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Getting a SB 200

Mr Clean

Active Member
May 21, 2005
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I have heard it on the air and it sounds great. Its been went through lately. Just waiting on new caps. Anyone using one?
 

I love it so far. Driving it with 100 watts pep seeing about 600 to 650 watts. Can drive the shot out of it and see more but want to run it clean. May get a SB220 later but this will be inline most of the time. Now for some beams in the spring and watch out! This duck may still be a duck but at least im a Big Duck 8)
 
Mr Clean said:
I love it so far. Driving it with 100 watts pep seeing about 600 to 650 watts. Can drive the shot out of it and see more but want to run it clean. May get a SB220 later but this will be inline most of the time. Now for some beams in the spring and watch out! This duck may still be a duck but at least im a Big Duck 8)

Have you noticed that your 600 watts of clean output will smoke all those 4 pill competition amps producing two to three times the claimed output?

When you get the SB220, you can use the sb200 as a driver. Just don't drive the 200 with more than a radio :) Your output will be very clean and very linear. :)

--Toll_Free
 
Yes I am starting to see this also. I talk to a guy about 45 miles from here. With a 2 pill doing 125 watts swinging 425 or so he could hear me fine but I would just barely move his needle unless groundwave conditions were really good. Now 3 S units all the time with 25 more DK watts and 175 more PEP watts. Power wise not much of a jump. This is running a Pogostick at 36 ft to the feed.That tells me more of the watts are staying on freq and this is a good thing Mr Toll Free. Im starting to see said the blindman and that is very good info tollfree :D
 
SB-200 is a true workhorse, it's also a SSB CW amplifier. You can certainly use it on AM but watch the grid current as it will max out fast. Better yet, make sure the metering resistors for the grid HV meter are in good condition as they tend to burn up over time leaving your meter off scale. Keep an eye on it. My last sb-200, I went through it and fixed all the problems and made it like new with full output, sold it to a fellow CB'er a short time later and he ruined a new set of tubes in just two evenings on AM.
Probably none of my business but I figured i'd share this.
Rooster
 
rockinredsrooster said:
Better yet, make sure the metering resistors for the grid HV meter are in good condition as they tend to burn up over time leaving your meter off scale. Keep an eye on it. .
Rooster

Some of the SB-220's seem to have the same problem.

Thanks for the info.............
 
Yea 194, the sb-200 and 220 are not properly biased for AM use. The bias circuit can be rebuilt to make them work fine on AM but your not going to find much documentation if any to do so. There simply built to produce full output on CW and sideband. If you watch the grid current while on AM it will be up around max at 250-300 watts. All around a great amplifier, I have bought 3 of them off eBay, they don't ship well as all had significant damage from transit, even well packed and double boxed. The transformer bends the chassis up when thrown around by carriers.
 
One of the big problems with using ythe SB-200 on AM is the wimpy power supply.It uses a voltage double instead of a regular fullwave bridge type and as such the voltage sags under full load and the transformer is being run maxed out.The cooling is not that great either.With a pep rating of 600 watts output the SB-200 should have no more than a 150 watt carrier on AM and preferably no more than 75-100 watts in order to keep plate disipation to within reason.AM service is MUCH harder on an amplifier than SSB or CW mode.There is absouletly NO rest period between words in AM service and the amp must have the headroom to make 4 times the carrier output.When run at reduced output the SB-200 can be a good amp on AM but that is true with all amplifiers not designed for AM service.You should see the PA sections and power supplies of commercial AM transmitters. :shock: The same components used in SSB service would be waaaaaaayy overkill.
 

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