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Re: [Amps] Thoughts on LK-550

To: "'Carl'" <>, "'Craig Taylor'" <>, <>
Subject: Re: [Amps] Thoughts on LK-550
From: "Dick Green WC1M" <>
Date: Fri, 13 Oct 2017 13:26:58 -0400
List-post: <>
I have a 550ZC as well. If it's in good operating order with three good
tubes $1,200 is an excellent price -- a bargain I'd say. That said, I'd
probably part with mine for that because I haven't used it in years.

Check carefully for any damage to the plate choke. The stock unit doesn't
have a glitch resistor to protect it. I added one to my 550ZC. Also, I had
to replace the meter resistors in mine, I think because the originals had
aged enough to throw off the readings.

The fans in the stock model are *very* noisy. Pretty much a freight train
when they kick into high speed. I did a mod that increased the low speed
(and I think also decreased the high speed, but I'm not sure.) The idea is
to put up with slightly more noise at low speed to reduce the frequency of
the fans kicking into high speed.

73, Dick WC1M

-----Original Message-----
From: Carl [] 
Sent: Thursday, October 12, 2017 1:40 PM
To: Craig Taylor <>;
Subject: Re: [Amps] Thoughts on LK-550

If it is the later 550ZC model that is an excellent price considering that
massive external transformer.
OTOH 3 tubes a  bit squirrely on 10M and removing one tube will make little
if any difference on any band unless you need the extra plate didssipation.

Ive used a two tube LK-500ZC  since 1986 with the external PAC-5 and it
easily does 1500W altho I run at 1200W since that is the sweet reduced drive
spot for my transceiver for best IMD.

----- Original Message -----
From: "Craig Taylor" <>
To: <>
Sent: Wednesday, October 11, 2017 10:56 PM
Subject: [Amps] Thoughts on LK-550

>I have an opportunity to purchase an LK-550 in very good condition. The 
>asking price is $1300.00. Is this a good value?  Thank you, W9OD
> Sent from my mini iPad
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