shared what they thought was good about the amp and also the shortcomings they found.
Worth a read I think.
"Oh what a tangled web we weave when first we practice to receive."
-Otto Watt Sept. 5 1925
It is a nice amp, I actually had one for a while about 30 years ago. Although the bandswitch was labeled "AUX" and not 10 meters, the amp worked fine on 10 meters (and probably 12m too, although I'm not even sure we had the 12m band available to us at the time).
Originally Posted by K7MH
Amp Supply made lots of changes, though, and some were "improvements" while some probably weren't. I know the internal parts used in the amp I had didn't match the schematic or parts list in many areas, indicating what I'd call "undocumented changes."
Some reported filament pin overheating with this amp due to lack of adequate base cooling. Whether that's really a problem or not likely depends on exactly how the particular amp was built. If the pins get so hot the solder melts, that can also harden the socket contacts and make them unreliable.
Probably any issues are caused by hard service such as RTTY or AM, or using the amp very hard on CW. With normal SSB duty cycles, the tubes don't get all that hot.
I live on my sailboat. I'd have to *make* a dedicated 240v line on the boat.
Originally Posted by AC0H
Thanks for the info guys. As far as the wiring goes, I'm on a 30amp 110v shore power for the boat. So not sure yet what I'll do, I'd hate to bring a second line in just for the radio (FT 107) and amp. I'll figure something out. Right now my tuner, feedline and antenna all max out at 300 watts, so I'm not in an all fired hurry I guess to push legal limit LOL.
The amp will use almost all of that available line power, by itself. I guess the "give it a try and see what happens" approach is probably best.
Originally Posted by KF7MJF