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Better check again. It is rated at 2000 watts PEP INPUT or about a kilowatt or a bit better OUTPUT.It uses a pair of 3-500Z tubes.

QRN -

I didn't know what the ratings on the amp are. I bought it used down here without any documentation. It deadkeys about 800 watts and around 1500 modulated with the setup I described. I don't run the box very often. I get good results with my solid state amps and I really don't need that much power. The price was right, so I bought it. BTW, mine has 3-400Z tubes.

- 399

3-400's and 3-500's are directly interchangable.The 3-400's are older than the 500's so if that amp has the original tubes in it, it's a real oldy.Nothing wrong with that BTW. Just be sure not to run those 400's too hard.1500 watts max pep would be all I would ever try and geyt out of them uif you want them to last. A pair of graphite anode 3-500Z's would be good for 2000 watts pep in sane operation.

WOW...1500Watts modulated output...even reading on a good PEP wattmeter might be a bit strong for a pair of 3/400's on AM...MHO...bet you could cook hot dogs with the plates glowing cherry red that way. I would back that thing down to about 800w's with tone output...less than 1/2 of an "S" unit difference and NO one will notice!...unless you want to be making a $400 to $500 purchase for new tubes in the short time...even the SB221 can self implode with out a little TLC on AM...run SSB and treat that old girl nice at 1500w out and she will give you many years of good service...
Good Luck
All the Best
BJ

Ooops I missed the AM part. I NEVER use AM so I always think about SSB.My figures above were for SSB service.Those kind of numbers for AM service would be nearly fatal for the tubes. Sorry about that.I worked last night and have had less than 3 hours sleep in the last 39 hours so allow me a little slack. Maybe even a lot.

BJ Radionut -

You're right about the heat, which is why I don't run it very much. It's hot enough here as is. I appreciate the info, and when l hook it up next time, I'll back it down a bunch. Thanks again

- 399

From transmitter?

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XDX74

The ratings for the SB200/220 series (and all other amplifiers of that vintage) were for DC input (not RF input from the transmitter/exciter). Simple math: Plate voltage times plate current.

It comes from the 1950-1975 (or thereabouts) era, when RF wattmeters were really expensive and therefore didn't exist in the typical hamshack. The FCC mandated all RF amplifiers to be rated at DC input to the final amplifier, and the maximum power on most bands for a General class licensee was 1KW. Hence the 1000 watt input specification.

When SSB became the rule rather than the exception on phone, it was a lot harder to determine the input power, but fortunately, RF wattmeters of reasonable accuracy were becoming plentiful. So away went the DC input ratings, replaced by the RF power OUTput specs, using peak envelope power (PEP) as the method of measurement.

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If you're like everybody else,
you're about average.
73 de K7KBN

Now I understand what 74IN was saying. He was talking about DRIVE LEVELS and not INPUT LEVELS. When talking about amplifier power levels the input is how much electrical power it takes to operate the amp. The drive level is how much RF power is required from the transmitter to achieve the rated RF power output from the amp.

Hi guys,

I swapped a uniden 510 for a MaCo 200 amplifier - figured it was a good deal for me. However I know nothing about the amp so any help will be appreciated.

For those not entirely familiar with the amp it as a power switch, Hi Lo switch, Standby switch, SSB switch, Tune and Load dials on the front.
On the rear there is a screw dial called "Match".

I did a quick tune after letting the amp warm up in Standby mode for about 1/2 hour or so. The reports were that is sounded like I was on FM and not getting clear audio. I shut it off and have not attempted to mess with it.

Two questions in mine are:
1) is this amp also AM capable - sound dumb but the amp only indicates SSB in the up position so I figured that in the down position it was AM but I don't know for sure.
2) what is the "match" screw dial on the back for? And how do I adjust it. Do I adjust it for max power or lowest SWR or what?

Thanks for help.