Amp Supply made good amps with quality components, my 1986 LK-500ZC still
runs the original Eimac tubes. Output with 80W of drive is still 1200W, even
on 160.
It came with the external transformer option and a vacuum relay and never
burped during many years of contesting and DXing. Used a lot on AM these
days; good anode color keeps them happy and gettered.
The NT series were designed for those who stayed put on nets, etc and didnt
have much tuning ability.
If an amp doesnt have sufficient L or C adding to the LOAD cap does
nothing!! Add C to the TUNE cap to get actual rsonance first and then deal
with the Load cap for proper grid current..
Use a GDO if you understand them.
The NT can be converted to a regular amp by buying the variables from
Ameritron as well as RF fixed value caps as needed.. I did that with many
LK-800NT's as those tubes are too fraagile for many to deal with and cheap
medical pulls are long gone.
Carl
----- Original Message -----
From: "gudguyham--- via Amps" <amps@contesting.com>
To: <tom.hellem@gmail.com>
Cc: <Amps@contesting.com>
Sent: Tuesday, December 15, 2020 4:58 PM
Subject: Re: [Amps] Amp Supply Amps
The LK5OOnt is good for nothing in my book. You have to select a frequency
in each band that you want to optimize the output and then load it for
that frequency on each band. It will work ok “ on and around “ the
frequency you load if for. QSY too far and the power drops off the further
away from the loaded frequency. This amp is good for a net control
operator who operates the same frequency all the time on different bands
and other such “channelized” type operation. The LK800 on the other hand
is a powerhouse amp with 3 3cx800 tubes. Good for 3kw easy or loaf at
legal limit. Has a big external transformer. Nice amp. Both amps however
do not work very well on 160 because they lack sufficient inductance. It
manifests itself by seeming to always want more capacitance. You can pad
the load indefinitely with more C and it still won’t be enough. There is
no substitute for the correct amount of inductance. A few vintage amps
suffer from this. Similar is the TT Centurian. You get what you get on 160
and that’s it. I had a ***mint*** LK550ntc I couldn’t sell it at a bargain
price. I could have “stuck” somebody with it for a decent price if I didn’t
offer to interrogate the buyer to see if he knew exactly what it was. Lost
every sale when I explained that amp throughly. The LK800 is a gem
however.
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On Tuesday, December 15, 2020, Tom Hellem <tom.hellem@gmail.com> wrote:
Recently inherited a LK 800C and a LK 500 NT from the estate of an SK.
I know nothing about this particular brand of amp.
Any input from members of the group would be appreciated.
Are they worth keeping around? Are there known issues with either of
these?
The grid current meter seems not to work on the LK800, and it seems to
require full mesh on the loading and plate tuning capacitors on the low
bands, feeling like there may not be enough capacity to really realize the
output that the amp is capable of.
The LK500 is a no-tune amp because it has a separate output network for
each band, adjusted by the factory I presume. Does anyone know if the
output networks need to be tweaked for full output after a number of years
of use?
Thanks in advance for any thoughts or suggestions.
Tom
K0SN
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