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Reviews Categories | Amplifiers: RF Power - HF & HF+6M | Amp Supply LK-500-ZB Help

Reviews Summary for Amp Supply LK-500-ZB
Amp Supply LK-500-ZB Reviews: 19 Average rating: 4.8/5 MSRP: $1,295 in 1988
Description: Runs a pair of 3-500Z tubes, Legal Limit output, built like a tank! Covers 160-10 meters.
Product is not in production.
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W1ES Rating: 4/5 Oct 17, 2002 08:43 Send this review to a friend
Good Amp for Low Bux!  Time owned: more than 12 months
Bought mine back in the 1980s and have used it for DXing and contesting all these years. It's built very well and has been a real warhorse!

The shortcomings, some of which have been mentioned here by others, are the QSK circuit (you can't run the amp in standby if it's wired for QSK without an annoying sidetone), high filament voltage (corrected), king-kong band-switch detents(corrected-- removed one of the two ball bearings-- what a difference!)and lack of step-start for the PS. THere is plenty of room inside to do mods, however, and I've done several: extra cooling holes to the outside through a level beneath the deck, voltage-dropping wire to bring fil voltage to 4.75V and AG6K mods to anode & grid circuits.

With a good QSK circuit (which I swear I've been meaning to get around to playing with for 15 years but haven't) this represents the absolute best bang-for-the buck out there! Because the brand is an orphan, you can get them for a lot cheaper than they should be selling for! Frequently, you can get these for less than an SB-220 and it is a MUCH (I can't stress this enough!) better amplifier that also does 160m!
W5MG Rating: 5/5 Oct 4, 2002 15:53 Send this review to a friend
Built to last!!!  Time owned: 6 to 12 months
I have owned my LK-500ZB for 6 months. This is one of the finest amps I have ever owned. I own an Alpha 78 and an Alpha 76CA. If Alpha had built an amp that ran 2 3-500z tubes they would have built it like this amp. If you have an opportunity to purchase one jump on it. You won't be sorry.
KG4ENZ Rating: 5/5 Aug 8, 2002 18:20 Send this review to a friend
LK500ZC  Time owned: 6 to 12 months
W4VD Rating: 5/5 Nov 9, 2001 13:13 Send this review to a friend
Great Amp  Time owned: 0 to 3 months
I bought this amp on ebay a few weeks ago and I am very pleased with it. I have the "ZC" model. It has a Kilovac vacuum relay for QSK and works like a dream on VOX, I get right at legal limit output on most bands, and the WARC bands are very acceptable, with 1200-1300 watts out on 12 and 17 meters. The tuned input is excellent, even on the WARC bands. The solid state tranciever likes the LK50ZC very much. The 2 speed fan is handy during heavy duty operation. The 6 to 1 reduction drives on the tune and load control make for a very smooth tune up and the dial scale makes for easy "tune by the numbers" once the settings have been determined and logged. All in all it's a good amplifier for the money and Omega Electronics has the parts and expertise to keep it running long into the future.
W8JJW Rating: 5/5 Oct 4, 2001 11:41 Send this review to a friend
Really Solid Amp  Time owned: 6 to 12 months
I bought this amp at Dayton this year..been using it on 160 mostly on a wire and on 17-10M through beams with excellent loading and output. I typically run 1kw with 30-40W input depending on the band. I have the LK-500ZC. Built like a tank.
G4VGO Rating: 5/5 Jul 14, 2001 04:19 Send this review to a friend
Awsome!  Time owned: 0 to 3 months
My amp is the LK-550 NTC (No Tune, Three Hole 3-500's) and it is a very good performer. This is the second Amp Supply unit I have tried, the first being the LK-850 with three 3CX800's in it a few years back.

On CW the QSK is smooth and does a great job with my FT1000D. The only problem is minor, a change in the L/C ratio of the 160m band is called for as is a beefier set of caps in the output circuit because the caps will heat up at full power out on that band. However, at legal power over here, it runs STONE COLD on all bands, all day long, 24 hours a day in a contest.

Very good value for money, and I am sure it will be contesting long after I am gone.

If you can buy one, do it, the external Peter Dahl transformer makes a good foot rest and at 1.2 KW+ on RTTY, a good foot warmer I am sure.
K6EGW Rating: 5/5 Jun 16, 2001 22:03 Send this review to a friend
More than good  Time owned: more than 12 months
Instant on. I have beat mine up for many years. Instructions say "tune for maximum smoke." 1.2 KW
output on all bands.

I now listen to the boss and turn down the input. The tubes do not like 100 watts.

QSK. I never use the fan in high position. Same tubes. My God, what more could you ask for. Built like a brick. The instant on gets me on in front of many.

Get one if you can find one. 73's
N2NFG Rating: 5/5 Nov 28, 2000 21:21 Send this review to a friend
SOLID PREFORMER  Time owned: more than 12 months
When I bought this amp 8 years ago, it arrived badly damaged from a fall off a UPS truck. (not US, we don't drop things!) After a trip to OMEGA amp repair, it was as good as new and gave excellent service for several more years, until I developed a liking for RTTY. Even keeping it well within the limits of the manufacturer, the solder would melt from the pins of the tubes. (I will admit that this was still under extreme use, RTTY contesting) But now I had the good fortune of living only a short drive from OMEGA, so in the truck it went for a ride to Knightdale, NC. Bill took a good amp and made it even better. For anyone who runs a ZB or ZA, especially for contesting or continuous duty modes, the mods that Bill at OMEGA can do are highly recommended. First, the deck holding the tube sockets is replaced with one with perforations to allow better cooling of the tube pins. Second, a plate is installed between the tubes and tuning circuit to allow more air to flow past the tubes. Third, a beefier fan is installed for even more air flow. Last, a temp. sensitive switch is installed to kick the fan up to high automatically. I don't expect any tube failure for a long, long time:) Other mods worth considering are the QSK board, and step start protection. (the original QSK scheme leaves a lot to be desired) I know that this sort of turned into a review of OMEGA, but these amps are getting kinda old, and there are a lot of them floating around out there. For a very reasonale price, these amps can be retrofitted with features that will turn one into a better two tube 3-500Z than anything currently available new. 73, Bob N2NFG
WA9UEW Rating: 5/5 Nov 28, 2000 18:12 Send this review to a friend
Great Amp  Time owned: more than 12 months
Have had the amp for about a year and a half. Been a great performer. Works great on all modes. I use it on AM with a 950sdx, Put out a whale of an AM signal. Very solid amp!!!! Works great on QSK also. Has vacuum relays. Very quiet. Don`t see too many of them for sale. Am really happy with mine.
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